Merge branch 'for-6.0/dax' into libnvdimm-fixes

[people/ms/linux.git] / fs / btrfs / ioctl.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Oracle.  All rights reserved.
 */

#include <linux/kernel.h>
#include <linux/bio.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fsnotify.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/time.h>
#include <linux/string.h>
#include <linux/backing-dev.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/writeback.h>
#include <linux/compat.h>
#include <linux/security.h>
#include <linux/xattr.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/uuid.h>
#include <linux/btrfs.h>
#include <linux/uaccess.h>
#include <linux/iversion.h>
#include <linux/fileattr.h>
#include <linux/fsverity.h>
#include <linux/sched/xacct.h>
#include "ctree.h"
#include "disk-io.h"
#include "export.h"
#include "transaction.h"
#include "btrfs_inode.h"
#include "print-tree.h"
#include "volumes.h"
#include "locking.h"
#include "backref.h"
#include "rcu-string.h"
#include "send.h"
#include "dev-replace.h"
#include "props.h"
#include "sysfs.h"
#include "qgroup.h"
#include "tree-log.h"
#include "compression.h"
#include "space-info.h"
#include "delalloc-space.h"
#include "block-group.h"
#include "subpage.h"

#ifdef CONFIG_64BIT
/* If we have a 32-bit userspace and 64-bit kernel, then the UAPI
 * structures are incorrect, as the timespec structure from userspace
 * is 4 bytes too small. We define these alternatives here to teach
 * the kernel about the 32-bit struct packing.
 */
struct btrfs_ioctl_timespec_32 {
        __u64 sec;
        __u32 nsec;
} __attribute__ ((__packed__));

struct btrfs_ioctl_received_subvol_args_32 {
        char    uuid[BTRFS_UUID_SIZE];  /* in */
        __u64   stransid;               /* in */
        __u64   rtransid;               /* out */
        struct btrfs_ioctl_timespec_32 stime; /* in */
        struct btrfs_ioctl_timespec_32 rtime; /* out */
        __u64   flags;                  /* in */
        __u64   reserved[16];           /* in */
} __attribute__ ((__packed__));

#define BTRFS_IOC_SET_RECEIVED_SUBVOL_32 _IOWR(BTRFS_IOCTL_MAGIC, 37, \
                                struct btrfs_ioctl_received_subvol_args_32)
#endif

#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
struct btrfs_ioctl_send_args_32 {
        __s64 send_fd;                  /* in */
        __u64 clone_sources_count;      /* in */
        compat_uptr_t clone_sources;    /* in */
        __u64 parent_root;              /* in */
        __u64 flags;                    /* in */
        __u32 version;                  /* in */
        __u8  reserved[28];             /* in */
} __attribute__ ((__packed__));

#define BTRFS_IOC_SEND_32 _IOW(BTRFS_IOCTL_MAGIC, 38, \
                               struct btrfs_ioctl_send_args_32)

struct btrfs_ioctl_encoded_io_args_32 {
        compat_uptr_t iov;
        compat_ulong_t iovcnt;
        __s64 offset;
        __u64 flags;
        __u64 len;
        __u64 unencoded_len;
        __u64 unencoded_offset;
        __u32 compression;
        __u32 encryption;
        __u8 reserved[64];
};

#define BTRFS_IOC_ENCODED_READ_32 _IOR(BTRFS_IOCTL_MAGIC, 64, \
                                       struct btrfs_ioctl_encoded_io_args_32)
#define BTRFS_IOC_ENCODED_WRITE_32 _IOW(BTRFS_IOCTL_MAGIC, 64, \
                                        struct btrfs_ioctl_encoded_io_args_32)
#endif

/* Mask out flags that are inappropriate for the given type of inode. */
static unsigned int btrfs_mask_fsflags_for_type(struct inode *inode,
                unsigned int flags)
{
        if (S_ISDIR(inode->i_mode))
                return flags;
        else if (S_ISREG(inode->i_mode))
                return flags & ~FS_DIRSYNC_FL;
        else
                return flags & (FS_NODUMP_FL | FS_NOATIME_FL);
}

/*
 * Export internal inode flags to the format expected by the FS_IOC_GETFLAGS
 * ioctl.
 */
static unsigned int btrfs_inode_flags_to_fsflags(struct btrfs_inode *binode)
{
        unsigned int iflags = 0;
        u32 flags = binode->flags;
        u32 ro_flags = binode->ro_flags;

        if (flags & BTRFS_INODE_SYNC)
                iflags |= FS_SYNC_FL;
        if (flags & BTRFS_INODE_IMMUTABLE)
                iflags |= FS_IMMUTABLE_FL;
        if (flags & BTRFS_INODE_APPEND)
                iflags |= FS_APPEND_FL;
        if (flags & BTRFS_INODE_NODUMP)
                iflags |= FS_NODUMP_FL;
        if (flags & BTRFS_INODE_NOATIME)
                iflags |= FS_NOATIME_FL;
        if (flags & BTRFS_INODE_DIRSYNC)
                iflags |= FS_DIRSYNC_FL;
        if (flags & BTRFS_INODE_NODATACOW)
                iflags |= FS_NOCOW_FL;
        if (ro_flags & BTRFS_INODE_RO_VERITY)
                iflags |= FS_VERITY_FL;

        if (flags & BTRFS_INODE_NOCOMPRESS)
                iflags |= FS_NOCOMP_FL;
        else if (flags & BTRFS_INODE_COMPRESS)
                iflags |= FS_COMPR_FL;

        return iflags;
}

/*
 * Update inode->i_flags based on the btrfs internal flags.
 */
void btrfs_sync_inode_flags_to_i_flags(struct inode *inode)
{
        struct btrfs_inode *binode = BTRFS_I(inode);
        unsigned int new_fl = 0;

        if (binode->flags & BTRFS_INODE_SYNC)
                new_fl |= S_SYNC;
        if (binode->flags & BTRFS_INODE_IMMUTABLE)
                new_fl |= S_IMMUTABLE;
        if (binode->flags & BTRFS_INODE_APPEND)
                new_fl |= S_APPEND;
        if (binode->flags & BTRFS_INODE_NOATIME)
                new_fl |= S_NOATIME;
        if (binode->flags & BTRFS_INODE_DIRSYNC)
                new_fl |= S_DIRSYNC;
        if (binode->ro_flags & BTRFS_INODE_RO_VERITY)
                new_fl |= S_VERITY;

        set_mask_bits(&inode->i_flags,
                      S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME | S_DIRSYNC |
                      S_VERITY, new_fl);
}

/*
 * Check if @flags are a supported and valid set of FS_*_FL flags and that
 * the old and new flags are not conflicting
 */
static int check_fsflags(unsigned int old_flags, unsigned int flags)
{
        if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
                      FS_NOATIME_FL | FS_NODUMP_FL | \
                      FS_SYNC_FL | FS_DIRSYNC_FL | \
                      FS_NOCOMP_FL | FS_COMPR_FL |
                      FS_NOCOW_FL))
                return -EOPNOTSUPP;

        /* COMPR and NOCOMP on new/old are valid */
        if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
                return -EINVAL;

        if ((flags & FS_COMPR_FL) && (flags & FS_NOCOW_FL))
                return -EINVAL;

        /* NOCOW and compression options are mutually exclusive */
        if ((old_flags & FS_NOCOW_FL) && (flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
                return -EINVAL;
        if ((flags & FS_NOCOW_FL) && (old_flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
                return -EINVAL;

        return 0;
}

static int check_fsflags_compatible(struct btrfs_fs_info *fs_info,
                                    unsigned int flags)
{
        if (btrfs_is_zoned(fs_info) && (flags & FS_NOCOW_FL))
                return -EPERM;

        return 0;
}

/*
 * Set flags/xflags from the internal inode flags. The remaining items of
 * fsxattr are zeroed.
 */
int btrfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
{
        struct btrfs_inode *binode = BTRFS_I(d_inode(dentry));

        fileattr_fill_flags(fa, btrfs_inode_flags_to_fsflags(binode));
        return 0;
}

int btrfs_fileattr_set(struct user_namespace *mnt_userns,
                       struct dentry *dentry, struct fileattr *fa)
{
        struct inode *inode = d_inode(dentry);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_inode *binode = BTRFS_I(inode);
        struct btrfs_root *root = binode->root;
        struct btrfs_trans_handle *trans;
        unsigned int fsflags, old_fsflags;
        int ret;
        const char *comp = NULL;
        u32 binode_flags;

        if (btrfs_root_readonly(root))
                return -EROFS;

        if (fileattr_has_fsx(fa))
                return -EOPNOTSUPP;

        fsflags = btrfs_mask_fsflags_for_type(inode, fa->flags);
        old_fsflags = btrfs_inode_flags_to_fsflags(binode);
        ret = check_fsflags(old_fsflags, fsflags);
        if (ret)
                return ret;

        ret = check_fsflags_compatible(fs_info, fsflags);
        if (ret)
                return ret;

        binode_flags = binode->flags;
        if (fsflags & FS_SYNC_FL)
                binode_flags |= BTRFS_INODE_SYNC;
        else
                binode_flags &= ~BTRFS_INODE_SYNC;
        if (fsflags & FS_IMMUTABLE_FL)
                binode_flags |= BTRFS_INODE_IMMUTABLE;
        else
                binode_flags &= ~BTRFS_INODE_IMMUTABLE;
        if (fsflags & FS_APPEND_FL)
                binode_flags |= BTRFS_INODE_APPEND;
        else
                binode_flags &= ~BTRFS_INODE_APPEND;
        if (fsflags & FS_NODUMP_FL)
                binode_flags |= BTRFS_INODE_NODUMP;
        else
                binode_flags &= ~BTRFS_INODE_NODUMP;
        if (fsflags & FS_NOATIME_FL)
                binode_flags |= BTRFS_INODE_NOATIME;
        else
                binode_flags &= ~BTRFS_INODE_NOATIME;

        /* If coming from FS_IOC_FSSETXATTR then skip unconverted flags */
        if (!fa->flags_valid) {
                /* 1 item for the inode */
                trans = btrfs_start_transaction(root, 1);
                if (IS_ERR(trans))
                        return PTR_ERR(trans);
                goto update_flags;
        }

        if (fsflags & FS_DIRSYNC_FL)
                binode_flags |= BTRFS_INODE_DIRSYNC;
        else
                binode_flags &= ~BTRFS_INODE_DIRSYNC;
        if (fsflags & FS_NOCOW_FL) {
                if (S_ISREG(inode->i_mode)) {
                        /*
                         * It's safe to turn csums off here, no extents exist.
                         * Otherwise we want the flag to reflect the real COW
                         * status of the file and will not set it.
                         */
                        if (inode->i_size == 0)
                                binode_flags |= BTRFS_INODE_NODATACOW |
                                                BTRFS_INODE_NODATASUM;
                } else {
                        binode_flags |= BTRFS_INODE_NODATACOW;
                }
        } else {
                /*
                 * Revert back under same assumptions as above
                 */
                if (S_ISREG(inode->i_mode)) {
                        if (inode->i_size == 0)
                                binode_flags &= ~(BTRFS_INODE_NODATACOW |
                                                  BTRFS_INODE_NODATASUM);
                } else {
                        binode_flags &= ~BTRFS_INODE_NODATACOW;
                }
        }

        /*
         * The COMPRESS flag can only be changed by users, while the NOCOMPRESS
         * flag may be changed automatically if compression code won't make
         * things smaller.
         */
        if (fsflags & FS_NOCOMP_FL) {
                binode_flags &= ~BTRFS_INODE_COMPRESS;
                binode_flags |= BTRFS_INODE_NOCOMPRESS;
        } else if (fsflags & FS_COMPR_FL) {

                if (IS_SWAPFILE(inode))
                        return -ETXTBSY;

                binode_flags |= BTRFS_INODE_COMPRESS;
                binode_flags &= ~BTRFS_INODE_NOCOMPRESS;

                comp = btrfs_compress_type2str(fs_info->compress_type);
                if (!comp || comp[0] == 0)
                        comp = btrfs_compress_type2str(BTRFS_COMPRESS_ZLIB);
        } else {
                binode_flags &= ~(BTRFS_INODE_COMPRESS | BTRFS_INODE_NOCOMPRESS);
        }

        /*
         * 1 for inode item
         * 2 for properties
         */
        trans = btrfs_start_transaction(root, 3);
        if (IS_ERR(trans))
                return PTR_ERR(trans);

        if (comp) {
                ret = btrfs_set_prop(trans, inode, "btrfs.compression", comp,
                                     strlen(comp), 0);
                if (ret) {
                        btrfs_abort_transaction(trans, ret);
                        goto out_end_trans;
                }
        } else {
                ret = btrfs_set_prop(trans, inode, "btrfs.compression", NULL,
                                     0, 0);
                if (ret && ret != -ENODATA) {
                        btrfs_abort_transaction(trans, ret);
                        goto out_end_trans;
                }
        }

update_flags:
        binode->flags = binode_flags;
        btrfs_sync_inode_flags_to_i_flags(inode);
        inode_inc_iversion(inode);
        inode->i_ctime = current_time(inode);
        ret = btrfs_update_inode(trans, root, BTRFS_I(inode));

 out_end_trans:
        btrfs_end_transaction(trans);
        return ret;
}

/*
 * Start exclusive operation @type, return true on success
 */
bool btrfs_exclop_start(struct btrfs_fs_info *fs_info,
                        enum btrfs_exclusive_operation type)
{
        bool ret = false;

        spin_lock(&fs_info->super_lock);
        if (fs_info->exclusive_operation == BTRFS_EXCLOP_NONE) {
                fs_info->exclusive_operation = type;
                ret = true;
        }
        spin_unlock(&fs_info->super_lock);

        return ret;
}

/*
 * Conditionally allow to enter the exclusive operation in case it's compatible
 * with the running one.  This must be paired with btrfs_exclop_start_unlock and
 * btrfs_exclop_finish.
 *
 * Compatibility:
 * - the same type is already running
 * - when trying to add a device and balance has been paused
 * - not BTRFS_EXCLOP_NONE - this is intentionally incompatible and the caller
 *   must check the condition first that would allow none -> @type
 */
bool btrfs_exclop_start_try_lock(struct btrfs_fs_info *fs_info,
                                 enum btrfs_exclusive_operation type)
{
        spin_lock(&fs_info->super_lock);
        if (fs_info->exclusive_operation == type ||
            (fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED &&
             type == BTRFS_EXCLOP_DEV_ADD))
                return true;

        spin_unlock(&fs_info->super_lock);
        return false;
}

void btrfs_exclop_start_unlock(struct btrfs_fs_info *fs_info)
{
        spin_unlock(&fs_info->super_lock);
}

void btrfs_exclop_finish(struct btrfs_fs_info *fs_info)
{
        spin_lock(&fs_info->super_lock);
        WRITE_ONCE(fs_info->exclusive_operation, BTRFS_EXCLOP_NONE);
        spin_unlock(&fs_info->super_lock);
        sysfs_notify(&fs_info->fs_devices->fsid_kobj, NULL, "exclusive_operation");
}

void btrfs_exclop_balance(struct btrfs_fs_info *fs_info,
                          enum btrfs_exclusive_operation op)
{
        switch (op) {
        case BTRFS_EXCLOP_BALANCE_PAUSED:
                spin_lock(&fs_info->super_lock);
                ASSERT(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE ||
                       fs_info->exclusive_operation == BTRFS_EXCLOP_DEV_ADD);
                fs_info->exclusive_operation = BTRFS_EXCLOP_BALANCE_PAUSED;
                spin_unlock(&fs_info->super_lock);
                break;
        case BTRFS_EXCLOP_BALANCE:
                spin_lock(&fs_info->super_lock);
                ASSERT(fs_info->exclusive_operation == BTRFS_EXCLOP_BALANCE_PAUSED);
                fs_info->exclusive_operation = BTRFS_EXCLOP_BALANCE;
                spin_unlock(&fs_info->super_lock);
                break;
        default:
                btrfs_warn(fs_info,
                        "invalid exclop balance operation %d requested", op);
        }
}

static int btrfs_ioctl_getversion(struct inode *inode, int __user *arg)
{
        return put_user(inode->i_generation, arg);
}

static noinline int btrfs_ioctl_fitrim(struct btrfs_fs_info *fs_info,
                                        void __user *arg)
{
        struct btrfs_device *device;
        struct fstrim_range range;
        u64 minlen = ULLONG_MAX;
        u64 num_devices = 0;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        /*
         * btrfs_trim_block_group() depends on space cache, which is not
         * available in zoned filesystem. So, disallow fitrim on a zoned
         * filesystem for now.
         */
        if (btrfs_is_zoned(fs_info))
                return -EOPNOTSUPP;

        /*
         * If the fs is mounted with nologreplay, which requires it to be
         * mounted in RO mode as well, we can not allow discard on free space
         * inside block groups, because log trees refer to extents that are not
         * pinned in a block group's free space cache (pinning the extents is
         * precisely the first phase of replaying a log tree).
         */
        if (btrfs_test_opt(fs_info, NOLOGREPLAY))
                return -EROFS;

        rcu_read_lock();
        list_for_each_entry_rcu(device, &fs_info->fs_devices->devices,
                                dev_list) {
                if (!device->bdev || !bdev_max_discard_sectors(device->bdev))
                        continue;
                num_devices++;
                minlen = min_t(u64, bdev_discard_granularity(device->bdev),
                                    minlen);
        }
        rcu_read_unlock();

        if (!num_devices)
                return -EOPNOTSUPP;
        if (copy_from_user(&range, arg, sizeof(range)))
                return -EFAULT;

        /*
         * NOTE: Don't truncate the range using super->total_bytes.  Bytenr of
         * block group is in the logical address space, which can be any
         * sectorsize aligned bytenr in  the range [0, U64_MAX].
         */
        if (range.len < fs_info->sb->s_blocksize)
                return -EINVAL;

        range.minlen = max(range.minlen, minlen);
        ret = btrfs_trim_fs(fs_info, &range);
        if (ret < 0)
                return ret;

        if (copy_to_user(arg, &range, sizeof(range)))
                return -EFAULT;

        return 0;
}

int __pure btrfs_is_empty_uuid(u8 *uuid)
{
        int i;

        for (i = 0; i < BTRFS_UUID_SIZE; i++) {
                if (uuid[i])
                        return 0;
        }
        return 1;
}

/*
 * Calculate the number of transaction items to reserve for creating a subvolume
 * or snapshot, not including the inode, directory entries, or parent directory.
 */
static unsigned int create_subvol_num_items(struct btrfs_qgroup_inherit *inherit)
{
        /*
         * 1 to add root block
         * 1 to add root item
         * 1 to add root ref
         * 1 to add root backref
         * 1 to add UUID item
         * 1 to add qgroup info
         * 1 to add qgroup limit
         *
         * Ideally the last two would only be accounted if qgroups are enabled,
         * but that can change between now and the time we would insert them.
         */
        unsigned int num_items = 7;

        if (inherit) {
                /* 2 to add qgroup relations for each inherited qgroup */
                num_items += 2 * inherit->num_qgroups;
        }
        return num_items;
}

static noinline int create_subvol(struct user_namespace *mnt_userns,
                                  struct inode *dir, struct dentry *dentry,
                                  struct btrfs_qgroup_inherit *inherit)
{
        struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
        struct btrfs_trans_handle *trans;
        struct btrfs_key key;
        struct btrfs_root_item *root_item;
        struct btrfs_inode_item *inode_item;
        struct extent_buffer *leaf;
        struct btrfs_root *root = BTRFS_I(dir)->root;
        struct btrfs_root *new_root;
        struct btrfs_block_rsv block_rsv;
        struct timespec64 cur_time = current_time(dir);
        struct btrfs_new_inode_args new_inode_args = {
                .dir = dir,
                .dentry = dentry,
                .subvol = true,
        };
        unsigned int trans_num_items;
        int ret;
        dev_t anon_dev;
        u64 objectid;

        root_item = kzalloc(sizeof(*root_item), GFP_KERNEL);
        if (!root_item)
                return -ENOMEM;

        ret = btrfs_get_free_objectid(fs_info->tree_root, &objectid);
        if (ret)
                goto out_root_item;

