percpu-rwsem: kill CONFIG_PERCPU_RWSEM

[linux/fpc-iii.git] / fs / xfs / xfs_trans.c

/*
 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
 * Copyright (C) 2010 Red Hat, 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_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_extent_busy.h"
#include "xfs_quota.h"
#include "xfs_trans.h"
#include "xfs_trans_priv.h"
#include "xfs_log.h"
#include "xfs_trace.h"
#include "xfs_error.h"

kmem_zone_t     *xfs_trans_zone;
kmem_zone_t     *xfs_log_item_desc_zone;

/*
 * Initialize the precomputed transaction reservation values
 * in the mount structure.
 */
void
xfs_trans_init(
        struct xfs_mount        *mp)
{
        xfs_trans_resv_calc(mp, M_RES(mp));
}

/*
 * This routine is called to allocate a transaction structure.
 * The type parameter indicates the type of the transaction.  These
 * are enumerated in xfs_trans.h.
 *
 * Dynamically allocate the transaction structure from the transaction
 * zone, initialize it, and return it to the caller.
 */
xfs_trans_t *
xfs_trans_alloc(
        xfs_mount_t     *mp,
        uint            type)
{
        xfs_trans_t     *tp;

        sb_start_intwrite(mp->m_super);
        tp = _xfs_trans_alloc(mp, type, KM_SLEEP);
        tp->t_flags |= XFS_TRANS_FREEZE_PROT;
        return tp;
}

xfs_trans_t *
_xfs_trans_alloc(
        xfs_mount_t     *mp,
        uint            type,
        xfs_km_flags_t  memflags)
{
        xfs_trans_t     *tp;

        WARN_ON(mp->m_super->s_writers.frozen == SB_FREEZE_COMPLETE);
        atomic_inc(&mp->m_active_trans);

        tp = kmem_zone_zalloc(xfs_trans_zone, memflags);
        tp->t_magic = XFS_TRANS_HEADER_MAGIC;
        tp->t_type = type;
        tp->t_mountp = mp;
        INIT_LIST_HEAD(&tp->t_items);
        INIT_LIST_HEAD(&tp->t_busy);
        return tp;
}

/*
 * Free the transaction structure.  If there is more clean up
 * to do when the structure is freed, add it here.
 */
STATIC void
xfs_trans_free(
        struct xfs_trans        *tp)
{
        xfs_extent_busy_sort(&tp->t_busy);
        xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false);

        atomic_dec(&tp->t_mountp->m_active_trans);
        if (tp->t_flags & XFS_TRANS_FREEZE_PROT)
                sb_end_intwrite(tp->t_mountp->m_super);
        xfs_trans_free_dqinfo(tp);
        kmem_zone_free(xfs_trans_zone, tp);
}

/*
 * This is called to create a new transaction which will share the
 * permanent log reservation of the given transaction.  The remaining
 * unused block and rt extent reservations are also inherited.  This
 * implies that the original transaction is no longer allowed to allocate
 * blocks.  Locks and log items, however, are no inherited.  They must
 * be added to the new transaction explicitly.
 */
STATIC xfs_trans_t *
xfs_trans_dup(
        xfs_trans_t     *tp)
{
        xfs_trans_t     *ntp;

        ntp = kmem_zone_zalloc(xfs_trans_zone, KM_SLEEP);

        /*
         * Initialize the new transaction structure.
         */
        ntp->t_magic = XFS_TRANS_HEADER_MAGIC;
        ntp->t_type = tp->t_type;
        ntp->t_mountp = tp->t_mountp;
        INIT_LIST_HEAD(&ntp->t_items);
        INIT_LIST_HEAD(&ntp->t_busy);

        ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
        ASSERT(tp->t_ticket != NULL);

        ntp->t_flags = XFS_TRANS_PERM_LOG_RES |
                       (tp->t_flags & XFS_TRANS_RESERVE) |
                       (tp->t_flags & XFS_TRANS_FREEZE_PROT);
        /* We gave our writer reference to the new transaction */
        tp->t_flags &= ~XFS_TRANS_FREEZE_PROT;
        ntp->t_ticket = xfs_log_ticket_get(tp->t_ticket);
        ntp->t_blk_res = tp->t_blk_res - tp->t_blk_res_used;
        tp->t_blk_res = tp->t_blk_res_used;
        ntp->t_rtx_res = tp->t_rtx_res - tp->t_rtx_res_used;
        tp->t_rtx_res = tp->t_rtx_res_used;
        ntp->t_pflags = tp->t_pflags;

        xfs_trans_dup_dqinfo(tp, ntp);

