xfs_fsops.c

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/*
 * 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 "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_btree.h"
#include "xfs_error.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_fsops.h"
#include "xfs_itable.h"
#include "xfs_trans_space.h"
#include "xfs_rtalloc.h"
#include "xfs_filestream.h"
#include "xfs_trace.h"

/*
 * File system operations
 */

int
xfs_fs_geometry(
    xfs_mount_t     *mp,
    xfs_fsop_geom_t     *geo,
    int         new_version)
{

    memset(geo, 0, sizeof(*geo));

    geo->blocksize = mp->m_sb.sb_blocksize;
    geo->rtextsize = mp->m_sb.sb_rextsize;
    geo->agblocks = mp->m_sb.sb_agblocks;
    geo->agcount = mp->m_sb.sb_agcount;
    geo->logblocks = mp->m_sb.sb_logblocks;
    geo->sectsize = mp->m_sb.sb_sectsize;
    geo->inodesize = mp->m_sb.sb_inodesize;
    geo->imaxpct = mp->m_sb.sb_imax_pct;
    geo->datablocks = mp->m_sb.sb_dblocks;
    geo->rtblocks = mp->m_sb.sb_rblocks;
    geo->rtextents = mp->m_sb.sb_rextents;
    geo->logstart = mp->m_sb.sb_logstart;
    ASSERT(sizeof(geo->uuid)==sizeof(mp->m_sb.sb_uuid));
    memcpy(geo->uuid, &mp->m_sb.sb_uuid, sizeof(mp->m_sb.sb_uuid));
    if (new_version >= 2) {
        geo->sunit = mp->m_sb.sb_unit;
        geo->swidth = mp->m_sb.sb_width;
    }
    if (new_version >= 3) {
        geo->version = XFS_FSOP_GEOM_VERSION;
        geo->flags =
            (xfs_sb_version_hasattr(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_ATTR : 0) |
            (xfs_sb_version_hasnlink(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_NLINK : 0) |
            (xfs_sb_version_hasquota(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_QUOTA : 0) |
            (xfs_sb_version_hasalign(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_IALIGN : 0) |
            (xfs_sb_version_hasdalign(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_DALIGN : 0) |
            (xfs_sb_version_hasshared(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_SHARED : 0) |
            (xfs_sb_version_hasextflgbit(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_EXTFLG : 0) |
            (xfs_sb_version_hasdirv2(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_DIRV2 : 0) |
            (xfs_sb_version_hassector(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_SECTOR : 0) |
            (xfs_sb_version_hasasciici(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_DIRV2CI : 0) |
            (xfs_sb_version_haslazysbcount(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_LAZYSB : 0) |
            (xfs_sb_version_hasattr2(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_ATTR2 : 0);
        geo->logsectsize = xfs_sb_version_hassector(&mp->m_sb) ?
                mp->m_sb.sb_logsectsize : BBSIZE;
        geo->rtsectsize = mp->m_sb.sb_blocksize;
        geo->dirblocksize = mp->m_dirblksize;
    }
    if (new_version >= 4) {
        geo->flags |=
            (xfs_sb_version_haslogv2(&mp->m_sb) ?
                XFS_FSOP_GEOM_FLAGS_LOGV2 : 0);
        geo->logsunit = mp->m_sb.sb_logsunit;
    }
    return 0;
}

static int
xfs_growfs_data_private(
    xfs_mount_t     *mp,        /* mount point for filesystem */
    xfs_growfs_data_t   *in)        /* growfs data input struct */
{
    xfs_agf_t       *agf;
    xfs_agi_t       *agi;
    xfs_agnumber_t      agno;
    xfs_extlen_t        agsize;
    xfs_extlen_t        tmpsize;
    xfs_alloc_rec_t     *arec;
    struct xfs_btree_block  *block;
    xfs_buf_t       *bp;
    int         bucket;
    int         dpct;
    int         error;
    xfs_agnumber_t      nagcount;
    xfs_agnumber_t      nagimax = 0;
    xfs_rfsblock_t      nb, nb_mod;
    xfs_rfsblock_t      new;
    xfs_rfsblock_t      nfree;
    xfs_agnumber_t      oagcount;
    int         pct;
    xfs_trans_t     *tp;

