xfs: change xfs_bmap_{finish,cancel,init,free} -> xfs_defer_*

[thirdparty/xfsprogs-dev.git] / libxfs / util.c

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include "libxfs_priv.h"
#include "libxfs_io.h"
#include "init.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_defer.h"
#include "xfs_inode_buf.h"
#include "xfs_inode_fork.h"
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_trans_space.h"
#include "xfs_ialloc.h"
#include "xfs_alloc.h"
#include "xfs_bit.h"

/*
 * Calculate the worst case log unit reservation for a given superblock
 * configuration. Copied and munged from the kernel code, and assumes a
 * worse case header usage (maximum log buffer sizes)
 */
int
xfs_log_calc_unit_res(
        struct xfs_mount        *mp,
        int                     unit_bytes)
{
        int                     iclog_space;
        int                     iclog_header_size;
        int                     iclog_size;
        uint                    num_headers;

        if (xfs_sb_version_haslogv2(&mp->m_sb)) {
                iclog_size = XLOG_MAX_RECORD_BSIZE;
                iclog_header_size = BBTOB(iclog_size / XLOG_HEADER_CYCLE_SIZE);
        } else {
                iclog_size = XLOG_BIG_RECORD_BSIZE;
                iclog_header_size = BBSIZE;
        }

        /*
         * Permanent reservations have up to 'cnt'-1 active log operations
         * in the log.  A unit in this case is the amount of space for one
         * of these log operations.  Normal reservations have a cnt of 1
         * and their unit amount is the total amount of space required.
         *
         * The following lines of code account for non-transaction data
         * which occupy space in the on-disk log.
         *
         * Normal form of a transaction is:
         * <oph><trans-hdr><start-oph><reg1-oph><reg1><reg2-oph>...<commit-oph>
         * and then there are LR hdrs, split-recs and roundoff at end of syncs.
         *
         * We need to account for all the leadup data and trailer data
         * around the transaction data.
         * And then we need to account for the worst case in terms of using
         * more space.
         * The worst case will happen if:
         * - the placement of the transaction happens to be such that the
         *   roundoff is at its maximum
         * - the transaction data is synced before the commit record is synced
         *   i.e. <transaction-data><roundoff> | <commit-rec><roundoff>
         *   Therefore the commit record is in its own Log Record.
         *   This can happen as the commit record is called with its
         *   own region to xlog_write().
         *   This then means that in the worst case, roundoff can happen for
         *   the commit-rec as well.
         *   The commit-rec is smaller than padding in this scenario and so it is
         *   not added separately.
         */

        /* for trans header */
        unit_bytes += sizeof(xlog_op_header_t);
        unit_bytes += sizeof(xfs_trans_header_t);

        /* for start-rec */
        unit_bytes += sizeof(xlog_op_header_t);

        /*
         * for LR headers - the space for data in an iclog is the size minus
         * the space used for the headers. If we use the iclog size, then we
         * undercalculate the number of headers required.
         *
         * Furthermore - the addition of op headers for split-recs might
         * increase the space required enough to require more log and op
         * headers, so take that into account too.
         *
         * IMPORTANT: This reservation makes the assumption that if this
         * transaction is the first in an iclog and hence has the LR headers
         * accounted to it, then the remaining space in the iclog is
         * exclusively for this transaction.  i.e. if the transaction is larger
         * than the iclog, it will be the only thing in that iclog.
         * Fundamentally, this means we must pass the entire log vector to
         * xlog_write to guarantee this.
         */
        iclog_space = iclog_size - iclog_header_size;
        num_headers = howmany(unit_bytes, iclog_space);

        /* for split-recs - ophdrs added when data split over LRs */
        unit_bytes += sizeof(xlog_op_header_t) * num_headers;

        /* add extra header reservations if we overrun */
        while (!num_headers ||
               howmany(unit_bytes, iclog_space) > num_headers) {
                unit_bytes += sizeof(xlog_op_header_t);
                num_headers++;
        }
        unit_bytes += iclog_header_size * num_headers;

        /* for commit-rec LR header - note: padding will subsume the ophdr */
        unit_bytes += iclog_header_size;

