[people/ms/linux.git] / fs / remap_range.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/sched/xacct.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/fsnotify.h>
#include <linux/security.h>
#include <linux/export.h>
#include <linux/syscalls.h>
#include <linux/pagemap.h>
#include <linux/splice.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/fs.h>
#include "internal.h"

#include <linux/uaccess.h>
#include <asm/unistd.h>

/*
 * Performs necessary checks before doing a clone.
 *
 * Can adjust amount of bytes to clone via @req_count argument.
 * Returns appropriate error code that caller should return or
 * zero in case the clone should be allowed.
 */
static int generic_remap_checks(struct file *file_in, loff_t pos_in,
				struct file *file_out, loff_t pos_out,
				loff_t *req_count, unsigned int remap_flags)
{
	struct inode *inode_in = file_in->f_mapping->host;
	struct inode *inode_out = file_out->f_mapping->host;
	uint64_t count = *req_count;
	uint64_t bcount;
	loff_t size_in, size_out;
	loff_t bs = inode_out->i_sb->s_blocksize;
	int ret;

	/* The start of both ranges must be aligned to an fs block. */
	if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
		return -EINVAL;

	/* Ensure offsets don't wrap. */
	if (pos_in + count < pos_in || pos_out + count < pos_out)
		return -EINVAL;

	size_in = i_size_read(inode_in);
	size_out = i_size_read(inode_out);

	/* Dedupe requires both ranges to be within EOF. */
	if ((remap_flags & REMAP_FILE_DEDUP) &&
	    (pos_in >= size_in || pos_in + count > size_in ||
	     pos_out >= size_out || pos_out + count > size_out))
		return -EINVAL;

	/* Ensure the infile range is within the infile. */
	if (pos_in >= size_in)
		return -EINVAL;
	count = min(count, size_in - (uint64_t)pos_in);

	ret = generic_write_check_limits(file_out, pos_out, &count);
	if (ret)
		return ret;

	/*
	 * If the user wanted us to link to the infile's EOF, round up to the
	 * next block boundary for this check.
	 *
	 * Otherwise, make sure the count is also block-aligned, having
	 * already confirmed the starting offsets' block alignment.
	 */
	if (pos_in + count == size_in) {
		bcount = ALIGN(size_in, bs) - pos_in;
	} else {
		if (!IS_ALIGNED(count, bs))
			count = ALIGN_DOWN(count, bs);
		bcount = count;
	}

	/* Don't allow overlapped cloning within the same file. */
	if (inode_in == inode_out &&
	    pos_out + bcount > pos_in &&
	    pos_out < pos_in + bcount)
		return -EINVAL;

	/*
	 * We shortened the request but the caller can't deal with that, so
	 * bounce the request back to userspace.
	 */
	if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
		return -EINVAL;

	*req_count = count;
	return 0;
}

static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
			     bool write)
{
	if (unlikely(pos < 0 || len < 0))
		return -EINVAL;

	if (unlikely((loff_t) (pos + len) < 0))
		return -EINVAL;

	return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
}

/*
 * Ensure that we don't remap a partial EOF block in the middle of something
 * else.  Assume that the offsets have already been checked for block
 * alignment.
 *
 * For clone we only link a partial EOF block above or at the destination file's
 * EOF.  For deduplication we accept a partial EOF block only if it ends at the
 * destination file's EOF (can not link it into the middle of a file).
 *
 * Shorten the request if possible.
 */
static int generic_remap_check_len(struct inode *inode_in,
				   struct inode *inode_out,
				   loff_t pos_out,
				   loff_t *len,
				   unsigned int remap_flags)
{
	u64 blkmask = i_blocksize(inode_in) - 1;
	loff_t new_len = *len;

	if ((*len & blkmask) == 0)
		return 0;

	if (pos_out + *len < i_size_read(inode_out))
		new_len &= ~blkmask;

	if (new_len == *len)
		return 0;

	if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
		*len = new_len;
		return 0;
	}

	return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
}

/* Read a page's worth of file data into the page cache. */
static struct folio *vfs_dedupe_get_folio(struct file *file, loff_t pos)
{
	struct folio *folio;

	folio = read_mapping_folio(file->f_mapping, pos >> PAGE_SHIFT, file);
	if (IS_ERR(folio))
		return folio;
	if (!folio_test_uptodate(folio)) {
		folio_put(folio);
		return ERR_PTR(-EIO);
	}
	return folio;
}