        /*
         * Don't create subvolume whose level is not zero. Or qgroup will be
         * screwed up since it assumes subvolume qgroup's level to be 0.
         */
        if (btrfs_qgroup_level(objectid)) {
                ret = -ENOSPC;
                goto out_root_item;
        }

        ret = get_anon_bdev(&anon_dev);
        if (ret < 0)
                goto out_root_item;

        new_inode_args.inode = btrfs_new_subvol_inode(mnt_userns, dir);
        if (!new_inode_args.inode) {
                ret = -ENOMEM;
                goto out_anon_dev;
        }
        ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
        if (ret)
                goto out_inode;
        trans_num_items += create_subvol_num_items(inherit);

        btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
        ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
                                               trans_num_items, false);
        if (ret)
                goto out_new_inode_args;

        trans = btrfs_start_transaction(root, 0);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                btrfs_subvolume_release_metadata(root, &block_rsv);
                goto out_new_inode_args;
        }
        trans->block_rsv = &block_rsv;
        trans->bytes_reserved = block_rsv.size;

        ret = btrfs_qgroup_inherit(trans, 0, objectid, inherit);
        if (ret)
                goto out;

        leaf = btrfs_alloc_tree_block(trans, root, 0, objectid, NULL, 0, 0, 0,
                                      BTRFS_NESTING_NORMAL);
        if (IS_ERR(leaf)) {
                ret = PTR_ERR(leaf);
                goto out;
        }

        btrfs_mark_buffer_dirty(leaf);

        inode_item = &root_item->inode;
        btrfs_set_stack_inode_generation(inode_item, 1);
        btrfs_set_stack_inode_size(inode_item, 3);
        btrfs_set_stack_inode_nlink(inode_item, 1);
        btrfs_set_stack_inode_nbytes(inode_item,
                                     fs_info->nodesize);
        btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755);

        btrfs_set_root_flags(root_item, 0);
        btrfs_set_root_limit(root_item, 0);
        btrfs_set_stack_inode_flags(inode_item, BTRFS_INODE_ROOT_ITEM_INIT);

        btrfs_set_root_bytenr(root_item, leaf->start);
        btrfs_set_root_generation(root_item, trans->transid);
        btrfs_set_root_level(root_item, 0);
        btrfs_set_root_refs(root_item, 1);
        btrfs_set_root_used(root_item, leaf->len);
        btrfs_set_root_last_snapshot(root_item, 0);

        btrfs_set_root_generation_v2(root_item,
                        btrfs_root_generation(root_item));
        generate_random_guid(root_item->uuid);
        btrfs_set_stack_timespec_sec(&root_item->otime, cur_time.tv_sec);
        btrfs_set_stack_timespec_nsec(&root_item->otime, cur_time.tv_nsec);
        root_item->ctime = root_item->otime;
        btrfs_set_root_ctransid(root_item, trans->transid);
        btrfs_set_root_otransid(root_item, trans->transid);

        btrfs_tree_unlock(leaf);

        btrfs_set_root_dirid(root_item, BTRFS_FIRST_FREE_OBJECTID);

        key.objectid = objectid;
        key.offset = 0;
        key.type = BTRFS_ROOT_ITEM_KEY;
        ret = btrfs_insert_root(trans, fs_info->tree_root, &key,
                                root_item);
        if (ret) {
                /*
                 * Since we don't abort the transaction in this case, free the
                 * tree block so that we don't leak space and leave the
                 * filesystem in an inconsistent state (an extent item in the
                 * extent tree with a backreference for a root that does not
                 * exists).
                 */
                btrfs_tree_lock(leaf);
                btrfs_clean_tree_block(leaf);
                btrfs_tree_unlock(leaf);
                btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
                free_extent_buffer(leaf);
                goto out;
        }

        free_extent_buffer(leaf);
        leaf = NULL;

        new_root = btrfs_get_new_fs_root(fs_info, objectid, anon_dev);
        if (IS_ERR(new_root)) {
                ret = PTR_ERR(new_root);
                btrfs_abort_transaction(trans, ret);
                goto out;
        }
        /* anon_dev is owned by new_root now. */
        anon_dev = 0;
        BTRFS_I(new_inode_args.inode)->root = new_root;
        /* ... and new_root is owned by new_inode_args.inode now. */

        ret = btrfs_record_root_in_trans(trans, new_root);
        if (ret) {
                btrfs_abort_transaction(trans, ret);
                goto out;
        }

        ret = btrfs_uuid_tree_add(trans, root_item->uuid,
                                  BTRFS_UUID_KEY_SUBVOL, objectid);
        if (ret) {
                btrfs_abort_transaction(trans, ret);
                goto out;
        }

        ret = btrfs_create_new_inode(trans, &new_inode_args);
        if (ret) {
                btrfs_abort_transaction(trans, ret);
                goto out;
        }

        d_instantiate_new(dentry, new_inode_args.inode);
        new_inode_args.inode = NULL;

out:
        trans->block_rsv = NULL;
        trans->bytes_reserved = 0;
        btrfs_subvolume_release_metadata(root, &block_rsv);

        if (ret)
                btrfs_end_transaction(trans);
        else
                ret = btrfs_commit_transaction(trans);
out_new_inode_args:
        btrfs_new_inode_args_destroy(&new_inode_args);
out_inode:
        iput(new_inode_args.inode);
out_anon_dev:
        if (anon_dev)
                free_anon_bdev(anon_dev);
out_root_item:
        kfree(root_item);
        return ret;
}

static int create_snapshot(struct btrfs_root *root, struct inode *dir,
                           struct dentry *dentry, bool readonly,
                           struct btrfs_qgroup_inherit *inherit)
{
        struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
        struct inode *inode;
        struct btrfs_pending_snapshot *pending_snapshot;
        unsigned int trans_num_items;
        struct btrfs_trans_handle *trans;
        int ret;

        /* We do not support snapshotting right now. */
        if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
                btrfs_warn(fs_info,
                           "extent tree v2 doesn't support snapshotting yet");
                return -EOPNOTSUPP;
        }

        if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
                return -EINVAL;

        if (atomic_read(&root->nr_swapfiles)) {
                btrfs_warn(fs_info,
                           "cannot snapshot subvolume with active swapfile");
                return -ETXTBSY;
        }

        pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_KERNEL);
        if (!pending_snapshot)
                return -ENOMEM;

        ret = get_anon_bdev(&pending_snapshot->anon_dev);
        if (ret < 0)
                goto free_pending;
        pending_snapshot->root_item = kzalloc(sizeof(struct btrfs_root_item),
                        GFP_KERNEL);
        pending_snapshot->path = btrfs_alloc_path();
        if (!pending_snapshot->root_item || !pending_snapshot->path) {
                ret = -ENOMEM;
                goto free_pending;
        }

        btrfs_init_block_rsv(&pending_snapshot->block_rsv,
                             BTRFS_BLOCK_RSV_TEMP);
        /*
         * 1 to add dir item
         * 1 to add dir index
         * 1 to update parent inode item
         */
        trans_num_items = create_subvol_num_items(inherit) + 3;
        ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
                                               &pending_snapshot->block_rsv,
                                               trans_num_items, false);
        if (ret)
                goto free_pending;

        pending_snapshot->dentry = dentry;
        pending_snapshot->root = root;
        pending_snapshot->readonly = readonly;
        pending_snapshot->dir = dir;
        pending_snapshot->inherit = inherit;

        trans = btrfs_start_transaction(root, 0);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto fail;
        }

        trans->pending_snapshot = pending_snapshot;

        ret = btrfs_commit_transaction(trans);
        if (ret)
                goto fail;

        ret = pending_snapshot->error;
        if (ret)
                goto fail;

        ret = btrfs_orphan_cleanup(pending_snapshot->snap);
        if (ret)
                goto fail;

        inode = btrfs_lookup_dentry(d_inode(dentry->d_parent), dentry);
        if (IS_ERR(inode)) {
                ret = PTR_ERR(inode);
                goto fail;
        }

        d_instantiate(dentry, inode);
        ret = 0;
        pending_snapshot->anon_dev = 0;
fail:
        /* Prevent double freeing of anon_dev */
        if (ret && pending_snapshot->snap)
                pending_snapshot->snap->anon_dev = 0;
        btrfs_put_root(pending_snapshot->snap);
        btrfs_subvolume_release_metadata(root, &pending_snapshot->block_rsv);
free_pending:
        if (pending_snapshot->anon_dev)
                free_anon_bdev(pending_snapshot->anon_dev);
        kfree(pending_snapshot->root_item);
        btrfs_free_path(pending_snapshot->path);
        kfree(pending_snapshot);

        return ret;
}

/*  copy of may_delete in fs/namei.c()
 *      Check whether we can remove a link victim from directory dir, check
 *  whether the type of victim is right.
 *  1. We can't do it if dir is read-only (done in permission())
 *  2. We should have write and exec permissions on dir
 *  3. We can't remove anything from append-only dir
 *  4. We can't do anything with immutable dir (done in permission())
 *  5. If the sticky bit on dir is set we should either
 *      a. be owner of dir, or
 *      b. be owner of victim, or
 *      c. have CAP_FOWNER capability
 *  6. If the victim is append-only or immutable we can't do anything with
 *     links pointing to it.
 *  7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
 *  8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
 *  9. We can't remove a root or mountpoint.
 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
 *     nfs_async_unlink().
 */

static int btrfs_may_delete(struct user_namespace *mnt_userns,
                            struct inode *dir, struct dentry *victim, int isdir)
{
        int error;

        if (d_really_is_negative(victim))
                return -ENOENT;

        BUG_ON(d_inode(victim->d_parent) != dir);
        audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);

        error = inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
        if (error)
                return error;
        if (IS_APPEND(dir))
                return -EPERM;
        if (check_sticky(mnt_userns, dir, d_inode(victim)) ||
            IS_APPEND(d_inode(victim)) || IS_IMMUTABLE(d_inode(victim)) ||
            IS_SWAPFILE(d_inode(victim)))
                return -EPERM;
        if (isdir) {
                if (!d_is_dir(victim))
                        return -ENOTDIR;
                if (IS_ROOT(victim))
                        return -EBUSY;
        } else if (d_is_dir(victim))
                return -EISDIR;
        if (IS_DEADDIR(dir))
                return -ENOENT;
        if (victim->d_flags & DCACHE_NFSFS_RENAMED)
                return -EBUSY;
        return 0;
}

/* copy of may_create in fs/namei.c() */
static inline int btrfs_may_create(struct user_namespace *mnt_userns,
                                   struct inode *dir, struct dentry *child)
{
        if (d_really_is_positive(child))
                return -EEXIST;
        if (IS_DEADDIR(dir))
                return -ENOENT;
        if (!fsuidgid_has_mapping(dir->i_sb, mnt_userns))
                return -EOVERFLOW;
        return inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
}

/*
 * Create a new subvolume below @parent.  This is largely modeled after
 * sys_mkdirat and vfs_mkdir, but we only do a single component lookup
 * inside this filesystem so it's quite a bit simpler.
 */
static noinline int btrfs_mksubvol(const struct path *parent,
                                   struct user_namespace *mnt_userns,
                                   const char *name, int namelen,
                                   struct btrfs_root *snap_src,
                                   bool readonly,
                                   struct btrfs_qgroup_inherit *inherit)
{
        struct inode *dir = d_inode(parent->dentry);
        struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
        struct dentry *dentry;
        int error;

        error = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
        if (error == -EINTR)
                return error;

        dentry = lookup_one(mnt_userns, name, parent->dentry, namelen);
        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto out_unlock;

        error = btrfs_may_create(mnt_userns, dir, dentry);
        if (error)
                goto out_dput;

        /*
         * even if this name doesn't exist, we may get hash collisions.
         * check for them now when we can safely fail
         */
        error = btrfs_check_dir_item_collision(BTRFS_I(dir)->root,
                                               dir->i_ino, name,
                                               namelen);
        if (error)
                goto out_dput;

        down_read(&fs_info->subvol_sem);

        if (btrfs_root_refs(&BTRFS_I(dir)->root->root_item) == 0)
                goto out_up_read;

        if (snap_src)
                error = create_snapshot(snap_src, dir, dentry, readonly, inherit);
        else
                error = create_subvol(mnt_userns, dir, dentry, inherit);

        if (!error)
                fsnotify_mkdir(dir, dentry);
out_up_read:
        up_read(&fs_info->subvol_sem);
out_dput:
        dput(dentry);
out_unlock:
        btrfs_inode_unlock(dir, 0);
        return error;
}

static noinline int btrfs_mksnapshot(const struct path *parent,
                                   struct user_namespace *mnt_userns,
                                   const char *name, int namelen,
                                   struct btrfs_root *root,
                                   bool readonly,
                                   struct btrfs_qgroup_inherit *inherit)
{
        int ret;
        bool snapshot_force_cow = false;

        /*
         * Force new buffered writes to reserve space even when NOCOW is
         * possible. This is to avoid later writeback (running dealloc) to
         * fallback to COW mode and unexpectedly fail with ENOSPC.
         */
        btrfs_drew_read_lock(&root->snapshot_lock);

        ret = btrfs_start_delalloc_snapshot(root, false);
        if (ret)
                goto out;

        /*
         * All previous writes have started writeback in NOCOW mode, so now
         * we force future writes to fallback to COW mode during snapshot
         * creation.
         */
        atomic_inc(&root->snapshot_force_cow);
        snapshot_force_cow = true;

        btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);

        ret = btrfs_mksubvol(parent, mnt_userns, name, namelen,
                             root, readonly, inherit);
out:
        if (snapshot_force_cow)
                atomic_dec(&root->snapshot_force_cow);
        btrfs_drew_read_unlock(&root->snapshot_lock);
        return ret;
}

/*
 * Defrag specific helper to get an extent map.
 *
 * Differences between this and btrfs_get_extent() are:
 *
 * - No extent_map will be added to inode->extent_tree
 *   To reduce memory usage in the long run.
 *
 * - Extra optimization to skip file extents older than @newer_than
 *   By using btrfs_search_forward() we can skip entire file ranges that
 *   have extents created in past transactions, because btrfs_search_forward()
 *   will not visit leaves and nodes with a generation smaller than given
 *   minimal generation threshold (@newer_than).
 *
 * Return valid em if we find a file extent matching the requirement.
 * Return NULL if we can not find a file extent matching the requirement.
 *
 * Return ERR_PTR() for error.
 */
static struct extent_map *defrag_get_extent(struct btrfs_inode *inode,
                                            u64 start, u64 newer_than)
{
        struct btrfs_root *root = inode->root;
        struct btrfs_file_extent_item *fi;
        struct btrfs_path path = { 0 };
        struct extent_map *em;
        struct btrfs_key key;
        u64 ino = btrfs_ino(inode);
        int ret;

        em = alloc_extent_map();
        if (!em) {
                ret = -ENOMEM;
                goto err;
        }

        key.objectid = ino;
        key.type = BTRFS_EXTENT_DATA_KEY;
        key.offset = start;

        if (newer_than) {
                ret = btrfs_search_forward(root, &key, &path, newer_than);
                if (ret < 0)
                        goto err;
                /* Can't find anything newer */
                if (ret > 0)
                        goto not_found;
        } else {
                ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
                if (ret < 0)
                        goto err;
        }
        if (path.slots[0] >= btrfs_header_nritems(path.nodes[0])) {
                /*
                 * If btrfs_search_slot() makes path to point beyond nritems,
                 * we should not have an empty leaf, as this inode must at
                 * least have its INODE_ITEM.
                 */
                ASSERT(btrfs_header_nritems(path.nodes[0]));
                path.slots[0] = btrfs_header_nritems(path.nodes[0]) - 1;
        }
        btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
        /* Perfect match, no need to go one slot back */
        if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY &&
            key.offset == start)
                goto iterate;

        /* We didn't find a perfect match, needs to go one slot back */
        if (path.slots[0] > 0) {
                btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
                if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY)
                        path.slots[0]--;
        }

iterate:
        /* Iterate through the path to find a file extent covering @start */
        while (true) {
                u64 extent_end;

                if (path.slots[0] >= btrfs_header_nritems(path.nodes[0]))
                        goto next;

                btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);

                /*
                 * We may go one slot back to INODE_REF/XATTR item, then
                 * need to go forward until we reach an EXTENT_DATA.
                 * But we should still has the correct ino as key.objectid.
                 */
                if (WARN_ON(key.objectid < ino) || key.type < BTRFS_EXTENT_DATA_KEY)
                        goto next;

                /* It's beyond our target range, definitely not extent found */
                if (key.objectid > ino || key.type > BTRFS_EXTENT_DATA_KEY)
                        goto not_found;

                /*
                 *      |       |<- File extent ->|
                 *      \- start
                 *
                 * This means there is a hole between start and key.offset.
                 */
                if (key.offset > start) {
                        em->start = start;
                        em->orig_start = start;
                        em->block_start = EXTENT_MAP_HOLE;
                        em->len = key.offset - start;
                        break;
                }

                fi = btrfs_item_ptr(path.nodes[0], path.slots[0],
                                    struct btrfs_file_extent_item);
                extent_end = btrfs_file_extent_end(&path);

                /*
                 *      |<- file extent ->|     |
                 *                              \- start
                 *
                 * We haven't reached start, search next slot.
                 */
                if (extent_end <= start)
                        goto next;

                /* Now this extent covers @start, convert it to em */
                btrfs_extent_item_to_extent_map(inode, &path, fi, false, em);
                break;
next:
                ret = btrfs_next_item(root, &path);
                if (ret < 0)
                        goto err;
                if (ret > 0)
                        goto not_found;
        }
        btrfs_release_path(&path);
        return em;

not_found:
        btrfs_release_path(&path);
        free_extent_map(em);
        return NULL;

err:
        btrfs_release_path(&path);
        free_extent_map(em);
        return ERR_PTR(ret);
}

static struct extent_map *defrag_lookup_extent(struct inode *inode, u64 start,
                                               u64 newer_than, bool locked)
{
        struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
        struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
        struct extent_map *em;
        const u32 sectorsize = BTRFS_I(inode)->root->fs_info->sectorsize;

        /*
         * hopefully we have this extent in the tree already, try without
         * the full extent lock
         */
        read_lock(&em_tree->lock);
        em = lookup_extent_mapping(em_tree, start, sectorsize);
        read_unlock(&em_tree->lock);

        /*
         * We can get a merged extent, in that case, we need to re-search
         * tree to get the original em for defrag.
         *
         * If @newer_than is 0 or em::generation < newer_than, we can trust
         * this em, as either we don't care about the generation, or the
         * merged extent map will be rejected anyway.
         */
        if (em && test_bit(EXTENT_FLAG_MERGED, &em->flags) &&
            newer_than && em->generation >= newer_than) {
                free_extent_map(em);
                em = NULL;
        }

        if (!em) {
                struct extent_state *cached = NULL;
                u64 end = start + sectorsize - 1;

                /* get the big lock and read metadata off disk */
                if (!locked)
                        lock_extent_bits(io_tree, start, end, &cached);
                em = defrag_get_extent(BTRFS_I(inode), start, newer_than);
                if (!locked)
                        unlock_extent_cached(io_tree, start, end, &cached);

                if (IS_ERR(em))
                        return NULL;
        }

        return em;
}

static u32 get_extent_max_capacity(const struct btrfs_fs_info *fs_info,
                                   const struct extent_map *em)
{
        if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags))
                return BTRFS_MAX_COMPRESSED;
        return fs_info->max_extent_size;
}

static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em,
                                     u32 extent_thresh, u64 newer_than, bool locked)
{
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct extent_map *next;
        bool ret = false;

        /* this is the last extent */
        if (em->start + em->len >= i_size_read(inode))
                return false;

        /*
         * Here we need to pass @newer_then when checking the next extent, or
         * we will hit a case we mark current extent for defrag, but the next
         * one will not be a target.
         * This will just cause extra IO without really reducing the fragments.
         */
        next = defrag_lookup_extent(inode, em->start + em->len, newer_than, locked);
        /* No more em or hole */
        if (!next || next->block_start >= EXTENT_MAP_LAST_BYTE)
                goto out;
        if (test_bit(EXTENT_FLAG_PREALLOC, &next->flags))
                goto out;
        /*
         * If the next extent is at its max capacity, defragging current extent
         * makes no sense, as the total number of extents won't change.
         */
        if (next->len >= get_extent_max_capacity(fs_info, em))
                goto out;
        /* Skip older extent */
        if (next->generation < newer_than)
                goto out;
        /* Also check extent size */
        if (next->len >= extent_thresh)
                goto out;

        ret = true;
out:
        free_extent_map(next);
        return ret;
}

/*
 * Prepare one page to be defragged.
 *
 * This will ensure:
 *
 * - Returned page is locked and has been set up properly.
 * - No ordered extent exists in the page.
 * - The page is uptodate.
 *
 * NOTE: Caller should also wait for page writeback after the cluster is
 * prepared, here we don't do writeback wait for each page.
 */
static struct page *defrag_prepare_one_page(struct btrfs_inode *inode,
                                            pgoff_t index)
{
        struct address_space *mapping = inode->vfs_inode.i_mapping;
        gfp_t mask = btrfs_alloc_write_mask(mapping);
        u64 page_start = (u64)index << PAGE_SHIFT;
        u64 page_end = page_start + PAGE_SIZE - 1;
        struct extent_state *cached_state = NULL;
        struct page *page;
        int ret;

again:
        page = find_or_create_page(mapping, index, mask);
        if (!page)
                return ERR_PTR(-ENOMEM);

        /*
         * Since we can defragment files opened read-only, we can encounter
         * transparent huge pages here (see CONFIG_READ_ONLY_THP_FOR_FS). We
         * can't do I/O using huge pages yet, so return an error for now.
         * Filesystem transparent huge pages are typically only used for
         * executables that explicitly enable them, so this isn't very
         * restrictive.
         */
        if (PageCompound(page)) {
                unlock_page(page);
                put_page(page);
                return ERR_PTR(-ETXTBSY);
        }

        ret = set_page_extent_mapped(page);
        if (ret < 0) {
                unlock_page(page);
                put_page(page);
                return ERR_PTR(ret);
        }

