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>

3 files changed, 10 insertions, 5 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)) {
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index d56f732ba95e..a8ffecd0b491 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -232,11 +232,12 @@ int btrfs_add_ordered_sum(struct inode *inode,
  * to make sure this function only returns 1 once for a given ordered extent.
  */
 int btrfs_dec_test_ordered_pending(struct inode *inode,
+                                   struct btrfs_ordered_extent **cached,
                                    u64 file_offset, u64 io_size)
 {
         struct btrfs_ordered_inode_tree *tree;
         struct rb_node *node;
-        struct btrfs_ordered_extent *entry;
+        struct btrfs_ordered_extent *entry = NULL;
         int ret;
 
         tree = &BTRFS_I(inode)->ordered_tree;
@@ -264,6 +265,10 @@ int btrfs_dec_test_ordered_pending(struct inode *inode,
         else
                 ret = 1;
 out:
+        if (!ret && cached && entry) {
+                *cached = entry;
+                atomic_inc(&entry->refs);
+        }
         spin_unlock(&tree->lock);
         return ret == 0;
 }
diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
index bfbcebbb0adc..c82f76a9f040 100644
--- a/fs/btrfs/ordered-data.h
+++ b/fs/btrfs/ordered-data.h
@@ -137,7 +137,8 @@ int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry);
 int btrfs_remove_ordered_extent(struct inode *inode,
                                 struct btrfs_ordered_extent *entry);
 int btrfs_dec_test_ordered_pending(struct inode *inode,
-                                       u64 file_offset, u64 io_size);
+                                   struct btrfs_ordered_extent **cached,
+                                   u64 file_offset, u64 io_size);
 int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
                              u64 start, u64 len, u64 disk_len, int tyep);
 int btrfs_add_ordered_sum(struct inode *inode,