Messages in this thread Patch in this message | | | From | Takafumi Kubota <> | Subject | [PATCH v2] Btrfs: add another missing end_page_writeback on submit_extent_page failure | Date | Thu, 9 Feb 2017 17:24:33 +0900 |
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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 <takafumi.kubota1012@sslab.ics.keio.ac.jp> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Cc: David Sterba <dsterba@suse.cz> --- 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 4ac383a..aa1908a 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3445,8 +3445,11 @@ 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; @@ -3767,7 +3770,8 @@ 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; -- 1.9.3
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