From fe01aa65385c226d822013b90608b67c485f8dc6 Mon Sep 17 00:00:00 2001 From: Takafumi Kubota Date: Thu, 9 Feb 2017 17:24:33 +0900 Subject: [PATCH] Btrfs: add another missing end_page_writeback on submit_extent_page failure If btrfs_bio_alloc fails in submit_extent_page, submit_extent_page returns without clearing the writeback bit of the failed page. __extent_writepage_io, that is a caller of submit_extent_page, does not clear the remaining writeback bit anywhere. As a result, this will cause the hang at filemap_fdatawait_range, because it waits the writeback bit to be cleared from the failed page. So, we have to call end_page_writeback to clear the writeback bit. For reproducing the hang, we inject a fault like if (should_failtest()) { // I define should_failtest() bio = NULL; } else { bio = btrfs_bio_alloc(...); } in submit_extent_page. We should also check whether page has the bit before end_page_writeback, to avoid the conflict against the other end_page_writeback in bio_endio. Thus, we add PageWriteback checks not only in __extent_writepage_io, but also in write_one_eb too, because it misses the check. Signed-off-by: Takafumi Kubota Reviewed-by: Liu Bo Cc: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent_io.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 4a8b119..9df6ed3 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3437,8 +3437,11 @@ static noinline_for_stack int __extent_writepage_io(struct inode *inode, bdev, &epd->bio, max_nr, end_bio_extent_writepage, 0, 0, 0, false); - if (ret) + if (ret) { SetPageError(page); + if (PageWriteback(page)) + end_page_writeback(page); + } cur = cur + iosize; pg_offset += iosize; @@ -3754,7 +3757,8 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb, epd->bio_flags = bio_flags; if (ret) { set_btree_ioerr(p); - end_page_writeback(p); + if (PageWriteback(p)) + end_page_writeback(p); if (atomic_sub_and_test(num_pages - i, &eb->io_pages)) end_extent_buffer_writeback(eb); ret = -EIO; -- 2.7.4