/*
 * Lock two folios, ensuring that we lock in offset order if the folios
 * are from the same file.
 */
static void vfs_lock_two_folios(struct folio *folio1, struct folio *folio2)
{
	/* Always lock in order of increasing index. */
	if (folio1->index > folio2->index)
		swap(folio1, folio2);

	folio_lock(folio1);
	if (folio1 != folio2)
		folio_lock(folio2);
}

/* Unlock two folios, being careful not to unlock the same folio twice. */
static void vfs_unlock_two_folios(struct folio *folio1, struct folio *folio2)
{
	folio_unlock(folio1);
	if (folio1 != folio2)
		folio_unlock(folio2);
}

/*
 * Compare extents of two files to see if they are the same.
 * Caller must have locked both inodes to prevent write races.
 */
static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff,
					 struct file *dest, loff_t dstoff,
					 loff_t len, bool *is_same)
{
	bool same = true;
	int error = -EINVAL;

	while (len) {
		struct folio *src_folio, *dst_folio;
		void *src_addr, *dst_addr;
		loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff),
				     PAGE_SIZE - offset_in_page(dstoff));

		cmp_len = min(cmp_len, len);
		if (cmp_len <= 0)
			goto out_error;

		src_folio = vfs_dedupe_get_folio(src, srcoff);
		if (IS_ERR(src_folio)) {
			error = PTR_ERR(src_folio);
			goto out_error;
		}
		dst_folio = vfs_dedupe_get_folio(dest, dstoff);
		if (IS_ERR(dst_folio)) {
			error = PTR_ERR(dst_folio);
			folio_put(src_folio);
			goto out_error;
		}

		vfs_lock_two_folios(src_folio, dst_folio);

		/*
		 * Now that we've locked both folios, make sure they're still
		 * mapped to the file data we're interested in.  If not,
		 * someone is invalidating pages on us and we lose.
		 */
		if (!folio_test_uptodate(src_folio) || !folio_test_uptodate(dst_folio) ||
		    src_folio->mapping != src->f_mapping ||
		    dst_folio->mapping != dest->f_mapping) {
			same = false;
			goto unlock;
		}

		src_addr = kmap_local_folio(src_folio,
					offset_in_folio(src_folio, srcoff));
		dst_addr = kmap_local_folio(dst_folio,
					offset_in_folio(dst_folio, dstoff));

		flush_dcache_folio(src_folio);
		flush_dcache_folio(dst_folio);

		if (memcmp(src_addr, dst_addr, cmp_len))
			same = false;

		kunmap_local(dst_addr);
		kunmap_local(src_addr);
unlock:
		vfs_unlock_two_folios(src_folio, dst_folio);
		folio_put(dst_folio);
		folio_put(src_folio);

		if (!same)
			break;

		srcoff += cmp_len;
		dstoff += cmp_len;
		len -= cmp_len;
	}

	*is_same = same;
	return 0;

out_error:
	return error;
}

/*
 * Check that the two inodes are eligible for cloning, the ranges make
 * sense, and then flush all dirty data.  Caller must ensure that the
 * inodes have been locked against any other modifications.
 *
 * If there's an error, then the usual negative error code is returned.
 * Otherwise returns 0 with *len set to the request length.
 */
int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
				  struct file *file_out, loff_t pos_out,
				  loff_t *len, unsigned int remap_flags)
{
	struct inode *inode_in = file_inode(file_in);
	struct inode *inode_out = file_inode(file_out);
	bool same_inode = (inode_in == inode_out);
	int ret;

	/* Don't touch certain kinds of inodes */
	if (IS_IMMUTABLE(inode_out))
		return -EPERM;

	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
		return -ETXTBSY;

	/* Don't reflink dirs, pipes, sockets... */
	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
		return -EISDIR;
	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
		return -EINVAL;

	/* Zero length dedupe exits immediately; reflink goes to EOF. */
	if (*len == 0) {
		loff_t isize = i_size_read(inode_in);

		if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize)
			return 0;
		if (pos_in > isize)
			return -EINVAL;
		*len = isize - pos_in;
		if (*len == 0)
			return 0;
	}

	/* Check that we don't violate system file offset limits. */
	ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
			remap_flags);
	if (ret)
		return ret;

	/* Wait for the completion of any pending IOs on both files */
	inode_dio_wait(inode_in);
	if (!same_inode)
		inode_dio_wait(inode_out);

	ret = filemap_write_and_wait_range(inode_in->i_mapping,
			pos_in, pos_in + *len - 1);
	if (ret)
		return ret;

	ret = filemap_write_and_wait_range(inode_out->i_mapping,
			pos_out, pos_out + *len - 1);
	if (ret)
		return ret;

