btrfs: fix wrong allocating flag when reading page

the space cache use extent_readpages() to read free space information,
so we can not use GFP_KERNEL flag to allocate memory, or it may lead
to deadlock.

Signed-off-by: Itaru Kitayama <kitayama@cl.bb4u.ne.jp>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 5ae0bff..0d1196d 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2681,7 +2681,7 @@ int extent_readpages(struct extent_io_tree *tree,
                prefetchw(&page->flags);
                list_del(&page->lru);
                if (!add_to_page_cache_lru(page, mapping,
-                                       page->index, GFP_KERNEL)) {
+                                       page->index, GFP_NOFS)) {
                        __extent_read_full_page(tree, page, get_extent,
                                                &bio, 0, &bio_flags);
                }