Btrfs: avoid NULL pointer deref in try_release_extent_buffer

If we fail to find a pointer in the radix tree, don't try
to deref the NULL one we do have.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index f60aa3c35c23..143d3f541d64 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3837,8 +3837,10 @@ int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
 
         spin_lock(&tree->buffer_lock);
         eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
-        if (!eb)
-                goto out;
+        if (!eb) {
+                spin_unlock(&tree->buffer_lock);
+                return ret;
+        }
 
         if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
                 ret = 0;