From 0d01e247a06b9f36f685edf6c2e74f79f60df9cd Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Wed, 21 Oct 2020 14:25:02 +0800 Subject: [PATCH] btrfs: assert page mapping lock in attach_extent_buffer_page When calling attach_extent_buffer_page(), either we're attaching anonymous pages, called from btrfs_clone_extent_buffer(), or we're attaching btree inode pages, called from alloc_extent_buffer(). For the latter case, we should hold page->mapping->private_lock to avoid parallel changes to page->private. Reviewed-by: Nikolay Borisov Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent_io.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 119ced4..092ccb8 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3102,6 +3102,15 @@ static int submit_extent_page(unsigned int opf, static void attach_extent_buffer_page(struct extent_buffer *eb, struct page *page) { + /* + * If the page is mapped to btree inode, we should hold the private + * lock to prevent race. + * For cloned or dummy extent buffers, their pages are not mapped and + * will not race with any other ebs. + */ + if (page->mapping) + lockdep_assert_held(&page->mapping->private_lock); + if (!PagePrivate(page)) attach_page_private(page, eb); else -- 2.7.4