    nb = in->newblocks;
    pct = in->imaxpct;
    if (nb < mp->m_sb.sb_dblocks || pct < 0 || pct > 100)
        return XFS_ERROR(EINVAL);
    if ((error = xfs_sb_validate_fsb_count(&mp->m_sb, nb)))
        return error;
    dpct = pct - mp->m_sb.sb_imax_pct;
    bp = xfs_buf_read_uncached(mp->m_ddev_targp,
                XFS_FSB_TO_BB(mp, nb) - XFS_FSS_TO_BB(mp, 1),
                XFS_FSS_TO_BB(mp, 1), 0);
    if (!bp)
        return EIO;
    xfs_buf_relse(bp);

    new = nb;   /* use new as a temporary here */
    nb_mod = do_div(new, mp->m_sb.sb_agblocks);
    nagcount = new + (nb_mod != 0);
    if (nb_mod && nb_mod < XFS_MIN_AG_BLOCKS) {
        nagcount--;
        nb = (xfs_rfsblock_t)nagcount * mp->m_sb.sb_agblocks;
        if (nb < mp->m_sb.sb_dblocks)
            return XFS_ERROR(EINVAL);
    }
    new = nb - mp->m_sb.sb_dblocks;
    oagcount = mp->m_sb.sb_agcount;

    /* allocate the new per-ag structures */
    if (nagcount > oagcount) {
        error = xfs_initialize_perag(mp, nagcount, &nagimax);
        if (error)
            return error;
    }

    tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFS);
    tp->t_flags |= XFS_TRANS_RESERVE;
    if ((error = xfs_trans_reserve(tp, XFS_GROWFS_SPACE_RES(mp),
            XFS_GROWDATA_LOG_RES(mp), 0, 0, 0))) {
        xfs_trans_cancel(tp, 0);
        return error;
    }

    /*
     * Write new AG headers to disk. Non-transactional, but written
     * synchronously so they are completed prior to the growfs transaction
     * being logged.
     */
    nfree = 0;
    for (agno = nagcount - 1; agno >= oagcount; agno--, new -= agsize) {
        /*
         * AG freelist header block
         */
        bp = xfs_buf_get(mp->m_ddev_targp,
                 XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp)),
                 XFS_FSS_TO_BB(mp, 1), 0);
        if (!bp) {
            error = ENOMEM;
            goto error0;
        }
        agf = XFS_BUF_TO_AGF(bp);
        memset(agf, 0, mp->m_sb.sb_sectsize);
        agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
        agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
        agf->agf_seqno = cpu_to_be32(agno);
        if (agno == nagcount - 1)
            agsize =
                nb -
                (agno * (xfs_rfsblock_t)mp->m_sb.sb_agblocks);
        else
            agsize = mp->m_sb.sb_agblocks;
        agf->agf_length = cpu_to_be32(agsize);
        agf->agf_roots[XFS_BTNUM_BNOi] = cpu_to_be32(XFS_BNO_BLOCK(mp));
        agf->agf_roots[XFS_BTNUM_CNTi] = cpu_to_be32(XFS_CNT_BLOCK(mp));
        agf->agf_levels[XFS_BTNUM_BNOi] = cpu_to_be32(1);
        agf->agf_levels[XFS_BTNUM_CNTi] = cpu_to_be32(1);
        agf->agf_flfirst = 0;
        agf->agf_fllast = cpu_to_be32(XFS_AGFL_SIZE(mp) - 1);
        agf->agf_flcount = 0;
        tmpsize = agsize - XFS_PREALLOC_BLOCKS(mp);
        agf->agf_freeblks = cpu_to_be32(tmpsize);
        agf->agf_longest = cpu_to_be32(tmpsize);
        error = xfs_bwrite(bp);
        xfs_buf_relse(bp);
        if (error)
            goto error0;

        /*
         * AG inode header block
         */
        bp = xfs_buf_get(mp->m_ddev_targp,
                 XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
                 XFS_FSS_TO_BB(mp, 1), 0);
        if (!bp) {
            error = ENOMEM;
            goto error0;
        }
        agi = XFS_BUF_TO_AGI(bp);
        memset(agi, 0, mp->m_sb.sb_sectsize);
        agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
        agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
        agi->agi_seqno = cpu_to_be32(agno);
        agi->agi_length = cpu_to_be32(agsize);
        agi->agi_count = 0;
        agi->agi_root = cpu_to_be32(XFS_IBT_BLOCK(mp));
        agi->agi_level = cpu_to_be32(1);
        agi->agi_freecount = 0;
        agi->agi_newino = cpu_to_be32(NULLAGINO);
        agi->agi_dirino = cpu_to_be32(NULLAGINO);
        for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++)
            agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
        error = xfs_bwrite(bp);
        xfs_buf_relse(bp);
        if (error)
            goto error0;