        atomic_inc(&tp->t_mountp->m_active_trans);
        return ntp;
}

/*
 * This is called to reserve free disk blocks and log space for the
 * given transaction.  This must be done before allocating any resources
 * within the transaction.
 *
 * This will return ENOSPC if there are not enough blocks available.
 * It will sleep waiting for available log space.
 * The only valid value for the flags parameter is XFS_RES_LOG_PERM, which
 * is used by long running transactions.  If any one of the reservations
 * fails then they will all be backed out.
 *
 * This does not do quota reservations. That typically is done by the
 * caller afterwards.
 */
int
xfs_trans_reserve(
        struct xfs_trans        *tp,
        struct xfs_trans_res    *resp,
        uint                    blocks,
        uint                    rtextents)
{
        int             error = 0;
        bool            rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;

        /* Mark this thread as being in a transaction */
        current_set_flags_nested(&tp->t_pflags, PF_FSTRANS);

        /*
         * Attempt to reserve the needed disk blocks by decrementing
         * the number needed from the number available.  This will
         * fail if the count would go below zero.
         */
        if (blocks > 0) {
                error = xfs_mod_fdblocks(tp->t_mountp, -((int64_t)blocks), rsvd);
                if (error != 0) {
                        current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
                        return -ENOSPC;
                }
                tp->t_blk_res += blocks;
        }

        /*
         * Reserve the log space needed for this transaction.
         */
        if (resp->tr_logres > 0) {
                bool    permanent = false;

                ASSERT(tp->t_log_res == 0 ||
                       tp->t_log_res == resp->tr_logres);
                ASSERT(tp->t_log_count == 0 ||
                       tp->t_log_count == resp->tr_logcount);

                if (resp->tr_logflags & XFS_TRANS_PERM_LOG_RES) {
                        tp->t_flags |= XFS_TRANS_PERM_LOG_RES;
                        permanent = true;
                } else {
                        ASSERT(tp->t_ticket == NULL);
                        ASSERT(!(tp->t_flags & XFS_TRANS_PERM_LOG_RES));
                }

                if (tp->t_ticket != NULL) {
                        ASSERT(resp->tr_logflags & XFS_TRANS_PERM_LOG_RES);
                        error = xfs_log_regrant(tp->t_mountp, tp->t_ticket);
                } else {
                        error = xfs_log_reserve(tp->t_mountp,
                                                resp->tr_logres,
                                                resp->tr_logcount,
                                                &tp->t_ticket, XFS_TRANSACTION,
                                                permanent, tp->t_type);
                }

                if (error)
                        goto undo_blocks;

                tp->t_log_res = resp->tr_logres;
                tp->t_log_count = resp->tr_logcount;
        }

        /*
         * Attempt to reserve the needed realtime extents by decrementing
         * the number needed from the number available.  This will
         * fail if the count would go below zero.
         */
        if (rtextents > 0) {
                error = xfs_mod_frextents(tp->t_mountp, -((int64_t)rtextents));
                if (error) {
                        error = -ENOSPC;
                        goto undo_log;
                }
                tp->t_rtx_res += rtextents;
        }

        return 0;

        /*
         * Error cases jump to one of these labels to undo any
         * reservations which have already been performed.
         */
undo_log:
        if (resp->tr_logres > 0) {
                xfs_log_done(tp->t_mountp, tp->t_ticket, NULL, false);
                tp->t_ticket = NULL;
                tp->t_log_res = 0;
                tp->t_flags &= ~XFS_TRANS_PERM_LOG_RES;
        }

undo_blocks:
        if (blocks > 0) {
                xfs_mod_fdblocks(tp->t_mountp, -((int64_t)blocks), rsvd);
                tp->t_blk_res = 0;
        }

        current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);

        return error;
}

/*
 * Record the indicated change to the given field for application
 * to the file system's superblock when the transaction commits.
 * For now, just store the change in the transaction structure.
 *
 * Mark the transaction structure to indicate that the superblock
 * needs to be updated before committing.
 *
 * Because we may not be keeping track of allocated/free inodes and
 * used filesystem blocks in the superblock, we do not mark the
 * superblock dirty in this transaction if we modify these fields.
 * We still need to update the transaction deltas so that they get
 * applied to the incore superblock, but we don't want them to
 * cause the superblock to get locked and logged if these are the
 * only fields in the superblock that the transaction modifies.
 */
void
xfs_trans_mod_sb(
        xfs_trans_t     *tp,
        uint            field,
        int64_t         delta)
{
        uint32_t        flags = (XFS_TRANS_DIRTY|XFS_TRANS_SB_DIRTY);
        xfs_mount_t     *mp = tp->t_mountp;