        /* Wait for any existing ordered extent in the range */
        while (1) {
                struct btrfs_ordered_extent *ordered;

                lock_extent_bits(&inode->io_tree, page_start, page_end, &cached_state);
                ordered = btrfs_lookup_ordered_range(inode, page_start, PAGE_SIZE);
                unlock_extent_cached(&inode->io_tree, page_start, page_end,
                                     &cached_state);
                if (!ordered)
                        break;

                unlock_page(page);
                btrfs_start_ordered_extent(ordered, 1);
                btrfs_put_ordered_extent(ordered);
                lock_page(page);
                /*
                 * We unlocked the page above, so we need check if it was
                 * released or not.
                 */
                if (page->mapping != mapping || !PagePrivate(page)) {
                        unlock_page(page);
                        put_page(page);
                        goto again;
                }
        }

        /*
         * Now the page range has no ordered extent any more.  Read the page to
         * make it uptodate.
         */
        if (!PageUptodate(page)) {
                btrfs_read_folio(NULL, page_folio(page));
                lock_page(page);
                if (page->mapping != mapping || !PagePrivate(page)) {
                        unlock_page(page);
                        put_page(page);
                        goto again;
                }
                if (!PageUptodate(page)) {
                        unlock_page(page);
                        put_page(page);
                        return ERR_PTR(-EIO);
                }
        }
        return page;
}

struct defrag_target_range {
        struct list_head list;
        u64 start;
        u64 len;
};

/*
 * Collect all valid target extents.
 *
 * @start:         file offset to lookup
 * @len:           length to lookup
 * @extent_thresh: file extent size threshold, any extent size >= this value
 *                 will be ignored
 * @newer_than:    only defrag extents newer than this value
 * @do_compress:   whether the defrag is doing compression
 *                 if true, @extent_thresh will be ignored and all regular
 *                 file extents meeting @newer_than will be targets.
 * @locked:        if the range has already held extent lock
 * @target_list:   list of targets file extents
 */
static int defrag_collect_targets(struct btrfs_inode *inode,
                                  u64 start, u64 len, u32 extent_thresh,
                                  u64 newer_than, bool do_compress,
                                  bool locked, struct list_head *target_list,
                                  u64 *last_scanned_ret)
{
        struct btrfs_fs_info *fs_info = inode->root->fs_info;
        bool last_is_target = false;
        u64 cur = start;
        int ret = 0;

        while (cur < start + len) {
                struct extent_map *em;
                struct defrag_target_range *new;
                bool next_mergeable = true;
                u64 range_len;

                last_is_target = false;
                em = defrag_lookup_extent(&inode->vfs_inode, cur,
                                          newer_than, locked);
                if (!em)
                        break;

                /*
                 * If the file extent is an inlined one, we may still want to
                 * defrag it (fallthrough) if it will cause a regular extent.
                 * This is for users who want to convert inline extents to
                 * regular ones through max_inline= mount option.
                 */
                if (em->block_start == EXTENT_MAP_INLINE &&
                    em->len <= inode->root->fs_info->max_inline)
                        goto next;

                /* Skip hole/delalloc/preallocated extents */
                if (em->block_start == EXTENT_MAP_HOLE ||
                    em->block_start == EXTENT_MAP_DELALLOC ||
                    test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
                        goto next;

                /* Skip older extent */
                if (em->generation < newer_than)
                        goto next;

                /* This em is under writeback, no need to defrag */
                if (em->generation == (u64)-1)
                        goto next;

                /*
                 * Our start offset might be in the middle of an existing extent
                 * map, so take that into account.
                 */
                range_len = em->len - (cur - em->start);
                /*
                 * If this range of the extent map is already flagged for delalloc,
                 * skip it, because:
                 *
                 * 1) We could deadlock later, when trying to reserve space for
                 *    delalloc, because in case we can't immediately reserve space
                 *    the flusher can start delalloc and wait for the respective
                 *    ordered extents to complete. The deadlock would happen
                 *    because we do the space reservation while holding the range
                 *    locked, and starting writeback, or finishing an ordered
                 *    extent, requires locking the range;
                 *
                 * 2) If there's delalloc there, it means there's dirty pages for
                 *    which writeback has not started yet (we clean the delalloc
                 *    flag when starting writeback and after creating an ordered
                 *    extent). If we mark pages in an adjacent range for defrag,
                 *    then we will have a larger contiguous range for delalloc,
                 *    very likely resulting in a larger extent after writeback is
                 *    triggered (except in a case of free space fragmentation).
                 */
                if (test_range_bit(&inode->io_tree, cur, cur + range_len - 1,
                                   EXTENT_DELALLOC, 0, NULL))
                        goto next;

                /*
                 * For do_compress case, we want to compress all valid file
                 * extents, thus no @extent_thresh or mergeable check.
                 */
                if (do_compress)
                        goto add;

                /* Skip too large extent */
                if (range_len >= extent_thresh)
                        goto next;

                /*
                 * Skip extents already at its max capacity, this is mostly for
                 * compressed extents, which max cap is only 128K.
                 */
                if (em->len >= get_extent_max_capacity(fs_info, em))
                        goto next;

                /*
                 * Normally there are no more extents after an inline one, thus
                 * @next_mergeable will normally be false and not defragged.
                 * So if an inline extent passed all above checks, just add it
                 * for defrag, and be converted to regular extents.
                 */
                if (em->block_start == EXTENT_MAP_INLINE)
                        goto add;

                next_mergeable = defrag_check_next_extent(&inode->vfs_inode, em,
                                                extent_thresh, newer_than, locked);
                if (!next_mergeable) {
                        struct defrag_target_range *last;

                        /* Empty target list, no way to merge with last entry */
                        if (list_empty(target_list))
                                goto next;
                        last = list_entry(target_list->prev,
                                          struct defrag_target_range, list);
                        /* Not mergeable with last entry */
                        if (last->start + last->len != cur)
                                goto next;

                        /* Mergeable, fall through to add it to @target_list. */
                }

add:
                last_is_target = true;
                range_len = min(extent_map_end(em), start + len) - cur;
                /*
                 * This one is a good target, check if it can be merged into
                 * last range of the target list.
                 */
                if (!list_empty(target_list)) {
                        struct defrag_target_range *last;

                        last = list_entry(target_list->prev,
                                          struct defrag_target_range, list);
                        ASSERT(last->start + last->len <= cur);
                        if (last->start + last->len == cur) {
                                /* Mergeable, enlarge the last entry */
                                last->len += range_len;
                                goto next;
                        }
                        /* Fall through to allocate a new entry */
                }

                /* Allocate new defrag_target_range */
                new = kmalloc(sizeof(*new), GFP_NOFS);
                if (!new) {
                        free_extent_map(em);
                        ret = -ENOMEM;
                        break;
                }
                new->start = cur;
                new->len = range_len;
                list_add_tail(&new->list, target_list);

next:
                cur = extent_map_end(em);
                free_extent_map(em);
        }
        if (ret < 0) {
                struct defrag_target_range *entry;
                struct defrag_target_range *tmp;

                list_for_each_entry_safe(entry, tmp, target_list, list) {
                        list_del_init(&entry->list);
                        kfree(entry);
                }
        }
        if (!ret && last_scanned_ret) {
                /*
                 * If the last extent is not a target, the caller can skip to
                 * the end of that extent.
                 * Otherwise, we can only go the end of the specified range.
                 */
                if (!last_is_target)
                        *last_scanned_ret = max(cur, *last_scanned_ret);
                else
                        *last_scanned_ret = max(start + len, *last_scanned_ret);
        }
        return ret;
}

#define CLUSTER_SIZE    (SZ_256K)
static_assert(IS_ALIGNED(CLUSTER_SIZE, PAGE_SIZE));

/*
 * Defrag one contiguous target range.
 *
 * @inode:      target inode
 * @target:     target range to defrag
 * @pages:      locked pages covering the defrag range
 * @nr_pages:   number of locked pages
 *
 * Caller should ensure:
 *
 * - Pages are prepared
 *   Pages should be locked, no ordered extent in the pages range,
 *   no writeback.
 *
 * - Extent bits are locked
 */
static int defrag_one_locked_target(struct btrfs_inode *inode,
                                    struct defrag_target_range *target,
                                    struct page **pages, int nr_pages,
                                    struct extent_state **cached_state)
{
        struct btrfs_fs_info *fs_info = inode->root->fs_info;
        struct extent_changeset *data_reserved = NULL;
        const u64 start = target->start;
        const u64 len = target->len;
        unsigned long last_index = (start + len - 1) >> PAGE_SHIFT;
        unsigned long start_index = start >> PAGE_SHIFT;
        unsigned long first_index = page_index(pages[0]);
        int ret = 0;
        int i;

        ASSERT(last_index - first_index + 1 <= nr_pages);

        ret = btrfs_delalloc_reserve_space(inode, &data_reserved, start, len);
        if (ret < 0)
                return ret;
        clear_extent_bit(&inode->io_tree, start, start + len - 1,
                         EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
                         EXTENT_DEFRAG, 0, 0, cached_state);
        set_extent_defrag(&inode->io_tree, start, start + len - 1, cached_state);

        /* Update the page status */
        for (i = start_index - first_index; i <= last_index - first_index; i++) {
                ClearPageChecked(pages[i]);
                btrfs_page_clamp_set_dirty(fs_info, pages[i], start, len);
        }
        btrfs_delalloc_release_extents(inode, len);
        extent_changeset_free(data_reserved);

        return ret;
}

static int defrag_one_range(struct btrfs_inode *inode, u64 start, u32 len,
                            u32 extent_thresh, u64 newer_than, bool do_compress,
                            u64 *last_scanned_ret)
{
        struct extent_state *cached_state = NULL;
        struct defrag_target_range *entry;
        struct defrag_target_range *tmp;
        LIST_HEAD(target_list);
        struct page **pages;
        const u32 sectorsize = inode->root->fs_info->sectorsize;
        u64 last_index = (start + len - 1) >> PAGE_SHIFT;
        u64 start_index = start >> PAGE_SHIFT;
        unsigned int nr_pages = last_index - start_index + 1;
        int ret = 0;
        int i;

        ASSERT(nr_pages <= CLUSTER_SIZE / PAGE_SIZE);
        ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(len, sectorsize));

        pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
        if (!pages)
                return -ENOMEM;

        /* Prepare all pages */
        for (i = 0; i < nr_pages; i++) {
                pages[i] = defrag_prepare_one_page(inode, start_index + i);
                if (IS_ERR(pages[i])) {
                        ret = PTR_ERR(pages[i]);
                        pages[i] = NULL;
                        goto free_pages;
                }
        }
        for (i = 0; i < nr_pages; i++)
                wait_on_page_writeback(pages[i]);

        /* Lock the pages range */
        lock_extent_bits(&inode->io_tree, start_index << PAGE_SHIFT,
                         (last_index << PAGE_SHIFT) + PAGE_SIZE - 1,
                         &cached_state);
        /*
         * Now we have a consistent view about the extent map, re-check
         * which range really needs to be defragged.
         *
         * And this time we have extent locked already, pass @locked = true
         * so that we won't relock the extent range and cause deadlock.
         */
        ret = defrag_collect_targets(inode, start, len, extent_thresh,
                                     newer_than, do_compress, true,
                                     &target_list, last_scanned_ret);
        if (ret < 0)
                goto unlock_extent;

        list_for_each_entry(entry, &target_list, list) {
                ret = defrag_one_locked_target(inode, entry, pages, nr_pages,
                                               &cached_state);
                if (ret < 0)
                        break;
        }

        list_for_each_entry_safe(entry, tmp, &target_list, list) {
                list_del_init(&entry->list);
                kfree(entry);
        }
unlock_extent:
        unlock_extent_cached(&inode->io_tree, start_index << PAGE_SHIFT,
                             (last_index << PAGE_SHIFT) + PAGE_SIZE - 1,
                             &cached_state);
free_pages:
        for (i = 0; i < nr_pages; i++) {
                if (pages[i]) {
                        unlock_page(pages[i]);
                        put_page(pages[i]);
                }
        }
        kfree(pages);
        return ret;
}

static int defrag_one_cluster(struct btrfs_inode *inode,
                              struct file_ra_state *ra,
                              u64 start, u32 len, u32 extent_thresh,
                              u64 newer_than, bool do_compress,
                              unsigned long *sectors_defragged,
                              unsigned long max_sectors,
                              u64 *last_scanned_ret)
{
        const u32 sectorsize = inode->root->fs_info->sectorsize;
        struct defrag_target_range *entry;
        struct defrag_target_range *tmp;
        LIST_HEAD(target_list);
        int ret;

        ret = defrag_collect_targets(inode, start, len, extent_thresh,
                                     newer_than, do_compress, false,
                                     &target_list, NULL);
        if (ret < 0)
                goto out;

        list_for_each_entry(entry, &target_list, list) {
                u32 range_len = entry->len;

                /* Reached or beyond the limit */
                if (max_sectors && *sectors_defragged >= max_sectors) {
                        ret = 1;
                        break;
                }

                if (max_sectors)
                        range_len = min_t(u32, range_len,
                                (max_sectors - *sectors_defragged) * sectorsize);

                /*
                 * If defrag_one_range() has updated last_scanned_ret,
                 * our range may already be invalid (e.g. hole punched).
                 * Skip if our range is before last_scanned_ret, as there is
                 * no need to defrag the range anymore.
                 */
                if (entry->start + range_len <= *last_scanned_ret)
                        continue;

                if (ra)
                        page_cache_sync_readahead(inode->vfs_inode.i_mapping,
                                ra, NULL, entry->start >> PAGE_SHIFT,
                                ((entry->start + range_len - 1) >> PAGE_SHIFT) -
                                (entry->start >> PAGE_SHIFT) + 1);
                /*
                 * Here we may not defrag any range if holes are punched before
                 * we locked the pages.
                 * But that's fine, it only affects the @sectors_defragged
                 * accounting.
                 */
                ret = defrag_one_range(inode, entry->start, range_len,
                                       extent_thresh, newer_than, do_compress,
                                       last_scanned_ret);
                if (ret < 0)
                        break;
                *sectors_defragged += range_len >>
                                      inode->root->fs_info->sectorsize_bits;
        }
out:
        list_for_each_entry_safe(entry, tmp, &target_list, list) {
                list_del_init(&entry->list);
                kfree(entry);
        }
        if (ret >= 0)
                *last_scanned_ret = max(*last_scanned_ret, start + len);
        return ret;
}

/*
 * Entry point to file defragmentation.
 *
 * @inode:         inode to be defragged
 * @ra:            readahead state (can be NUL)
 * @range:         defrag options including range and flags
 * @newer_than:    minimum transid to defrag
 * @max_to_defrag: max number of sectors to be defragged, if 0, the whole inode
 *                 will be defragged.
 *
 * Return <0 for error.
 * Return >=0 for the number of sectors defragged, and range->start will be updated
 * to indicate the file offset where next defrag should be started at.
 * (Mostly for autodefrag, which sets @max_to_defrag thus we may exit early without
 *  defragging all the range).
 */
int btrfs_defrag_file(struct inode *inode, struct file_ra_state *ra,
                      struct btrfs_ioctl_defrag_range_args *range,
                      u64 newer_than, unsigned long max_to_defrag)
{
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        unsigned long sectors_defragged = 0;
        u64 isize = i_size_read(inode);
        u64 cur;
        u64 last_byte;
        bool do_compress = range->flags & BTRFS_DEFRAG_RANGE_COMPRESS;
        bool ra_allocated = false;
        int compress_type = BTRFS_COMPRESS_ZLIB;
        int ret = 0;
        u32 extent_thresh = range->extent_thresh;
        pgoff_t start_index;

        if (isize == 0)
                return 0;

        if (range->start >= isize)
                return -EINVAL;

        if (do_compress) {
                if (range->compress_type >= BTRFS_NR_COMPRESS_TYPES)
                        return -EINVAL;
                if (range->compress_type)
                        compress_type = range->compress_type;
        }

        if (extent_thresh == 0)
                extent_thresh = SZ_256K;

        if (range->start + range->len > range->start) {
                /* Got a specific range */
                last_byte = min(isize, range->start + range->len);
        } else {
                /* Defrag until file end */
                last_byte = isize;
        }

        /* Align the range */
        cur = round_down(range->start, fs_info->sectorsize);
        last_byte = round_up(last_byte, fs_info->sectorsize) - 1;

        /*
         * If we were not given a ra, allocate a readahead context. As
         * readahead is just an optimization, defrag will work without it so
         * we don't error out.
         */
        if (!ra) {
                ra_allocated = true;
                ra = kzalloc(sizeof(*ra), GFP_KERNEL);
                if (ra)
                        file_ra_state_init(ra, inode->i_mapping);
        }

        /*
         * Make writeback start from the beginning of the range, so that the
         * defrag range can be written sequentially.
         */
        start_index = cur >> PAGE_SHIFT;
        if (start_index < inode->i_mapping->writeback_index)
                inode->i_mapping->writeback_index = start_index;

        while (cur < last_byte) {
                const unsigned long prev_sectors_defragged = sectors_defragged;
                u64 last_scanned = cur;
                u64 cluster_end;

                if (btrfs_defrag_cancelled(fs_info)) {
                        ret = -EAGAIN;
                        break;
                }

                /* We want the cluster end at page boundary when possible */
                cluster_end = (((cur >> PAGE_SHIFT) +
                               (SZ_256K >> PAGE_SHIFT)) << PAGE_SHIFT) - 1;
                cluster_end = min(cluster_end, last_byte);

                btrfs_inode_lock(inode, 0);
                if (IS_SWAPFILE(inode)) {
                        ret = -ETXTBSY;
                        btrfs_inode_unlock(inode, 0);
                        break;
                }
                if (!(inode->i_sb->s_flags & SB_ACTIVE)) {
                        btrfs_inode_unlock(inode, 0);
                        break;
                }
                if (do_compress)
                        BTRFS_I(inode)->defrag_compress = compress_type;
                ret = defrag_one_cluster(BTRFS_I(inode), ra, cur,
                                cluster_end + 1 - cur, extent_thresh,
                                newer_than, do_compress, &sectors_defragged,
                                max_to_defrag, &last_scanned);

                if (sectors_defragged > prev_sectors_defragged)
                        balance_dirty_pages_ratelimited(inode->i_mapping);

                btrfs_inode_unlock(inode, 0);
                if (ret < 0)
                        break;
                cur = max(cluster_end + 1, last_scanned);
                if (ret > 0) {
                        ret = 0;
                        break;
                }
                cond_resched();
        }

        if (ra_allocated)
                kfree(ra);
        /*
         * Update range.start for autodefrag, this will indicate where to start
         * in next run.
         */
        range->start = cur;
        if (sectors_defragged) {
                /*
                 * We have defragged some sectors, for compression case they
                 * need to be written back immediately.
                 */
                if (range->flags & BTRFS_DEFRAG_RANGE_START_IO) {
                        filemap_flush(inode->i_mapping);
                        if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
                                     &BTRFS_I(inode)->runtime_flags))
                                filemap_flush(inode->i_mapping);
                }
                if (range->compress_type == BTRFS_COMPRESS_LZO)
                        btrfs_set_fs_incompat(fs_info, COMPRESS_LZO);
                else if (range->compress_type == BTRFS_COMPRESS_ZSTD)
                        btrfs_set_fs_incompat(fs_info, COMPRESS_ZSTD);
                ret = sectors_defragged;
        }
        if (do_compress) {
                btrfs_inode_lock(inode, 0);
                BTRFS_I(inode)->defrag_compress = BTRFS_COMPRESS_NONE;
                btrfs_inode_unlock(inode, 0);
        }
        return ret;
}

/*
 * Try to start exclusive operation @type or cancel it if it's running.
 *
 * Return:
 *   0        - normal mode, newly claimed op started
 *  >0        - normal mode, something else is running,
 *              return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS to user space
 * ECANCELED  - cancel mode, successful cancel
 * ENOTCONN   - cancel mode, operation not running anymore
 */
static int exclop_start_or_cancel_reloc(struct btrfs_fs_info *fs_info,
                        enum btrfs_exclusive_operation type, bool cancel)
{
        if (!cancel) {
                /* Start normal op */
                if (!btrfs_exclop_start(fs_info, type))
                        return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
                /* Exclusive operation is now claimed */
                return 0;
        }

