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xfs_trans.c

/*
 * Copyright (c) 2000-2003,2005 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_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_error.h"
#include "xfs_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_alloc.h"
#include "xfs_bmap.h"
#include "xfs_quota.h"
#include "xfs_trans_priv.h"
#include "xfs_trans_space.h"


STATIC void xfs_trans_apply_sb_deltas(xfs_trans_t *);
STATIC uint xfs_trans_count_vecs(xfs_trans_t *);
STATIC void xfs_trans_fill_vecs(xfs_trans_t *, xfs_log_iovec_t *);
STATIC void xfs_trans_uncommit(xfs_trans_t *, uint);
STATIC void xfs_trans_committed(xfs_trans_t *, int);
STATIC void xfs_trans_chunk_committed(xfs_log_item_chunk_t *, xfs_lsn_t, int);
STATIC void xfs_trans_free(xfs_trans_t *);

kmem_zone_t *xfs_trans_zone;


/*
 * Reservation functions here avoid a huge stack in xfs_trans_init
 * due to register overflow from temporaries in the calculations.
 */

STATIC uint
xfs_calc_write_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_WRITE_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_itruncate_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_ITRUNCATE_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_rename_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_RENAME_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_link_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_LINK_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_remove_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_REMOVE_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_symlink_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_SYMLINK_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_create_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_CREATE_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_mkdir_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_MKDIR_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_ifree_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_IFREE_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_ichange_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_ICHANGE_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_growdata_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_GROWDATA_LOG_RES(mp);
}

STATIC uint
xfs_calc_growrtalloc_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_GROWRTALLOC_LOG_RES(mp);
}

STATIC uint
xfs_calc_growrtzero_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_GROWRTZERO_LOG_RES(mp);
}

STATIC uint
xfs_calc_growrtfree_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_GROWRTFREE_LOG_RES(mp);
}

STATIC uint
xfs_calc_swrite_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_SWRITE_LOG_RES(mp);
}

STATIC uint
xfs_calc_writeid_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_WRITEID_LOG_RES(mp);
}

STATIC uint
xfs_calc_addafork_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_ADDAFORK_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_attrinval_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_ATTRINVAL_LOG_RES(mp);
}

STATIC uint
xfs_calc_attrset_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_ATTRSET_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_attrrm_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_ATTRRM_LOG_RES(mp) + XFS_DQUOT_LOGRES(mp);
}

STATIC uint
xfs_calc_clear_agi_bucket_reservation(xfs_mount_t *mp)
{
      return XFS_CALC_CLEAR_AGI_BUCKET_LOG_RES(mp);
}

/*
 * Initialize the precomputed transaction reservation values
 * in the mount structure.
 */
void
xfs_trans_init(
      xfs_mount_t *mp)
{
      xfs_trans_reservations_t      *resp;

      resp = &(mp->m_reservations);
      resp->tr_write = xfs_calc_write_reservation(mp);
      resp->tr_itruncate = xfs_calc_itruncate_reservation(mp);
      resp->tr_rename = xfs_calc_rename_reservation(mp);
      resp->tr_link = xfs_calc_link_reservation(mp);
      resp->tr_remove = xfs_calc_remove_reservation(mp);
      resp->tr_symlink = xfs_calc_symlink_reservation(mp);
      resp->tr_create = xfs_calc_create_reservation(mp);
      resp->tr_mkdir = xfs_calc_mkdir_reservation(mp);
      resp->tr_ifree = xfs_calc_ifree_reservation(mp);
      resp->tr_ichange = xfs_calc_ichange_reservation(mp);
      resp->tr_growdata = xfs_calc_growdata_reservation(mp);
      resp->tr_swrite = xfs_calc_swrite_reservation(mp);
      resp->tr_writeid = xfs_calc_writeid_reservation(mp);
      resp->tr_addafork = xfs_calc_addafork_reservation(mp);
      resp->tr_attrinval = xfs_calc_attrinval_reservation(mp);
      resp->tr_attrset = xfs_calc_attrset_reservation(mp);
      resp->tr_attrrm = xfs_calc_attrrm_reservation(mp);
      resp->tr_clearagi = xfs_calc_clear_agi_bucket_reservation(mp);
      resp->tr_growrtalloc = xfs_calc_growrtalloc_reservation(mp);
      resp->tr_growrtzero = xfs_calc_growrtzero_reservation(mp);
      resp->tr_growrtfree = xfs_calc_growrtfree_reservation(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_wait_for_freeze(mp, SB_FREEZE_TRANS);
      return _xfs_trans_alloc(mp, type);
}