        /*
         * BNO btree root block
         */
        bp = xfs_buf_get(mp->m_ddev_targp,
                 XFS_AGB_TO_DADDR(mp, agno, XFS_BNO_BLOCK(mp)),
                 BTOBB(mp->m_sb.sb_blocksize), 0);
        if (!bp) {
            error = ENOMEM;
            goto error0;
        }
        block = XFS_BUF_TO_BLOCK(bp);
        memset(block, 0, mp->m_sb.sb_blocksize);
        block->bb_magic = cpu_to_be32(XFS_ABTB_MAGIC);
        block->bb_level = 0;
        block->bb_numrecs = cpu_to_be16(1);
        block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
        block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
        arec = XFS_ALLOC_REC_ADDR(mp, block, 1);
        arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
        arec->ar_blockcount = cpu_to_be32(
            agsize - be32_to_cpu(arec->ar_startblock));
        error = xfs_bwrite(bp);
        xfs_buf_relse(bp);
        if (error)
            goto error0;

        /*
         * CNT btree root block
         */
        bp = xfs_buf_get(mp->m_ddev_targp,
                 XFS_AGB_TO_DADDR(mp, agno, XFS_CNT_BLOCK(mp)),
                 BTOBB(mp->m_sb.sb_blocksize), 0);
        if (!bp) {
            error = ENOMEM;
            goto error0;
        }
        block = XFS_BUF_TO_BLOCK(bp);
        memset(block, 0, mp->m_sb.sb_blocksize);
        block->bb_magic = cpu_to_be32(XFS_ABTC_MAGIC);
        block->bb_level = 0;
        block->bb_numrecs = cpu_to_be16(1);
        block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
        block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
        arec = XFS_ALLOC_REC_ADDR(mp, block, 1);
        arec->ar_startblock = cpu_to_be32(XFS_PREALLOC_BLOCKS(mp));
        arec->ar_blockcount = cpu_to_be32(
            agsize - be32_to_cpu(arec->ar_startblock));
        nfree += be32_to_cpu(arec->ar_blockcount);
        error = xfs_bwrite(bp);
        xfs_buf_relse(bp);
        if (error)
            goto error0;

        /*
         * INO btree root block
         */
        bp = xfs_buf_get(mp->m_ddev_targp,
                 XFS_AGB_TO_DADDR(mp, agno, XFS_IBT_BLOCK(mp)),
                 BTOBB(mp->m_sb.sb_blocksize), 0);
        if (!bp) {
            error = ENOMEM;
            goto error0;
        }
        block = XFS_BUF_TO_BLOCK(bp);
        memset(block, 0, mp->m_sb.sb_blocksize);
        block->bb_magic = cpu_to_be32(XFS_IBT_MAGIC);
        block->bb_level = 0;
        block->bb_numrecs = 0;
        block->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
        block->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
        error = xfs_bwrite(bp);
        xfs_buf_relse(bp);
        if (error)
            goto error0;
    }
    xfs_trans_agblocks_delta(tp, nfree);
    /*
     * There are new blocks in the old last a.g.
     */
    if (new) {
        /*
         * Change the agi length.
         */
        error = xfs_ialloc_read_agi(mp, tp, agno, &bp);
        if (error) {
            goto error0;
        }
        ASSERT(bp);
        agi = XFS_BUF_TO_AGI(bp);
        be32_add_cpu(&agi->agi_length, new);
        ASSERT(nagcount == oagcount ||
               be32_to_cpu(agi->agi_length) == mp->m_sb.sb_agblocks);
        xfs_ialloc_log_agi(tp, bp, XFS_AGI_LENGTH);
        /*
         * Change agf length.
         */
        error = xfs_alloc_read_agf(mp, tp, agno, 0, &bp);
        if (error) {
            goto error0;
        }
        ASSERT(bp);
        agf = XFS_BUF_TO_AGF(bp);
        be32_add_cpu(&agf->agf_length, new);
        ASSERT(be32_to_cpu(agf->agf_length) ==
               be32_to_cpu(agi->agi_length));

        xfs_alloc_log_agf(tp, bp, XFS_AGF_LENGTH);
        /*
         * Free the new space.
         */
        error = xfs_free_extent(tp, XFS_AGB_TO_FSB(mp, agno,
            be32_to_cpu(agf->agf_length) - new), new);
        if (error) {
            goto error0;
        }
    }