        /* Cancel running op */
        if (btrfs_exclop_start_try_lock(fs_info, type)) {
                /*
                 * This blocks any exclop finish from setting it to NONE, so we
                 * request cancellation. Either it runs and we will wait for it,
                 * or it has finished and no waiting will happen.
                 */
                atomic_inc(&fs_info->reloc_cancel_req);
                btrfs_exclop_start_unlock(fs_info);

                if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags))
                        wait_on_bit(&fs_info->flags, BTRFS_FS_RELOC_RUNNING,
                                    TASK_INTERRUPTIBLE);

                return -ECANCELED;
        }

        /* Something else is running or none */
        return -ENOTCONN;
}

static noinline int btrfs_ioctl_resize(struct file *file,
                                        void __user *arg)
{
        BTRFS_DEV_LOOKUP_ARGS(args);
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        u64 new_size;
        u64 old_size;
        u64 devid = 1;
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_ioctl_vol_args *vol_args;
        struct btrfs_trans_handle *trans;
        struct btrfs_device *device = NULL;
        char *sizestr;
        char *retptr;
        char *devstr = NULL;
        int ret = 0;
        int mod = 0;
        bool cancel;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        /*
         * Read the arguments before checking exclusivity to be able to
         * distinguish regular resize and cancel
         */
        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args)) {
                ret = PTR_ERR(vol_args);
                goto out_drop;
        }
        vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
        sizestr = vol_args->name;
        cancel = (strcmp("cancel", sizestr) == 0);
        ret = exclop_start_or_cancel_reloc(fs_info, BTRFS_EXCLOP_RESIZE, cancel);
        if (ret)
                goto out_free;
        /* Exclusive operation is now claimed */

        devstr = strchr(sizestr, ':');
        if (devstr) {
                sizestr = devstr + 1;
                *devstr = '\0';
                devstr = vol_args->name;
                ret = kstrtoull(devstr, 10, &devid);
                if (ret)
                        goto out_finish;
                if (!devid) {
                        ret = -EINVAL;
                        goto out_finish;
                }
                btrfs_info(fs_info, "resizing devid %llu", devid);
        }

        args.devid = devid;
        device = btrfs_find_device(fs_info->fs_devices, &args);
        if (!device) {
                btrfs_info(fs_info, "resizer unable to find device %llu",
                           devid);
                ret = -ENODEV;
                goto out_finish;
        }

        if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) {
                btrfs_info(fs_info,
                           "resizer unable to apply on readonly device %llu",
                       devid);
                ret = -EPERM;
                goto out_finish;
        }

        if (!strcmp(sizestr, "max"))
                new_size = bdev_nr_bytes(device->bdev);
        else {
                if (sizestr[0] == '-') {
                        mod = -1;
                        sizestr++;
                } else if (sizestr[0] == '+') {
                        mod = 1;
                        sizestr++;
                }
                new_size = memparse(sizestr, &retptr);
                if (*retptr != '\0' || new_size == 0) {
                        ret = -EINVAL;
                        goto out_finish;
                }
        }

        if (test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
                ret = -EPERM;
                goto out_finish;
        }

        old_size = btrfs_device_get_total_bytes(device);

        if (mod < 0) {
                if (new_size > old_size) {
                        ret = -EINVAL;
                        goto out_finish;
                }
                new_size = old_size - new_size;
        } else if (mod > 0) {
                if (new_size > ULLONG_MAX - old_size) {
                        ret = -ERANGE;
                        goto out_finish;
                }
                new_size = old_size + new_size;
        }

        if (new_size < SZ_256M) {
                ret = -EINVAL;
                goto out_finish;
        }
        if (new_size > bdev_nr_bytes(device->bdev)) {
                ret = -EFBIG;
                goto out_finish;
        }

        new_size = round_down(new_size, fs_info->sectorsize);

        if (new_size > old_size) {
                trans = btrfs_start_transaction(root, 0);
                if (IS_ERR(trans)) {
                        ret = PTR_ERR(trans);
                        goto out_finish;
                }
                ret = btrfs_grow_device(trans, device, new_size);
                btrfs_commit_transaction(trans);
        } else if (new_size < old_size) {
                ret = btrfs_shrink_device(device, new_size);
        } /* equal, nothing need to do */

        if (ret == 0 && new_size != old_size)
                btrfs_info_in_rcu(fs_info,
                        "resize device %s (devid %llu) from %llu to %llu",
                        rcu_str_deref(device->name), device->devid,
                        old_size, new_size);
out_finish:
        btrfs_exclop_finish(fs_info);
out_free:
        kfree(vol_args);
out_drop:
        mnt_drop_write_file(file);
        return ret;
}

static noinline int __btrfs_ioctl_snap_create(struct file *file,
                                struct user_namespace *mnt_userns,
                                const char *name, unsigned long fd, int subvol,
                                bool readonly,
                                struct btrfs_qgroup_inherit *inherit)
{
        int namelen;
        int ret = 0;

        if (!S_ISDIR(file_inode(file)->i_mode))
                return -ENOTDIR;

        ret = mnt_want_write_file(file);
        if (ret)
                goto out;

        namelen = strlen(name);
        if (strchr(name, '/')) {
                ret = -EINVAL;
                goto out_drop_write;
        }

        if (name[0] == '.' &&
           (namelen == 1 || (name[1] == '.' && namelen == 2))) {
                ret = -EEXIST;
                goto out_drop_write;
        }

        if (subvol) {
                ret = btrfs_mksubvol(&file->f_path, mnt_userns, name,
                                     namelen, NULL, readonly, inherit);
        } else {
                struct fd src = fdget(fd);
                struct inode *src_inode;
                if (!src.file) {
                        ret = -EINVAL;
                        goto out_drop_write;
                }

                src_inode = file_inode(src.file);
                if (src_inode->i_sb != file_inode(file)->i_sb) {
                        btrfs_info(BTRFS_I(file_inode(file))->root->fs_info,
                                   "Snapshot src from another FS");
                        ret = -EXDEV;
                } else if (!inode_owner_or_capable(mnt_userns, src_inode)) {
                        /*
                         * Subvolume creation is not restricted, but snapshots
                         * are limited to own subvolumes only
                         */
                        ret = -EPERM;
                } else {
                        ret = btrfs_mksnapshot(&file->f_path, mnt_userns,
                                               name, namelen,
                                               BTRFS_I(src_inode)->root,
                                               readonly, inherit);
                }
                fdput(src);
        }
out_drop_write:
        mnt_drop_write_file(file);
out:
        return ret;
}

static noinline int btrfs_ioctl_snap_create(struct file *file,
                                            void __user *arg, int subvol)
{
        struct btrfs_ioctl_vol_args *vol_args;
        int ret;

        if (!S_ISDIR(file_inode(file)->i_mode))
                return -ENOTDIR;

        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args))
                return PTR_ERR(vol_args);
        vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';

        ret = __btrfs_ioctl_snap_create(file, file_mnt_user_ns(file),
                                        vol_args->name, vol_args->fd, subvol,
                                        false, NULL);

        kfree(vol_args);
        return ret;
}

static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
                                               void __user *arg, int subvol)
{
        struct btrfs_ioctl_vol_args_v2 *vol_args;
        int ret;
        bool readonly = false;
        struct btrfs_qgroup_inherit *inherit = NULL;

        if (!S_ISDIR(file_inode(file)->i_mode))
                return -ENOTDIR;

        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args))
                return PTR_ERR(vol_args);
        vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';

        if (vol_args->flags & ~BTRFS_SUBVOL_CREATE_ARGS_MASK) {
                ret = -EOPNOTSUPP;
                goto free_args;
        }

        if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
                readonly = true;
        if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
                u64 nums;

                if (vol_args->size < sizeof(*inherit) ||
                    vol_args->size > PAGE_SIZE) {
                        ret = -EINVAL;
                        goto free_args;
                }
                inherit = memdup_user(vol_args->qgroup_inherit, vol_args->size);
                if (IS_ERR(inherit)) {
                        ret = PTR_ERR(inherit);
                        goto free_args;
                }

                if (inherit->num_qgroups > PAGE_SIZE ||
                    inherit->num_ref_copies > PAGE_SIZE ||
                    inherit->num_excl_copies > PAGE_SIZE) {
                        ret = -EINVAL;
                        goto free_inherit;
                }

                nums = inherit->num_qgroups + 2 * inherit->num_ref_copies +
                       2 * inherit->num_excl_copies;
                if (vol_args->size != struct_size(inherit, qgroups, nums)) {
                        ret = -EINVAL;
                        goto free_inherit;
                }
        }

        ret = __btrfs_ioctl_snap_create(file, file_mnt_user_ns(file),
                                        vol_args->name, vol_args->fd, subvol,
                                        readonly, inherit);
        if (ret)
                goto free_inherit;
free_inherit:
        kfree(inherit);
free_args:
        kfree(vol_args);
        return ret;
}

static noinline int btrfs_ioctl_subvol_getflags(struct inode *inode,
                                                void __user *arg)
{
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        int ret = 0;
        u64 flags = 0;

        if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID)
                return -EINVAL;

        down_read(&fs_info->subvol_sem);
        if (btrfs_root_readonly(root))
                flags |= BTRFS_SUBVOL_RDONLY;
        up_read(&fs_info->subvol_sem);

        if (copy_to_user(arg, &flags, sizeof(flags)))
                ret = -EFAULT;

        return ret;
}

static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
                                              void __user *arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_trans_handle *trans;
        u64 root_flags;
        u64 flags;
        int ret = 0;

        if (!inode_owner_or_capable(file_mnt_user_ns(file), inode))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                goto out;

        if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
                ret = -EINVAL;
                goto out_drop_write;
        }

        if (copy_from_user(&flags, arg, sizeof(flags))) {
                ret = -EFAULT;
                goto out_drop_write;
        }

        if (flags & ~BTRFS_SUBVOL_RDONLY) {
                ret = -EOPNOTSUPP;
                goto out_drop_write;
        }

        down_write(&fs_info->subvol_sem);

        /* nothing to do */
        if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root))
                goto out_drop_sem;

        root_flags = btrfs_root_flags(&root->root_item);
        if (flags & BTRFS_SUBVOL_RDONLY) {
                btrfs_set_root_flags(&root->root_item,
                                     root_flags | BTRFS_ROOT_SUBVOL_RDONLY);
        } else {
                /*
                 * Block RO -> RW transition if this subvolume is involved in
                 * send
                 */
                spin_lock(&root->root_item_lock);
                if (root->send_in_progress == 0) {
                        btrfs_set_root_flags(&root->root_item,
                                     root_flags & ~BTRFS_ROOT_SUBVOL_RDONLY);
                        spin_unlock(&root->root_item_lock);
                } else {
                        spin_unlock(&root->root_item_lock);
                        btrfs_warn(fs_info,
                                   "Attempt to set subvolume %llu read-write during send",
                                   root->root_key.objectid);
                        ret = -EPERM;
                        goto out_drop_sem;
                }
        }

        trans = btrfs_start_transaction(root, 1);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto out_reset;
        }

        ret = btrfs_update_root(trans, fs_info->tree_root,
                                &root->root_key, &root->root_item);
        if (ret < 0) {
                btrfs_end_transaction(trans);
                goto out_reset;
        }

        ret = btrfs_commit_transaction(trans);

out_reset:
        if (ret)
                btrfs_set_root_flags(&root->root_item, root_flags);
out_drop_sem:
        up_write(&fs_info->subvol_sem);
out_drop_write:
        mnt_drop_write_file(file);
out:
        return ret;
}

static noinline int key_in_sk(struct btrfs_key *key,
                              struct btrfs_ioctl_search_key *sk)
{
        struct btrfs_key test;
        int ret;

        test.objectid = sk->min_objectid;
        test.type = sk->min_type;
        test.offset = sk->min_offset;

        ret = btrfs_comp_cpu_keys(key, &test);
        if (ret < 0)
                return 0;

        test.objectid = sk->max_objectid;
        test.type = sk->max_type;
        test.offset = sk->max_offset;

        ret = btrfs_comp_cpu_keys(key, &test);
        if (ret > 0)
                return 0;
        return 1;
}

static noinline int copy_to_sk(struct btrfs_path *path,
                               struct btrfs_key *key,
                               struct btrfs_ioctl_search_key *sk,
                               size_t *buf_size,
                               char __user *ubuf,
                               unsigned long *sk_offset,
                               int *num_found)
{
        u64 found_transid;
        struct extent_buffer *leaf;
        struct btrfs_ioctl_search_header sh;
        struct btrfs_key test;
        unsigned long item_off;
        unsigned long item_len;
        int nritems;
        int i;
        int slot;
        int ret = 0;

        leaf = path->nodes[0];
        slot = path->slots[0];
        nritems = btrfs_header_nritems(leaf);

        if (btrfs_header_generation(leaf) > sk->max_transid) {
                i = nritems;
                goto advance_key;
        }
        found_transid = btrfs_header_generation(leaf);

        for (i = slot; i < nritems; i++) {
                item_off = btrfs_item_ptr_offset(leaf, i);
                item_len = btrfs_item_size(leaf, i);

                btrfs_item_key_to_cpu(leaf, key, i);
                if (!key_in_sk(key, sk))
                        continue;

                if (sizeof(sh) + item_len > *buf_size) {
                        if (*num_found) {
                                ret = 1;
                                goto out;
                        }

                        /*
                         * return one empty item back for v1, which does not
                         * handle -EOVERFLOW
                         */

                        *buf_size = sizeof(sh) + item_len;
                        item_len = 0;
                        ret = -EOVERFLOW;
                }

                if (sizeof(sh) + item_len + *sk_offset > *buf_size) {
                        ret = 1;
                        goto out;
                }

                sh.objectid = key->objectid;
                sh.offset = key->offset;
                sh.type = key->type;
                sh.len = item_len;
                sh.transid = found_transid;

                /*
                 * Copy search result header. If we fault then loop again so we
                 * can fault in the pages and -EFAULT there if there's a
                 * problem. Otherwise we'll fault and then copy the buffer in
                 * properly this next time through
                 */
                if (copy_to_user_nofault(ubuf + *sk_offset, &sh, sizeof(sh))) {
                        ret = 0;
                        goto out;
                }

                *sk_offset += sizeof(sh);

                if (item_len) {
                        char __user *up = ubuf + *sk_offset;
                        /*
                         * Copy the item, same behavior as above, but reset the
                         * * sk_offset so we copy the full thing again.
                         */
                        if (read_extent_buffer_to_user_nofault(leaf, up,
                                                item_off, item_len)) {
                                ret = 0;
                                *sk_offset -= sizeof(sh);
                                goto out;
                        }

                        *sk_offset += item_len;
                }
                (*num_found)++;

                if (ret) /* -EOVERFLOW from above */
                        goto out;

                if (*num_found >= sk->nr_items) {
                        ret = 1;
                        goto out;
                }
        }
advance_key:
        ret = 0;
        test.objectid = sk->max_objectid;
        test.type = sk->max_type;
        test.offset = sk->max_offset;
        if (btrfs_comp_cpu_keys(key, &test) >= 0)
                ret = 1;
        else if (key->offset < (u64)-1)
                key->offset++;
        else if (key->type < (u8)-1) {
                key->offset = 0;
                key->type++;
        } else if (key->objectid < (u64)-1) {
                key->offset = 0;
                key->type = 0;
                key->objectid++;
        } else
                ret = 1;
out:
        /*
         *  0: all items from this leaf copied, continue with next
         *  1: * more items can be copied, but unused buffer is too small
         *     * all items were found
         *     Either way, it will stops the loop which iterates to the next
         *     leaf
         *  -EOVERFLOW: item was to large for buffer
         *  -EFAULT: could not copy extent buffer back to userspace
         */
        return ret;
}

static noinline int search_ioctl(struct inode *inode,
                                 struct btrfs_ioctl_search_key *sk,
                                 size_t *buf_size,
                                 char __user *ubuf)
{
        struct btrfs_fs_info *info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root;
        struct btrfs_key key;
        struct btrfs_path *path;
        int ret;
        int num_found = 0;
        unsigned long sk_offset = 0;

        if (*buf_size < sizeof(struct btrfs_ioctl_search_header)) {
                *buf_size = sizeof(struct btrfs_ioctl_search_header);
                return -EOVERFLOW;
        }

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        if (sk->tree_id == 0) {
                /* search the root of the inode that was passed */
                root = btrfs_grab_root(BTRFS_I(inode)->root);
        } else {
                root = btrfs_get_fs_root(info, sk->tree_id, true);
                if (IS_ERR(root)) {
                        btrfs_free_path(path);
                        return PTR_ERR(root);
                }
        }

        key.objectid = sk->min_objectid;
        key.type = sk->min_type;
        key.offset = sk->min_offset;

        while (1) {
                ret = -EFAULT;
                /*
                 * Ensure that the whole user buffer is faulted in at sub-page
                 * granularity, otherwise the loop may live-lock.
                 */
                if (fault_in_subpage_writeable(ubuf + sk_offset,
                                               *buf_size - sk_offset))
                        break;

                ret = btrfs_search_forward(root, &key, path, sk->min_transid);
                if (ret != 0) {
                        if (ret > 0)
                                ret = 0;
                        goto err;
                }
                ret = copy_to_sk(path, &key, sk, buf_size, ubuf,
                                 &sk_offset, &num_found);
                btrfs_release_path(path);
                if (ret)
                        break;

        }
        if (ret > 0)
                ret = 0;
err:
        sk->nr_items = num_found;
        btrfs_put_root(root);
        btrfs_free_path(path);
        return ret;
}

static noinline int btrfs_ioctl_tree_search(struct inode *inode,
                                            void __user *argp)
{
        struct btrfs_ioctl_search_args __user *uargs = argp;
        struct btrfs_ioctl_search_key sk;
        int ret;
        size_t buf_size;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (copy_from_user(&sk, &uargs->key, sizeof(sk)))
                return -EFAULT;

        buf_size = sizeof(uargs->buf);

        ret = search_ioctl(inode, &sk, &buf_size, uargs->buf);

        /*
         * In the origin implementation an overflow is handled by returning a
         * search header with a len of zero, so reset ret.
         */
        if (ret == -EOVERFLOW)
                ret = 0;

        if (ret == 0 && copy_to_user(&uargs->key, &sk, sizeof(sk)))
                ret = -EFAULT;
        return ret;
}

static noinline int btrfs_ioctl_tree_search_v2(struct inode *inode,
                                               void __user *argp)
{
        struct btrfs_ioctl_search_args_v2 __user *uarg = argp;
        struct btrfs_ioctl_search_args_v2 args;
        int ret;
        size_t buf_size;
        const size_t buf_limit = SZ_16M;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        /* copy search header and buffer size */
        if (copy_from_user(&args, uarg, sizeof(args)))
                return -EFAULT;

        buf_size = args.buf_size;

        /* limit result size to 16MB */
        if (buf_size > buf_limit)
                buf_size = buf_limit;

        ret = search_ioctl(inode, &args.key, &buf_size,
                           (char __user *)(&uarg->buf[0]));
        if (ret == 0 && copy_to_user(&uarg->key, &args.key, sizeof(args.key)))
                ret = -EFAULT;
        else if (ret == -EOVERFLOW &&
                copy_to_user(&uarg->buf_size, &buf_size, sizeof(buf_size)))
                ret = -EFAULT;

        return ret;
}

/*
 * Search INODE_REFs to identify path name of 'dirid' directory
 * in a 'tree_id' tree. and sets path name to 'name'.
 */
static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
                                u64 tree_id, u64 dirid, char *name)
{
        struct btrfs_root *root;
        struct btrfs_key key;
        char *ptr;
        int ret = -1;
        int slot;
        int len;
        int total_len = 0;
        struct btrfs_inode_ref *iref;
        struct extent_buffer *l;
        struct btrfs_path *path;

        if (dirid == BTRFS_FIRST_FREE_OBJECTID) {
                name[0]='\0';
                return 0;
        }

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        ptr = &name[BTRFS_INO_LOOKUP_PATH_MAX - 1];

        root = btrfs_get_fs_root(info, tree_id, true);
        if (IS_ERR(root)) {
                ret = PTR_ERR(root);
                root = NULL;
                goto out;
        }

        key.objectid = dirid;
        key.type = BTRFS_INODE_REF_KEY;
        key.offset = (u64)-1;

        while (1) {
                ret = btrfs_search_backwards(root, &key, path);
                if (ret < 0)
                        goto out;
                else if (ret > 0) {
                        ret = -ENOENT;
                        goto out;
                }

                l = path->nodes[0];
                slot = path->slots[0];

                iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);
                len = btrfs_inode_ref_name_len(l, iref);
                ptr -= len + 1;
                total_len += len + 1;
                if (ptr < name) {
                        ret = -ENAMETOOLONG;
                        goto out;
                }