	/*
	 * Check that the extents are the same.
	 */
	if (remap_flags & REMAP_FILE_DEDUP) {
		bool		is_same = false;

		ret = vfs_dedupe_file_range_compare(file_in, pos_in,
				file_out, pos_out, *len, &is_same);
		if (ret)
			return ret;
		if (!is_same)
			return -EBADE;
	}

	ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
			remap_flags);
	if (ret)
		return ret;

	/* If can't alter the file contents, we're done. */
	if (!(remap_flags & REMAP_FILE_DEDUP))
		ret = file_modified(file_out);

	return ret;
}
EXPORT_SYMBOL(generic_remap_file_range_prep);

loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
			   struct file *file_out, loff_t pos_out,
			   loff_t len, unsigned int remap_flags)
{
	loff_t ret;

	WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);

	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
		return -EXDEV;

	ret = generic_file_rw_checks(file_in, file_out);
	if (ret < 0)
		return ret;

	if (!file_in->f_op->remap_file_range)
		return -EOPNOTSUPP;

	ret = remap_verify_area(file_in, pos_in, len, false);
	if (ret)
		return ret;

	ret = remap_verify_area(file_out, pos_out, len, true);
	if (ret)
		return ret;

	ret = file_in->f_op->remap_file_range(file_in, pos_in,
			file_out, pos_out, len, remap_flags);
	if (ret < 0)
		return ret;

	fsnotify_access(file_in);
	fsnotify_modify(file_out);
	return ret;
}
EXPORT_SYMBOL(do_clone_file_range);

loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
			    struct file *file_out, loff_t pos_out,
			    loff_t len, unsigned int remap_flags)
{
	loff_t ret;

	file_start_write(file_out);
	ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
				  remap_flags);
	file_end_write(file_out);

	return ret;
}
EXPORT_SYMBOL(vfs_clone_file_range);

/* Check whether we are allowed to dedupe the destination file */
static bool allow_file_dedupe(struct file *file)
{
	struct user_namespace *mnt_userns = file_mnt_user_ns(file);
	struct inode *inode = file_inode(file);

	if (capable(CAP_SYS_ADMIN))
		return true;
	if (file->f_mode & FMODE_WRITE)
		return true;
	if (uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)))
		return true;
	if (!inode_permission(mnt_userns, inode, MAY_WRITE))
		return true;
	return false;
}

loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
				 struct file *dst_file, loff_t dst_pos,
				 loff_t len, unsigned int remap_flags)
{
	loff_t ret;

	WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP |
				     REMAP_FILE_CAN_SHORTEN));

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

	/*
	 * This is redundant if called from vfs_dedupe_file_range(), but other
	 * callers need it and it's not performance sesitive...
	 */
	ret = remap_verify_area(src_file, src_pos, len, false);
	if (ret)
		goto out_drop_write;

	ret = remap_verify_area(dst_file, dst_pos, len, true);
	if (ret)
		goto out_drop_write;

	ret = -EPERM;
	if (!allow_file_dedupe(dst_file))
		goto out_drop_write;

	ret = -EXDEV;
	if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb)
		goto out_drop_write;

	ret = -EISDIR;
	if (S_ISDIR(file_inode(dst_file)->i_mode))
		goto out_drop_write;

	ret = -EINVAL;
	if (!dst_file->f_op->remap_file_range)
		goto out_drop_write;

	if (len == 0) {
		ret = 0;
		goto out_drop_write;
	}

	ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
			dst_pos, len, remap_flags | REMAP_FILE_DEDUP);
out_drop_write:
	mnt_drop_write_file(dst_file);

	return ret;
}
EXPORT_SYMBOL(vfs_dedupe_file_range_one);

int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
{
	struct file_dedupe_range_info *info;
	struct inode *src = file_inode(file);
	u64 off;
	u64 len;
	int i;
	int ret;
	u16 count = same->dest_count;
	loff_t deduped;

	if (!(file->f_mode & FMODE_READ))
		return -EINVAL;

	if (same->reserved1 || same->reserved2)
		return -EINVAL;

	off = same->src_offset;
	len = same->src_length;

	if (S_ISDIR(src->i_mode))
		return -EISDIR;

	if (!S_ISREG(src->i_mode))
		return -EINVAL;

	if (!file->f_op->remap_file_range)
		return -EOPNOTSUPP;

	ret = remap_verify_area(file, off, len, false);
	if (ret < 0)
		return ret;
	ret = 0;

	if (off + len > i_size_read(src))
		return -EINVAL;