    /*
     * Update changed superblock fields transactionally. These are not
     * seen by the rest of the world until the transaction commit applies
     * them atomically to the superblock.
     */
    if (nagcount > oagcount)
        xfs_trans_mod_sb(tp, XFS_TRANS_SB_AGCOUNT, nagcount - oagcount);
    if (nb > mp->m_sb.sb_dblocks)
        xfs_trans_mod_sb(tp, XFS_TRANS_SB_DBLOCKS,
                 nb - mp->m_sb.sb_dblocks);
    if (nfree)
        xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, nfree);
    if (dpct)
        xfs_trans_mod_sb(tp, XFS_TRANS_SB_IMAXPCT, dpct);
    error = xfs_trans_commit(tp, 0);
    if (error)
        return error;

    /* New allocation groups fully initialized, so update mount struct */
    if (nagimax)
        mp->m_maxagi = nagimax;
    if (mp->m_sb.sb_imax_pct) {
        __uint64_t icount = mp->m_sb.sb_dblocks * mp->m_sb.sb_imax_pct;
        do_div(icount, 100);
        mp->m_maxicount = icount << mp->m_sb.sb_inopblog;
    } else
        mp->m_maxicount = 0;
    xfs_set_low_space_thresholds(mp);

    /* update secondary superblocks. */
    for (agno = 1; agno < nagcount; agno++) {
        error = 0;
        /*
         * new secondary superblocks need to be zeroed, not read from
         * disk as the contents of the new area we are growing into is
         * completely unknown.
         */
        if (agno < oagcount) {
            error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,
                  XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
                  XFS_FSS_TO_BB(mp, 1), 0, &bp);
        } else {
            bp = xfs_trans_get_buf(NULL, mp->m_ddev_targp,
                  XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
                  XFS_FSS_TO_BB(mp, 1), 0);
            if (bp)
                xfs_buf_zero(bp, 0, BBTOB(bp->b_length));
            else
                error = ENOMEM;
        }

        if (error) {
            xfs_warn(mp,
        "error %d reading secondary superblock for ag %d",
                error, agno);
            break;
        }
        xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, XFS_SB_ALL_BITS);
        /*
         * If we get an error writing out the alternate superblocks,
         * just issue a warning and continue.  The real work is
         * already done and committed.
         */
        error = xfs_bwrite(bp);
        xfs_buf_relse(bp);
        if (error) {
            xfs_warn(mp,
        "write error %d updating secondary superblock for ag %d",
                error, agno);
            break; /* no point in continuing */
        }
    }
    return error;

 error0:
    xfs_trans_cancel(tp, XFS_TRANS_ABORT);
    return error;
}

static int
xfs_growfs_log_private(
    xfs_mount_t     *mp,    /* mount point for filesystem */
    xfs_growfs_log_t    *in)    /* growfs log input struct */
{
    xfs_extlen_t        nb;

    nb = in->newblocks;
    if (nb < XFS_MIN_LOG_BLOCKS || nb < XFS_B_TO_FSB(mp, XFS_MIN_LOG_BYTES))
        return XFS_ERROR(EINVAL);
    if (nb == mp->m_sb.sb_logblocks &&
        in->isint == (mp->m_sb.sb_logstart != 0))
        return XFS_ERROR(EINVAL);
    /*
     * Moving the log is hard, need new interfaces to sync
     * the log first, hold off all activity while moving it.
     * Can have shorter or longer log in the same space,
     * or transform internal to external log or vice versa.
     */
    return XFS_ERROR(ENOSYS);
}

/*
 * protected versions of growfs function acquire and release locks on the mount
 * point - exported through ioctls: XFS_IOC_FSGROWFSDATA, XFS_IOC_FSGROWFSLOG,
 * XFS_IOC_FSGROWFSRT
 */


int
xfs_growfs_data(
    xfs_mount_t     *mp,
    xfs_growfs_data_t   *in)
{
    int error;

    if (!capable(CAP_SYS_ADMIN))
        return XFS_ERROR(EPERM);
    if (!mutex_trylock(&mp->m_growlock))
        return XFS_ERROR(EWOULDBLOCK);
    error = xfs_growfs_data_private(mp, in);
    mutex_unlock(&mp->m_growlock);
    return error;
}

int
xfs_growfs_log(
    xfs_mount_t     *mp,
    xfs_growfs_log_t    *in)
{
    int error;

    if (!capable(CAP_SYS_ADMIN))
        return XFS_ERROR(EPERM);
    if (!mutex_trylock(&mp->m_growlock))
        return XFS_ERROR(EWOULDBLOCK);
    error = xfs_growfs_log_private(mp, in);
    mutex_unlock(&mp->m_growlock);
    return error;
}