                *(ptr + len) = '/';
                read_extent_buffer(l, ptr, (unsigned long)(iref + 1), len);

                if (key.offset == BTRFS_FIRST_FREE_OBJECTID)
                        break;

                btrfs_release_path(path);
                key.objectid = key.offset;
                key.offset = (u64)-1;
                dirid = key.objectid;
        }
        memmove(name, ptr, total_len);
        name[total_len] = '\0';
        ret = 0;
out:
        btrfs_put_root(root);
        btrfs_free_path(path);
        return ret;
}

static int btrfs_search_path_in_tree_user(struct user_namespace *mnt_userns,
                                struct inode *inode,
                                struct btrfs_ioctl_ino_lookup_user_args *args)
{
        struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
        struct super_block *sb = inode->i_sb;
        struct btrfs_key upper_limit = BTRFS_I(inode)->location;
        u64 treeid = BTRFS_I(inode)->root->root_key.objectid;
        u64 dirid = args->dirid;
        unsigned long item_off;
        unsigned long item_len;
        struct btrfs_inode_ref *iref;
        struct btrfs_root_ref *rref;
        struct btrfs_root *root = NULL;
        struct btrfs_path *path;
        struct btrfs_key key, key2;
        struct extent_buffer *leaf;
        struct inode *temp_inode;
        char *ptr;
        int slot;
        int len;
        int total_len = 0;
        int ret;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        /*
         * If the bottom subvolume does not exist directly under upper_limit,
         * construct the path in from the bottom up.
         */
        if (dirid != upper_limit.objectid) {
                ptr = &args->path[BTRFS_INO_LOOKUP_USER_PATH_MAX - 1];

                root = btrfs_get_fs_root(fs_info, treeid, true);
                if (IS_ERR(root)) {
                        ret = PTR_ERR(root);
                        goto out;
                }

                key.objectid = dirid;
                key.type = BTRFS_INODE_REF_KEY;
                key.offset = (u64)-1;
                while (1) {
                        ret = btrfs_search_backwards(root, &key, path);
                        if (ret < 0)
                                goto out_put;
                        else if (ret > 0) {
                                ret = -ENOENT;
                                goto out_put;
                        }

                        leaf = path->nodes[0];
                        slot = path->slots[0];

                        iref = btrfs_item_ptr(leaf, slot, struct btrfs_inode_ref);
                        len = btrfs_inode_ref_name_len(leaf, iref);
                        ptr -= len + 1;
                        total_len += len + 1;
                        if (ptr < args->path) {
                                ret = -ENAMETOOLONG;
                                goto out_put;
                        }

                        *(ptr + len) = '/';
                        read_extent_buffer(leaf, ptr,
                                        (unsigned long)(iref + 1), len);

                        /* Check the read+exec permission of this directory */
                        ret = btrfs_previous_item(root, path, dirid,
                                                  BTRFS_INODE_ITEM_KEY);
                        if (ret < 0) {
                                goto out_put;
                        } else if (ret > 0) {
                                ret = -ENOENT;
                                goto out_put;
                        }

                        leaf = path->nodes[0];
                        slot = path->slots[0];
                        btrfs_item_key_to_cpu(leaf, &key2, slot);
                        if (key2.objectid != dirid) {
                                ret = -ENOENT;
                                goto out_put;
                        }

                        temp_inode = btrfs_iget(sb, key2.objectid, root);
                        if (IS_ERR(temp_inode)) {
                                ret = PTR_ERR(temp_inode);
                                goto out_put;
                        }
                        ret = inode_permission(mnt_userns, temp_inode,
                                               MAY_READ | MAY_EXEC);
                        iput(temp_inode);
                        if (ret) {
                                ret = -EACCES;
                                goto out_put;
                        }

                        if (key.offset == upper_limit.objectid)
                                break;
                        if (key.objectid == BTRFS_FIRST_FREE_OBJECTID) {
                                ret = -EACCES;
                                goto out_put;
                        }

                        btrfs_release_path(path);
                        key.objectid = key.offset;
                        key.offset = (u64)-1;
                        dirid = key.objectid;
                }

                memmove(args->path, ptr, total_len);
                args->path[total_len] = '\0';
                btrfs_put_root(root);
                root = NULL;
                btrfs_release_path(path);
        }

        /* Get the bottom subvolume's name from ROOT_REF */
        key.objectid = treeid;
        key.type = BTRFS_ROOT_REF_KEY;
        key.offset = args->treeid;
        ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
        if (ret < 0) {
                goto out;
        } else if (ret > 0) {
                ret = -ENOENT;
                goto out;
        }

        leaf = path->nodes[0];
        slot = path->slots[0];
        btrfs_item_key_to_cpu(leaf, &key, slot);

        item_off = btrfs_item_ptr_offset(leaf, slot);
        item_len = btrfs_item_size(leaf, slot);
        /* Check if dirid in ROOT_REF corresponds to passed dirid */
        rref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
        if (args->dirid != btrfs_root_ref_dirid(leaf, rref)) {
                ret = -EINVAL;
                goto out;
        }

        /* Copy subvolume's name */
        item_off += sizeof(struct btrfs_root_ref);
        item_len -= sizeof(struct btrfs_root_ref);
        read_extent_buffer(leaf, args->name, item_off, item_len);
        args->name[item_len] = 0;

out_put:
        btrfs_put_root(root);
out:
        btrfs_free_path(path);
        return ret;
}

static noinline int btrfs_ioctl_ino_lookup(struct btrfs_root *root,
                                           void __user *argp)
{
        struct btrfs_ioctl_ino_lookup_args *args;
        int ret = 0;

        args = memdup_user(argp, sizeof(*args));
        if (IS_ERR(args))
                return PTR_ERR(args);

        /*
         * Unprivileged query to obtain the containing subvolume root id. The
         * path is reset so it's consistent with btrfs_search_path_in_tree.
         */
        if (args->treeid == 0)
                args->treeid = root->root_key.objectid;

        if (args->objectid == BTRFS_FIRST_FREE_OBJECTID) {
                args->name[0] = 0;
                goto out;
        }

        if (!capable(CAP_SYS_ADMIN)) {
                ret = -EPERM;
                goto out;
        }

        ret = btrfs_search_path_in_tree(root->fs_info,
                                        args->treeid, args->objectid,
                                        args->name);

out:
        if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
                ret = -EFAULT;

        kfree(args);
        return ret;
}

/*
 * Version of ino_lookup ioctl (unprivileged)
 *
 * The main differences from ino_lookup ioctl are:
 *
 *   1. Read + Exec permission will be checked using inode_permission() during
 *      path construction. -EACCES will be returned in case of failure.
 *   2. Path construction will be stopped at the inode number which corresponds
 *      to the fd with which this ioctl is called. If constructed path does not
 *      exist under fd's inode, -EACCES will be returned.
 *   3. The name of bottom subvolume is also searched and filled.
 */
static int btrfs_ioctl_ino_lookup_user(struct file *file, void __user *argp)
{
        struct btrfs_ioctl_ino_lookup_user_args *args;
        struct inode *inode;
        int ret;

        args = memdup_user(argp, sizeof(*args));
        if (IS_ERR(args))
                return PTR_ERR(args);

        inode = file_inode(file);

        if (args->dirid == BTRFS_FIRST_FREE_OBJECTID &&
            BTRFS_I(inode)->location.objectid != BTRFS_FIRST_FREE_OBJECTID) {
                /*
                 * The subvolume does not exist under fd with which this is
                 * called
                 */
                kfree(args);
                return -EACCES;
        }

        ret = btrfs_search_path_in_tree_user(file_mnt_user_ns(file), inode, args);

        if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))
                ret = -EFAULT;

        kfree(args);
        return ret;
}

/* Get the subvolume information in BTRFS_ROOT_ITEM and BTRFS_ROOT_BACKREF */
static int btrfs_ioctl_get_subvol_info(struct inode *inode, void __user *argp)
{
        struct btrfs_ioctl_get_subvol_info_args *subvol_info;
        struct btrfs_fs_info *fs_info;
        struct btrfs_root *root;
        struct btrfs_path *path;
        struct btrfs_key key;
        struct btrfs_root_item *root_item;
        struct btrfs_root_ref *rref;
        struct extent_buffer *leaf;
        unsigned long item_off;
        unsigned long item_len;
        int slot;
        int ret = 0;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        subvol_info = kzalloc(sizeof(*subvol_info), GFP_KERNEL);
        if (!subvol_info) {
                btrfs_free_path(path);
                return -ENOMEM;
        }

        fs_info = BTRFS_I(inode)->root->fs_info;

        /* Get root_item of inode's subvolume */
        key.objectid = BTRFS_I(inode)->root->root_key.objectid;
        root = btrfs_get_fs_root(fs_info, key.objectid, true);
        if (IS_ERR(root)) {
                ret = PTR_ERR(root);
                goto out_free;
        }
        root_item = &root->root_item;

        subvol_info->treeid = key.objectid;

        subvol_info->generation = btrfs_root_generation(root_item);
        subvol_info->flags = btrfs_root_flags(root_item);

        memcpy(subvol_info->uuid, root_item->uuid, BTRFS_UUID_SIZE);
        memcpy(subvol_info->parent_uuid, root_item->parent_uuid,
                                                    BTRFS_UUID_SIZE);
        memcpy(subvol_info->received_uuid, root_item->received_uuid,
                                                    BTRFS_UUID_SIZE);

        subvol_info->ctransid = btrfs_root_ctransid(root_item);
        subvol_info->ctime.sec = btrfs_stack_timespec_sec(&root_item->ctime);
        subvol_info->ctime.nsec = btrfs_stack_timespec_nsec(&root_item->ctime);

        subvol_info->otransid = btrfs_root_otransid(root_item);
        subvol_info->otime.sec = btrfs_stack_timespec_sec(&root_item->otime);
        subvol_info->otime.nsec = btrfs_stack_timespec_nsec(&root_item->otime);

        subvol_info->stransid = btrfs_root_stransid(root_item);
        subvol_info->stime.sec = btrfs_stack_timespec_sec(&root_item->stime);
        subvol_info->stime.nsec = btrfs_stack_timespec_nsec(&root_item->stime);

        subvol_info->rtransid = btrfs_root_rtransid(root_item);
        subvol_info->rtime.sec = btrfs_stack_timespec_sec(&root_item->rtime);
        subvol_info->rtime.nsec = btrfs_stack_timespec_nsec(&root_item->rtime);

        if (key.objectid != BTRFS_FS_TREE_OBJECTID) {
                /* Search root tree for ROOT_BACKREF of this subvolume */
                key.type = BTRFS_ROOT_BACKREF_KEY;
                key.offset = 0;
                ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
                if (ret < 0) {
                        goto out;
                } else if (path->slots[0] >=
                           btrfs_header_nritems(path->nodes[0])) {
                        ret = btrfs_next_leaf(fs_info->tree_root, path);
                        if (ret < 0) {
                                goto out;
                        } else if (ret > 0) {
                                ret = -EUCLEAN;
                                goto out;
                        }
                }

                leaf = path->nodes[0];
                slot = path->slots[0];
                btrfs_item_key_to_cpu(leaf, &key, slot);
                if (key.objectid == subvol_info->treeid &&
                    key.type == BTRFS_ROOT_BACKREF_KEY) {
                        subvol_info->parent_id = key.offset;

                        rref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
                        subvol_info->dirid = btrfs_root_ref_dirid(leaf, rref);

                        item_off = btrfs_item_ptr_offset(leaf, slot)
                                        + sizeof(struct btrfs_root_ref);
                        item_len = btrfs_item_size(leaf, slot)
                                        - sizeof(struct btrfs_root_ref);
                        read_extent_buffer(leaf, subvol_info->name,
                                           item_off, item_len);
                } else {
                        ret = -ENOENT;
                        goto out;
                }
        }

        if (copy_to_user(argp, subvol_info, sizeof(*subvol_info)))
                ret = -EFAULT;

out:
        btrfs_put_root(root);
out_free:
        btrfs_free_path(path);
        kfree(subvol_info);
        return ret;
}

/*
 * Return ROOT_REF information of the subvolume containing this inode
 * except the subvolume name.
 */
static int btrfs_ioctl_get_subvol_rootref(struct btrfs_root *root,
                                          void __user *argp)
{
        struct btrfs_ioctl_get_subvol_rootref_args *rootrefs;
        struct btrfs_root_ref *rref;
        struct btrfs_path *path;
        struct btrfs_key key;
        struct extent_buffer *leaf;
        u64 objectid;
        int slot;
        int ret;
        u8 found;

        path = btrfs_alloc_path();
        if (!path)
                return -ENOMEM;

        rootrefs = memdup_user(argp, sizeof(*rootrefs));
        if (IS_ERR(rootrefs)) {
                btrfs_free_path(path);
                return PTR_ERR(rootrefs);
        }

        objectid = root->root_key.objectid;
        key.objectid = objectid;
        key.type = BTRFS_ROOT_REF_KEY;
        key.offset = rootrefs->min_treeid;
        found = 0;

        root = root->fs_info->tree_root;
        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
        if (ret < 0) {
                goto out;
        } else if (path->slots[0] >=
                   btrfs_header_nritems(path->nodes[0])) {
                ret = btrfs_next_leaf(root, path);
                if (ret < 0) {
                        goto out;
                } else if (ret > 0) {
                        ret = -EUCLEAN;
                        goto out;
                }
        }
        while (1) {
                leaf = path->nodes[0];
                slot = path->slots[0];

                btrfs_item_key_to_cpu(leaf, &key, slot);
                if (key.objectid != objectid || key.type != BTRFS_ROOT_REF_KEY) {
                        ret = 0;
                        goto out;
                }

                if (found == BTRFS_MAX_ROOTREF_BUFFER_NUM) {
                        ret = -EOVERFLOW;
                        goto out;
                }

                rref = btrfs_item_ptr(leaf, slot, struct btrfs_root_ref);
                rootrefs->rootref[found].treeid = key.offset;
                rootrefs->rootref[found].dirid =
                                  btrfs_root_ref_dirid(leaf, rref);
                found++;

                ret = btrfs_next_item(root, path);
                if (ret < 0) {
                        goto out;
                } else if (ret > 0) {
                        ret = -EUCLEAN;
                        goto out;
                }
        }

out:
        if (!ret || ret == -EOVERFLOW) {
                rootrefs->num_items = found;
                /* update min_treeid for next search */
                if (found)
                        rootrefs->min_treeid =
                                rootrefs->rootref[found - 1].treeid + 1;
                if (copy_to_user(argp, rootrefs, sizeof(*rootrefs)))
                        ret = -EFAULT;
        }

        kfree(rootrefs);
        btrfs_free_path(path);

        return ret;
}

static noinline int btrfs_ioctl_snap_destroy(struct file *file,
                                             void __user *arg,
                                             bool destroy_v2)
{
        struct dentry *parent = file->f_path.dentry;
        struct btrfs_fs_info *fs_info = btrfs_sb(parent->d_sb);
        struct dentry *dentry;
        struct inode *dir = d_inode(parent);
        struct inode *inode;
        struct btrfs_root *root = BTRFS_I(dir)->root;
        struct btrfs_root *dest = NULL;
        struct btrfs_ioctl_vol_args *vol_args = NULL;
        struct btrfs_ioctl_vol_args_v2 *vol_args2 = NULL;
        struct user_namespace *mnt_userns = file_mnt_user_ns(file);
        char *subvol_name, *subvol_name_ptr = NULL;
        int subvol_namelen;
        int err = 0;
        bool destroy_parent = false;

        /* We don't support snapshots with extent tree v2 yet. */
        if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
                btrfs_err(fs_info,
                          "extent tree v2 doesn't support snapshot deletion yet");
                return -EOPNOTSUPP;
        }

        if (destroy_v2) {
                vol_args2 = memdup_user(arg, sizeof(*vol_args2));
                if (IS_ERR(vol_args2))
                        return PTR_ERR(vol_args2);

                if (vol_args2->flags & ~BTRFS_SUBVOL_DELETE_ARGS_MASK) {
                        err = -EOPNOTSUPP;
                        goto out;
                }

                /*
                 * If SPEC_BY_ID is not set, we are looking for the subvolume by
                 * name, same as v1 currently does.
                 */
                if (!(vol_args2->flags & BTRFS_SUBVOL_SPEC_BY_ID)) {
                        vol_args2->name[BTRFS_SUBVOL_NAME_MAX] = 0;
                        subvol_name = vol_args2->name;

                        err = mnt_want_write_file(file);
                        if (err)
                                goto out;
                } else {
                        struct inode *old_dir;

                        if (vol_args2->subvolid < BTRFS_FIRST_FREE_OBJECTID) {
                                err = -EINVAL;
                                goto out;
                        }

                        err = mnt_want_write_file(file);
                        if (err)
                                goto out;

                        dentry = btrfs_get_dentry(fs_info->sb,
                                        BTRFS_FIRST_FREE_OBJECTID,
                                        vol_args2->subvolid, 0, 0);
                        if (IS_ERR(dentry)) {
                                err = PTR_ERR(dentry);
                                goto out_drop_write;
                        }

                        /*
                         * Change the default parent since the subvolume being
                         * deleted can be outside of the current mount point.
                         */
                        parent = btrfs_get_parent(dentry);

                        /*
                         * At this point dentry->d_name can point to '/' if the
                         * subvolume we want to destroy is outsite of the
                         * current mount point, so we need to release the
                         * current dentry and execute the lookup to return a new
                         * one with ->d_name pointing to the
                         * <mount point>/subvol_name.
                         */
                        dput(dentry);
                        if (IS_ERR(parent)) {
                                err = PTR_ERR(parent);
                                goto out_drop_write;
                        }
                        old_dir = dir;
                        dir = d_inode(parent);

                        /*
                         * If v2 was used with SPEC_BY_ID, a new parent was
                         * allocated since the subvolume can be outside of the
                         * current mount point. Later on we need to release this
                         * new parent dentry.
                         */
                        destroy_parent = true;

                        /*
                         * On idmapped mounts, deletion via subvolid is
                         * restricted to subvolumes that are immediate
                         * ancestors of the inode referenced by the file
                         * descriptor in the ioctl. Otherwise the idmapping
                         * could potentially be abused to delete subvolumes
                         * anywhere in the filesystem the user wouldn't be able
                         * to delete without an idmapped mount.
                         */
                        if (old_dir != dir && mnt_userns != &init_user_ns) {
                                err = -EOPNOTSUPP;
                                goto free_parent;
                        }

                        subvol_name_ptr = btrfs_get_subvol_name_from_objectid(
                                                fs_info, vol_args2->subvolid);
                        if (IS_ERR(subvol_name_ptr)) {
                                err = PTR_ERR(subvol_name_ptr);
                                goto free_parent;
                        }
                        /* subvol_name_ptr is already nul terminated */
                        subvol_name = (char *)kbasename(subvol_name_ptr);
                }
        } else {
                vol_args = memdup_user(arg, sizeof(*vol_args));
                if (IS_ERR(vol_args))
                        return PTR_ERR(vol_args);

                vol_args->name[BTRFS_PATH_NAME_MAX] = 0;
                subvol_name = vol_args->name;

                err = mnt_want_write_file(file);
                if (err)
                        goto out;
        }

        subvol_namelen = strlen(subvol_name);

        if (strchr(subvol_name, '/') ||
            strncmp(subvol_name, "..", subvol_namelen) == 0) {
                err = -EINVAL;
                goto free_subvol_name;
        }

        if (!S_ISDIR(dir->i_mode)) {
                err = -ENOTDIR;
                goto free_subvol_name;
        }

        err = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
        if (err == -EINTR)
                goto free_subvol_name;
        dentry = lookup_one(mnt_userns, subvol_name, parent, subvol_namelen);
        if (IS_ERR(dentry)) {
                err = PTR_ERR(dentry);
                goto out_unlock_dir;
        }

        if (d_really_is_negative(dentry)) {
                err = -ENOENT;
                goto out_dput;
        }

        inode = d_inode(dentry);
        dest = BTRFS_I(inode)->root;
        if (!capable(CAP_SYS_ADMIN)) {
                /*
                 * Regular user.  Only allow this with a special mount
                 * option, when the user has write+exec access to the
                 * subvol root, and when rmdir(2) would have been
                 * allowed.
                 *
                 * Note that this is _not_ check that the subvol is
                 * empty or doesn't contain data that we wouldn't
                 * otherwise be able to delete.
                 *
                 * Users who want to delete empty subvols should try
                 * rmdir(2).
                 */
                err = -EPERM;
                if (!btrfs_test_opt(fs_info, USER_SUBVOL_RM_ALLOWED))
                        goto out_dput;

                /*
                 * Do not allow deletion if the parent dir is the same
                 * as the dir to be deleted.  That means the ioctl
                 * must be called on the dentry referencing the root
                 * of the subvol, not a random directory contained
                 * within it.
                 */
                err = -EINVAL;
                if (root == dest)
                        goto out_dput;

                err = inode_permission(mnt_userns, inode, MAY_WRITE | MAY_EXEC);
                if (err)
                        goto out_dput;
        }