        /* for roundoff padding for transaction data and one for commit record */
        if (xfs_sb_version_haslogv2(&mp->m_sb) && mp->m_sb.sb_logsunit > 1) {
                /* log su roundoff */
                unit_bytes += 2 * mp->m_sb.sb_logsunit;
        } else {
                /* BB roundoff */
                unit_bytes += 2 * BBSIZE;
        }

        return unit_bytes;
}

/*
 * Change the requested timestamp in the given inode.
 *
 * This was once shared with the kernel, but has diverged to the point
 * where it's no longer worth the hassle of maintaining common code.
 */
void
libxfs_trans_ichgtime(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        int                     flags)
{
        struct timespec tv;
        struct timeval  stv;

        gettimeofday(&stv, (struct timezone *)0);
        tv.tv_sec = stv.tv_sec;
        tv.tv_nsec = stv.tv_usec * 1000;
        if (flags & XFS_ICHGTIME_MOD)
                VFS_I(ip)->i_mtime = tv;
        if (flags & XFS_ICHGTIME_CHG)
                VFS_I(ip)->i_ctime = tv;
        if (flags & XFS_ICHGTIME_CREATE) {
                ip->i_d.di_crtime.t_sec = (__int32_t)tv.tv_sec;
                ip->i_d.di_crtime.t_nsec = (__int32_t)tv.tv_nsec;
        }
}

/*
 * Allocate an inode on disk and return a copy of its in-core version.
 * Set mode, nlink, and rdev appropriately within the inode.
 * The uid and gid for the inode are set according to the contents of
 * the given cred structure.
 *
 * This was once shared with the kernel, but has diverged to the point
 * where it's no longer worth the hassle of maintaining common code.
 */
int
libxfs_ialloc(
        xfs_trans_t     *tp,
        xfs_inode_t     *pip,
        mode_t          mode,
        nlink_t         nlink,
        xfs_dev_t       rdev,
        struct cred     *cr,
        struct fsxattr  *fsx,
        int             okalloc,
        xfs_buf_t       **ialloc_context,
        xfs_inode_t     **ipp)
{
        xfs_ino_t       ino;
        xfs_inode_t     *ip;
        uint            flags;
        int             error;

        /*
         * Call the space management code to pick
         * the on-disk inode to be allocated.
         */
        error = xfs_dialloc(tp, pip ? pip->i_ino : 0, mode, okalloc,
                            ialloc_context, &ino);
        if (error != 0)
                return error;
        if (*ialloc_context || ino == NULLFSINO) {
                *ipp = NULL;
                return 0;
        }
        ASSERT(*ialloc_context == NULL);

        error = xfs_trans_iget(tp->t_mountp, tp, ino, 0, 0, &ip);
        if (error != 0)
                return error;
        ASSERT(ip != NULL);

        VFS_I(ip)->i_mode = mode;
        set_nlink(VFS_I(ip), nlink);
        ip->i_d.di_uid = cr->cr_uid;
        ip->i_d.di_gid = cr->cr_gid;
        xfs_set_projid(&ip->i_d, pip ? 0 : fsx->fsx_projid);
        xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_CHG | XFS_ICHGTIME_MOD);

        /*
         * We only support filesystems that understand v2 format inodes. So if
         * this is currently an old format inode, then change the inode version
         * number now.  This way we only do the conversion here rather than here
         * and in the flush/logging code.
         */
        if (ip->i_d.di_version == 1) {
                ip->i_d.di_version = 2;
                /*
                 * old link count, projid_lo/hi field, pad field
                 * already zeroed
                 */
        }

        if (pip && (VFS_I(pip)->i_mode & S_ISGID)) {
                ip->i_d.di_gid = pip->i_d.di_gid;
                if ((VFS_I(pip)->i_mode & S_ISGID) && (mode & S_IFMT) == S_IFDIR)
                        VFS_I(ip)->i_mode |= S_ISGID;
        }

        ip->i_d.di_size = 0;
        ip->i_d.di_nextents = 0;
        ASSERT(ip->i_d.di_nblocks == 0);
        ip->i_d.di_extsize = pip ? 0 : fsx->fsx_extsize;
        ip->i_d.di_dmevmask = 0;
        ip->i_d.di_dmstate = 0;
        ip->i_d.di_flags = pip ? 0 : fsx->fsx_xflags;