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

      atomic_inc(&mp->m_active_trans);

      tp = kmem_zone_zalloc(xfs_trans_zone, KM_SLEEP);
      tp->t_magic = XFS_TRANS_MAGIC;
      tp->t_type = type;
      tp->t_mountp = mp;
      tp->t_items_free = XFS_LIC_NUM_SLOTS;
      tp->t_busy_free = XFS_LBC_NUM_SLOTS;
      XFS_LIC_INIT(&(tp->t_items));
      XFS_LBC_INIT(&(tp->t_busy));
      return 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.
 */
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_MAGIC;
      ntp->t_type = tp->t_type;
      ntp->t_mountp = tp->t_mountp;
      ntp->t_items_free = XFS_LIC_NUM_SLOTS;
      ntp->t_busy_free = XFS_LBC_NUM_SLOTS;
      XFS_LIC_INIT(&(ntp->t_items));
      XFS_LBC_INIT(&(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);
      ntp->t_ticket = 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->t_mountp, 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(
      xfs_trans_t *tp,
      uint        blocks,
      uint        logspace,
      uint        rtextents,
      uint        flags,
      uint        logcount)
{
      int         log_flags;
      int         error = 0;
      int         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_incore_sb(tp->t_mountp, XFS_SBS_FDBLOCKS,
                                -((int64_t)blocks), rsvd);
            if (error != 0) {
                  current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
                  return (XFS_ERROR(ENOSPC));
            }
            tp->t_blk_res += blocks;
      }

      /*
       * Reserve the log space needed for this transaction.
       */
      if (logspace > 0) {
            ASSERT((tp->t_log_res == 0) || (tp->t_log_res == logspace));
            ASSERT((tp->t_log_count == 0) ||
                  (tp->t_log_count == logcount));
            if (flags & XFS_TRANS_PERM_LOG_RES) {
                  log_flags = XFS_LOG_PERM_RESERV;
                  tp->t_flags |= XFS_TRANS_PERM_LOG_RES;
            } else {
                  ASSERT(tp->t_ticket == NULL);
                  ASSERT(!(tp->t_flags & XFS_TRANS_PERM_LOG_RES));
                  log_flags = 0;
            }

            error = xfs_log_reserve(tp->t_mountp, logspace, logcount,
                              &tp->t_ticket,
                              XFS_TRANSACTION, log_flags, tp->t_type);
            if (error) {
                  goto undo_blocks;
            }
            tp->t_log_res = logspace;
            tp->t_log_count = 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_incore_sb(tp->t_mountp, XFS_SBS_FREXTENTS,
                                -((int64_t)rtextents), rsvd);
            if (error) {
                  error = XFS_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 (logspace > 0) {
            if (flags & XFS_TRANS_PERM_LOG_RES) {
                  log_flags = XFS_LOG_REL_PERM_RESERV;
            } else {
                  log_flags = 0;
            }
            xfs_log_done(tp->t_mountp, tp->t_ticket, NULL, log_flags);
            tp->t_ticket = NULL;
            tp->t_log_res = 0;
            tp->t_flags &= ~XFS_TRANS_PERM_LOG_RES;
      }