        switch (field) {
        case XFS_TRANS_SB_ICOUNT:
                tp->t_icount_delta += delta;
                if (xfs_sb_version_haslazysbcount(&mp->m_sb))
                        flags &= ~XFS_TRANS_SB_DIRTY;
                break;
        case XFS_TRANS_SB_IFREE:
                tp->t_ifree_delta += delta;
                if (xfs_sb_version_haslazysbcount(&mp->m_sb))
                        flags &= ~XFS_TRANS_SB_DIRTY;
                break;
        case XFS_TRANS_SB_FDBLOCKS:
                /*
                 * Track the number of blocks allocated in the
                 * transaction.  Make sure it does not exceed the
                 * number reserved.
                 */
                if (delta < 0) {
                        tp->t_blk_res_used += (uint)-delta;
                        ASSERT(tp->t_blk_res_used <= tp->t_blk_res);
                }
                tp->t_fdblocks_delta += delta;
                if (xfs_sb_version_haslazysbcount(&mp->m_sb))
                        flags &= ~XFS_TRANS_SB_DIRTY;
                break;
        case XFS_TRANS_SB_RES_FDBLOCKS:
                /*
                 * The allocation has already been applied to the
                 * in-core superblock's counter.  This should only
                 * be applied to the on-disk superblock.
                 */
                ASSERT(delta < 0);
                tp->t_res_fdblocks_delta += delta;
                if (xfs_sb_version_haslazysbcount(&mp->m_sb))
                        flags &= ~XFS_TRANS_SB_DIRTY;
                break;
        case XFS_TRANS_SB_FREXTENTS:
                /*
                 * Track the number of blocks allocated in the
                 * transaction.  Make sure it does not exceed the
                 * number reserved.
                 */
                if (delta < 0) {
                        tp->t_rtx_res_used += (uint)-delta;
                        ASSERT(tp->t_rtx_res_used <= tp->t_rtx_res);
                }
                tp->t_frextents_delta += delta;
                break;
        case XFS_TRANS_SB_RES_FREXTENTS:
                /*
                 * The allocation has already been applied to the
                 * in-core superblock's counter.  This should only
                 * be applied to the on-disk superblock.
                 */
                ASSERT(delta < 0);
                tp->t_res_frextents_delta += delta;
                break;
        case XFS_TRANS_SB_DBLOCKS:
                ASSERT(delta > 0);
                tp->t_dblocks_delta += delta;
                break;
        case XFS_TRANS_SB_AGCOUNT:
                ASSERT(delta > 0);
                tp->t_agcount_delta += delta;
                break;
        case XFS_TRANS_SB_IMAXPCT:
                tp->t_imaxpct_delta += delta;
                break;
        case XFS_TRANS_SB_REXTSIZE:
                tp->t_rextsize_delta += delta;
                break;
        case XFS_TRANS_SB_RBMBLOCKS:
                tp->t_rbmblocks_delta += delta;
                break;
        case XFS_TRANS_SB_RBLOCKS:
                tp->t_rblocks_delta += delta;
                break;
        case XFS_TRANS_SB_REXTENTS:
                tp->t_rextents_delta += delta;
                break;
        case XFS_TRANS_SB_REXTSLOG:
                tp->t_rextslog_delta += delta;
                break;
        default:
                ASSERT(0);
                return;
        }

        tp->t_flags |= flags;
}

/*
 * xfs_trans_apply_sb_deltas() is called from the commit code
 * to bring the superblock buffer into the current transaction
 * and modify it as requested by earlier calls to xfs_trans_mod_sb().
 *
 * For now we just look at each field allowed to change and change
 * it if necessary.
 */
STATIC void
xfs_trans_apply_sb_deltas(
        xfs_trans_t     *tp)
{
        xfs_dsb_t       *sbp;
        xfs_buf_t       *bp;
        int             whole = 0;

        bp = xfs_trans_getsb(tp, tp->t_mountp, 0);
        sbp = XFS_BUF_TO_SBP(bp);

        /*
         * Check that superblock mods match the mods made to AGF counters.
         */
        ASSERT((tp->t_fdblocks_delta + tp->t_res_fdblocks_delta) ==
               (tp->t_ag_freeblks_delta + tp->t_ag_flist_delta +
                tp->t_ag_btree_delta));

