Btrfs: cache ordered extent when completing io

When finishing io we run btrfs_dec_test_ordered_pending, and then immediately
run btrfs_lookup_ordered_extent, but btrfs_dec_test_ordered_pending does that
already, so we're searching twice when we don't have to.  This patch lets us
pass a btrfs_ordered_extent in to btrfs_dec_test_ordered_pending so if we do
complete io on that ordered extent we can just use the one we found then instead
of having to do another btrfs_lookup_ordered_extent.  This made my fio job with
the other patch go from 24 mb/s to 29 mb/s.

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 50ce8840a99b..1824dda1d351 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1698,11 +1698,10 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
         int compressed = 0;
         int ret;
 
-        ret = btrfs_dec_test_ordered_pending(inode, start, end - start + 1);
+        ret = btrfs_dec_test_ordered_pending(inode, &ordered_extent, start,
+                                             end - start + 1);
         if (!ret)
                 return 0;
-
-        ordered_extent = btrfs_lookup_ordered_extent(inode, start);
         BUG_ON(!ordered_extent);
 
         if (test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags)) {