/*
 * exported through ioctl XFS_IOC_FSCOUNTS
 */

int
xfs_fs_counts(
    xfs_mount_t     *mp,
    xfs_fsop_counts_t   *cnt)
{
    xfs_icsb_sync_counters(mp, XFS_ICSB_LAZY_COUNT);
    spin_lock(&mp->m_sb_lock);
    cnt->freedata = mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
    cnt->freertx = mp->m_sb.sb_frextents;
    cnt->freeino = mp->m_sb.sb_ifree;
    cnt->allocino = mp->m_sb.sb_icount;
    spin_unlock(&mp->m_sb_lock);
    return 0;
}

/*
 * exported through ioctl XFS_IOC_SET_RESBLKS & XFS_IOC_GET_RESBLKS
 *
 * xfs_reserve_blocks is called to set m_resblks
 * in the in-core mount table. The number of unused reserved blocks
 * is kept in m_resblks_avail.
 *
 * Reserve the requested number of blocks if available. Otherwise return
 * as many as possible to satisfy the request. The actual number
 * reserved are returned in outval
 *
 * A null inval pointer indicates that only the current reserved blocks
 * available  should  be returned no settings are changed.
 */

int
xfs_reserve_blocks(
    xfs_mount_t             *mp,
    __uint64_t              *inval,
    xfs_fsop_resblks_t      *outval)
{
    __int64_t       lcounter, delta, fdblks_delta;
    __uint64_t      request;

    /* If inval is null, report current values and return */
    if (inval == (__uint64_t *)NULL) {
        if (!outval)
            return EINVAL;
        outval->resblks = mp->m_resblks;
        outval->resblks_avail = mp->m_resblks_avail;
        return 0;
    }

    request = *inval;

    /*
     * With per-cpu counters, this becomes an interesting
     * problem. we needto work out if we are freeing or allocation
     * blocks first, then we can do the modification as necessary.
     *
     * We do this under the m_sb_lock so that if we are near
     * ENOSPC, we will hold out any changes while we work out
     * what to do. This means that the amount of free space can
     * change while we do this, so we need to retry if we end up
     * trying to reserve more space than is available.
     *
     * We also use the xfs_mod_incore_sb() interface so that we
     * don't have to care about whether per cpu counter are
     * enabled, disabled or even compiled in....
     */
retry:
    spin_lock(&mp->m_sb_lock);
    xfs_icsb_sync_counters_locked(mp, 0);

    /*
     * If our previous reservation was larger than the current value,
     * then move any unused blocks back to the free pool.
     */
    fdblks_delta = 0;
    if (mp->m_resblks > request) {
        lcounter = mp->m_resblks_avail - request;
        if (lcounter  > 0) {        /* release unused blocks */
            fdblks_delta = lcounter;
            mp->m_resblks_avail -= lcounter;
        }
        mp->m_resblks = request;
    } else {
        __int64_t   free;

        free =  mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
        if (!free)
            goto out; /* ENOSPC and fdblks_delta = 0 */

        delta = request - mp->m_resblks;
        lcounter = free - delta;
        if (lcounter < 0) {
            /* We can't satisfy the request, just get what we can */
            mp->m_resblks += free;
            mp->m_resblks_avail += free;
            fdblks_delta = -free;
        } else {
            fdblks_delta = -delta;
            mp->m_resblks = request;
            mp->m_resblks_avail += delta;
        }
    }
out:
    if (outval) {
        outval->resblks = mp->m_resblks;
        outval->resblks_avail = mp->m_resblks_avail;
    }
    spin_unlock(&mp->m_sb_lock);

    if (fdblks_delta) {
        /*
         * If we are putting blocks back here, m_resblks_avail is
         * already at its max so this will put it in the free pool.
         *
         * If we need space, we'll either succeed in getting it
         * from the free block count or we'll get an enospc. If
         * we get a ENOSPC, it means things changed while we were
         * calculating fdblks_delta and so we should try again to
         * see if there is anything left to reserve.
         *
         * Don't set the reserved flag here - we don't want to reserve
         * the extra reserve blocks from the reserve.....
         */
        int error;
        error = xfs_icsb_modify_counters(mp, XFS_SBS_FDBLOCKS,
                         fdblks_delta, 0);
        if (error == ENOSPC)
            goto retry;
    }
    return 0;
}

