xfs: do not use xfs_mod_incore_sb_batch for per-cpu counters

Update the per-cpu counters manually in xfs_trans_unreserve_and_mod_sb
and remove support for per-cpu counters from xfs_mod_incore_sb_batch
to simplify it.  And added benefit is that we don't have to take
m_sb_lock for transactions that only modify per-cpu counters.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

2 files changed, 85 insertions, 107 deletions

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 20c67ff57536..00538b7e694a 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1856,98 +1856,54 @@ xfs_mod_incore_sb(
 }
 
 /*
- * xfs_mod_incore_sb_batch() is used to change more than one field
- * in the in-core superblock structure at a time.  This modification
- * is protected by a lock internal to this module.  The fields and
- * changes to those fields are specified in the array of xfs_mod_sb
- * structures passed in.
+ * Change more than one field in the in-core superblock structure at a time.
  *
- * Either all of the specified deltas will be applied or none of
- * them will.  If any modified field dips below 0, then all modifications
- * will be backed out and EINVAL will be returned.
+ * The fields and changes to those fields are specified in the array of
+ * xfs_mod_sb structures passed in.  Either all of the specified deltas
+ * will be applied or none of them will.  If any modified field dips below 0,
+ * then all modifications will be backed out and EINVAL will be returned.
+ *
+ * Note that this function may not be used for the superblock values that
+ * are tracked with the in-memory per-cpu counters - a direct call to
+ * xfs_icsb_modify_counters is required for these.
  */
 int
-xfs_mod_incore_sb_batch(xfs_mount_t *mp, xfs_mod_sb_t *msb, uint nmsb, int rsvd)
+xfs_mod_incore_sb_batch(
+        struct xfs_mount        *mp,
+        xfs_mod_sb_t            *msb,
+        uint                    nmsb,
+        int                     rsvd)
 {
-        int             status=0;
-        xfs_mod_sb_t    *msbp;
+        xfs_mod_sb_t            *msbp = &msb[0];
+        int                     error = 0;
 
         /*
-         * Loop through the array of mod structures and apply each
-         * individually.  If any fail, then back out all those
-         * which have already been applied.  Do all of this within
-         * the scope of the m_sb_lock so that all of the changes will
-         * be atomic.
+         * Loop through the array of mod structures and apply each individually.
+         * If any fail, then back out all those which have already been applied.
+         * Do all of this within the scope of the m_sb_lock so that all of the
+         * changes will be atomic.
          */
         spin_lock(&mp->m_sb_lock);
-        msbp = &msb[0];
         for (msbp = &msbp[0]; msbp < (msb + nmsb); msbp++) {
-                /*
-                 * Apply the delta at index n.  If it fails, break
-                 * from the loop so we'll fall into the undo loop
-                 * below.
-                 */
-                switch (msbp->msb_field) {
-#ifdef HAVE_PERCPU_SB
-                case XFS_SBS_ICOUNT:
-                case XFS_SBS_IFREE:
-                case XFS_SBS_FDBLOCKS:
-                        spin_unlock(&mp->m_sb_lock);
-                        status = xfs_icsb_modify_counters(mp,
-                                                msbp->msb_field,
-                                                msbp->msb_delta, rsvd);
-                        spin_lock(&mp->m_sb_lock);
-                        break;
-#endif
-                default:
-                        status = xfs_mod_incore_sb_unlocked(mp,
-                                                msbp->msb_field,
-                                                msbp->msb_delta, rsvd);
-                        break;
-                }
+                ASSERT(msbp->msb_field < XFS_SBS_ICOUNT ||
+                       msbp->msb_field > XFS_SBS_FDBLOCKS);
 
-                if (status != 0) {
-                        break;
-                }
+                error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
+                                                   msbp->msb_delta, rsvd);
+                if (error)
+                        goto unwind;
         }
+        spin_unlock(&mp->m_sb_lock);
+        return 0;
 
