Btrfs: read lock extent buffer while walking backrefs
Before processing the extent buffer, acquire a read lock on it, so
that we're safe against concurrent updates on the extent buffer.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index e25564b..a1efd39 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1001,8 +1001,11 @@
ret = -EIO;
goto out;
}
+ btrfs_tree_read_lock(eb);
+ btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
ret = find_extent_in_eb(eb, bytenr,
*extent_item_pos, &eie);
+ btrfs_tree_read_unlock_blocking(eb);
free_extent_buffer(eb);
if (ret < 0)
goto out;