undo_blocks:
      if (blocks > 0) {
            (void) xfs_mod_incore_sb(tp->t_mountp, XFS_SBS_FDBLOCKS,
                               (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(&sbp->sb_icount, tp->t_icount_delta);
            if (tp->t_ifree_delta)
                  be64_add(&sbp->sb_ifree, tp->t_ifree_delta);
            if (tp->t_fdblocks_delta)
                  be64_add(&sbp->sb_fdblocks, tp->t_fdblocks_delta);
            if (tp->t_res_fdblocks_delta)
                  be64_add(&sbp->sb_fdblocks, tp->t_res_fdblocks_delta);
      }

      if (tp->t_frextents_delta)
            be64_add(&sbp->sb_frextents, tp->t_frextents_delta);
      if (tp->t_res_frextents_delta)
            be64_add(&sbp->sb_frextents, tp->t_res_frextents_delta);

      if (tp->t_dblocks_delta) {
            be64_add(&sbp->sb_dblocks, tp->t_dblocks_delta);
            whole = 1;
      }
      if (tp->t_agcount_delta) {
            be32_add(&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(&sbp->sb_rextsize, tp->t_rextsize_delta);
            whole = 1;
      }
      if (tp->t_rbmblocks_delta) {
            be32_add(&sbp->sb_rbmblocks, tp->t_rbmblocks_delta);
            whole = 1;
      }
      if (tp->t_rblocks_delta) {
            be64_add(&sbp->sb_rblocks, tp->t_rblocks_delta);
            whole = 1;
      }
      if (tp->t_rextents_delta) {
            be64_add(&sbp->sb_rextents, tp->t_rextents_delta);
            whole = 1;
      }
      if (tp->t_rextslog_delta) {
            sbp->sb_rextslog += tp->t_rextslog_delta;
            whole = 1;
      }

      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);

      tp->t_mountp->m_super->s_dirt = 1;
}

/*
 * 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.
 *
 * This is done efficiently with a single call to xfs_mod_incore_sb_batch().
 * However, we have to ensure that we only modify each superblock field only
 * once because the application of the delta values may not be atomic. That can
 * lead to ENOSPC races occurring if we have two separate modifcations of the
 * free space counter to put back the entire reservation and then take away
 * what we used.
 *
 * 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.
 */
STATIC void
xfs_trans_unreserve_and_mod_sb(
      xfs_trans_t *tp)
{
      xfs_mod_sb_t      msb[14];    /* If you add cases, add entries */
      xfs_mod_sb_t      *msbp;
      xfs_mount_t *mp = tp->t_mountp;
      /* REFERENCED */
      int         error;
      int         rsvd;
      int64_t           blkdelta = 0;
      int64_t           rtxdelta = 0;

      msbp = msb;
      rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;

      /* calculate free blocks delta */
      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 (blkdelta != 0) {
            msbp->msb_field = XFS_SBS_FDBLOCKS;
            msbp->msb_delta = blkdelta;
            msbp++;
      }

      /* calculate free realtime extents 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 (rtxdelta != 0) {
            msbp->msb_field = XFS_SBS_FREXTENTS;
            msbp->msb_delta = rtxdelta;
            msbp++;
      }

      /* apply remaining deltas */

      if (xfs_sb_version_haslazysbcount(&mp->m_sb) ||
           (tp->t_flags & XFS_TRANS_SB_DIRTY)) {
            if (tp->t_icount_delta != 0) {
                  msbp->msb_field = XFS_SBS_ICOUNT;
                  msbp->msb_delta = tp->t_icount_delta;
                  msbp++;
            }
            if (tp->t_ifree_delta != 0) {
                  msbp->msb_field = XFS_SBS_IFREE;
                  msbp->msb_delta = tp->t_ifree_delta;
                  msbp++;
            }
      }