        /* check if subvolume may be deleted by a user */
        err = btrfs_may_delete(mnt_userns, dir, dentry, 1);
        if (err)
                goto out_dput;

        if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
                err = -EINVAL;
                goto out_dput;
        }

        btrfs_inode_lock(inode, 0);
        err = btrfs_delete_subvolume(dir, dentry);
        btrfs_inode_unlock(inode, 0);
        if (!err)
                d_delete_notify(dir, dentry);

out_dput:
        dput(dentry);
out_unlock_dir:
        btrfs_inode_unlock(dir, 0);
free_subvol_name:
        kfree(subvol_name_ptr);
free_parent:
        if (destroy_parent)
                dput(parent);
out_drop_write:
        mnt_drop_write_file(file);
out:
        kfree(vol_args2);
        kfree(vol_args);
        return err;
}

static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
{
        struct inode *inode = file_inode(file);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_ioctl_defrag_range_args range = {0};
        int ret;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        if (btrfs_root_readonly(root)) {
                ret = -EROFS;
                goto out;
        }

        switch (inode->i_mode & S_IFMT) {
        case S_IFDIR:
                if (!capable(CAP_SYS_ADMIN)) {
                        ret = -EPERM;
                        goto out;
                }
                ret = btrfs_defrag_root(root);
                break;
        case S_IFREG:
                /*
                 * Note that this does not check the file descriptor for write
                 * access. This prevents defragmenting executables that are
                 * running and allows defrag on files open in read-only mode.
                 */
                if (!capable(CAP_SYS_ADMIN) &&
                    inode_permission(&init_user_ns, inode, MAY_WRITE)) {
                        ret = -EPERM;
                        goto out;
                }

                if (argp) {
                        if (copy_from_user(&range, argp, sizeof(range))) {
                                ret = -EFAULT;
                                goto out;
                        }
                        /* compression requires us to start the IO */
                        if ((range.flags & BTRFS_DEFRAG_RANGE_COMPRESS)) {
                                range.flags |= BTRFS_DEFRAG_RANGE_START_IO;
                                range.extent_thresh = (u32)-1;
                        }
                } else {
                        /* the rest are all set to zero by kzalloc */
                        range.len = (u64)-1;
                }
                ret = btrfs_defrag_file(file_inode(file), &file->f_ra,
                                        &range, BTRFS_OLDEST_GENERATION, 0);
                if (ret > 0)
                        ret = 0;
                break;
        default:
                ret = -EINVAL;
        }
out:
        mnt_drop_write_file(file);
        return ret;
}

static long btrfs_ioctl_add_dev(struct btrfs_fs_info *fs_info, void __user *arg)
{
        struct btrfs_ioctl_vol_args *vol_args;
        bool restore_op = false;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
                btrfs_err(fs_info, "device add not supported on extent tree v2 yet");
                return -EINVAL;
        }

        if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_ADD)) {
                if (!btrfs_exclop_start_try_lock(fs_info, BTRFS_EXCLOP_DEV_ADD))
                        return BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;

                /*
                 * We can do the device add because we have a paused balanced,
                 * change the exclusive op type and remember we should bring
                 * back the paused balance
                 */
                fs_info->exclusive_operation = BTRFS_EXCLOP_DEV_ADD;
                btrfs_exclop_start_unlock(fs_info);
                restore_op = true;
        }

        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args)) {
                ret = PTR_ERR(vol_args);
                goto out;
        }

        vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
        ret = btrfs_init_new_device(fs_info, vol_args->name);

        if (!ret)
                btrfs_info(fs_info, "disk added %s", vol_args->name);

        kfree(vol_args);
out:
        if (restore_op)
                btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE_PAUSED);
        else
                btrfs_exclop_finish(fs_info);
        return ret;
}

static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
{
        BTRFS_DEV_LOOKUP_ARGS(args);
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_ioctl_vol_args_v2 *vol_args;
        struct block_device *bdev = NULL;
        fmode_t mode;
        int ret;
        bool cancel = false;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args))
                return PTR_ERR(vol_args);

        if (vol_args->flags & ~BTRFS_DEVICE_REMOVE_ARGS_MASK) {
                ret = -EOPNOTSUPP;
                goto out;
        }

        vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
        if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID) {
                args.devid = vol_args->devid;
        } else if (!strcmp("cancel", vol_args->name)) {
                cancel = true;
        } else {
                ret = btrfs_get_dev_args_from_path(fs_info, &args, vol_args->name);
                if (ret)
                        goto out;
        }

        ret = mnt_want_write_file(file);
        if (ret)
                goto out;

        ret = exclop_start_or_cancel_reloc(fs_info, BTRFS_EXCLOP_DEV_REMOVE,
                                           cancel);
        if (ret)
                goto err_drop;

        /* Exclusive operation is now claimed */
        ret = btrfs_rm_device(fs_info, &args, &bdev, &mode);

        btrfs_exclop_finish(fs_info);

        if (!ret) {
                if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID)
                        btrfs_info(fs_info, "device deleted: id %llu",
                                        vol_args->devid);
                else
                        btrfs_info(fs_info, "device deleted: %s",
                                        vol_args->name);
        }
err_drop:
        mnt_drop_write_file(file);
        if (bdev)
                blkdev_put(bdev, mode);
out:
        btrfs_put_dev_args_from_path(&args);
        kfree(vol_args);
        return ret;
}

static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
{
        BTRFS_DEV_LOOKUP_ARGS(args);
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_ioctl_vol_args *vol_args;
        struct block_device *bdev = NULL;
        fmode_t mode;
        int ret;
        bool cancel = false;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        vol_args = memdup_user(arg, sizeof(*vol_args));
        if (IS_ERR(vol_args))
                return PTR_ERR(vol_args);

        vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
        if (!strcmp("cancel", vol_args->name)) {
                cancel = true;
        } else {
                ret = btrfs_get_dev_args_from_path(fs_info, &args, vol_args->name);
                if (ret)
                        goto out;
        }

        ret = mnt_want_write_file(file);
        if (ret)
                goto out;

        ret = exclop_start_or_cancel_reloc(fs_info, BTRFS_EXCLOP_DEV_REMOVE,
                                           cancel);
        if (ret == 0) {
                ret = btrfs_rm_device(fs_info, &args, &bdev, &mode);
                if (!ret)
                        btrfs_info(fs_info, "disk deleted %s", vol_args->name);
                btrfs_exclop_finish(fs_info);
        }

        mnt_drop_write_file(file);
        if (bdev)
                blkdev_put(bdev, mode);
out:
        btrfs_put_dev_args_from_path(&args);
        kfree(vol_args);
        return ret;
}

static long btrfs_ioctl_fs_info(struct btrfs_fs_info *fs_info,
                                void __user *arg)
{
        struct btrfs_ioctl_fs_info_args *fi_args;
        struct btrfs_device *device;
        struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
        u64 flags_in;
        int ret = 0;

        fi_args = memdup_user(arg, sizeof(*fi_args));
        if (IS_ERR(fi_args))
                return PTR_ERR(fi_args);

        flags_in = fi_args->flags;
        memset(fi_args, 0, sizeof(*fi_args));

        rcu_read_lock();
        fi_args->num_devices = fs_devices->num_devices;

        list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
                if (device->devid > fi_args->max_id)
                        fi_args->max_id = device->devid;
        }
        rcu_read_unlock();

        memcpy(&fi_args->fsid, fs_devices->fsid, sizeof(fi_args->fsid));
        fi_args->nodesize = fs_info->nodesize;
        fi_args->sectorsize = fs_info->sectorsize;
        fi_args->clone_alignment = fs_info->sectorsize;

        if (flags_in & BTRFS_FS_INFO_FLAG_CSUM_INFO) {
                fi_args->csum_type = btrfs_super_csum_type(fs_info->super_copy);
                fi_args->csum_size = btrfs_super_csum_size(fs_info->super_copy);
                fi_args->flags |= BTRFS_FS_INFO_FLAG_CSUM_INFO;
        }

        if (flags_in & BTRFS_FS_INFO_FLAG_GENERATION) {
                fi_args->generation = fs_info->generation;
                fi_args->flags |= BTRFS_FS_INFO_FLAG_GENERATION;
        }

        if (flags_in & BTRFS_FS_INFO_FLAG_METADATA_UUID) {
                memcpy(&fi_args->metadata_uuid, fs_devices->metadata_uuid,
                       sizeof(fi_args->metadata_uuid));
                fi_args->flags |= BTRFS_FS_INFO_FLAG_METADATA_UUID;
        }

        if (copy_to_user(arg, fi_args, sizeof(*fi_args)))
                ret = -EFAULT;

        kfree(fi_args);
        return ret;
}

static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
                                 void __user *arg)
{
        BTRFS_DEV_LOOKUP_ARGS(args);
        struct btrfs_ioctl_dev_info_args *di_args;
        struct btrfs_device *dev;
        int ret = 0;

        di_args = memdup_user(arg, sizeof(*di_args));
        if (IS_ERR(di_args))
                return PTR_ERR(di_args);

        args.devid = di_args->devid;
        if (!btrfs_is_empty_uuid(di_args->uuid))
                args.uuid = di_args->uuid;

        rcu_read_lock();
        dev = btrfs_find_device(fs_info->fs_devices, &args);
        if (!dev) {
                ret = -ENODEV;
                goto out;
        }

        di_args->devid = dev->devid;
        di_args->bytes_used = btrfs_device_get_bytes_used(dev);
        di_args->total_bytes = btrfs_device_get_total_bytes(dev);
        memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
        if (dev->name) {
                strncpy(di_args->path, rcu_str_deref(dev->name),
                                sizeof(di_args->path) - 1);
                di_args->path[sizeof(di_args->path) - 1] = 0;
        } else {
                di_args->path[0] = '\0';
        }

out:
        rcu_read_unlock();
        if (ret == 0 && copy_to_user(arg, di_args, sizeof(*di_args)))
                ret = -EFAULT;

        kfree(di_args);
        return ret;
}

static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_root *new_root;
        struct btrfs_dir_item *di;
        struct btrfs_trans_handle *trans;
        struct btrfs_path *path = NULL;
        struct btrfs_disk_key disk_key;
        u64 objectid = 0;
        u64 dir_id;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        if (copy_from_user(&objectid, argp, sizeof(objectid))) {
                ret = -EFAULT;
                goto out;
        }

        if (!objectid)
                objectid = BTRFS_FS_TREE_OBJECTID;

        new_root = btrfs_get_fs_root(fs_info, objectid, true);
        if (IS_ERR(new_root)) {
                ret = PTR_ERR(new_root);
                goto out;
        }
        if (!is_fstree(new_root->root_key.objectid)) {
                ret = -ENOENT;
                goto out_free;
        }

        path = btrfs_alloc_path();
        if (!path) {
                ret = -ENOMEM;
                goto out_free;
        }

        trans = btrfs_start_transaction(root, 1);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto out_free;
        }

        dir_id = btrfs_super_root_dir(fs_info->super_copy);
        di = btrfs_lookup_dir_item(trans, fs_info->tree_root, path,
                                   dir_id, "default", 7, 1);
        if (IS_ERR_OR_NULL(di)) {
                btrfs_release_path(path);
                btrfs_end_transaction(trans);
                btrfs_err(fs_info,
                          "Umm, you don't have the default diritem, this isn't going to work");
                ret = -ENOENT;
                goto out_free;
        }

        btrfs_cpu_key_to_disk(&disk_key, &new_root->root_key);
        btrfs_set_dir_item_key(path->nodes[0], di, &disk_key);
        btrfs_mark_buffer_dirty(path->nodes[0]);
        btrfs_release_path(path);

        btrfs_set_fs_incompat(fs_info, DEFAULT_SUBVOL);
        btrfs_end_transaction(trans);
out_free:
        btrfs_put_root(new_root);
        btrfs_free_path(path);
out:
        mnt_drop_write_file(file);
        return ret;
}

static void get_block_group_info(struct list_head *groups_list,
                                 struct btrfs_ioctl_space_info *space)
{
        struct btrfs_block_group *block_group;

        space->total_bytes = 0;
        space->used_bytes = 0;
        space->flags = 0;
        list_for_each_entry(block_group, groups_list, list) {
                space->flags = block_group->flags;
                space->total_bytes += block_group->length;
                space->used_bytes += block_group->used;
        }
}

static long btrfs_ioctl_space_info(struct btrfs_fs_info *fs_info,
                                   void __user *arg)
{
        struct btrfs_ioctl_space_args space_args;
        struct btrfs_ioctl_space_info space;
        struct btrfs_ioctl_space_info *dest;
        struct btrfs_ioctl_space_info *dest_orig;
        struct btrfs_ioctl_space_info __user *user_dest;
        struct btrfs_space_info *info;
        static const u64 types[] = {
                BTRFS_BLOCK_GROUP_DATA,
                BTRFS_BLOCK_GROUP_SYSTEM,
                BTRFS_BLOCK_GROUP_METADATA,
                BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA
        };
        int num_types = 4;
        int alloc_size;
        int ret = 0;
        u64 slot_count = 0;
        int i, c;

        if (copy_from_user(&space_args,
                           (struct btrfs_ioctl_space_args __user *)arg,
                           sizeof(space_args)))
                return -EFAULT;

        for (i = 0; i < num_types; i++) {
                struct btrfs_space_info *tmp;

                info = NULL;
                list_for_each_entry(tmp, &fs_info->space_info, list) {
                        if (tmp->flags == types[i]) {
                                info = tmp;
                                break;
                        }
                }

                if (!info)
                        continue;

                down_read(&info->groups_sem);
                for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
                        if (!list_empty(&info->block_groups[c]))
                                slot_count++;
                }
                up_read(&info->groups_sem);
        }

        /*
         * Global block reserve, exported as a space_info
         */
        slot_count++;

        /* space_slots == 0 means they are asking for a count */
        if (space_args.space_slots == 0) {
                space_args.total_spaces = slot_count;
                goto out;
        }

        slot_count = min_t(u64, space_args.space_slots, slot_count);

        alloc_size = sizeof(*dest) * slot_count;

        /* we generally have at most 6 or so space infos, one for each raid
         * level.  So, a whole page should be more than enough for everyone
         */
        if (alloc_size > PAGE_SIZE)
                return -ENOMEM;

        space_args.total_spaces = 0;
        dest = kmalloc(alloc_size, GFP_KERNEL);
        if (!dest)
                return -ENOMEM;
        dest_orig = dest;

        /* now we have a buffer to copy into */
        for (i = 0; i < num_types; i++) {
                struct btrfs_space_info *tmp;

                if (!slot_count)
                        break;

                info = NULL;
                list_for_each_entry(tmp, &fs_info->space_info, list) {
                        if (tmp->flags == types[i]) {
                                info = tmp;
                                break;
                        }
                }

                if (!info)
                        continue;
                down_read(&info->groups_sem);
                for (c = 0; c < BTRFS_NR_RAID_TYPES; c++) {
                        if (!list_empty(&info->block_groups[c])) {
                                get_block_group_info(&info->block_groups[c],
                                                     &space);
                                memcpy(dest, &space, sizeof(space));
                                dest++;
                                space_args.total_spaces++;
                                slot_count--;
                        }
                        if (!slot_count)
                                break;
                }
                up_read(&info->groups_sem);
        }

        /*
         * Add global block reserve
         */
        if (slot_count) {
                struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;

                spin_lock(&block_rsv->lock);
                space.total_bytes = block_rsv->size;
                space.used_bytes = block_rsv->size - block_rsv->reserved;
                spin_unlock(&block_rsv->lock);
                space.flags = BTRFS_SPACE_INFO_GLOBAL_RSV;
                memcpy(dest, &space, sizeof(space));
                space_args.total_spaces++;
        }

        user_dest = (struct btrfs_ioctl_space_info __user *)
                (arg + sizeof(struct btrfs_ioctl_space_args));

        if (copy_to_user(user_dest, dest_orig, alloc_size))
                ret = -EFAULT;

        kfree(dest_orig);
out:
        if (ret == 0 && copy_to_user(arg, &space_args, sizeof(space_args)))
                ret = -EFAULT;

        return ret;
}

static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
                                            void __user *argp)
{
        struct btrfs_trans_handle *trans;
        u64 transid;

        trans = btrfs_attach_transaction_barrier(root);
        if (IS_ERR(trans)) {
                if (PTR_ERR(trans) != -ENOENT)
                        return PTR_ERR(trans);

                /* No running transaction, don't bother */
                transid = root->fs_info->last_trans_committed;
                goto out;
        }
        transid = trans->transid;
        btrfs_commit_transaction_async(trans);
out:
        if (argp)
                if (copy_to_user(argp, &transid, sizeof(transid)))
                        return -EFAULT;
        return 0;
}

static noinline long btrfs_ioctl_wait_sync(struct btrfs_fs_info *fs_info,
                                           void __user *argp)
{
        u64 transid;

        if (argp) {
                if (copy_from_user(&transid, argp, sizeof(transid)))
                        return -EFAULT;
        } else {
                transid = 0;  /* current trans */
        }
        return btrfs_wait_for_commit(fs_info, transid);
}

static long btrfs_ioctl_scrub(struct file *file, void __user *arg)
{
        struct btrfs_fs_info *fs_info = btrfs_sb(file_inode(file)->i_sb);
        struct btrfs_ioctl_scrub_args *sa;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
                btrfs_err(fs_info, "scrub is not supported on extent tree v2 yet");
                return -EINVAL;
        }

        sa = memdup_user(arg, sizeof(*sa));
        if (IS_ERR(sa))
                return PTR_ERR(sa);

        if (!(sa->flags & BTRFS_SCRUB_READONLY)) {
                ret = mnt_want_write_file(file);
                if (ret)
                        goto out;
        }

        ret = btrfs_scrub_dev(fs_info, sa->devid, sa->start, sa->end,
                              &sa->progress, sa->flags & BTRFS_SCRUB_READONLY,
                              0);

        /*
         * Copy scrub args to user space even if btrfs_scrub_dev() returned an
         * error. This is important as it allows user space to know how much
         * progress scrub has done. For example, if scrub is canceled we get
         * -ECANCELED from btrfs_scrub_dev() and return that error back to user
         * space. Later user space can inspect the progress from the structure
         * btrfs_ioctl_scrub_args and resume scrub from where it left off
         * previously (btrfs-progs does this).
         * If we fail to copy the btrfs_ioctl_scrub_args structure to user space
         * then return -EFAULT to signal the structure was not copied or it may
         * be corrupt and unreliable due to a partial copy.
         */
        if (copy_to_user(arg, sa, sizeof(*sa)))
                ret = -EFAULT;

        if (!(sa->flags & BTRFS_SCRUB_READONLY))
                mnt_drop_write_file(file);
out:
        kfree(sa);
        return ret;
}

static long btrfs_ioctl_scrub_cancel(struct btrfs_fs_info *fs_info)
{
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        return btrfs_scrub_cancel(fs_info);
}

static long btrfs_ioctl_scrub_progress(struct btrfs_fs_info *fs_info,
                                       void __user *arg)
{
        struct btrfs_ioctl_scrub_args *sa;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        sa = memdup_user(arg, sizeof(*sa));
        if (IS_ERR(sa))
                return PTR_ERR(sa);

        ret = btrfs_scrub_progress(fs_info, sa->devid, &sa->progress);

        if (ret == 0 && copy_to_user(arg, sa, sizeof(*sa)))
                ret = -EFAULT;

        kfree(sa);
        return ret;
}

static long btrfs_ioctl_get_dev_stats(struct btrfs_fs_info *fs_info,
                                      void __user *arg)
{
        struct btrfs_ioctl_get_dev_stats *sa;
        int ret;

        sa = memdup_user(arg, sizeof(*sa));
        if (IS_ERR(sa))
                return PTR_ERR(sa);

        if ((sa->flags & BTRFS_DEV_STATS_RESET) && !capable(CAP_SYS_ADMIN)) {
                kfree(sa);
                return -EPERM;
        }

        ret = btrfs_get_dev_stats(fs_info, sa);

        if (ret == 0 && copy_to_user(arg, sa, sizeof(*sa)))
                ret = -EFAULT;

        kfree(sa);
        return ret;
}

static long btrfs_ioctl_dev_replace(struct btrfs_fs_info *fs_info,
                                    void __user *arg)
{
        struct btrfs_ioctl_dev_replace_args *p;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
                btrfs_err(fs_info, "device replace not supported on extent tree v2 yet");
                return -EINVAL;
        }

        p = memdup_user(arg, sizeof(*p));
        if (IS_ERR(p))
                return PTR_ERR(p);

        switch (p->cmd) {
        case BTRFS_IOCTL_DEV_REPLACE_CMD_START:
                if (sb_rdonly(fs_info->sb)) {
                        ret = -EROFS;
                        goto out;
                }
                if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
                        ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
                } else {
                        ret = btrfs_dev_replace_by_ioctl(fs_info, p);
                        btrfs_exclop_finish(fs_info);
                }
                break;
        case BTRFS_IOCTL_DEV_REPLACE_CMD_STATUS:
                btrfs_dev_replace_status(fs_info, p);
                ret = 0;
                break;
        case BTRFS_IOCTL_DEV_REPLACE_CMD_CANCEL:
                p->result = btrfs_dev_replace_cancel(fs_info);
                ret = 0;
                break;
        default:
                ret = -EINVAL;
                break;
        }

        if ((ret == 0 || ret == -ECANCELED) && copy_to_user(arg, p, sizeof(*p)))
                ret = -EFAULT;
out:
        kfree(p);
        return ret;
}

static long btrfs_ioctl_ino_to_path(struct btrfs_root *root, void __user *arg)
{
        int ret = 0;
        int i;
        u64 rel_ptr;
        int size;
        struct btrfs_ioctl_ino_path_args *ipa = NULL;
        struct inode_fs_paths *ipath = NULL;
        struct btrfs_path *path;

