xfs: don't commit the first deferred transaction without intents

If the first operation in a string of defer ops has no intents,
then there is no reason to commit it before running the first call
to xfs_defer_finish_one(). This allows the defer ops to be used
effectively for non-intent based operations without requiring an
unnecessary extra transaction commit when first called.

This fixes a regression in per-attribute modification transaction
count when delayed attributes are not being used.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index 0805ade2d300b264ce38d97b327a148a4b940d6c..1aa32bfdf0ccd2dda02191a3218c4ff8a58680bc 100644 (file)
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -186,7 +186,7 @@ static const struct xfs_defer_op_type *defer_op_types[] = {
        [XFS_DEFER_OPS_TYPE_AGFL_FREE]  = &xfs_agfl_free_defer_type,
 };
 
-static void
+static bool
 xfs_defer_create_intent(
        struct xfs_trans                *tp,
        struct xfs_defer_pending        *dfp,
@@ -197,6 +197,7 @@ xfs_defer_create_intent(
        if (!dfp->dfp_intent)
                dfp->dfp_intent = ops->create_intent(tp, &dfp->dfp_work,
                                                     dfp->dfp_count, sort);
+       return dfp->dfp_intent != NULL;
 }
 
 /*
@@ -204,16 +205,18 @@ xfs_defer_create_intent(
  * associated extents, then add the entire intake list to the end of
  * the pending list.
  */
-STATIC void
+static bool
 xfs_defer_create_intents(
        struct xfs_trans                *tp)
 {
        struct xfs_defer_pending        *dfp;
+       bool                            ret = false;
 
        list_for_each_entry(dfp, &tp->t_dfops, dfp_list) {
                trace_xfs_defer_create_intent(tp->t_mountp, dfp);
-               xfs_defer_create_intent(tp, dfp, true);
+               ret |= xfs_defer_create_intent(tp, dfp, true);
        }
+       return ret;
 }
 
 /* Abort all the intents that were committed. */
@@ -487,7 +490,7 @@ int
 xfs_defer_finish_noroll(
        struct xfs_trans                **tp)
 {
-       struct xfs_defer_pending        *dfp;
+       struct xfs_defer_pending        *dfp = NULL;
        int                             error = 0;
        LIST_HEAD(dop_pending);
 
@@ -506,17 +509,20 @@ xfs_defer_finish_noroll(
                 * of time that any one intent item can stick around in memory,
                 * pinning the log tail.
                 */
-               xfs_defer_create_intents(*tp);
+               bool has_intents = xfs_defer_create_intents(*tp);
+
                list_splice_init(&(*tp)->t_dfops, &dop_pending);
 
-               error = xfs_defer_trans_roll(tp);
-               if (error)
-                       goto out_shutdown;
+               if (has_intents || dfp) {
+                       error = xfs_defer_trans_roll(tp);
+                       if (error)
+                               goto out_shutdown;
 
-               /* Possibly relog intent items to keep the log moving. */
-               error = xfs_defer_relog(tp, &dop_pending);
-               if (error)
-                       goto out_shutdown;
+                       /* Relog intent items to keep the log moving. */
+                       error = xfs_defer_relog(tp, &dop_pending);
+                       if (error)
+                               goto out_shutdown;
+               }
 
                dfp = list_first_entry(&dop_pending, struct xfs_defer_pending,
                                       dfp_list);