Btrfs: make sure we retry if page is a retriable exception

In inode.c:btrfs_page_exists_in_range(), if the page we get from the
radix tree is an exception which should make us retry, set page to
NULL in order to really retry, because otherwise we don't get another
loop iteration executed (page != NULL makes the while loop exit).
This also was making us call page_cache_release after exiting the loop,
which isn't correct because page doesn't point to a valid page, and
possibly return true from the function when we shouldn't.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index cdbd20e62bb65fccbbc99ab26ccf2f74b80577e3..f265f413acba39e59c99aac57b58998f98ab1d3c 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6767,8 +6767,10 @@ bool btrfs_page_exists_in_range(struct inode *inode, loff_t start, loff_t end)
                        break;
 
                if (radix_tree_exception(page)) {
-                       if (radix_tree_deref_retry(page))
+                       if (radix_tree_deref_retry(page)) {
+                               page = NULL;
                                continue;
+                       }
                        /*
                         * Otherwise, shmem/tmpfs must be storing a swap entry
                         * here as an exceptional entry: so return it without