      if (tp->t_flags & XFS_TRANS_SB_DIRTY) {
            if (tp->t_dblocks_delta != 0) {
                  msbp->msb_field = XFS_SBS_DBLOCKS;
                  msbp->msb_delta = tp->t_dblocks_delta;
                  msbp++;
            }
            if (tp->t_agcount_delta != 0) {
                  msbp->msb_field = XFS_SBS_AGCOUNT;
                  msbp->msb_delta = tp->t_agcount_delta;
                  msbp++;
            }
            if (tp->t_imaxpct_delta != 0) {
                  msbp->msb_field = XFS_SBS_IMAX_PCT;
                  msbp->msb_delta = tp->t_imaxpct_delta;
                  msbp++;
            }
            if (tp->t_rextsize_delta != 0) {
                  msbp->msb_field = XFS_SBS_REXTSIZE;
                  msbp->msb_delta = tp->t_rextsize_delta;
                  msbp++;
            }
            if (tp->t_rbmblocks_delta != 0) {
                  msbp->msb_field = XFS_SBS_RBMBLOCKS;
                  msbp->msb_delta = tp->t_rbmblocks_delta;
                  msbp++;
            }
            if (tp->t_rblocks_delta != 0) {
                  msbp->msb_field = XFS_SBS_RBLOCKS;
                  msbp->msb_delta = tp->t_rblocks_delta;
                  msbp++;
            }
            if (tp->t_rextents_delta != 0) {
                  msbp->msb_field = XFS_SBS_REXTENTS;
                  msbp->msb_delta = tp->t_rextents_delta;
                  msbp++;
            }
            if (tp->t_rextslog_delta != 0) {
                  msbp->msb_field = XFS_SBS_REXTSLOG;
                  msbp->msb_delta = tp->t_rextslog_delta;
                  msbp++;
            }
      }

      /*
       * If we need to change anything, do it.
       */
      if (msbp > msb) {
            error = xfs_mod_incore_sb_batch(tp->t_mountp, msb,
                  (uint)(msbp - msb), rsvd);
            ASSERT(error == 0);
      }
}


/*
 * xfs_trans_commit
 *
 * Commit the given transaction to the log a/synchronously.
 *
 * 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.
 */
 /*ARGSUSED*/
int
_xfs_trans_commit(
      xfs_trans_t *tp,
      uint        flags,
      int         *log_flushed)
{
      xfs_log_iovec_t         *log_vector;
      int               nvec;
      xfs_mount_t       *mp;
      xfs_lsn_t         commit_lsn;
      /* REFERENCED */
      int               error;
      int               log_flags;
      int               sync;
#define     XFS_TRANS_LOGVEC_COUNT  16
      xfs_log_iovec_t         log_vector_fast[XFS_TRANS_LOGVEC_COUNT];
      void              *commit_iclog;
      int               shutdown;

      commit_lsn = -1;

      /*
       * Determine whether this commit is releasing a permanent
       * log reservation or not.
       */
      if (flags & XFS_TRANS_RELEASE_LOG_RES) {
            ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
            log_flags = XFS_LOG_REL_PERM_RESERV;
      } else {
            log_flags = 0;
      }
      mp = tp->t_mountp;

      /*
       * 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.
       */
shut_us_down:
      shutdown = XFS_FORCED_SHUTDOWN(mp) ? EIO : 0;
      if (!(tp->t_flags & XFS_TRANS_DIRTY) || shutdown) {
            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(mp, tp);
            if (tp->t_ticket) {
                  commit_lsn = xfs_log_done(mp, tp->t_ticket,
                                          NULL, log_flags);
                  if (commit_lsn == -1 && !shutdown)
                        shutdown = XFS_ERROR(EIO);
            }
            current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
            xfs_trans_free_items(tp, shutdown? XFS_TRANS_ABORT : 0);
            xfs_trans_free_busy(tp);
            xfs_trans_free(tp);
            XFS_STATS_INC(xs_trans_empty);
            return (shutdown);
      }
      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(mp, tp);