	/* Arbitrary 1G limit on a single dedupe request, can be raised. */
	len = min_t(u64, len, 1 << 30);

	/* pre-format output fields to sane values */
	for (i = 0; i < count; i++) {
		same->info[i].bytes_deduped = 0ULL;
		same->info[i].status = FILE_DEDUPE_RANGE_SAME;
	}

	for (i = 0, info = same->info; i < count; i++, info++) {
		struct fd dst_fd = fdget(info->dest_fd);
		struct file *dst_file = dst_fd.file;

		if (!dst_file) {
			info->status = -EBADF;
			goto next_loop;
		}

		if (info->reserved) {
			info->status = -EINVAL;
			goto next_fdput;
		}

		deduped = vfs_dedupe_file_range_one(file, off, dst_file,
						    info->dest_offset, len,
						    REMAP_FILE_CAN_SHORTEN);
		if (deduped == -EBADE)
			info->status = FILE_DEDUPE_RANGE_DIFFERS;
		else if (deduped < 0)
			info->status = deduped;
		else
			info->bytes_deduped = len;

next_fdput:
		fdput(dst_fd);
next_loop:
		if (fatal_signal_pending(current))
			break;
	}
	return ret;
}
EXPORT_SYMBOL(vfs_dedupe_file_range);
Commit	Line	Data
02e83f46 DW	1	// SPDX-License-Identifier: GPL-2.0-only
	2	#include <linux/slab.h>
	3	#include <linux/stat.h>
	4	#include <linux/sched/xacct.h>
	5	#include <linux/fcntl.h>
	6	#include <linux/file.h>
	7	#include <linux/uio.h>
	8	#include <linux/fsnotify.h>
	9	#include <linux/security.h>
	10	#include <linux/export.h>
	11	#include <linux/syscalls.h>
	12	#include <linux/pagemap.h>
	13	#include <linux/splice.h>
	14	#include <linux/compat.h>
	15	#include <linux/mount.h>
	16	#include <linux/fs.h>
	17	#include "internal.h"
	18
	19	#include <linux/uaccess.h>
	20	#include <asm/unistd.h>
	21
	22	/*
	23	* Performs necessary checks before doing a clone.
	24	*
	25	* Can adjust amount of bytes to clone via @req_count argument.
	26	* Returns appropriate error code that caller should return or
	27	* zero in case the clone should be allowed.
	28	*/
1b2c54d6 DW	29	static int generic_remap_checks(struct file *file_in, loff_t pos_in,
	30	struct file *file_out, loff_t pos_out,
	31	loff_t *req_count, unsigned int remap_flags)
02e83f46 DW	32	{
	33	struct inode *inode_in = file_in->f_mapping->host;
	34	struct inode *inode_out = file_out->f_mapping->host;
	35	uint64_t count = *req_count;
	36	uint64_t bcount;
	37	loff_t size_in, size_out;
	38	loff_t bs = inode_out->i_sb->s_blocksize;
	39	int ret;
	40
	41	/* The start of both ranges must be aligned to an fs block. */
	42	if (!IS_ALIGNED(pos_in, bs) \|\| !IS_ALIGNED(pos_out, bs))
	43	return -EINVAL;
	44
	45	/* Ensure offsets don't wrap. */
	46	if (pos_in + count < pos_in \|\| pos_out + count < pos_out)
	47	return -EINVAL;
	48
	49	size_in = i_size_read(inode_in);
	50	size_out = i_size_read(inode_out);
	51
	52	/* Dedupe requires both ranges to be within EOF. */
	53	if ((remap_flags & REMAP_FILE_DEDUP) &&
	54	(pos_in >= size_in \|\| pos_in + count > size_in \|\|
	55	pos_out >= size_out \|\| pos_out + count > size_out))
	56	return -EINVAL;
	57
	58	/* Ensure the infile range is within the infile. */
	59	if (pos_in >= size_in)
	60	return -EINVAL;
	61	count = min(count, size_in - (uint64_t)pos_in);
	62
	63	ret = generic_write_check_limits(file_out, pos_out, &count);
	64	if (ret)
	65	return ret;
	66
	67	/*
	68	* If the user wanted us to link to the infile's EOF, round up to the
	69	* next block boundary for this check.
	70	*
	71	* Otherwise, make sure the count is also block-aligned, having
	72	* already confirmed the starting offsets' block alignment.
	73	*/
	74	if (pos_in + count == size_in) {
	75	bcount = ALIGN(size_in, bs) - pos_in;
	76	} else {