        if (ip->i_d.di_version == 3) {
                ASSERT(ip->i_d.di_ino == ino);
                ASSERT(uuid_equal(&ip->i_d.di_uuid, &mp->m_sb.sb_meta_uuid));
                VFS_I(ip)->i_version = 1;
                ip->i_d.di_flags2 = 0;
                ip->i_d.di_crtime.t_sec = (__int32_t)VFS_I(ip)->i_mtime.tv_sec;
                ip->i_d.di_crtime.t_nsec = (__int32_t)VFS_I(ip)->i_mtime.tv_nsec;
        }

        flags = XFS_ILOG_CORE;
        switch (mode & S_IFMT) {
        case S_IFIFO:
        case S_IFSOCK:
                /* doesn't make sense to set an rdev for these */
                rdev = 0;
                /* FALLTHROUGH */
        case S_IFCHR:
        case S_IFBLK:
                ip->i_d.di_format = XFS_DINODE_FMT_DEV;
                ip->i_df.if_u2.if_rdev = rdev;
                flags |= XFS_ILOG_DEV;
                break;
        case S_IFREG:
        case S_IFDIR:
                if (pip && (pip->i_d.di_flags & XFS_DIFLAG_ANY)) {
                        uint    di_flags = 0;

                        if ((mode & S_IFMT) == S_IFDIR) {
                                if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT)
                                        di_flags |= XFS_DIFLAG_RTINHERIT;
                                if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
                                        di_flags |= XFS_DIFLAG_EXTSZINHERIT;
                                        ip->i_d.di_extsize = pip->i_d.di_extsize;
                                }
                        } else {
                                if (pip->i_d.di_flags & XFS_DIFLAG_RTINHERIT) {
                                        di_flags |= XFS_DIFLAG_REALTIME;
                                }
                                if (pip->i_d.di_flags & XFS_DIFLAG_EXTSZINHERIT) {
                                        di_flags |= XFS_DIFLAG_EXTSIZE;
                                        ip->i_d.di_extsize = pip->i_d.di_extsize;
                                }
                        }
                        if (pip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT)
                                di_flags |= XFS_DIFLAG_PROJINHERIT;
                        ip->i_d.di_flags |= di_flags;
                }
                /* FALLTHROUGH */
        case S_IFLNK:
                ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
                ip->i_df.if_flags = XFS_IFEXTENTS;
                ip->i_df.if_bytes = ip->i_df.if_real_bytes = 0;
                ip->i_df.if_u1.if_extents = NULL;
                break;
        default:
                ASSERT(0);
        }
        /* Attribute fork settings for new inode. */
        ip->i_d.di_aformat = XFS_DINODE_FMT_EXTENTS;
        ip->i_d.di_anextents = 0;

        /*
         * set up the inode ops structure that the libxfs code relies on
         */
        if (XFS_ISDIR(ip))
                ip->d_ops = ip->i_mount->m_dir_inode_ops;
        else
                ip->d_ops = ip->i_mount->m_nondir_inode_ops;

        /*
         * Log the new values stuffed into the inode.
         */
        xfs_trans_log_inode(tp, ip, flags);
        *ipp = ip;
        return 0;
}

void
libxfs_iprint(
        xfs_inode_t             *ip)
{
        struct xfs_icdinode     *dip;
        xfs_bmbt_rec_host_t     *ep;
        xfs_extnum_t            i;
        xfs_extnum_t            nextents;

        printf("Inode %lx\n", (unsigned long)ip);
        printf("    i_ino %llx\n", (unsigned long long)ip->i_ino);

        if (ip->i_df.if_flags & XFS_IFEXTENTS)
                printf("EXTENTS ");
        printf("\n");
        printf("    i_df.if_bytes %d\n", ip->i_df.if_bytes);
        printf("    i_df.if_u1.if_extents/if_data %lx\n",
                (unsigned long)ip->i_df.if_u1.if_extents);
        if (ip->i_df.if_flags & XFS_IFEXTENTS) {
                nextents = ip->i_df.if_bytes / (uint)sizeof(*ep);
                for (ep = ip->i_df.if_u1.if_extents, i = 0; i < nextents;
                                                                i++, ep++) {
                        xfs_bmbt_irec_t rec;