-        /*
-         * If we didn't complete the loop above, then back out
-         * any changes made to the superblock.  If you add code
-         * between the loop above and here, make sure that you
-         * preserve the value of status. Loop back until
-         * we step below the beginning of the array.  Make sure
-         * we don't touch anything back there.
-         */
-        if (status != 0) {
-                msbp--;
-                while (msbp >= msb) {
-                        switch (msbp->msb_field) {
-#ifdef HAVE_PERCPU_SB
-                        case XFS_SBS_ICOUNT:
-                        case XFS_SBS_IFREE:
-                        case XFS_SBS_FDBLOCKS:
-                                spin_unlock(&mp->m_sb_lock);
-                                status = xfs_icsb_modify_counters(mp,
-                                                msbp->msb_field,
-                                                -(msbp->msb_delta),
-                                                rsvd);
-                                spin_lock(&mp->m_sb_lock);
-                                break;
-#endif
-                        default:
-                                status = xfs_mod_incore_sb_unlocked(mp,
-                                                        msbp->msb_field,
-                                                        -(msbp->msb_delta),
-                                                        rsvd);
-                                break;
-                        }
-                        ASSERT(status == 0);
-                        msbp--;
-                }
+unwind:
+        while (--msbp >= msb) {
+                error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
+                                                   -msbp->msb_delta, rsvd);
+                ASSERT(error == 0);
         }
         spin_unlock(&mp->m_sb_lock);
-        return status;
+        return error;
 }
 
 /*
@@ -2478,7 +2434,7 @@ xfs_icsb_balance_counter(
         spin_unlock(&mp->m_sb_lock);
 }
 
-STATIC int
+int
 xfs_icsb_modify_counters(
         xfs_mount_t     *mp,
         xfs_sb_field_t  field,
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 73cf8f45725e..5fab0e6bf86e 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -1009,7 +1009,7 @@ 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    msb[9]; /* If you add cases, add entries */
         xfs_mod_sb_t    *msbp;
         xfs_mount_t     *mp = tp->t_mountp;
         /* REFERENCED */
@@ -1017,55 +1017,61 @@ xfs_trans_unreserve_and_mod_sb(
         int             rsvd;
         int64_t         blkdelta = 0;
         int64_t         rtxdelta = 0;
+        int64_t         idelta = 0;
+        int64_t         ifreedelta = 0;
 
         msbp = msb;
         rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;
 
-        /* calculate free blocks delta */
+        /* 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 (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 (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_icsb_modify_counters(mp, XFS_SBS_FDBLOCKS,
+                                                 blkdelta, rsvd);
+                if (error)
+                        goto out;
+        }
+
+        if (idelta) {
+                error = xfs_icsb_modify_counters(mp, XFS_SBS_ICOUNT,
+                                                 idelta, rsvd);
+                if (error)
+                        goto out_undo_fdblocks;
+        }
+
+        if (ifreedelta) {
+                error = xfs_icsb_modify_counters(mp, XFS_SBS_IFREE,
+                                                 ifreedelta, rsvd);
+                if (error)
+                        goto out_undo_icount;
+        }
+
+        /* apply remaining deltas */
         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;
@@ -1115,8 +1121,24 @@ xfs_trans_unreserve_and_mod_sb(
         if (msbp > msb) {
                 error = xfs_mod_incore_sb_batch(tp->t_mountp, msb,
                         (uint)(msbp - msb), rsvd);
-                ASSERT(error == 0);
+                if (error)
+                        goto out_undo_ifreecount;
         }
+
+        return;
+
+out_undo_ifreecount:
+        if (ifreedelta)
+                xfs_icsb_modify_counters(mp, XFS_SBS_IFREE, -ifreedelta, rsvd);
+out_undo_icount:
+        if (idelta)
+                xfs_icsb_modify_counters(mp, XFS_SBS_ICOUNT, -idelta, rsvd);
+out_undo_fdblocks:
+        if (blkdelta)
+                xfs_icsb_modify_counters(mp, XFS_SBS_FDBLOCKS, -blkdelta, rsvd);
+out:
+        ASSERT(error = 0);
+        return;
 }
 
 /*