xfs: reduce the number of pagb_lock roundtrips in xfs_alloc_clear_busy

Instead of finding the per-ag and then taking and releasing the pagb_lock
for every single busy extent completed sort the list of busy extents and
only switch betweens AGs where nessecary.  This becomes especially important
with the online discard support which will hit this lock more often.

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

1 files changed, 2 insertions, 4 deletions

diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 76922793f64f..d1f24858ccc4 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -608,10 +608,8 @@ STATIC void
 xfs_trans_free(
         struct xfs_trans        *tp)
 {
-        struct xfs_busy_extent  *busyp, *n;
-
-        list_for_each_entry_safe(busyp, n, &tp->t_busy, list)
-                xfs_alloc_busy_clear(tp->t_mountp, busyp);
+        xfs_alloc_busy_sort(&tp->t_busy);
+        xfs_alloc_busy_clear(tp->t_mountp, &tp->t_busy);
 
         atomic_dec(&tp->t_mountp->m_active_trans);
         xfs_trans_free_dqinfo(tp);