	77	if (!IS_ALIGNED(count, bs))
	78	count = ALIGN_DOWN(count, bs);
	79	bcount = count;
	80	}
	81
	82	/* Don't allow overlapped cloning within the same file. */
	83	if (inode_in == inode_out &&
	84	pos_out + bcount > pos_in &&
	85	pos_out < pos_in + bcount)
	86	return -EINVAL;
	87
	88	/*
	89	* We shortened the request but the caller can't deal with that, so
	90	* bounce the request back to userspace.
	91	*/
	92	if (*req_count != count && !(remap_flags & REMAP_FILE_CAN_SHORTEN))
	93	return -EINVAL;
	94
	95	*req_count = count;
96	return 0;
97	}
1b2c54d6 DW	98
	99	static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
	100	bool write)
	101	{
1b2c54d6 DW	102	if (unlikely(pos < 0 \|\| len < 0))
	103	return -EINVAL;
	104
	105	if (unlikely((loff_t) (pos + len) < 0))
	106	return -EINVAL;
	107
1b2c54d6 DW	108	return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
	109	}
	110
	111	/*
	112	* Ensure that we don't remap a partial EOF block in the middle of something
	113	* else. Assume that the offsets have already been checked for block
	114	* alignment.
	115	*
	116	* For clone we only link a partial EOF block above or at the destination file's
	117	* EOF. For deduplication we accept a partial EOF block only if it ends at the
	118	* destination file's EOF (can not link it into the middle of a file).
	119	*
	120	* Shorten the request if possible.
	121	*/
	122	static int generic_remap_check_len(struct inode *inode_in,
	123	struct inode *inode_out,
	124	loff_t pos_out,
	125	loff_t *len,
	126	unsigned int remap_flags)
	127	{
	128	u64 blkmask = i_blocksize(inode_in) - 1;
	129	loff_t new_len = *len;
	130
	131	if ((*len & blkmask) == 0)
	132	return 0;
	133
	134	if (pos_out + *len < i_size_read(inode_out))
	135	new_len &= ~blkmask;
	136
	137	if (new_len == *len)
	138	return 0;
	139
	140	if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
	141	*len = new_len;
	142	return 0;
	143	}
	144
	145	return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
	146	}
	147
	148	/* Read a page's worth of file data into the page cache. */
4495a96c	149	static struct folio vfs_dedupe_get_folio(struct file file, loff_t pos)
1b2c54d6	150	{
338f379c	151	struct folio *folio;
1b2c54d6	152
4495a96c	153	folio = read_mapping_folio(file->f_mapping, pos >> PAGE_SHIFT, file);
338f379c MWO	154	if (IS_ERR(folio))
	155	return folio;
	156	if (!folio_test_uptodate(folio)) {
	157	folio_put(folio);
1b2c54d6 DW	158	return ERR_PTR(-EIO);
1b2c54d6 DW	159	}
338f379c	160	return folio;
1b2c54d6 DW	161	}
	162
	163	/*
338f379c MWO	164	* Lock two folios, ensuring that we lock in offset order if the folios
338f379c MWO	165	* are from the same file.
1b2c54d6	166	*/
338f379c	167	static void vfs_lock_two_folios(struct folio folio1, struct folio folio2)
1b2c54d6 DW	168	{
1b2c54d6 DW	169	/* Always lock in order of increasing index. */
338f379c MWO	170	if (folio1->index > folio2->index)
338f379c MWO	171	swap(folio1, folio2);
1b2c54d6	172
338f379c MWO	173	folio_lock(folio1);
	174	if (folio1 != folio2)
	175	folio_lock(folio2);
1b2c54d6 DW	176	}
1b2c54d6 DW	177
338f379c MWO	178	/* Unlock two folios, being careful not to unlock the same folio twice. */
338f379c MWO	179	static void vfs_unlock_two_folios(struct folio folio1, struct folio folio2)
1b2c54d6	180	{
338f379c MWO	181	folio_unlock(folio1);
	182	if (folio1 != folio2)
	183	folio_unlock(folio2);
1b2c54d6 DW	184	}
	185
	186	/*
	187	* Compare extents of two files to see if they are the same.
	188	* Caller must have locked both inodes to prevent write races.