/*
 * Dump a transaction into the log that contains no real change. This is needed
 * to be able to make the log dirty or stamp the current tail LSN into the log
 * during the covering operation.
 *
 * We cannot use an inode here for this - that will push dirty state back up
 * into the VFS and then periodic inode flushing will prevent log covering from
 * making progress. Hence we log a field in the superblock instead and use a
 * synchronous transaction to ensure the superblock is immediately unpinned
 * and can be written back.
 */
int
xfs_fs_log_dummy(
    xfs_mount_t *mp)
{
    xfs_trans_t *tp;
    int     error;

    tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
    error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
                    XFS_DEFAULT_LOG_COUNT);
    if (error) {
        xfs_trans_cancel(tp, 0);
        return error;
    }

    /* log the UUID because it is an unchanging field */
    xfs_mod_sb(tp, XFS_SB_UUID);
    xfs_trans_set_sync(tp);
    return xfs_trans_commit(tp, 0);
}

int
xfs_fs_goingdown(
    xfs_mount_t *mp,
    __uint32_t  inflags)
{
    switch (inflags) {
    case XFS_FSOP_GOING_FLAGS_DEFAULT: {
        struct super_block *sb = freeze_bdev(mp->m_super->s_bdev);

        if (sb && !IS_ERR(sb)) {
            xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
            thaw_bdev(sb->s_bdev, sb);
        }

        break;
    }
    case XFS_FSOP_GOING_FLAGS_LOGFLUSH:
        xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT);
        break;
    case XFS_FSOP_GOING_FLAGS_NOLOGFLUSH:
        xfs_force_shutdown(mp,
                SHUTDOWN_FORCE_UMOUNT | SHUTDOWN_LOG_IO_ERROR);
        break;
    default:
        return XFS_ERROR(EINVAL);
    }

    return 0;
}

/*
 * Force a shutdown of the filesystem instantly while keeping the filesystem
 * consistent. We don't do an unmount here; just shutdown the shop, make sure
 * that absolutely nothing persistent happens to this filesystem after this
 * point.
 */
void
xfs_do_force_shutdown(
    xfs_mount_t *mp,
    int     flags,
    char        *fname,
    int     lnnum)
{
    int     logerror;

    logerror = flags & SHUTDOWN_LOG_IO_ERROR;

    if (!(flags & SHUTDOWN_FORCE_UMOUNT)) {
        xfs_notice(mp,
    "%s(0x%x) called from line %d of file %s.  Return address = 0x%p",
            __func__, flags, lnnum, fname, __return_address);
    }
    /*
     * No need to duplicate efforts.
     */
    if (XFS_FORCED_SHUTDOWN(mp) && !logerror)
        return;

    /*
     * This flags XFS_MOUNT_FS_SHUTDOWN, makes sure that we don't
     * queue up anybody new on the log reservations, and wakes up
     * everybody who's sleeping on log reservations to tell them
     * the bad news.
     */
    if (xfs_log_force_umount(mp, logerror))
        return;

    if (flags & SHUTDOWN_CORRUPT_INCORE) {
        xfs_alert_tag(mp, XFS_PTAG_SHUTDOWN_CORRUPT,
    "Corruption of in-memory data detected.  Shutting down filesystem");
        if (XFS_ERRLEVEL_HIGH <= xfs_error_level)
            xfs_stack_trace();
    } else if (!(flags & SHUTDOWN_FORCE_UMOUNT)) {
        if (logerror) {
            xfs_alert_tag(mp, XFS_PTAG_SHUTDOWN_LOGERROR,
        "Log I/O Error Detected.  Shutting down filesystem");
        } else if (flags & SHUTDOWN_DEVICE_REQ) {
            xfs_alert_tag(mp, XFS_PTAG_SHUTDOWN_IOERROR,
        "All device paths lost.  Shutting down filesystem");
        } else if (!(flags & SHUTDOWN_REMOTE_REQ)) {
            xfs_alert_tag(mp, XFS_PTAG_SHUTDOWN_IOERROR,
        "I/O Error Detected. Shutting down filesystem");
        }
    }
    if (!(flags & SHUTDOWN_FORCE_UMOUNT)) {
        xfs_alert(mp,
    "Please umount the filesystem and rectify the problem(s)");
    }
}