        if (!capable(CAP_DAC_READ_SEARCH))
                return -EPERM;

        path = btrfs_alloc_path();
        if (!path) {
                ret = -ENOMEM;
                goto out;
        }

        ipa = memdup_user(arg, sizeof(*ipa));
        if (IS_ERR(ipa)) {
                ret = PTR_ERR(ipa);
                ipa = NULL;
                goto out;
        }

        size = min_t(u32, ipa->size, 4096);
        ipath = init_ipath(size, root, path);
        if (IS_ERR(ipath)) {
                ret = PTR_ERR(ipath);
                ipath = NULL;
                goto out;
        }

        ret = paths_from_inode(ipa->inum, ipath);
        if (ret < 0)
                goto out;

        for (i = 0; i < ipath->fspath->elem_cnt; ++i) {
                rel_ptr = ipath->fspath->val[i] -
                          (u64)(unsigned long)ipath->fspath->val;
                ipath->fspath->val[i] = rel_ptr;
        }

        ret = copy_to_user((void __user *)(unsigned long)ipa->fspath,
                           ipath->fspath, size);
        if (ret) {
                ret = -EFAULT;
                goto out;
        }

out:
        btrfs_free_path(path);
        free_ipath(ipath);
        kfree(ipa);

        return ret;
}

static long btrfs_ioctl_logical_to_ino(struct btrfs_fs_info *fs_info,
                                        void __user *arg, int version)
{
        int ret = 0;
        int size;
        struct btrfs_ioctl_logical_ino_args *loi;
        struct btrfs_data_container *inodes = NULL;
        struct btrfs_path *path = NULL;
        bool ignore_offset;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        loi = memdup_user(arg, sizeof(*loi));
        if (IS_ERR(loi))
                return PTR_ERR(loi);

        if (version == 1) {
                ignore_offset = false;
                size = min_t(u32, loi->size, SZ_64K);
        } else {
                /* All reserved bits must be 0 for now */
                if (memchr_inv(loi->reserved, 0, sizeof(loi->reserved))) {
                        ret = -EINVAL;
                        goto out_loi;
                }
                /* Only accept flags we have defined so far */
                if (loi->flags & ~(BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET)) {
                        ret = -EINVAL;
                        goto out_loi;
                }
                ignore_offset = loi->flags & BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET;
                size = min_t(u32, loi->size, SZ_16M);
        }

        path = btrfs_alloc_path();
        if (!path) {
                ret = -ENOMEM;
                goto out;
        }

        inodes = init_data_container(size);
        if (IS_ERR(inodes)) {
                ret = PTR_ERR(inodes);
                inodes = NULL;
                goto out;
        }

        ret = iterate_inodes_from_logical(loi->logical, fs_info, path,
                                          inodes, ignore_offset);
        if (ret == -EINVAL)
                ret = -ENOENT;
        if (ret < 0)
                goto out;

        ret = copy_to_user((void __user *)(unsigned long)loi->inodes, inodes,
                           size);
        if (ret)
                ret = -EFAULT;

out:
        btrfs_free_path(path);
        kvfree(inodes);
out_loi:
        kfree(loi);

        return ret;
}

void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
                               struct btrfs_ioctl_balance_args *bargs)
{
        struct btrfs_balance_control *bctl = fs_info->balance_ctl;

        bargs->flags = bctl->flags;

        if (test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags))
                bargs->state |= BTRFS_BALANCE_STATE_RUNNING;
        if (atomic_read(&fs_info->balance_pause_req))
                bargs->state |= BTRFS_BALANCE_STATE_PAUSE_REQ;
        if (atomic_read(&fs_info->balance_cancel_req))
                bargs->state |= BTRFS_BALANCE_STATE_CANCEL_REQ;

        memcpy(&bargs->data, &bctl->data, sizeof(bargs->data));
        memcpy(&bargs->meta, &bctl->meta, sizeof(bargs->meta));
        memcpy(&bargs->sys, &bctl->sys, sizeof(bargs->sys));

        spin_lock(&fs_info->balance_lock);
        memcpy(&bargs->stat, &bctl->stat, sizeof(bargs->stat));
        spin_unlock(&fs_info->balance_lock);
}

/**
 * Try to acquire fs_info::balance_mutex as well as set BTRFS_EXLCOP_BALANCE as
 * required.
 *
 * @fs_info:       the filesystem
 * @excl_acquired: ptr to boolean value which is set to false in case balance
 *                 is being resumed
 *
 * Return 0 on success in which case both fs_info::balance is acquired as well
 * as exclusive ops are blocked. In case of failure return an error code.
 */
static int btrfs_try_lock_balance(struct btrfs_fs_info *fs_info, bool *excl_acquired)
{
        int ret;

        /*
         * Exclusive operation is locked. Three possibilities:
         *   (1) some other op is running
         *   (2) balance is running
         *   (3) balance is paused -- special case (think resume)
         */
        while (1) {
                if (btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) {
                        *excl_acquired = true;
                        mutex_lock(&fs_info->balance_mutex);
                        return 0;
                }

                mutex_lock(&fs_info->balance_mutex);
                if (fs_info->balance_ctl) {
                        /* This is either (2) or (3) */
                        if (test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)) {
                                /* This is (2) */
                                ret = -EINPROGRESS;
                                goto out_failure;

                        } else {
                                mutex_unlock(&fs_info->balance_mutex);
                                /*
                                 * Lock released to allow other waiters to
                                 * continue, we'll reexamine the status again.
                                 */
                                mutex_lock(&fs_info->balance_mutex);

                                if (fs_info->balance_ctl &&
                                    !test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags)) {
                                        /* This is (3) */
                                        *excl_acquired = false;
                                        return 0;
                                }
                        }
                } else {
                        /* This is (1) */
                        ret = BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS;
                        goto out_failure;
                }

                mutex_unlock(&fs_info->balance_mutex);
        }

out_failure:
        mutex_unlock(&fs_info->balance_mutex);
        *excl_acquired = false;
        return ret;
}

static long btrfs_ioctl_balance(struct file *file, void __user *arg)
{
        struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
        struct btrfs_fs_info *fs_info = root->fs_info;
        struct btrfs_ioctl_balance_args *bargs;
        struct btrfs_balance_control *bctl;
        bool need_unlock = true;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        bargs = memdup_user(arg, sizeof(*bargs));
        if (IS_ERR(bargs)) {
                ret = PTR_ERR(bargs);
                bargs = NULL;
                goto out;
        }

        ret = btrfs_try_lock_balance(fs_info, &need_unlock);
        if (ret)
                goto out;

        lockdep_assert_held(&fs_info->balance_mutex);

        if (bargs->flags & BTRFS_BALANCE_RESUME) {
                if (!fs_info->balance_ctl) {
                        ret = -ENOTCONN;
                        goto out_unlock;
                }

                bctl = fs_info->balance_ctl;
                spin_lock(&fs_info->balance_lock);
                bctl->flags |= BTRFS_BALANCE_RESUME;
                spin_unlock(&fs_info->balance_lock);
                btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE);

                goto do_balance;
        }

        if (bargs->flags & ~(BTRFS_BALANCE_ARGS_MASK | BTRFS_BALANCE_TYPE_MASK)) {
                ret = -EINVAL;
                goto out_unlock;
        }

        if (fs_info->balance_ctl) {
                ret = -EINPROGRESS;
                goto out_unlock;
        }

        bctl = kzalloc(sizeof(*bctl), GFP_KERNEL);
        if (!bctl) {
                ret = -ENOMEM;
                goto out_unlock;
        }

        memcpy(&bctl->data, &bargs->data, sizeof(bctl->data));
        memcpy(&bctl->meta, &bargs->meta, sizeof(bctl->meta));
        memcpy(&bctl->sys, &bargs->sys, sizeof(bctl->sys));

        bctl->flags = bargs->flags;
do_balance:
        /*
         * Ownership of bctl and exclusive operation goes to btrfs_balance.
         * bctl is freed in reset_balance_state, or, if restriper was paused
         * all the way until unmount, in free_fs_info.  The flag should be
         * cleared after reset_balance_state.
         */
        need_unlock = false;

        ret = btrfs_balance(fs_info, bctl, bargs);
        bctl = NULL;

        if (ret == 0 || ret == -ECANCELED) {
                if (copy_to_user(arg, bargs, sizeof(*bargs)))
                        ret = -EFAULT;
        }

        kfree(bctl);
out_unlock:
        mutex_unlock(&fs_info->balance_mutex);
        if (need_unlock)
                btrfs_exclop_finish(fs_info);
out:
        mnt_drop_write_file(file);
        kfree(bargs);
        return ret;
}

static long btrfs_ioctl_balance_ctl(struct btrfs_fs_info *fs_info, int cmd)
{
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        switch (cmd) {
        case BTRFS_BALANCE_CTL_PAUSE:
                return btrfs_pause_balance(fs_info);
        case BTRFS_BALANCE_CTL_CANCEL:
                return btrfs_cancel_balance(fs_info);
        }

        return -EINVAL;
}

static long btrfs_ioctl_balance_progress(struct btrfs_fs_info *fs_info,
                                         void __user *arg)
{
        struct btrfs_ioctl_balance_args *bargs;
        int ret = 0;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        mutex_lock(&fs_info->balance_mutex);
        if (!fs_info->balance_ctl) {
                ret = -ENOTCONN;
                goto out;
        }

        bargs = kzalloc(sizeof(*bargs), GFP_KERNEL);
        if (!bargs) {
                ret = -ENOMEM;
                goto out;
        }

        btrfs_update_ioctl_balance_args(fs_info, bargs);

        if (copy_to_user(arg, bargs, sizeof(*bargs)))
                ret = -EFAULT;

        kfree(bargs);
out:
        mutex_unlock(&fs_info->balance_mutex);
        return ret;
}

static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_ioctl_quota_ctl_args *sa;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        sa = memdup_user(arg, sizeof(*sa));
        if (IS_ERR(sa)) {
                ret = PTR_ERR(sa);
                goto drop_write;
        }

        down_write(&fs_info->subvol_sem);

        switch (sa->cmd) {
        case BTRFS_QUOTA_CTL_ENABLE:
                ret = btrfs_quota_enable(fs_info);
                break;
        case BTRFS_QUOTA_CTL_DISABLE:
                ret = btrfs_quota_disable(fs_info);
                break;
        default:
                ret = -EINVAL;
                break;
        }

        kfree(sa);
        up_write(&fs_info->subvol_sem);
drop_write:
        mnt_drop_write_file(file);
        return ret;
}

static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_ioctl_qgroup_assign_args *sa;
        struct btrfs_trans_handle *trans;
        int ret;
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        sa = memdup_user(arg, sizeof(*sa));
        if (IS_ERR(sa)) {
                ret = PTR_ERR(sa);
                goto drop_write;
        }

        trans = btrfs_join_transaction(root);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto out;
        }

        if (sa->assign) {
                ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst);
        } else {
                ret = btrfs_del_qgroup_relation(trans, sa->src, sa->dst);
        }

        /* update qgroup status and info */
        err = btrfs_run_qgroups(trans);
        if (err < 0)
                btrfs_handle_fs_error(fs_info, err,
                                      "failed to update qgroup status and info");
        err = btrfs_end_transaction(trans);
        if (err && !ret)
                ret = err;

out:
        kfree(sa);
drop_write:
        mnt_drop_write_file(file);
        return ret;
}

static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_ioctl_qgroup_create_args *sa;
        struct btrfs_trans_handle *trans;
        int ret;
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        sa = memdup_user(arg, sizeof(*sa));
        if (IS_ERR(sa)) {
                ret = PTR_ERR(sa);
                goto drop_write;
        }

        if (!sa->qgroupid) {
                ret = -EINVAL;
                goto out;
        }

        trans = btrfs_join_transaction(root);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto out;
        }

        if (sa->create) {
                ret = btrfs_create_qgroup(trans, sa->qgroupid);
        } else {
                ret = btrfs_remove_qgroup(trans, sa->qgroupid);
        }

        err = btrfs_end_transaction(trans);
        if (err && !ret)
                ret = err;

out:
        kfree(sa);
drop_write:
        mnt_drop_write_file(file);
        return ret;
}

static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_ioctl_qgroup_limit_args *sa;
        struct btrfs_trans_handle *trans;
        int ret;
        int err;
        u64 qgroupid;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        sa = memdup_user(arg, sizeof(*sa));
        if (IS_ERR(sa)) {
                ret = PTR_ERR(sa);
                goto drop_write;
        }

        trans = btrfs_join_transaction(root);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto out;
        }

        qgroupid = sa->qgroupid;
        if (!qgroupid) {
                /* take the current subvol as qgroup */
                qgroupid = root->root_key.objectid;
        }

        ret = btrfs_limit_qgroup(trans, qgroupid, &sa->lim);

        err = btrfs_end_transaction(trans);
        if (err && !ret)
                ret = err;

out:
        kfree(sa);
drop_write:
        mnt_drop_write_file(file);
        return ret;
}

static long btrfs_ioctl_quota_rescan(struct file *file, void __user *arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_ioctl_quota_rescan_args *qsa;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        qsa = memdup_user(arg, sizeof(*qsa));
        if (IS_ERR(qsa)) {
                ret = PTR_ERR(qsa);
                goto drop_write;
        }

        if (qsa->flags) {
                ret = -EINVAL;
                goto out;
        }

        ret = btrfs_qgroup_rescan(fs_info);

out:
        kfree(qsa);
drop_write:
        mnt_drop_write_file(file);
        return ret;
}

static long btrfs_ioctl_quota_rescan_status(struct btrfs_fs_info *fs_info,
                                                void __user *arg)
{
        struct btrfs_ioctl_quota_rescan_args qsa = {0};

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
                qsa.flags = 1;
                qsa.progress = fs_info->qgroup_rescan_progress.objectid;
        }

        if (copy_to_user(arg, &qsa, sizeof(qsa)))
                return -EFAULT;

        return 0;
}

static long btrfs_ioctl_quota_rescan_wait(struct btrfs_fs_info *fs_info,
                                                void __user *arg)
{
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        return btrfs_qgroup_wait_for_completion(fs_info, true);
}

static long _btrfs_ioctl_set_received_subvol(struct file *file,
                                            struct user_namespace *mnt_userns,
                                            struct btrfs_ioctl_received_subvol_args *sa)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_root_item *root_item = &root->root_item;
        struct btrfs_trans_handle *trans;
        struct timespec64 ct = current_time(inode);
        int ret = 0;
        int received_uuid_changed;

        if (!inode_owner_or_capable(mnt_userns, inode))
                return -EPERM;

        ret = mnt_want_write_file(file);
        if (ret < 0)
                return ret;

        down_write(&fs_info->subvol_sem);

        if (btrfs_ino(BTRFS_I(inode)) != BTRFS_FIRST_FREE_OBJECTID) {
                ret = -EINVAL;
                goto out;
        }

        if (btrfs_root_readonly(root)) {
                ret = -EROFS;
                goto out;
        }

        /*
         * 1 - root item
         * 2 - uuid items (received uuid + subvol uuid)
         */
        trans = btrfs_start_transaction(root, 3);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                trans = NULL;
                goto out;
        }

        sa->rtransid = trans->transid;
        sa->rtime.sec = ct.tv_sec;
        sa->rtime.nsec = ct.tv_nsec;

        received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
                                       BTRFS_UUID_SIZE);
        if (received_uuid_changed &&
            !btrfs_is_empty_uuid(root_item->received_uuid)) {
                ret = btrfs_uuid_tree_remove(trans, root_item->received_uuid,
                                          BTRFS_UUID_KEY_RECEIVED_SUBVOL,
                                          root->root_key.objectid);
                if (ret && ret != -ENOENT) {
                        btrfs_abort_transaction(trans, ret);
                        btrfs_end_transaction(trans);
                        goto out;
                }
        }
        memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
        btrfs_set_root_stransid(root_item, sa->stransid);
        btrfs_set_root_rtransid(root_item, sa->rtransid);
        btrfs_set_stack_timespec_sec(&root_item->stime, sa->stime.sec);
        btrfs_set_stack_timespec_nsec(&root_item->stime, sa->stime.nsec);
        btrfs_set_stack_timespec_sec(&root_item->rtime, sa->rtime.sec);
        btrfs_set_stack_timespec_nsec(&root_item->rtime, sa->rtime.nsec);

        ret = btrfs_update_root(trans, fs_info->tree_root,
                                &root->root_key, &root->root_item);
        if (ret < 0) {
                btrfs_end_transaction(trans);
                goto out;
        }
        if (received_uuid_changed && !btrfs_is_empty_uuid(sa->uuid)) {
                ret = btrfs_uuid_tree_add(trans, sa->uuid,
                                          BTRFS_UUID_KEY_RECEIVED_SUBVOL,
                                          root->root_key.objectid);
                if (ret < 0 && ret != -EEXIST) {
                        btrfs_abort_transaction(trans, ret);
                        btrfs_end_transaction(trans);
                        goto out;
                }
        }
        ret = btrfs_commit_transaction(trans);
out:
        up_write(&fs_info->subvol_sem);
        mnt_drop_write_file(file);
        return ret;
}

#ifdef CONFIG_64BIT
static long btrfs_ioctl_set_received_subvol_32(struct file *file,
                                                void __user *arg)
{
        struct btrfs_ioctl_received_subvol_args_32 *args32 = NULL;
        struct btrfs_ioctl_received_subvol_args *args64 = NULL;
        int ret = 0;

        args32 = memdup_user(arg, sizeof(*args32));
        if (IS_ERR(args32))
                return PTR_ERR(args32);

        args64 = kmalloc(sizeof(*args64), GFP_KERNEL);
        if (!args64) {
                ret = -ENOMEM;
                goto out;
        }

        memcpy(args64->uuid, args32->uuid, BTRFS_UUID_SIZE);
        args64->stransid = args32->stransid;
        args64->rtransid = args32->rtransid;
        args64->stime.sec = args32->stime.sec;
        args64->stime.nsec = args32->stime.nsec;
        args64->rtime.sec = args32->rtime.sec;
        args64->rtime.nsec = args32->rtime.nsec;
        args64->flags = args32->flags;

        ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_user_ns(file), args64);
        if (ret)
                goto out;

        memcpy(args32->uuid, args64->uuid, BTRFS_UUID_SIZE);
        args32->stransid = args64->stransid;
        args32->rtransid = args64->rtransid;
        args32->stime.sec = args64->stime.sec;
        args32->stime.nsec = args64->stime.nsec;
        args32->rtime.sec = args64->rtime.sec;
        args32->rtime.nsec = args64->rtime.nsec;
        args32->flags = args64->flags;

        ret = copy_to_user(arg, args32, sizeof(*args32));
        if (ret)
                ret = -EFAULT;

out:
        kfree(args32);
        kfree(args64);
        return ret;
}
#endif

static long btrfs_ioctl_set_received_subvol(struct file *file,
                                            void __user *arg)
{
        struct btrfs_ioctl_received_subvol_args *sa = NULL;
        int ret = 0;

        sa = memdup_user(arg, sizeof(*sa));
        if (IS_ERR(sa))
                return PTR_ERR(sa);

        ret = _btrfs_ioctl_set_received_subvol(file, file_mnt_user_ns(file), sa);

        if (ret)
                goto out;

        ret = copy_to_user(arg, sa, sizeof(*sa));
        if (ret)
                ret = -EFAULT;

out:
        kfree(sa);
        return ret;
}

static int btrfs_ioctl_get_fslabel(struct btrfs_fs_info *fs_info,
                                        void __user *arg)
{
        size_t len;
        int ret;
        char label[BTRFS_LABEL_SIZE];

        spin_lock(&fs_info->super_lock);
        memcpy(label, fs_info->super_copy->label, BTRFS_LABEL_SIZE);
        spin_unlock(&fs_info->super_lock);

        len = strnlen(label, BTRFS_LABEL_SIZE);

        if (len == BTRFS_LABEL_SIZE) {
                btrfs_warn(fs_info,
                           "label is too long, return the first %zu bytes",
                           --len);
        }

        ret = copy_to_user(arg, label, len);

        return ret ? -EFAULT : 0;
}

static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_super_block *super_block = fs_info->super_copy;
        struct btrfs_trans_handle *trans;
        char label[BTRFS_LABEL_SIZE];
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (copy_from_user(label, arg, sizeof(label)))
                return -EFAULT;

        if (strnlen(label, BTRFS_LABEL_SIZE) == BTRFS_LABEL_SIZE) {
                btrfs_err(fs_info,
                          "unable to set label with more than %d bytes",
                          BTRFS_LABEL_SIZE - 1);
                return -EINVAL;
        }

