btrfs: avoid duplicated resolution of indirect backrefs during fiemap

[linux-2.6-microblaze.git] / fs / btrfs / backref.h

diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index fda78db..6dac462 100644 (file)
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -28,6 +28,19 @@ struct btrfs_backref_shared_cache_entry {
 struct btrfs_backref_share_check_ctx {
        /* Ulists used during backref walking. */
        struct ulist refs;
+       /*
+        * The current leaf the caller of btrfs_is_data_extent_shared() is at.
+        * Typically the caller (at the moment only fiemap) tries to determine
+        * the sharedness of data extents point by file extent items from entire
+        * leaves.
+        */
+       u64 curr_leaf_bytenr;
+       /*
+        * The previous leaf the caller was at in the previous call to
+        * btrfs_is_data_extent_shared(). This may be the same as the current
+        * leaf. On the first call it must be 0.
+        */
+       u64 prev_leaf_bytenr;
        /*
         * A path from a root to a leaf that has a file extent item pointing to
         * a given data extent should never exceed the maximum b+tree height.