        /*
         * Only update the superblock counters if we are logging them
         */
        if (!xfs_sb_version_haslazysbcount(&(tp->t_mountp->m_sb))) {
                if (tp->t_icount_delta)
                        be64_add_cpu(&sbp->sb_icount, tp->t_icount_delta);
                if (tp->t_ifree_delta)
                        be64_add_cpu(&sbp->sb_ifree, tp->t_ifree_delta);
                if (tp->t_fdblocks_delta)
                        be64_add_cpu(&sbp->sb_fdblocks, tp->t_fdblocks_delta);
                if (tp->t_res_fdblocks_delta)
                        be64_add_cpu(&sbp->sb_fdblocks, tp->t_res_fdblocks_delta);
        }

        if (tp->t_frextents_delta)
                be64_add_cpu(&sbp->sb_frextents, tp->t_frextents_delta);
        if (tp->t_res_frextents_delta)
                be64_add_cpu(&sbp->sb_frextents, tp->t_res_frextents_delta);

        if (tp->t_dblocks_delta) {
                be64_add_cpu(&sbp->sb_dblocks, tp->t_dblocks_delta);
                whole = 1;
        }
        if (tp->t_agcount_delta) {
                be32_add_cpu(&sbp->sb_agcount, tp->t_agcount_delta);
                whole = 1;
        }
        if (tp->t_imaxpct_delta) {
                sbp->sb_imax_pct += tp->t_imaxpct_delta;
                whole = 1;
        }
        if (tp->t_rextsize_delta) {
                be32_add_cpu(&sbp->sb_rextsize, tp->t_rextsize_delta);
                whole = 1;
        }
        if (tp->t_rbmblocks_delta) {
                be32_add_cpu(&sbp->sb_rbmblocks, tp->t_rbmblocks_delta);
                whole = 1;
        }
        if (tp->t_rblocks_delta) {
                be64_add_cpu(&sbp->sb_rblocks, tp->t_rblocks_delta);
                whole = 1;
        }
        if (tp->t_rextents_delta) {
                be64_add_cpu(&sbp->sb_rextents, tp->t_rextents_delta);
                whole = 1;
        }
        if (tp->t_rextslog_delta) {
                sbp->sb_rextslog += tp->t_rextslog_delta;
                whole = 1;
        }

        xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SB_BUF);
        if (whole)
                /*
                 * Log the whole thing, the fields are noncontiguous.
                 */
                xfs_trans_log_buf(tp, bp, 0, sizeof(xfs_dsb_t) - 1);
        else
                /*
                 * Since all the modifiable fields are contiguous, we
                 * can get away with this.
                 */
                xfs_trans_log_buf(tp, bp, offsetof(xfs_dsb_t, sb_icount),
                                  offsetof(xfs_dsb_t, sb_frextents) +
                                  sizeof(sbp->sb_frextents) - 1);
}

STATIC int
xfs_sb_mod8(
        uint8_t                 *field,
        int8_t                  delta)
{
        int8_t                  counter = *field;

        counter += delta;
        if (counter < 0) {
                ASSERT(0);
                return -EINVAL;
        }
        *field = counter;
        return 0;
}

STATIC int
xfs_sb_mod32(
        uint32_t                *field,
        int32_t                 delta)
{
        int32_t                 counter = *field;

        counter += delta;
        if (counter < 0) {
                ASSERT(0);
                return -EINVAL;
        }
        *field = counter;
        return 0;
}

STATIC int
xfs_sb_mod64(
        uint64_t                *field,
        int64_t                 delta)
{
        int64_t                 counter = *field;

        counter += delta;
        if (counter < 0) {
                ASSERT(0);
                return -EINVAL;
        }
        *field = counter;
        return 0;
}

/*
 * xfs_trans_unreserve_and_mod_sb() is called to release unused reservations
 * and apply superblock counter changes to the in-core superblock.  The
 * t_res_fdblocks_delta and t_res_frextents_delta fields are explicitly NOT
 * applied to the in-core superblock.  The idea is that that has already been
 * done.
 *
 * If we are not logging superblock counters, then the inode allocated/free and
 * used block counts are not updated in the on disk superblock. In this case,
 * XFS_TRANS_SB_DIRTY will not be set when the transaction is updated but we
 * still need to update the incore superblock with the changes.
 */
void
xfs_trans_unreserve_and_mod_sb(
        struct xfs_trans        *tp)
{
        struct xfs_mount        *mp = tp->t_mountp;
        bool                    rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;
        int64_t                 blkdelta = 0;
        int64_t                 rtxdelta = 0;
        int64_t                 idelta = 0;
        int64_t                 ifreedelta = 0;
        int                     error;

