Btrfs: fix crash of btrfs_release_extent_buffer_page

This is actually inspired by Filipe's patch.  When write_one_eb() fails on
submit_extent_page(), it'll give up writing this eb and mark it with
EXTENT_BUFFER_IOERR.  So if it's not the last page that encounter the failure,
there are some left pages which remain DIRTY, and if a later COW on this eb
happens, ie. eb is COWed and freed, it'd run into BUG_ON in
btrfs_release_extent_buffer_page() for the DIRTY page, ie. BUG_ON(PageDirty(page));

This adds the missing clear_page_dirty_for_io() for the rest pages of eb.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
(cherry picked from commit 8146502820231da924ca22d147cdcf733ac9a057)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index af0359dcf337dbfec421b49fedbb8b5d0ecbf8b8..e68a1d994ccbb67e8d242f892fb1ebc15aa61134 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3597,6 +3597,7 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb,
        if (unlikely(ret)) {
                for (; i < num_pages; i++) {
                        struct page *p = extent_buffer_page(eb, i);
+                       clear_page_dirty_for_io(p);
                        unlock_page(p);
                }
        }