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        trans = btrfs_start_transaction(root, 0);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto out_unlock;
        }

        spin_lock(&fs_info->super_lock);
        strcpy(super_block->label, label);
        spin_unlock(&fs_info->super_lock);
        ret = btrfs_commit_transaction(trans);

out_unlock:
        mnt_drop_write_file(file);
        return ret;
}

#define INIT_FEATURE_FLAGS(suffix) \
        { .compat_flags = BTRFS_FEATURE_COMPAT_##suffix, \
          .compat_ro_flags = BTRFS_FEATURE_COMPAT_RO_##suffix, \
          .incompat_flags = BTRFS_FEATURE_INCOMPAT_##suffix }

int btrfs_ioctl_get_supported_features(void __user *arg)
{
        static const struct btrfs_ioctl_feature_flags features[3] = {
                INIT_FEATURE_FLAGS(SUPP),
                INIT_FEATURE_FLAGS(SAFE_SET),
                INIT_FEATURE_FLAGS(SAFE_CLEAR)
        };

        if (copy_to_user(arg, &features, sizeof(features)))
                return -EFAULT;

        return 0;
}

static int btrfs_ioctl_get_features(struct btrfs_fs_info *fs_info,
                                        void __user *arg)
{
        struct btrfs_super_block *super_block = fs_info->super_copy;
        struct btrfs_ioctl_feature_flags features;

        features.compat_flags = btrfs_super_compat_flags(super_block);
        features.compat_ro_flags = btrfs_super_compat_ro_flags(super_block);
        features.incompat_flags = btrfs_super_incompat_flags(super_block);

        if (copy_to_user(arg, &features, sizeof(features)))
                return -EFAULT;

        return 0;
}

static int check_feature_bits(struct btrfs_fs_info *fs_info,
                              enum btrfs_feature_set set,
                              u64 change_mask, u64 flags, u64 supported_flags,
                              u64 safe_set, u64 safe_clear)
{
        const char *type = btrfs_feature_set_name(set);
        char *names;
        u64 disallowed, unsupported;
        u64 set_mask = flags & change_mask;
        u64 clear_mask = ~flags & change_mask;

        unsupported = set_mask & ~supported_flags;
        if (unsupported) {
                names = btrfs_printable_features(set, unsupported);
                if (names) {
                        btrfs_warn(fs_info,
                                   "this kernel does not support the %s feature bit%s",
                                   names, strchr(names, ',') ? "s" : "");
                        kfree(names);
                } else
                        btrfs_warn(fs_info,
                                   "this kernel does not support %s bits 0x%llx",
                                   type, unsupported);
                return -EOPNOTSUPP;
        }

        disallowed = set_mask & ~safe_set;
        if (disallowed) {
                names = btrfs_printable_features(set, disallowed);
                if (names) {
                        btrfs_warn(fs_info,
                                   "can't set the %s feature bit%s while mounted",
                                   names, strchr(names, ',') ? "s" : "");
                        kfree(names);
                } else
                        btrfs_warn(fs_info,
                                   "can't set %s bits 0x%llx while mounted",
                                   type, disallowed);
                return -EPERM;
        }

        disallowed = clear_mask & ~safe_clear;
        if (disallowed) {
                names = btrfs_printable_features(set, disallowed);
                if (names) {
                        btrfs_warn(fs_info,
                                   "can't clear the %s feature bit%s while mounted",
                                   names, strchr(names, ',') ? "s" : "");
                        kfree(names);
                } else
                        btrfs_warn(fs_info,
                                   "can't clear %s bits 0x%llx while mounted",
                                   type, disallowed);
                return -EPERM;
        }

        return 0;
}

#define check_feature(fs_info, change_mask, flags, mask_base)   \
check_feature_bits(fs_info, FEAT_##mask_base, change_mask, flags,       \
                   BTRFS_FEATURE_ ## mask_base ## _SUPP,        \
                   BTRFS_FEATURE_ ## mask_base ## _SAFE_SET,    \
                   BTRFS_FEATURE_ ## mask_base ## _SAFE_CLEAR)

static int btrfs_ioctl_set_features(struct file *file, void __user *arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        struct btrfs_super_block *super_block = fs_info->super_copy;
        struct btrfs_ioctl_feature_flags flags[2];
        struct btrfs_trans_handle *trans;
        u64 newflags;
        int ret;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (copy_from_user(flags, arg, sizeof(flags)))
                return -EFAULT;

        /* Nothing to do */
        if (!flags[0].compat_flags && !flags[0].compat_ro_flags &&
            !flags[0].incompat_flags)
                return 0;

        ret = check_feature(fs_info, flags[0].compat_flags,
                            flags[1].compat_flags, COMPAT);
        if (ret)
                return ret;

        ret = check_feature(fs_info, flags[0].compat_ro_flags,
                            flags[1].compat_ro_flags, COMPAT_RO);
        if (ret)
                return ret;

        ret = check_feature(fs_info, flags[0].incompat_flags,
                            flags[1].incompat_flags, INCOMPAT);
        if (ret)
                return ret;

        ret = mnt_want_write_file(file);
        if (ret)
                return ret;

        trans = btrfs_start_transaction(root, 0);
        if (IS_ERR(trans)) {
                ret = PTR_ERR(trans);
                goto out_drop_write;
        }

        spin_lock(&fs_info->super_lock);
        newflags = btrfs_super_compat_flags(super_block);
        newflags |= flags[0].compat_flags & flags[1].compat_flags;
        newflags &= ~(flags[0].compat_flags & ~flags[1].compat_flags);
        btrfs_set_super_compat_flags(super_block, newflags);

        newflags = btrfs_super_compat_ro_flags(super_block);
        newflags |= flags[0].compat_ro_flags & flags[1].compat_ro_flags;
        newflags &= ~(flags[0].compat_ro_flags & ~flags[1].compat_ro_flags);
        btrfs_set_super_compat_ro_flags(super_block, newflags);

        newflags = btrfs_super_incompat_flags(super_block);
        newflags |= flags[0].incompat_flags & flags[1].incompat_flags;
        newflags &= ~(flags[0].incompat_flags & ~flags[1].incompat_flags);
        btrfs_set_super_incompat_flags(super_block, newflags);
        spin_unlock(&fs_info->super_lock);

        ret = btrfs_commit_transaction(trans);
out_drop_write:
        mnt_drop_write_file(file);

        return ret;
}

static int _btrfs_ioctl_send(struct inode *inode, void __user *argp, bool compat)
{
        struct btrfs_ioctl_send_args *arg;
        int ret;

        if (compat) {
#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
                struct btrfs_ioctl_send_args_32 args32;

                ret = copy_from_user(&args32, argp, sizeof(args32));
                if (ret)
                        return -EFAULT;
                arg = kzalloc(sizeof(*arg), GFP_KERNEL);
                if (!arg)
                        return -ENOMEM;
                arg->send_fd = args32.send_fd;
                arg->clone_sources_count = args32.clone_sources_count;
                arg->clone_sources = compat_ptr(args32.clone_sources);
                arg->parent_root = args32.parent_root;
                arg->flags = args32.flags;
                memcpy(arg->reserved, args32.reserved,
                       sizeof(args32.reserved));
#else
                return -ENOTTY;
#endif
        } else {
                arg = memdup_user(argp, sizeof(*arg));
                if (IS_ERR(arg))
                        return PTR_ERR(arg);
        }
        ret = btrfs_ioctl_send(inode, arg);
        kfree(arg);
        return ret;
}

static int btrfs_ioctl_encoded_read(struct file *file, void __user *argp,
                                    bool compat)
{
        struct btrfs_ioctl_encoded_io_args args = { 0 };
        size_t copy_end_kernel = offsetofend(struct btrfs_ioctl_encoded_io_args,
                                             flags);
        size_t copy_end;
        struct iovec iovstack[UIO_FASTIOV];
        struct iovec *iov = iovstack;
        struct iov_iter iter;
        loff_t pos;
        struct kiocb kiocb;
        ssize_t ret;

        if (!capable(CAP_SYS_ADMIN)) {
                ret = -EPERM;
                goto out_acct;
        }

        if (compat) {
#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
                struct btrfs_ioctl_encoded_io_args_32 args32;

                copy_end = offsetofend(struct btrfs_ioctl_encoded_io_args_32,
                                       flags);
                if (copy_from_user(&args32, argp, copy_end)) {
                        ret = -EFAULT;
                        goto out_acct;
                }
                args.iov = compat_ptr(args32.iov);
                args.iovcnt = args32.iovcnt;
                args.offset = args32.offset;
                args.flags = args32.flags;
#else
                return -ENOTTY;
#endif
        } else {
                copy_end = copy_end_kernel;
                if (copy_from_user(&args, argp, copy_end)) {
                        ret = -EFAULT;
                        goto out_acct;
                }
        }
        if (args.flags != 0) {
                ret = -EINVAL;
                goto out_acct;
        }

        ret = import_iovec(READ, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
                           &iov, &iter);
        if (ret < 0)
                goto out_acct;

        if (iov_iter_count(&iter) == 0) {
                ret = 0;
                goto out_iov;
        }
        pos = args.offset;
        ret = rw_verify_area(READ, file, &pos, args.len);
        if (ret < 0)
                goto out_iov;

        init_sync_kiocb(&kiocb, file);
        kiocb.ki_pos = pos;

        ret = btrfs_encoded_read(&kiocb, &iter, &args);
        if (ret >= 0) {
                fsnotify_access(file);
                if (copy_to_user(argp + copy_end,
                                 (char *)&args + copy_end_kernel,
                                 sizeof(args) - copy_end_kernel))
                        ret = -EFAULT;
        }

out_iov:
        kfree(iov);
out_acct:
        if (ret > 0)
                add_rchar(current, ret);
        inc_syscr(current);
        return ret;
}

static int btrfs_ioctl_encoded_write(struct file *file, void __user *argp, bool compat)
{
        struct btrfs_ioctl_encoded_io_args args;
        struct iovec iovstack[UIO_FASTIOV];
        struct iovec *iov = iovstack;
        struct iov_iter iter;
        loff_t pos;
        struct kiocb kiocb;
        ssize_t ret;

        if (!capable(CAP_SYS_ADMIN)) {
                ret = -EPERM;
                goto out_acct;
        }

        if (!(file->f_mode & FMODE_WRITE)) {
                ret = -EBADF;
                goto out_acct;
        }

        if (compat) {
#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
                struct btrfs_ioctl_encoded_io_args_32 args32;

                if (copy_from_user(&args32, argp, sizeof(args32))) {
                        ret = -EFAULT;
                        goto out_acct;
                }
                args.iov = compat_ptr(args32.iov);
                args.iovcnt = args32.iovcnt;
                args.offset = args32.offset;
                args.flags = args32.flags;
                args.len = args32.len;
                args.unencoded_len = args32.unencoded_len;
                args.unencoded_offset = args32.unencoded_offset;
                args.compression = args32.compression;
                args.encryption = args32.encryption;
                memcpy(args.reserved, args32.reserved, sizeof(args.reserved));
#else
                return -ENOTTY;
#endif
        } else {
                if (copy_from_user(&args, argp, sizeof(args))) {
                        ret = -EFAULT;
                        goto out_acct;
                }
        }

        ret = -EINVAL;
        if (args.flags != 0)
                goto out_acct;
        if (memchr_inv(args.reserved, 0, sizeof(args.reserved)))
                goto out_acct;
        if (args.compression == BTRFS_ENCODED_IO_COMPRESSION_NONE &&
            args.encryption == BTRFS_ENCODED_IO_ENCRYPTION_NONE)
                goto out_acct;
        if (args.compression >= BTRFS_ENCODED_IO_COMPRESSION_TYPES ||
            args.encryption >= BTRFS_ENCODED_IO_ENCRYPTION_TYPES)
                goto out_acct;
        if (args.unencoded_offset > args.unencoded_len)
                goto out_acct;
        if (args.len > args.unencoded_len - args.unencoded_offset)
                goto out_acct;

        ret = import_iovec(WRITE, args.iov, args.iovcnt, ARRAY_SIZE(iovstack),
                           &iov, &iter);
        if (ret < 0)
                goto out_acct;

        file_start_write(file);

        if (iov_iter_count(&iter) == 0) {
                ret = 0;
                goto out_end_write;
        }
        pos = args.offset;
        ret = rw_verify_area(WRITE, file, &pos, args.len);
        if (ret < 0)
                goto out_end_write;

        init_sync_kiocb(&kiocb, file);
        ret = kiocb_set_rw_flags(&kiocb, 0);
        if (ret)
                goto out_end_write;
        kiocb.ki_pos = pos;

        ret = btrfs_do_write_iter(&kiocb, &iter, &args);
        if (ret > 0)
                fsnotify_modify(file);

out_end_write:
        file_end_write(file);
        kfree(iov);
out_acct:
        if (ret > 0)
                add_wchar(current, ret);
        inc_syscw(current);
        return ret;
}

long btrfs_ioctl(struct file *file, unsigned int
                cmd, unsigned long arg)
{
        struct inode *inode = file_inode(file);
        struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
        struct btrfs_root *root = BTRFS_I(inode)->root;
        void __user *argp = (void __user *)arg;

        switch (cmd) {
        case FS_IOC_GETVERSION:
                return btrfs_ioctl_getversion(inode, argp);
        case FS_IOC_GETFSLABEL:
                return btrfs_ioctl_get_fslabel(fs_info, argp);
        case FS_IOC_SETFSLABEL:
                return btrfs_ioctl_set_fslabel(file, argp);
        case FITRIM:
                return btrfs_ioctl_fitrim(fs_info, argp);
        case BTRFS_IOC_SNAP_CREATE:
                return btrfs_ioctl_snap_create(file, argp, 0);
        case BTRFS_IOC_SNAP_CREATE_V2:
                return btrfs_ioctl_snap_create_v2(file, argp, 0);
        case BTRFS_IOC_SUBVOL_CREATE:
                return btrfs_ioctl_snap_create(file, argp, 1);
        case BTRFS_IOC_SUBVOL_CREATE_V2:
                return btrfs_ioctl_snap_create_v2(file, argp, 1);
        case BTRFS_IOC_SNAP_DESTROY:
                return btrfs_ioctl_snap_destroy(file, argp, false);
        case BTRFS_IOC_SNAP_DESTROY_V2:
                return btrfs_ioctl_snap_destroy(file, argp, true);
        case BTRFS_IOC_SUBVOL_GETFLAGS:
                return btrfs_ioctl_subvol_getflags(inode, argp);
        case BTRFS_IOC_SUBVOL_SETFLAGS:
                return btrfs_ioctl_subvol_setflags(file, argp);
        case BTRFS_IOC_DEFAULT_SUBVOL:
                return btrfs_ioctl_default_subvol(file, argp);
        case BTRFS_IOC_DEFRAG:
                return btrfs_ioctl_defrag(file, NULL);
        case BTRFS_IOC_DEFRAG_RANGE:
                return btrfs_ioctl_defrag(file, argp);
        case BTRFS_IOC_RESIZE:
                return btrfs_ioctl_resize(file, argp);
        case BTRFS_IOC_ADD_DEV:
                return btrfs_ioctl_add_dev(fs_info, argp);
        case BTRFS_IOC_RM_DEV:
                return btrfs_ioctl_rm_dev(file, argp);
        case BTRFS_IOC_RM_DEV_V2:
                return btrfs_ioctl_rm_dev_v2(file, argp);
        case BTRFS_IOC_FS_INFO:
                return btrfs_ioctl_fs_info(fs_info, argp);
        case BTRFS_IOC_DEV_INFO:
                return btrfs_ioctl_dev_info(fs_info, argp);
        case BTRFS_IOC_TREE_SEARCH:
                return btrfs_ioctl_tree_search(inode, argp);
        case BTRFS_IOC_TREE_SEARCH_V2:
                return btrfs_ioctl_tree_search_v2(inode, argp);
        case BTRFS_IOC_INO_LOOKUP:
                return btrfs_ioctl_ino_lookup(root, argp);
        case BTRFS_IOC_INO_PATHS:
                return btrfs_ioctl_ino_to_path(root, argp);
        case BTRFS_IOC_LOGICAL_INO:
                return btrfs_ioctl_logical_to_ino(fs_info, argp, 1);
        case BTRFS_IOC_LOGICAL_INO_V2:
                return btrfs_ioctl_logical_to_ino(fs_info, argp, 2);
        case BTRFS_IOC_SPACE_INFO:
                return btrfs_ioctl_space_info(fs_info, argp);
        case BTRFS_IOC_SYNC: {
                int ret;

                ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
                if (ret)
                        return ret;
                ret = btrfs_sync_fs(inode->i_sb, 1);
                /*
                 * The transaction thread may want to do more work,
                 * namely it pokes the cleaner kthread that will start
                 * processing uncleaned subvols.
                 */
                wake_up_process(fs_info->transaction_kthread);
                return ret;
        }
        case BTRFS_IOC_START_SYNC:
                return btrfs_ioctl_start_sync(root, argp);
        case BTRFS_IOC_WAIT_SYNC:
                return btrfs_ioctl_wait_sync(fs_info, argp);
        case BTRFS_IOC_SCRUB:
                return btrfs_ioctl_scrub(file, argp);
        case BTRFS_IOC_SCRUB_CANCEL:
                return btrfs_ioctl_scrub_cancel(fs_info);
        case BTRFS_IOC_SCRUB_PROGRESS:
                return btrfs_ioctl_scrub_progress(fs_info, argp);
        case BTRFS_IOC_BALANCE_V2:
                return btrfs_ioctl_balance(file, argp);
        case BTRFS_IOC_BALANCE_CTL:
                return btrfs_ioctl_balance_ctl(fs_info, arg);
        case BTRFS_IOC_BALANCE_PROGRESS:
                return btrfs_ioctl_balance_progress(fs_info, argp);
        case BTRFS_IOC_SET_RECEIVED_SUBVOL:
                return btrfs_ioctl_set_received_subvol(file, argp);
#ifdef CONFIG_64BIT
        case BTRFS_IOC_SET_RECEIVED_SUBVOL_32:
                return btrfs_ioctl_set_received_subvol_32(file, argp);
#endif
        case BTRFS_IOC_SEND:
                return _btrfs_ioctl_send(inode, argp, false);
#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
        case BTRFS_IOC_SEND_32:
                return _btrfs_ioctl_send(inode, argp, true);
#endif
        case BTRFS_IOC_GET_DEV_STATS:
                return btrfs_ioctl_get_dev_stats(fs_info, argp);
        case BTRFS_IOC_QUOTA_CTL:
                return btrfs_ioctl_quota_ctl(file, argp);
        case BTRFS_IOC_QGROUP_ASSIGN:
                return btrfs_ioctl_qgroup_assign(file, argp);
        case BTRFS_IOC_QGROUP_CREATE:
                return btrfs_ioctl_qgroup_create(file, argp);
        case BTRFS_IOC_QGROUP_LIMIT:
                return btrfs_ioctl_qgroup_limit(file, argp);
        case BTRFS_IOC_QUOTA_RESCAN:
                return btrfs_ioctl_quota_rescan(file, argp);
        case BTRFS_IOC_QUOTA_RESCAN_STATUS:
                return btrfs_ioctl_quota_rescan_status(fs_info, argp);
        case BTRFS_IOC_QUOTA_RESCAN_WAIT:
                return btrfs_ioctl_quota_rescan_wait(fs_info, argp);
        case BTRFS_IOC_DEV_REPLACE:
                return btrfs_ioctl_dev_replace(fs_info, argp);
        case BTRFS_IOC_GET_SUPPORTED_FEATURES:
                return btrfs_ioctl_get_supported_features(argp);
        case BTRFS_IOC_GET_FEATURES:
                return btrfs_ioctl_get_features(fs_info, argp);
        case BTRFS_IOC_SET_FEATURES:
                return btrfs_ioctl_set_features(file, argp);
        case BTRFS_IOC_GET_SUBVOL_INFO:
                return btrfs_ioctl_get_subvol_info(inode, argp);
        case BTRFS_IOC_GET_SUBVOL_ROOTREF:
                return btrfs_ioctl_get_subvol_rootref(root, argp);
        case BTRFS_IOC_INO_LOOKUP_USER:
                return btrfs_ioctl_ino_lookup_user(file, argp);
        case FS_IOC_ENABLE_VERITY:
                return fsverity_ioctl_enable(file, (const void __user *)argp);
        case FS_IOC_MEASURE_VERITY:
                return fsverity_ioctl_measure(file, argp);
        case BTRFS_IOC_ENCODED_READ:
                return btrfs_ioctl_encoded_read(file, argp, false);
        case BTRFS_IOC_ENCODED_WRITE:
                return btrfs_ioctl_encoded_write(file, argp, false);
#if defined(CONFIG_64BIT) && defined(CONFIG_COMPAT)
        case BTRFS_IOC_ENCODED_READ_32:
                return btrfs_ioctl_encoded_read(file, argp, true);
        case BTRFS_IOC_ENCODED_WRITE_32:
                return btrfs_ioctl_encoded_write(file, argp, true);
#endif
        }

        return -ENOTTY;
}

#ifdef CONFIG_COMPAT
long btrfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        /*
         * These all access 32-bit values anyway so no further
         * handling is necessary.
         */
        switch (cmd) {
        case FS_IOC32_GETVERSION:
                cmd = FS_IOC_GETVERSION;
                break;
        }

        return btrfs_ioctl(file, cmd, (unsigned long) compat_ptr(arg));
}
#endif