Btrfs: nuke fs wide allocation mutex V2

[linux-2.6-block.git] / fs / btrfs / extent_io.c

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 314041fdfa43a25d5df9cc865b6831563a2c4b64..7503bd46819b0b19d2ccf222ecdc24397434e495 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -938,6 +938,20 @@ int lock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask)
 }
 EXPORT_SYMBOL(lock_extent);
 
+int try_lock_extent(struct extent_io_tree *tree, u64 start, u64 end,
+                   gfp_t mask)
+{
+       int err;
+       u64 failed_start;
+
+       err = set_extent_bit(tree, start, end, EXTENT_LOCKED, 1,
+                            &failed_start, mask);
+       if (err == -EEXIST)
+               return 0;
+       return 1;
+}
+EXPORT_SYMBOL(try_lock_extent);
+
 int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end,
                  gfp_t mask)
 {