      /*
       * Ask each log item how many log_vector entries it will
       * need so we can figure out how many to allocate.
       * Try to avoid the kmem_alloc() call in the common case
       * by using a vector from the stack when it fits.
       */
      nvec = xfs_trans_count_vecs(tp);
      if (nvec == 0) {
            xfs_force_shutdown(mp, SHUTDOWN_LOG_IO_ERROR);
            goto shut_us_down;
      } else if (nvec <= XFS_TRANS_LOGVEC_COUNT) {
            log_vector = log_vector_fast;
      } else {
            log_vector = (xfs_log_iovec_t *)kmem_alloc(nvec *
                                       sizeof(xfs_log_iovec_t),
                                       KM_SLEEP);
      }

      /*
       * Fill in the log_vector and pin the logged items, and
       * then write the transaction to the log.
       */
      xfs_trans_fill_vecs(tp, log_vector);

      error = xfs_log_write(mp, log_vector, nvec, tp->t_ticket, &(tp->t_lsn));

      /*
       * The transaction is committed incore here, and can go out to disk
       * at any time after this call.  However, all the items associated
       * with the transaction are still locked and pinned in memory.
       */
      commit_lsn = xfs_log_done(mp, tp->t_ticket, &commit_iclog, log_flags);

      tp->t_commit_lsn = commit_lsn;
      if (nvec > XFS_TRANS_LOGVEC_COUNT) {
            kmem_free(log_vector, nvec * sizeof(xfs_log_iovec_t));
      }

      /*
       * If we got a log write error. Unpin the logitems that we
       * had pinned, clean up, free trans structure, and return error.
       */
      if (error || commit_lsn == -1) {
            current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
            xfs_trans_uncommit(tp, flags|XFS_TRANS_ABORT);
            return XFS_ERROR(EIO);
      }

      /*
       * Once the transaction has committed, unused
       * reservations need to be released and changes to
       * the superblock need to be reflected in the in-core
       * version.  Do that now.
       */
      xfs_trans_unreserve_and_mod_sb(tp);

      sync = tp->t_flags & XFS_TRANS_SYNC;

      /*
       * Tell the LM to call the transaction completion routine
       * when the log write with LSN commit_lsn completes (e.g.
       * when the transaction commit really hits the on-disk log).
       * After this call we cannot reference tp, because the call
       * can happen at any time and the call will free the transaction
       * structure pointed to by tp.  The only case where we call
       * the completion routine (xfs_trans_committed) directly is
       * if the log is turned off on a debug kernel or we're
       * running in simulation mode (the log is explicitly turned
       * off).
       */
      tp->t_logcb.cb_func = (void(*)(void*, int))xfs_trans_committed;
      tp->t_logcb.cb_arg = tp;

      /*
       * We need to pass the iclog buffer which was used for the
       * transaction commit record into this function, and attach
       * the callback to it. The callback must be attached before
       * the items are unlocked to avoid racing with other threads
       * waiting for an item to unlock.
       */
      shutdown = xfs_log_notify(mp, commit_iclog, &(tp->t_logcb));

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

      /*
       * Once all the items of the transaction have been copied
       * to the in core log and the callback is attached, the
       * items can be unlocked.
       *
       * This will free descriptors pointing to items which were
       * not logged since there is nothing more to do with them.
       * For items which were logged, we will keep pointers to them
       * so they can be unpinned after the transaction commits to disk.
       * This will also stamp each modified meta-data item with
       * the commit lsn of this transaction for dependency tracking
       * purposes.
       */
      xfs_trans_unlock_items(tp, commit_lsn);

      /*
       * If we detected a log error earlier, finish committing
       * the transaction now (unpin log items, etc).
       *
       * Order is critical here, to avoid using the transaction
       * pointer after its been freed (by xfs_trans_committed
       * either here now, or as a callback).  We cannot do this
       * step inside xfs_log_notify as was done earlier because
       * of this issue.
       */
      if (shutdown)
            xfs_trans_committed(tp, XFS_LI_ABORTED);

      /*
       * Now that the xfs_trans_committed callback has been attached,
       * and the items are released we can finally allow the iclog to
       * go to disk.
       */
      error = xfs_log_release_iclog(mp, commit_iclog);

