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Message-ID: <20190408111108.GB18662@quack2.suse.cz> Date: Mon, 8 Apr 2019 13:11:08 +0200 From: Jan Kara <jack@...e.cz> To: ZhangXiaoxu <zhangxiaoxu5@...wei.com> Cc: viro@...iv.linux.org.uk, tytso@....edu, adilger.kernel@...ger.ca, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, linux-ext4@...r.kernel.org, yi.zhang@...wei.com Subject: Re: [PATCH] fs/buffer.c: Fix data corruption when buffer write with IO error On Sat 06-04-19 15:13:13, ZhangXiaoxu wrote: > When the buffer write failed, 'end_buffer_write_sync' and > 'end_buffer_async_write' will clear the uptodate flag. But the > data in the buffer maybe newer than disk. In some case, this > will lead data corruption. > > For example: ext4 flush metadata to disk failed, it will clear > the uptodate flag. when a new coming call want the buffer, it will > read it from the disk(because the buffer no uptodate flag). But > the journal not checkpoint now, it will read old data from disk. > If read successfully, ext4 will write the old data to the new > journal, the data will corruption. > > So, don't clear the uptodate flag when write the buffer failed. > > Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@...wei.com> Thanks for the patch. But what are the chances that after the write has failed the read will succeed? Also there were places that were using buffer_uptodate() to detect IO errors. Did you check all those got converted to using buffer_write_io_error() instead? Honza > --- > fs/buffer.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/fs/buffer.c b/fs/buffer.c > index ce35760..9fe1827 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -172,7 +172,6 @@ void end_buffer_write_sync(struct buffer_head *bh, int uptodate) > } else { > buffer_io_error(bh, ", lost sync page write"); > mark_buffer_write_io_error(bh); > - clear_buffer_uptodate(bh); > } > unlock_buffer(bh); > put_bh(bh); > @@ -325,7 +324,6 @@ void end_buffer_async_write(struct buffer_head *bh, int uptodate) > } else { > buffer_io_error(bh, ", lost async page write"); > mark_buffer_write_io_error(bh); > - clear_buffer_uptodate(bh); > SetPageError(page); > } > > -- > 2.7.4 > -- Jan Kara <jack@...e.com> SUSE Labs, CR
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