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Message-Id: <1365438463-23025-1-git-send-email-jack@suse.cz> Date: Mon, 8 Apr 2013 18:27:43 +0200 From: Jan Kara <jack@...e.cz> To: Ted Tso <tytso@....edu> Cc: linux-ext4@...r.kernel.org, Jan Kara <jack@...e.cz> Subject: [PATCH] ext4: Fix data corruption with direct IO read in dioread_nolock mode When ext4 is mounted in dioread_nolock mode, it calls __blockdev_direct_IO() without DIO_LOCKING flag which also means mapping is not synced before direct IO starts. As a result consistency between buffered writes and following direct IO reads is broken. More importantly, if the file is truncated, and extented back, zeroing of the tail page is not visible to the following direct IO read which will return stale data. Fix the problem by flushing dirty pages before issuing direct IO read. Signed-off-by: Jan Kara <jack@...e.cz> --- fs/ext4/indirect.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index b505a14..c18bf1c 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -809,6 +809,10 @@ ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb, retry: if (rw == READ && ext4_should_dioread_nolock(inode)) { + ret = filemap_write_and_wait_range(inode->i_mapping, offset, + offset + count - 1); + if (ret) + goto out; if (unlikely(atomic_read(&EXT4_I(inode)->i_unwritten))) { mutex_lock(&inode->i_mutex); ext4_flush_unwritten_io(inode); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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