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

      return (error);
}


/*
 * Total up the number of log iovecs needed to commit this
 * transaction.  The transaction itself needs one for the
 * transaction header.  Ask each dirty item in turn how many
 * it needs to get the total.
 */
STATIC uint
xfs_trans_count_vecs(
      xfs_trans_t *tp)
{
      int               nvecs;
      xfs_log_item_desc_t     *lidp;

      nvecs = 1;
      lidp = xfs_trans_first_item(tp);
      ASSERT(lidp != NULL);

      /* In the non-debug case we need to start bailing out if we
       * didn't find a log_item here, return zero and let trans_commit
       * deal with it.
       */
      if (lidp == NULL)
            return 0;

      while (lidp != NULL) {
            /*
             * Skip items which aren't dirty in this transaction.
             */
            if (!(lidp->lid_flags & XFS_LID_DIRTY)) {
                  lidp = xfs_trans_next_item(tp, lidp);
                  continue;
            }
            lidp->lid_size = IOP_SIZE(lidp->lid_item);
            nvecs += lidp->lid_size;
            lidp = xfs_trans_next_item(tp, lidp);
      }

      return nvecs;
}

/*
 * Called from the trans_commit code when we notice that
 * the filesystem is in the middle of a forced shutdown.
 */
STATIC void
xfs_trans_uncommit(
      xfs_trans_t *tp,
      uint        flags)
{
      xfs_log_item_desc_t     *lidp;

      for (lidp = xfs_trans_first_item(tp);
           lidp != NULL;
           lidp = xfs_trans_next_item(tp, lidp)) {
            /*
             * Unpin all but those that aren't dirty.
             */
            if (lidp->lid_flags & XFS_LID_DIRTY)
                  IOP_UNPIN_REMOVE(lidp->lid_item, tp);
      }

      xfs_trans_unreserve_and_mod_sb(tp);
      XFS_TRANS_UNRESERVE_AND_MOD_DQUOTS(tp->t_mountp, tp);

      xfs_trans_free_items(tp, flags);
      xfs_trans_free_busy(tp);
      xfs_trans_free(tp);
}

/*
 * Fill in the vector with pointers to data to be logged
 * by this transaction.  The transaction header takes
 * the first vector, and then each dirty item takes the
 * number of vectors it indicated it needed in xfs_trans_count_vecs().
 *
 * As each item fills in the entries it needs, also pin the item
 * so that it cannot be flushed out until the log write completes.
 */
STATIC void
xfs_trans_fill_vecs(
      xfs_trans_t       *tp,
      xfs_log_iovec_t         *log_vector)
{
      xfs_log_item_desc_t     *lidp;
      xfs_log_iovec_t         *vecp;
      uint              nitems;

      /*
       * Skip over the entry for the transaction header, we'll
       * fill that in at the end.
       */
      vecp = log_vector + 1;        /* pointer arithmetic */

      nitems = 0;
      lidp = xfs_trans_first_item(tp);
      ASSERT(lidp != NULL);
      while (lidp != NULL) {
            /*
             * Skip items which aren't dirty in this transaction.
             */
            if (!(lidp->lid_flags & XFS_LID_DIRTY)) {
                  lidp = xfs_trans_next_item(tp, lidp);
                  continue;
            }
            /*
             * The item may be marked dirty but not log anything.
             * This can be used to get called when a transaction
             * is committed.
             */
            if (lidp->lid_size) {
                  nitems++;
            }
            IOP_FORMAT(lidp->lid_item, vecp);
            vecp += lidp->lid_size;       /* pointer arithmetic */
            IOP_PIN(lidp->lid_item);
            lidp = xfs_trans_next_item(tp, lidp);
      }

      /*
       * Now that we've counted the number of items in this
       * transaction, fill in the transaction header.
       */
      tp->t_header.th_magic = XFS_TRANS_HEADER_MAGIC;
      tp->t_header.th_type = tp->t_type;
      tp->t_header.th_num_items = nitems;
      log_vector->i_addr = (xfs_caddr_t)&tp->t_header;
      log_vector->i_len = sizeof(xfs_trans_header_t);
      XLOG_VEC_SET_TYPE(log_vector, XLOG_REG_TYPE_TRANSHDR);
}


