btrfs: fix race on ENOMEM in alloc_extent_buffer

[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 782f3bc4651d319529394b1ce29e20d58d01e62c..ea100eb188de50411f88e2617e5c4d1a0d1f2815 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4870,6 +4870,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
                                mark_extent_buffer_accessed(exists, p);
                                goto free_eb;
                        }
+                       exists = NULL;
 
                        /*
                         * Do this so attach doesn't complain and we need to
@@ -4933,12 +4934,12 @@ again:
        return eb;
 
 free_eb:
+       WARN_ON(!atomic_dec_and_test(&eb->refs));
        for (i = 0; i < num_pages; i++) {
                if (eb->pages[i])
                        unlock_page(eb->pages[i]);
        }
 
-       WARN_ON(!atomic_dec_and_test(&eb->refs));
        btrfs_release_extent_buffer(eb);
        return exists;
 }