        /* calculate deltas */
        if (tp->t_blk_res > 0)
                blkdelta = tp->t_blk_res;
        if ((tp->t_fdblocks_delta != 0) &&
            (xfs_sb_version_haslazysbcount(&mp->m_sb) ||
             (tp->t_flags & XFS_TRANS_SB_DIRTY)))
                blkdelta += tp->t_fdblocks_delta;

        if (tp->t_rtx_res > 0)
                rtxdelta = tp->t_rtx_res;
        if ((tp->t_frextents_delta != 0) &&
            (tp->t_flags & XFS_TRANS_SB_DIRTY))
                rtxdelta += tp->t_frextents_delta;

        if (xfs_sb_version_haslazysbcount(&mp->m_sb) ||
             (tp->t_flags & XFS_TRANS_SB_DIRTY)) {
                idelta = tp->t_icount_delta;
                ifreedelta = tp->t_ifree_delta;
        }

        /* apply the per-cpu counters */
        if (blkdelta) {
                error = xfs_mod_fdblocks(mp, blkdelta, rsvd);
                if (error)
                        goto out;
        }

        if (idelta) {
                error = xfs_mod_icount(mp, idelta);
                if (error)
                        goto out_undo_fdblocks;
        }

        if (ifreedelta) {
                error = xfs_mod_ifree(mp, ifreedelta);
                if (error)
                        goto out_undo_icount;
        }

        if (rtxdelta == 0 && !(tp->t_flags & XFS_TRANS_SB_DIRTY))
                return;

        /* apply remaining deltas */
        spin_lock(&mp->m_sb_lock);
        if (rtxdelta) {
                error = xfs_sb_mod64(&mp->m_sb.sb_frextents, rtxdelta);
                if (error)
                        goto out_undo_ifree;
        }

        if (tp->t_dblocks_delta != 0) {
                error = xfs_sb_mod64(&mp->m_sb.sb_dblocks, tp->t_dblocks_delta);
                if (error)
                        goto out_undo_frextents;
        }
        if (tp->t_agcount_delta != 0) {
                error = xfs_sb_mod32(&mp->m_sb.sb_agcount, tp->t_agcount_delta);
                if (error)
                        goto out_undo_dblocks;
        }
        if (tp->t_imaxpct_delta != 0) {
                error = xfs_sb_mod8(&mp->m_sb.sb_imax_pct, tp->t_imaxpct_delta);
                if (error)
                        goto out_undo_agcount;
        }
        if (tp->t_rextsize_delta != 0) {
                error = xfs_sb_mod32(&mp->m_sb.sb_rextsize,
                                     tp->t_rextsize_delta);
                if (error)
                        goto out_undo_imaxpct;
        }
        if (tp->t_rbmblocks_delta != 0) {
                error = xfs_sb_mod32(&mp->m_sb.sb_rbmblocks,
                                     tp->t_rbmblocks_delta);
                if (error)
                        goto out_undo_rextsize;
        }
        if (tp->t_rblocks_delta != 0) {
                error = xfs_sb_mod64(&mp->m_sb.sb_rblocks, tp->t_rblocks_delta);
                if (error)
                        goto out_undo_rbmblocks;
        }
        if (tp->t_rextents_delta != 0) {
                error = xfs_sb_mod64(&mp->m_sb.sb_rextents,
                                     tp->t_rextents_delta);
                if (error)
                        goto out_undo_rblocks;
        }
        if (tp->t_rextslog_delta != 0) {
                error = xfs_sb_mod8(&mp->m_sb.sb_rextslog,
                                     tp->t_rextslog_delta);
                if (error)
                        goto out_undo_rextents;
        }
        spin_unlock(&mp->m_sb_lock);
        return;

out_undo_rextents:
        if (tp->t_rextents_delta)
                xfs_sb_mod64(&mp->m_sb.sb_rextents, -tp->t_rextents_delta);
out_undo_rblocks:
        if (tp->t_rblocks_delta)
                xfs_sb_mod64(&mp->m_sb.sb_rblocks, -tp->t_rblocks_delta);
out_undo_rbmblocks:
        if (tp->t_rbmblocks_delta)
                xfs_sb_mod32(&mp->m_sb.sb_rbmblocks, -tp->t_rbmblocks_delta);
out_undo_rextsize:
        if (tp->t_rextsize_delta)
                xfs_sb_mod32(&mp->m_sb.sb_rextsize, -tp->t_rextsize_delta);
out_undo_imaxpct:
        if (tp->t_rextsize_delta)
                xfs_sb_mod8(&mp->m_sb.sb_imax_pct, -tp->t_imaxpct_delta);
out_undo_agcount:
        if (tp->t_agcount_delta)
                xfs_sb_mod32(&mp->m_sb.sb_agcount, -tp->t_agcount_delta);
out_undo_dblocks:
        if (tp->t_dblocks_delta)
                xfs_sb_mod64(&mp->m_sb.sb_dblocks, -tp->t_dblocks_delta);
out_undo_frextents:
        if (rtxdelta)
                xfs_sb_mod64(&mp->m_sb.sb_frextents, -rtxdelta);
out_undo_ifree:
        spin_unlock(&mp->m_sb_lock);
        if (ifreedelta)
                xfs_mod_ifree(mp, -ifreedelta);
out_undo_icount:
        if (idelta)
                xfs_mod_icount(mp, -idelta);
out_undo_fdblocks:
        if (blkdelta)
                xfs_mod_fdblocks(mp, -blkdelta, rsvd);
out:
        ASSERT(error == 0);
        return;
}