/*
 * 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(
      xfs_trans_t       *tp,
      int               flags)
{
      int               log_flags;
#ifdef DEBUG
      xfs_log_item_chunk_t    *licp;
      xfs_log_item_desc_t     *lidp;
      xfs_log_item_t          *lip;
      int               i;
#endif
      xfs_mount_t       *mp = tp->t_mountp;

      /*
       * See if the caller is being too lazy to figure out if
       * the transaction really needs an abort.
       */
      if ((flags & XFS_TRANS_ABORT) && !(tp->t_flags & XFS_TRANS_DIRTY))
            flags &= ~XFS_TRANS_ABORT;
      /*
       * 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 ((tp->t_flags & XFS_TRANS_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 (!(flags & XFS_TRANS_ABORT)) {
            licp = &(tp->t_items);
            while (licp != NULL) {
                  lidp = licp->lic_descs;
                  for (i = 0; i < licp->lic_unused; i++, lidp++) {
                        if (XFS_LIC_ISFREE(licp, i)) {
                              continue;
                        }

                        lip = lidp->lid_item;
                        if (!XFS_FORCED_SHUTDOWN(mp))
                              ASSERT(!(lip->li_type == XFS_LI_EFD));
                  }
                  licp = licp->lic_next;
            }
      }
#endif
      xfs_trans_unreserve_and_mod_sb(tp);
      XFS_TRANS_UNRESERVE_AND_MOD_DQUOTS(mp, tp);

      if (tp->t_ticket) {
            if (flags & XFS_TRANS_RELEASE_LOG_RES) {
                  ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
                  log_flags = XFS_LOG_REL_PERM_RESERV;
            } else {
                  log_flags = 0;
            }
            xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
      }

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

      xfs_trans_free_items(tp, flags);
      xfs_trans_free_busy(tp);
      xfs_trans_free(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(
      xfs_trans_t *tp)
{
      atomic_dec(&tp->t_mountp->m_active_trans);
      XFS_TRANS_FREE_DQINFO(tp->t_mountp, tp);
      kmem_zone_free(xfs_trans_zone, tp);
}


/*
 * THIS SHOULD BE REWRITTEN TO USE xfs_trans_next_item().
 *
 * This is typically called by the LM when a transaction has been fully
 * committed to disk.  It needs to unpin the items which have
 * been logged by the transaction and update their positions
 * in the AIL if necessary.
 * This also gets called when the transactions didn't get written out
 * because of an I/O error. Abortflag & XFS_LI_ABORTED is set then.
 *
 * Call xfs_trans_chunk_committed() to process the items in
 * each chunk.
 */
STATIC void
xfs_trans_committed(
      xfs_trans_t *tp,
      int         abortflag)
{
      xfs_log_item_chunk_t    *licp;
      xfs_log_item_chunk_t    *next_licp;
      xfs_log_busy_chunk_t    *lbcp;
      xfs_log_busy_slot_t     *lbsp;
      int               i;

      /*
       * Call the transaction's completion callback if there
       * is one.
       */
      if (tp->t_callback != NULL) {
            tp->t_callback(tp, tp->t_callarg);
      }

      /*
       * Special case the chunk embedded in the transaction.
       */
      licp = &(tp->t_items);
      if (!(XFS_LIC_ARE_ALL_FREE(licp))) {
            xfs_trans_chunk_committed(licp, tp->t_lsn, abortflag);
      }

      /*
       * Process the items in each chunk in turn.
       */
      licp = licp->lic_next;
      while (licp != NULL) {
            ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
            xfs_trans_chunk_committed(licp, tp->t_lsn, abortflag);
            next_licp = licp->lic_next;
            kmem_free(licp, sizeof(xfs_log_item_chunk_t));
            licp = next_licp;
      }