                        xfs_bmbt_get_all(ep, &rec);
                        printf("\t%d: startoff %llu, startblock 0x%llx,"
                                " blockcount %llu, state %d\n",
                                i, (unsigned long long)rec.br_startoff,
                                (unsigned long long)rec.br_startblock,
                                (unsigned long long)rec.br_blockcount,
                                (int)rec.br_state);
                }
        }
        printf("    i_df.if_broot %lx\n", (unsigned long)ip->i_df.if_broot);
        printf("    i_df.if_broot_bytes %x\n", ip->i_df.if_broot_bytes);

        dip = &ip->i_d;
        printf("\nOn disk portion\n");
        printf("    di_mode %o\n", VFS_I(ip)->i_mode);
        printf("    di_version %x\n", (uint)dip->di_version);
        switch (ip->i_d.di_format) {
        case XFS_DINODE_FMT_LOCAL:
                printf("    Inline inode\n");
                break;
        case XFS_DINODE_FMT_EXTENTS:
                printf("    Extents inode\n");
                break;
        case XFS_DINODE_FMT_BTREE:
                printf("    B-tree inode\n");
                break;
        default:
                printf("    Other inode\n");
                break;
        }
        printf("   di_nlink %x\n", VFS_I(ip)->i_nlink);
        printf("   di_uid %d\n", dip->di_uid);
        printf("   di_gid %d\n", dip->di_gid);
        printf("   di_nextents %d\n", dip->di_nextents);
        printf("   di_size %llu\n", (unsigned long long)dip->di_size);
        printf("   di_gen %x\n", VFS_I(ip)->i_generation);
        printf("   di_extsize %d\n", dip->di_extsize);
        printf("   di_flags %x\n", dip->di_flags);
        printf("   di_nblocks %llu\n", (unsigned long long)dip->di_nblocks);
}

/*
 * Writes a modified inode's changes out to the inode's on disk home.
 * Originally based on xfs_iflush_int() from xfs_inode.c in the kernel.
 */
int
libxfs_iflush_int(xfs_inode_t *ip, xfs_buf_t *bp)
{
        xfs_inode_log_item_t    *iip;
        xfs_dinode_t            *dip;
        xfs_mount_t             *mp;

        ASSERT(XFS_BUF_FSPRIVATE(bp, void *) != NULL);
        ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
                ip->i_d.di_nextents > ip->i_df.if_ext_max);
        ASSERT(ip->i_d.di_version > 1);

        iip = ip->i_itemp;
        mp = ip->i_mount;

        /* set *dip = inode's place in the buffer */
        dip = xfs_buf_offset(bp, ip->i_imap.im_boffset);

        ASSERT(ip->i_d.di_magic == XFS_DINODE_MAGIC);
        if (XFS_ISREG(ip)) {
                ASSERT( (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS) ||
                        (ip->i_d.di_format == XFS_DINODE_FMT_BTREE) );
        } else if (XFS_ISDIR(ip)) {
                ASSERT( (ip->i_d.di_format == XFS_DINODE_FMT_EXTENTS) ||
                        (ip->i_d.di_format == XFS_DINODE_FMT_BTREE)   ||
                        (ip->i_d.di_format == XFS_DINODE_FMT_LOCAL) );
        }
        ASSERT(ip->i_d.di_nextents+ip->i_d.di_anextents <= ip->i_d.di_nblocks);
        ASSERT(ip->i_d.di_forkoff <= mp->m_sb.sb_inodesize);

        /* bump the change count on v3 inodes */
        if (ip->i_d.di_version == 3)
                VFS_I(ip)->i_version++;

        /*
         * Copy the dirty parts of the inode into the on-disk
         * inode.  We always copy out the core of the inode,
         * because if the inode is dirty at all the core must
         * be.
         */
        xfs_inode_to_disk(ip, dip, iip->ili_item.li_lsn);

        xfs_iflush_fork(ip, dip, iip, XFS_DATA_FORK);
        if (XFS_IFORK_Q(ip))
                xfs_iflush_fork(ip, dip, iip, XFS_ATTR_FORK);

        /* generate the checksum. */
        xfs_dinode_calc_crc(mp, dip);

        return 0;
}

int
libxfs_mod_incore_sb(
        struct xfs_mount *mp,
        int             field,
        int64_t         delta,
        int             rsvd)
{
        long long       lcounter;       /* long counter for 64 bit fields */

        switch (field) {
        case XFS_TRANS_SB_FDBLOCKS:
                lcounter = (long long)mp->m_sb.sb_fdblocks;
                lcounter += delta;
                if (lcounter < 0)
                        return -ENOSPC;
                mp->m_sb.sb_fdblocks = lcounter;
                return 0;
        default:
                ASSERT(0);
                return -EINVAL;
        }
}

