xfs: add a short cut to xfs_dialloc for the non-NULL agbp case

In this case we already have selected an AG and know it has free space
beause the buffer lock never got released.  Jump directly into xfs_dialloc_ag
and short cut the AG selection loop.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_ialloc.c b/fs/xfs/xfs_ialloc.c
index 2b70952c9d8cc09b0942789a032aae66e57539ba..7aa8a02b793717635cd9a219af725239cace27a0 100644 (file)
--- a/fs/xfs/xfs_ialloc.c
+++ b/fs/xfs/xfs_ialloc.c
@@ -634,6 +634,10 @@ xfs_dialloc_ag(
 
        pag = xfs_perag_get(mp, agno);
 
+       ASSERT(pag->pagi_init);
+       ASSERT(pag->pagi_inodeok);
+       ASSERT(pag->pagi_freecount > 0);
+
  restart_pagno:
        cur = xfs_inobt_init_cursor(mp, tp, agbp, agno);
        /*
@@ -907,32 +911,32 @@ xfs_dialloc(
        xfs_agnumber_t          tagno;
        struct xfs_perag        *pag;
 
-       if (*IO_agbp == NULL) {
-               /*
-                * We do not have an agbp, so select an initial allocation
-                * group for inode allocation.
-                */
-               agbp = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
+       if (*IO_agbp) {
                /*
-                * Couldn't find an allocation group satisfying the
-                * criteria, give up.
-                */
-               if (!agbp) {
-                       *inop = NULLFSINO;
-                       return 0;
-               }
-               agi = XFS_BUF_TO_AGI(agbp);
-               ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));
-       } else {
-               /*
-                * Continue where we left off before.  In this case, we
+                * If the caller passes in a pointer to the AGI buffer,
+                * continue where we left off before.  In this case, we
                 * know that the allocation group has free inodes.
                 */
                agbp = *IO_agbp;
-               agi = XFS_BUF_TO_AGI(agbp);
-               ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));
-               ASSERT(be32_to_cpu(agi->agi_freecount) > 0);
+               goto out_alloc;
        }
+
+       /*
+        * We do not have an agbp, so select an initial allocation
+        * group for inode allocation.
+        */
+       agbp = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
+
+       /*
+        * Couldn't find an allocation group satisfying the
+        * criteria, give up.
+        */
+       if (!agbp) {
+               *inop = NULLFSINO;
+               return 0;
+       }
+       agi = XFS_BUF_TO_AGI(agbp);
+
        mp = tp->t_mountp;
        agno = be32_to_cpu(agi->agi_seqno);
        tagno = agno;
@@ -1012,6 +1016,7 @@ nextag:
                ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));
        }
 
+out_alloc:
        *IO_agbp = NULL;
        return xfs_dialloc_ag(tp, agbp, parent, inop);
 }