/*
 * Add the given log item to the transaction's list of log items.
 *
 * The log item will now point to its new descriptor with its li_desc field.
 */
void
xfs_trans_add_item(
        struct xfs_trans        *tp,
        struct xfs_log_item     *lip)
{
        struct xfs_log_item_desc *lidp;

        ASSERT(lip->li_mountp == tp->t_mountp);
        ASSERT(lip->li_ailp == tp->t_mountp->m_ail);

        lidp = kmem_zone_zalloc(xfs_log_item_desc_zone, KM_SLEEP | KM_NOFS);

        lidp->lid_item = lip;
        lidp->lid_flags = 0;
        list_add_tail(&lidp->lid_trans, &tp->t_items);

        lip->li_desc = lidp;
}

STATIC void
xfs_trans_free_item_desc(
        struct xfs_log_item_desc *lidp)
{
        list_del_init(&lidp->lid_trans);
        kmem_zone_free(xfs_log_item_desc_zone, lidp);
}

/*
 * Unlink and free the given descriptor.
 */
void
xfs_trans_del_item(
        struct xfs_log_item     *lip)
{
        xfs_trans_free_item_desc(lip->li_desc);
        lip->li_desc = NULL;
}

/*
 * Unlock all of the items of a transaction and free all the descriptors
 * of that transaction.
 */
void
xfs_trans_free_items(
        struct xfs_trans        *tp,
        xfs_lsn_t               commit_lsn,
        bool                    abort)
{
        struct xfs_log_item_desc *lidp, *next;

        list_for_each_entry_safe(lidp, next, &tp->t_items, lid_trans) {
                struct xfs_log_item     *lip = lidp->lid_item;

                lip->li_desc = NULL;

                if (commit_lsn != NULLCOMMITLSN)
                        lip->li_ops->iop_committing(lip, commit_lsn);
                if (abort)
                        lip->li_flags |= XFS_LI_ABORTED;
                lip->li_ops->iop_unlock(lip);

                xfs_trans_free_item_desc(lidp);
        }
}

static inline void
xfs_log_item_batch_insert(
        struct xfs_ail          *ailp,
        struct xfs_ail_cursor   *cur,
        struct xfs_log_item     **log_items,
        int                     nr_items,
        xfs_lsn_t               commit_lsn)
{
        int     i;

        spin_lock(&ailp->xa_lock);
        /* xfs_trans_ail_update_bulk drops ailp->xa_lock */
        xfs_trans_ail_update_bulk(ailp, cur, log_items, nr_items, commit_lsn);

        for (i = 0; i < nr_items; i++) {
                struct xfs_log_item *lip = log_items[i];

                lip->li_ops->iop_unpin(lip, 0);
        }
}

/*
 * Bulk operation version of xfs_trans_committed that takes a log vector of
 * items to insert into the AIL. This uses bulk AIL insertion techniques to
 * minimise lock traffic.
 *
 * If we are called with the aborted flag set, it is because a log write during
 * a CIL checkpoint commit has failed. In this case, all the items in the
 * checkpoint have already gone through iop_commited and iop_unlock, which
 * means that checkpoint commit abort handling is treated exactly the same
 * as an iclog write error even though we haven't started any IO yet. Hence in
 * this case all we need to do is iop_committed processing, followed by an
 * iop_unpin(aborted) call.
 *
 * The AIL cursor is used to optimise the insert process. If commit_lsn is not
 * at the end of the AIL, the insert cursor avoids the need to walk
 * the AIL to find the insertion point on every xfs_log_item_batch_insert()
 * call. This saves a lot of needless list walking and is a net win, even
 * though it slightly increases that amount of AIL lock traffic to set it up
 * and tear it down.
 */
void
xfs_trans_committed_bulk(
        struct xfs_ail          *ailp,
        struct xfs_log_vec      *log_vector,
        xfs_lsn_t               commit_lsn,
        int                     aborted)
{
#define LOG_ITEM_BATCH_SIZE     32
        struct xfs_log_item     *log_items[LOG_ITEM_BATCH_SIZE];
        struct xfs_log_vec      *lv;
        struct xfs_ail_cursor   cur;
        int                     i = 0;

        spin_lock(&ailp->xa_lock);
        xfs_trans_ail_cursor_last(ailp, &cur, commit_lsn);
        spin_unlock(&ailp->xa_lock);

