Btrfs: cache extent state in find_delalloc_range

This patch makes us cache the extent state we find in find_delalloc_range since
we'll have to lock the extent later on in the function.  This will keep us from
re-searching for the rang when we try to lock the extent.

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

1 files changed, 8 insertions, 3 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 355a973719a0..3c17c9eb0d98 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1171,7 +1171,8 @@ out:
  * 1 is returned if we find something, 0 if nothing was in the tree
  */
 static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
-                                        u64 *start, u64 *end, u64 max_bytes)
+                                        u64 *start, u64 *end, u64 max_bytes,
+                                        struct extent_state **cached_state)
 {
         struct rb_node *node;
         struct extent_state *state;
@@ -1203,8 +1204,11 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
                                 *end = state->end;
                         goto out;
                 }
-                if (!found)
+                if (!found) {
                         *start = state->start;
+                        *cached_state = state;
+                        atomic_inc(&state->refs);
+                }
                 found++;
                 *end = state->end;
                 cur_start = state->end + 1;
@@ -1336,10 +1340,11 @@ again:
         delalloc_start = *start;
         delalloc_end = 0;
         found = find_delalloc_range(tree, &delalloc_start, &delalloc_end,
-                                    max_bytes);
+                                    max_bytes, &cached_state);
         if (!found || delalloc_end <= *start) {
                 *start = delalloc_start;
                 *end = delalloc_end;
+                free_extent_state(cached_state);
                 return found;
         }