	189	*/
4495a96c MWO	190	static int vfs_dedupe_file_range_compare(struct file *src, loff_t srcoff,
4495a96c MWO	191	struct file *dest, loff_t dstoff,
1b2c54d6 DW	192	loff_t len, bool *is_same)
1b2c54d6 DW	193	{
338f379c MWO	194	bool same = true;
	195	int error = -EINVAL;
	196
1b2c54d6	197	while (len) {
338f379c MWO	198	struct folio src_folio, dst_folio;
	199	void src_addr, dst_addr;
	200	loff_t cmp_len = min(PAGE_SIZE - offset_in_page(srcoff),
	201	PAGE_SIZE - offset_in_page(dstoff));
	202
1b2c54d6 DW	203	cmp_len = min(cmp_len, len);
	204	if (cmp_len <= 0)
	205	goto out_error;
	206
338f379c MWO	207	src_folio = vfs_dedupe_get_folio(src, srcoff);
	208	if (IS_ERR(src_folio)) {
	209	error = PTR_ERR(src_folio);
1b2c54d6 DW	210	goto out_error;
1b2c54d6 DW	211	}
338f379c MWO	212	dst_folio = vfs_dedupe_get_folio(dest, dstoff);
	213	if (IS_ERR(dst_folio)) {
	214	error = PTR_ERR(dst_folio);
	215	folio_put(src_folio);
1b2c54d6 DW	216	goto out_error;
	217	}
	218
338f379c	219	vfs_lock_two_folios(src_folio, dst_folio);
1b2c54d6 DW	220
1b2c54d6 DW	221	/*
338f379c	222	* Now that we've locked both folios, make sure they're still
1b2c54d6 DW	223	* mapped to the file data we're interested in. If not,
	224	* someone is invalidating pages on us and we lose.
	225	*/
338f379c	226	if (!folio_test_uptodate(src_folio) \|\| !folio_test_uptodate(dst_folio) \|\|
4495a96c MWO	227	src_folio->mapping != src->f_mapping \|\|
4495a96c MWO	228	dst_folio->mapping != dest->f_mapping) {
1b2c54d6 DW	229	same = false;
	230	goto unlock;
	231	}
	232
338f379c MWO	233	src_addr = kmap_local_folio(src_folio,
	234	offset_in_folio(src_folio, srcoff));
	235	dst_addr = kmap_local_folio(dst_folio,
	236	offset_in_folio(dst_folio, dstoff));
1b2c54d6	237
338f379c MWO	238	flush_dcache_folio(src_folio);
338f379c MWO	239	flush_dcache_folio(dst_folio);
1b2c54d6	240
338f379c	241	if (memcmp(src_addr, dst_addr, cmp_len))
1b2c54d6 DW	242	same = false;
1b2c54d6 DW	243
338f379c MWO	244	kunmap_local(dst_addr);
338f379c MWO	245	kunmap_local(src_addr);
1b2c54d6	246	unlock:
338f379c MWO	247	vfs_unlock_two_folios(src_folio, dst_folio);
	248	folio_put(dst_folio);
	249	folio_put(src_folio);
1b2c54d6 DW	250
	251	if (!same)
	252	break;
	253
	254	srcoff += cmp_len;
338f379c	255	dstoff += cmp_len;
1b2c54d6 DW	256	len -= cmp_len;
	257	}
	258
	259	*is_same = same;
	260	return 0;
	261
	262	out_error:
	263	return error;
	264	}
	265
	266	/*
	267	* Check that the two inodes are eligible for cloning, the ranges make
	268	* sense, and then flush all dirty data. Caller must ensure that the
	269	* inodes have been locked against any other modifications.
	270	*
	271	* If there's an error, then the usual negative error code is returned.
	272	* Otherwise returns 0 with *len set to the request length.
	273	*/
	274	int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
	275	struct file *file_out, loff_t pos_out,
	276	loff_t *len, unsigned int remap_flags)
	277	{
	278	struct inode *inode_in = file_inode(file_in);
	279	struct inode *inode_out = file_inode(file_out);
	280	bool same_inode = (inode_in == inode_out);
	281	int ret;
	282
	283	/* Don't touch certain kinds of inodes */
	284	if (IS_IMMUTABLE(inode_out))
	285	return -EPERM;
	286
	287	if (IS_SWAPFILE(inode_in) \|\| IS_SWAPFILE(inode_out))
	288	return -ETXTBSY;
	289
	290	/* Don't reflink dirs, pipes, sockets... */
	291	if (S_ISDIR(inode_in->i_mode) \|\| S_ISDIR(inode_out->i_mode))
	292	return -EISDIR;
	293	if (!S_ISREG(inode_in->i_mode) \|\| !S_ISREG(inode_out->i_mode))