        /* unpin all the log items */
        for (lv = log_vector; lv; lv = lv->lv_next ) {
                struct xfs_log_item     *lip = lv->lv_item;
                xfs_lsn_t               item_lsn;

                if (aborted)
                        lip->li_flags |= XFS_LI_ABORTED;
                item_lsn = lip->li_ops->iop_committed(lip, commit_lsn);

                /* item_lsn of -1 means the item needs no further processing */
                if (XFS_LSN_CMP(item_lsn, (xfs_lsn_t)-1) == 0)
                        continue;

                /*
                 * if we are aborting the operation, no point in inserting the
                 * object into the AIL as we are in a shutdown situation.
                 */
                if (aborted) {
                        ASSERT(XFS_FORCED_SHUTDOWN(ailp->xa_mount));
                        lip->li_ops->iop_unpin(lip, 1);
                        continue;
                }

                if (item_lsn != commit_lsn) {

                        /*
                         * Not a bulk update option due to unusual item_lsn.
                         * Push into AIL immediately, rechecking the lsn once
                         * we have the ail lock. Then unpin the item. This does
                         * not affect the AIL cursor the bulk insert path is
                         * using.
                         */
                        spin_lock(&ailp->xa_lock);
                        if (XFS_LSN_CMP(item_lsn, lip->li_lsn) > 0)
                                xfs_trans_ail_update(ailp, lip, item_lsn);
                        else
                                spin_unlock(&ailp->xa_lock);
                        lip->li_ops->iop_unpin(lip, 0);
                        continue;
                }

                /* Item is a candidate for bulk AIL insert.  */
                log_items[i++] = lv->lv_item;
                if (i >= LOG_ITEM_BATCH_SIZE) {
                        xfs_log_item_batch_insert(ailp, &cur, log_items,
                                        LOG_ITEM_BATCH_SIZE, commit_lsn);
                        i = 0;
                }
        }

        /* make sure we insert the remainder! */
        if (i)
                xfs_log_item_batch_insert(ailp, &cur, log_items, i, commit_lsn);

        spin_lock(&ailp->xa_lock);
        xfs_trans_ail_cursor_done(&cur);
        spin_unlock(&ailp->xa_lock);
}

/*
 * Commit the given transaction to the log.
 *
 * XFS disk error handling mechanism is not based on a typical
 * transaction abort mechanism. Logically after the filesystem
 * gets marked 'SHUTDOWN', we can't let any new transactions
 * be durable - ie. committed to disk - because some metadata might
 * be inconsistent. In such cases, this returns an error, and the
 * caller may assume that all locked objects joined to the transaction
 * have already been unlocked as if the commit had succeeded.
 * Do not reference the transaction structure after this call.
 */
static int
__xfs_trans_commit(
        struct xfs_trans        *tp,
        bool                    regrant)
{
        struct xfs_mount        *mp = tp->t_mountp;
        xfs_lsn_t               commit_lsn = -1;
        int                     error = 0;
        int                     sync = tp->t_flags & XFS_TRANS_SYNC;

        /*
         * If there is nothing to be logged by the transaction,
         * then unlock all of the items associated with the
         * transaction and free the transaction structure.
         * Also make sure to return any reserved blocks to
         * the free pool.
         */
        if (!(tp->t_flags & XFS_TRANS_DIRTY))
                goto out_unreserve;

        if (XFS_FORCED_SHUTDOWN(mp)) {
                error = -EIO;
                goto out_unreserve;
        }

        ASSERT(tp->t_ticket != NULL);

        /*
         * If we need to update the superblock, then do it now.
         */
        if (tp->t_flags & XFS_TRANS_SB_DIRTY)
                xfs_trans_apply_sb_deltas(tp);
        xfs_trans_apply_dquot_deltas(tp);

        xfs_log_commit_cil(mp, tp, &commit_lsn, regrant);

        current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
        xfs_trans_free(tp);

