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Message-Id: <20170616193427.13955-8-jlayton@redhat.com> Date: Fri, 16 Jun 2017 15:34:12 -0400 From: Jeff Layton <jlayton@...hat.com> To: Andrew Morton <akpm@...ux-foundation.org>, Al Viro <viro@...IV.linux.org.uk>, Jan Kara <jack@...e.cz>, tytso@....edu, axboe@...nel.dk, mawilcox@...rosoft.com, ross.zwisler@...ux.intel.com, corbet@....net, Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>, David Sterba <dsterba@...e.com>, "Darrick J . Wong" <darrick.wong@...cle.com> Cc: Carlos Maiolino <cmaiolino@...hat.com>, Eryu Guan <eguan@...hat.com>, David Howells <dhowells@...hat.com>, Christoph Hellwig <hch@...radead.org>, linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org, linux-btrfs@...r.kernel.org, linux-block@...r.kernel.org Subject: [PATCH v7 07/22] mm: don't TestClearPageError in __filemap_fdatawait_range The -EIO returned here can end up overriding whatever error is marked in the address space, and be returned at fsync time, even when there is a more appropriate error stored in the mapping. Read errors are also sometimes tracked on a per-page level using PG_error. Suppose we have a read error on a page, and then that page is subsequently dirtied by overwriting the whole page. Writeback doesn't clear PG_error, so we can then end up successfully writing back that page and still return -EIO on fsync. Worse yet, PG_error is cleared during a sync() syscall, but the -EIO return from that is silently discarded. Any subsystem that is relying on PG_error to report errors during fsync can easily lose writeback errors due to this. All you need is a stray sync() call to wait for writeback to complete and you've lost the error. Since the handling of the PG_error flag is somewhat inconsistent across subsystems, let's just rely on marking the address space when there are writeback errors. Change the TestClearPageError call to ClearPageError, and make __filemap_fdatawait_range a void return function. Signed-off-by: Jeff Layton <jlayton@...hat.com> --- mm/filemap.c | 20 +++++--------------- 1 file changed, 5 insertions(+), 15 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index c349a5d3a34b..21e65c6ef1a0 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -388,17 +388,16 @@ int filemap_flush(struct address_space *mapping) } EXPORT_SYMBOL(filemap_flush); -static int __filemap_fdatawait_range(struct address_space *mapping, +static void __filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, loff_t end_byte) { pgoff_t index = start_byte >> PAGE_SHIFT; pgoff_t end = end_byte >> PAGE_SHIFT; struct pagevec pvec; int nr_pages; - int ret = 0; if (end_byte < start_byte) - goto out; + return; pagevec_init(&pvec, 0); while ((index <= end) && @@ -415,14 +414,11 @@ static int __filemap_fdatawait_range(struct address_space *mapping, continue; wait_on_page_writeback(page); - if (TestClearPageError(page)) - ret = -EIO; + ClearPageError(page); } pagevec_release(&pvec); cond_resched(); } -out: - return ret; } /** @@ -442,14 +438,8 @@ static int __filemap_fdatawait_range(struct address_space *mapping, int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte, loff_t end_byte) { - int ret, ret2; - - ret = __filemap_fdatawait_range(mapping, start_byte, end_byte); - ret2 = filemap_check_errors(mapping); - if (!ret) - ret = ret2; - - return ret; + __filemap_fdatawait_range(mapping, start_byte, end_byte); + return filemap_check_errors(mapping); } EXPORT_SYMBOL(filemap_fdatawait_range); -- 2.13.0
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