/*
 * This routine allocates disk space for the given file.
 * Originally derived from xfs_alloc_file_space().
 */
int
libxfs_alloc_file_space(
        xfs_inode_t     *ip,
        xfs_off_t       offset,
        xfs_off_t       len,
        int             alloc_type,
        int             attr_flags)
{
        xfs_mount_t     *mp;
        xfs_off_t       count;
        xfs_filblks_t   datablocks;
        xfs_filblks_t   allocated_fsb;
        xfs_filblks_t   allocatesize_fsb;
        xfs_fsblock_t   firstfsb;
        struct xfs_defer_ops free_list;
        xfs_bmbt_irec_t *imapp;
        xfs_bmbt_irec_t imaps[1];
        int             reccount;
        uint            resblks;
        xfs_fileoff_t   startoffset_fsb;
        xfs_trans_t     *tp;
        int             xfs_bmapi_flags;
        int             error;

        if (len <= 0)
                return -EINVAL;

        count = len;
        error = 0;
        imapp = &imaps[0];
        reccount = 1;
        xfs_bmapi_flags = alloc_type ? XFS_BMAPI_PREALLOC : 0;
        mp = ip->i_mount;
        startoffset_fsb = XFS_B_TO_FSBT(mp, offset);
        allocatesize_fsb = XFS_B_TO_FSB(mp, count);

        /* allocate file space until done or until there is an error */
        while (allocatesize_fsb && !error) {
                datablocks = allocatesize_fsb;

                resblks = (uint)XFS_DIOSTRAT_SPACE_RES(mp, datablocks);
                error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks,
                                        0, 0, &tp);
                /*
                 * Check for running out of space
                 */
                if (error) {
                        ASSERT(error == -ENOSPC);
                        break;
                }
                xfs_trans_ijoin(tp, ip, 0);

                xfs_defer_init(&free_list, &firstfsb);
                error = xfs_bmapi_write(tp, ip, startoffset_fsb, allocatesize_fsb,
                                xfs_bmapi_flags, &firstfsb, 0, imapp,
                                &reccount, &free_list);

                if (error)
                        goto error0;

                /* complete the transaction */
                error = xfs_defer_finish(&tp, &free_list, ip);
                if (error)
                        goto error0;

                error = xfs_trans_commit(tp);
                if (error)
                        break;

                allocated_fsb = imapp->br_blockcount;
                if (reccount == 0)
                        return -ENOSPC;

                startoffset_fsb += allocated_fsb;
                allocatesize_fsb -= allocated_fsb;
        }
        return error;

error0: /* Cancel bmap, cancel trans */
        xfs_defer_cancel(&free_list);
        xfs_trans_cancel(tp);
        return error;
}

unsigned int
libxfs_log2_roundup(unsigned int i)
{
        unsigned int    rval;

        for (rval = 0; rval < NBBY * sizeof(i); rval++) {
                if ((1 << rval) >= i)
                        break;
        }
        return rval;
}

/*
 * Wrapper around call to libxfs_ialloc. Takes care of committing and
 * allocating a new transaction as needed.
 *
 * Originally there were two copies of this code - one in mkfs, the
 * other in repair - now there is just the one.
 */
int
libxfs_inode_alloc(
        xfs_trans_t     **tp,
        xfs_inode_t     *pip,
        mode_t          mode,
        nlink_t         nlink,
        xfs_dev_t       rdev,
        struct cred     *cr,
        struct fsxattr  *fsx,
        xfs_inode_t     **ipp)
{
        xfs_buf_t       *ialloc_context;
        xfs_inode_t     *ip;
        int             error;

        ialloc_context = (xfs_buf_t *)0;
        error = libxfs_ialloc(*tp, pip, mode, nlink, rdev, cr, fsx,
                           1, &ialloc_context, &ip);
        if (error) {
                *ipp = NULL;
                return error;
        }
        if (!ialloc_context && !ip) {
                *ipp = NULL;
                return -ENOSPC;
        }

        if (ialloc_context) {

                xfs_trans_bhold(*tp, ialloc_context);

                error = xfs_trans_roll(tp, NULL);
                if (error) {
                        fprintf(stderr, _("%s: cannot duplicate transaction: %s\n"),
                                progname, strerror(error));
                        exit(1);
                }
                xfs_trans_bjoin(*tp, ialloc_context);
                error = libxfs_ialloc(*tp, pip, mode, nlink, rdev, cr,
                                   fsx, 1, &ialloc_context, &ip);
                if (!ip)
                        error = -ENOSPC;
                if (error)
                        return error;
        }