        /*
         * If the transaction needs to be synchronous, then force the
         * log out now and wait for it.
         */
        if (sync) {
                error = _xfs_log_force_lsn(mp, commit_lsn, XFS_LOG_SYNC, NULL);
                XFS_STATS_INC(xs_trans_sync);
        } else {
                XFS_STATS_INC(xs_trans_async);
        }

        return error;

out_unreserve:
        xfs_trans_unreserve_and_mod_sb(tp);

        /*
         * It is indeed possible for the transaction to be not dirty but
         * the dqinfo portion to be.  All that means is that we have some
         * (non-persistent) quota reservations that need to be unreserved.
         */
        xfs_trans_unreserve_and_mod_dquots(tp);
        if (tp->t_ticket) {
                commit_lsn = xfs_log_done(mp, tp->t_ticket, NULL, regrant);
                if (commit_lsn == -1 && !error)
                        error = -EIO;
        }
        current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
        xfs_trans_free_items(tp, NULLCOMMITLSN, !!error);
        xfs_trans_free(tp);

        XFS_STATS_INC(xs_trans_empty);
        return error;
}

int
xfs_trans_commit(
        struct xfs_trans        *tp)
{
        return __xfs_trans_commit(tp, false);
}

/*
 * Unlock all of the transaction's items and free the transaction.
 * The transaction must not have modified any of its items, because
 * there is no way to restore them to their previous state.
 *
 * If the transaction has made a log reservation, make sure to release
 * it as well.
 */
void
xfs_trans_cancel(
        struct xfs_trans        *tp)
{
        struct xfs_mount        *mp = tp->t_mountp;
        bool                    dirty = (tp->t_flags & XFS_TRANS_DIRTY);

        /*
         * See if the caller is relying on us to shut down the
         * filesystem.  This happens in paths where we detect
         * corruption and decide to give up.
         */
        if (dirty && !XFS_FORCED_SHUTDOWN(mp)) {
                XFS_ERROR_REPORT("xfs_trans_cancel", XFS_ERRLEVEL_LOW, mp);
                xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
        }
#ifdef DEBUG
        if (!dirty && !XFS_FORCED_SHUTDOWN(mp)) {
                struct xfs_log_item_desc *lidp;

                list_for_each_entry(lidp, &tp->t_items, lid_trans)
                        ASSERT(!(lidp->lid_item->li_type == XFS_LI_EFD));
        }
#endif
        xfs_trans_unreserve_and_mod_sb(tp);
        xfs_trans_unreserve_and_mod_dquots(tp);

        if (tp->t_ticket)
                xfs_log_done(mp, tp->t_ticket, NULL, false);

        /* mark this thread as no longer being in a transaction */
        current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);

        xfs_trans_free_items(tp, NULLCOMMITLSN, dirty);
        xfs_trans_free(tp);
}

/*
 * Roll from one trans in the sequence of PERMANENT transactions to
 * the next: permanent transactions are only flushed out when
 * committed with xfs_trans_commit(), but we still want as soon
 * as possible to let chunks of it go to the log. So we commit the
 * chunk we've been working on and get a new transaction to continue.
 */
int
xfs_trans_roll(
        struct xfs_trans        **tpp,
        struct xfs_inode        *dp)
{
        struct xfs_trans        *trans;
        struct xfs_trans_res    tres;
        int                     error;

        /*
         * Ensure that the inode is always logged.
         */
        trans = *tpp;
        if (dp)
                xfs_trans_log_inode(trans, dp, XFS_ILOG_CORE);

        /*
         * Copy the critical parameters from one trans to the next.
         */
        tres.tr_logres = trans->t_log_res;
        tres.tr_logcount = trans->t_log_count;
        *tpp = xfs_trans_dup(trans);

        /*
         * Commit the current transaction.
         * If this commit failed, then it'd just unlock those items that
         * are not marked ihold. That also means that a filesystem shutdown
         * is in progress. The caller takes the responsibility to cancel
         * the duplicate transaction that gets returned.
         */
        error = __xfs_trans_commit(trans, true);
        if (error)
                return error;

        trans = *tpp;

        /*
         * Reserve space in the log for th next transaction.
         * This also pushes items in the "AIL", the list of logged items,
         * out to disk if they are taking up space at the tail of the log
         * that we want to use.  This requires that either nothing be locked
         * across this call, or that anything that is locked be logged in
         * the prior and the next transactions.
         */
        tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
        error = xfs_trans_reserve(trans, &tres, 0, 0);
        /*
         *  Ensure that the inode is in the new transaction and locked.
         */
        if (error)
                return error;

        if (dp)
                xfs_trans_ijoin(trans, dp, 0);
        return 0;
}