	294	return -EINVAL;
	295
	296	/* Zero length dedupe exits immediately; reflink goes to EOF. */
	297	if (*len == 0) {
	298	loff_t isize = i_size_read(inode_in);
	299
	300	if ((remap_flags & REMAP_FILE_DEDUP) \|\| pos_in == isize)
	301	return 0;
	302	if (pos_in > isize)
	303	return -EINVAL;
	304	*len = isize - pos_in;
	305	if (*len == 0)
	306	return 0;
	307	}
	308
	309	/* Check that we don't violate system file offset limits. */
	310	ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
	311	remap_flags);
	312	if (ret)
	313	return ret;
	314
	315	/* Wait for the completion of any pending IOs on both files */
	316	inode_dio_wait(inode_in);
	317	if (!same_inode)
	318	inode_dio_wait(inode_out);
	319
320	ret = filemap_write_and_wait_range(inode_in->i_mapping,
321	pos_in, pos_in + *len - 1);
322	if (ret)
323	return ret;
324
325	ret = filemap_write_and_wait_range(inode_out->i_mapping,
326	pos_out, pos_out + *len - 1);
327	if (ret)
328	return ret;
329
330	/*
331	* Check that the extents are the same.
332	*/
333	if (remap_flags & REMAP_FILE_DEDUP) {
334	bool is_same = false;
335
4495a96c MWO	336	ret = vfs_dedupe_file_range_compare(file_in, pos_in,
4495a96c MWO	337	file_out, pos_out, *len, &is_same);
1b2c54d6 DW	338	if (ret)
	339	return ret;
	340	if (!is_same)
	341	return -EBADE;
	342	}
	343
	344	ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
	345	remap_flags);
	346	if (ret)
	347	return ret;
	348
	349	/* If can't alter the file contents, we're done. */
	350	if (!(remap_flags & REMAP_FILE_DEDUP))
	351	ret = file_modified(file_out);
	352
	353	return ret;
	354	}
	355	EXPORT_SYMBOL(generic_remap_file_range_prep);
	356
	357	loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
	358	struct file *file_out, loff_t pos_out,
	359	loff_t len, unsigned int remap_flags)
	360	{
	361	loff_t ret;
	362
	363	WARN_ON_ONCE(remap_flags & REMAP_FILE_DEDUP);
	364
1b2c54d6 DW	365	if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb)
	366	return -EXDEV;
	367
	368	ret = generic_file_rw_checks(file_in, file_out);
	369	if (ret < 0)
	370	return ret;
	371
	372	if (!file_in->f_op->remap_file_range)
	373	return -EOPNOTSUPP;
	374
	375	ret = remap_verify_area(file_in, pos_in, len, false);
	376	if (ret)
	377	return ret;
	378
	379	ret = remap_verify_area(file_out, pos_out, len, true);
	380	if (ret)
	381	return ret;
	382
	383	ret = file_in->f_op->remap_file_range(file_in, pos_in,
	384	file_out, pos_out, len, remap_flags);
	385	if (ret < 0)
	386	return ret;
	387
	388	fsnotify_access(file_in);
	389	fsnotify_modify(file_out);
	390	return ret;
	391	}
	392	EXPORT_SYMBOL(do_clone_file_range);
	393
	394	loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
	395	struct file *file_out, loff_t pos_out,
	396	loff_t len, unsigned int remap_flags)
	397	{
	398	loff_t ret;
	399
	400	file_start_write(file_out);
	401	ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
	402	remap_flags);
	403	file_end_write(file_out);
	404
	405	return ret;
	406	}
	407	EXPORT_SYMBOL(vfs_clone_file_range);
	408
	409	/* Check whether we are allowed to dedupe the destination file */
	410	static bool allow_file_dedupe(struct file *file)
	411	{
0f5d220b CB	412	struct user_namespace *mnt_userns = file_mnt_user_ns(file);
	413	struct inode *inode = file_inode(file);
	414
1b2c54d6 DW	415	if (capable(CAP_SYS_ADMIN))
	416	return true;
	417	if (file->f_mode & FMODE_WRITE)
	418	return true;
0f5d220b	419	if (uid_eq(current_fsuid(), i_uid_into_mnt(mnt_userns, inode)))
1b2c54d6	420	return true;