      /*
       * Clear all the per-AG busy list items listed in this transaction
       */
      lbcp = &tp->t_busy;
      while (lbcp != NULL) {
            for (i = 0, lbsp = lbcp->lbc_busy; i < lbcp->lbc_unused; i++, lbsp++) {
                  if (!XFS_LBC_ISFREE(lbcp, i)) {
                        xfs_alloc_clear_busy(tp, lbsp->lbc_ag,
                                         lbsp->lbc_idx);
                  }
            }
            lbcp = lbcp->lbc_next;
      }
      xfs_trans_free_busy(tp);

      /*
       * That's it for the transaction structure.  Free it.
       */
      xfs_trans_free(tp);
}

/*
 * This is called to perform the commit processing for each
 * item described by the given chunk.
 *
 * The commit processing consists of unlocking items which were
 * held locked with the SYNC_UNLOCK attribute, calling the committed
 * routine of each logged item, updating the item's position in the AIL
 * if necessary, and unpinning each item.  If the committed routine
 * returns -1, then do nothing further with the item because it
 * may have been freed.
 *
 * Since items are unlocked when they are copied to the incore
 * log, it is possible for two transactions to be completing
 * and manipulating the same item simultaneously.  The AIL lock
 * will protect the lsn field of each item.  The value of this
 * field can never go backwards.
 *
 * We unpin the items after repositioning them in the AIL, because
 * otherwise they could be immediately flushed and we'd have to race
 * with the flusher trying to pull the item from the AIL as we add it.
 */
STATIC void
xfs_trans_chunk_committed(
      xfs_log_item_chunk_t    *licp,
      xfs_lsn_t         lsn,
      int               aborted)
{
      xfs_log_item_desc_t     *lidp;
      xfs_log_item_t          *lip;
      xfs_lsn_t         item_lsn;
      struct xfs_mount  *mp;
      int               i;
      SPLDECL(s);

      lidp = licp->lic_descs;
      for (i = 0; i < licp->lic_unused; i++, lidp++) {
            if (XFS_LIC_ISFREE(licp, i)) {
                  continue;
            }

            lip = lidp->lid_item;
            if (aborted)
                  lip->li_flags |= XFS_LI_ABORTED;

            /*
             * Send in the ABORTED flag to the COMMITTED routine
             * so that it knows whether the transaction was aborted
             * or not.
             */
            item_lsn = IOP_COMMITTED(lip, lsn);

            /*
             * If the committed routine returns -1, make
             * no more references to the item.
             */
            if (XFS_LSN_CMP(item_lsn, (xfs_lsn_t)-1) == 0) {
                  continue;
            }

            /*
             * If the returned lsn is greater than what it
             * contained before, update the location of the
             * item in the AIL.  If it is not, then do nothing.
             * Items can never move backwards in the AIL.
             *
             * While the new lsn should usually be greater, it
             * is possible that a later transaction completing
             * simultaneously with an earlier one using the
             * same item could complete first with a higher lsn.
             * This would cause the earlier transaction to fail
             * the test below.
             */
            mp = lip->li_mountp;
            AIL_LOCK(mp,s);
            if (XFS_LSN_CMP(item_lsn, lip->li_lsn) > 0) {
                  /*
                   * This will set the item's lsn to item_lsn
                   * and update the position of the item in
                   * the AIL.
                   *
                   * xfs_trans_update_ail() drops the AIL lock.
                   */
                  xfs_trans_update_ail(mp, lip, item_lsn, s);
            } else {
                  AIL_UNLOCK(mp, s);
            }

            /*
             * Now that we've repositioned the item in the AIL,
             * unpin it so it can be flushed. Pass information
             * about buffer stale state down from the log item
             * flags, if anyone else stales the buffer we do not
             * want to pay any attention to it.
             */
            IOP_UNPIN(lip, lidp->lid_flags & XFS_LID_BUF_STALE);
      }
}

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