        *ipp = ip;
        return error;
}

/*
 * Userspace versions of common diagnostic routines (varargs fun).
 */
void
libxfs_fs_repair_cmn_err(int level, xfs_mount_t *mp, char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        fprintf(stderr, "  This is a bug.\n");
        fprintf(stderr, "%s version %s\n", progname, VERSION);
        fprintf(stderr, "Please capture the filesystem metadata with "
                        "xfs_metadump and\nreport it to xfs@oss.sgi.com.\n");
        va_end(ap);
}

void
libxfs_fs_cmn_err(int level, xfs_mount_t *mp, char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        fputs("\n", stderr);
        va_end(ap);
}

void
cmn_err(int level, char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        fputs("\n", stderr);
        va_end(ap);
}

/*
 * Warnings specifically for verifier errors.  Differentiate CRC vs. invalid
 * values, and omit the stack trace unless the error level is tuned high.
 */
void
xfs_verifier_error(
        struct xfs_buf          *bp)
{
        xfs_alert(NULL, "Metadata %s detected at %s block 0x%llx/0x%x",
                  bp->b_error == -EFSBADCRC ? "CRC error" : "corruption",
                  bp->b_ops->name, bp->b_bn, BBTOB(bp->b_length));
}

/*
 * This is called from I/O verifiers on v5 superblock filesystems. In the
 * kernel, it validates the metadata LSN parameter against the current LSN of
 * the active log. We don't have an active log in userspace so this kind of
 * validation is not required. Therefore, this function always returns true in
 * userspace.
 *
 * xfs_repair piggybacks off this mechanism to help track the largest metadata
 * LSN in use on a filesystem. Keep a record of the largest LSN seen such that
 * repair can validate it against the state of the log.
 */
xfs_lsn_t       libxfs_max_lsn = 0;
pthread_mutex_t libxfs_max_lsn_lock = PTHREAD_MUTEX_INITIALIZER;

bool
xfs_log_check_lsn(
        struct xfs_mount        *mp,
        xfs_lsn_t               lsn)
{
        int                     cycle = CYCLE_LSN(lsn);
        int                     block = BLOCK_LSN(lsn);
        int                     max_cycle;
        int                     max_block;

        if (lsn == NULLCOMMITLSN)
                return true;

        pthread_mutex_lock(&libxfs_max_lsn_lock);

        max_cycle = CYCLE_LSN(libxfs_max_lsn);
        max_block = BLOCK_LSN(libxfs_max_lsn);

        if ((cycle > max_cycle) ||
            (cycle == max_cycle && block > max_block))
                libxfs_max_lsn = lsn;

        pthread_mutex_unlock(&libxfs_max_lsn_lock);

        return true;
}

static struct xfs_buftarg *
xfs_find_bdev_for_inode(
        struct xfs_inode        *ip)
{
        struct xfs_mount        *mp = ip->i_mount;

        if (XFS_IS_REALTIME_INODE(ip))
                return mp->m_rtdev_targp;
        return mp->m_ddev_targp;
}

static xfs_daddr_t
xfs_fsb_to_db(struct xfs_inode *ip, xfs_fsblock_t fsb)
{
        if (XFS_IS_REALTIME_INODE(ip))
                 return XFS_FSB_TO_BB(ip->i_mount, fsb);
        return XFS_FSB_TO_DADDR(ip->i_mount, (fsb));
}

int
libxfs_zero_extent(
        struct xfs_inode *ip,
        xfs_fsblock_t   start_fsb,
        xfs_off_t       count_fsb)
{
        xfs_daddr_t     sector = xfs_fsb_to_db(ip, start_fsb);
        ssize_t         size = XFS_FSB_TO_BB(ip->i_mount, count_fsb);

        return libxfs_device_zero(xfs_find_bdev_for_inode(ip), sector, size);
}