0f5d220b	421	if (!inode_permission(mnt_userns, inode, MAY_WRITE))
1b2c54d6 DW	422	return true;
	423	return false;
	424	}
	425
	426	loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
	427	struct file *dst_file, loff_t dst_pos,
	428	loff_t len, unsigned int remap_flags)
	429	{
	430	loff_t ret;
	431
	432	WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP \|
	433	REMAP_FILE_CAN_SHORTEN));
	434
	435	ret = mnt_want_write_file(dst_file);
	436	if (ret)
	437	return ret;
	438
3078d85c MS	439	/*
	440	* This is redundant if called from vfs_dedupe_file_range(), but other
	441	* callers need it and it's not performance sesitive...
	442	*/
	443	ret = remap_verify_area(src_file, src_pos, len, false);
	444	if (ret)
	445	goto out_drop_write;
	446
1b2c54d6	447	ret = remap_verify_area(dst_file, dst_pos, len, true);
3078d85c	448	if (ret)
1b2c54d6 DW	449	goto out_drop_write;
	450
	451	ret = -EPERM;
	452	if (!allow_file_dedupe(dst_file))
	453	goto out_drop_write;
	454
	455	ret = -EXDEV;
9f5710bb	456	if (file_inode(src_file)->i_sb != file_inode(dst_file)->i_sb)
1b2c54d6 DW	457	goto out_drop_write;
	458
	459	ret = -EISDIR;
	460	if (S_ISDIR(file_inode(dst_file)->i_mode))
	461	goto out_drop_write;
	462
	463	ret = -EINVAL;
	464	if (!dst_file->f_op->remap_file_range)
	465	goto out_drop_write;
	466
	467	if (len == 0) {
	468	ret = 0;
	469	goto out_drop_write;
	470	}
	471
	472	ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
	473	dst_pos, len, remap_flags \| REMAP_FILE_DEDUP);
	474	out_drop_write:
	475	mnt_drop_write_file(dst_file);
	476
	477	return ret;
	478	}
	479	EXPORT_SYMBOL(vfs_dedupe_file_range_one);
	480
	481	int vfs_dedupe_file_range(struct file file, struct file_dedupe_range same)
	482	{
	483	struct file_dedupe_range_info *info;
	484	struct inode *src = file_inode(file);
	485	u64 off;
	486	u64 len;
	487	int i;
	488	int ret;
	489	u16 count = same->dest_count;
	490	loff_t deduped;
	491
	492	if (!(file->f_mode & FMODE_READ))
	493	return -EINVAL;
	494
	495	if (same->reserved1 \|\| same->reserved2)
	496	return -EINVAL;
	497
	498	off = same->src_offset;
	499	len = same->src_length;
	500
	501	if (S_ISDIR(src->i_mode))
	502	return -EISDIR;
	503
	504	if (!S_ISREG(src->i_mode))
	505	return -EINVAL;
	506
	507	if (!file->f_op->remap_file_range)
	508	return -EOPNOTSUPP;
	509
	510	ret = remap_verify_area(file, off, len, false);
	511	if (ret < 0)
	512	return ret;
	513	ret = 0;
	514
	515	if (off + len > i_size_read(src))
	516	return -EINVAL;
	517
	518	/* Arbitrary 1G limit on a single dedupe request, can be raised. */
	519	len = min_t(u64, len, 1 << 30);
	520
521	/* pre-format output fields to sane values */
522	for (i = 0; i < count; i++) {
523	same->info[i].bytes_deduped = 0ULL;
524	same->info[i].status = FILE_DEDUPE_RANGE_SAME;
525	}
526
527	for (i = 0, info = same->info; i < count; i++, info++) {
528	struct fd dst_fd = fdget(info->dest_fd);
529	struct file *dst_file = dst_fd.file;
530
531	if (!dst_file) {
532	info->status = -EBADF;
533	goto next_loop;
534	}
535
536	if (info->reserved) {
537	info->status = -EINVAL;
538	goto next_fdput;
539	}
540
541	deduped = vfs_dedupe_file_range_one(file, off, dst_file,
542	info->dest_offset, len,
543	REMAP_FILE_CAN_SHORTEN);
544	if (deduped == -EBADE)
545	info->status = FILE_DEDUPE_RANGE_DIFFERS;
546	else if (deduped < 0)
547	info->status = deduped;
548	else
549	info->bytes_deduped = len;
550
551	next_fdput:
552	fdput(dst_fd);
553	next_loop:
554	if (fatal_signal_pending(current))
555	break;
556	}
557	return ret;
558	}
559	EXPORT_SYMBOL(vfs_dedupe_file_range);