From: "Darrick J. Wong" Subject: [PATCH 9/9] blkdev: Fix up AIO+DIO+O_SYNC to do the sync part correctly Date: Mon, 19 Nov 2012 23:51:15 -0800 Message-ID: <20121120075115.25270.62451.stgit@blackbox.djwong.org> References: <20121120074116.24645.36369.stgit@blackbox.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, hch@infradead.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com To: axboe@kernel.dk, tytso@mit.edu, david@fromorbit.com, jmoyer@redhat.com, bpm@sgi.com, viro@zeniv.linux.org.uk, jack@suse.cz Return-path: In-Reply-To: <20121120074116.24645.36369.stgit@blackbox.djwong.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org When performing O_SYNC+AIO+DIO writes to block devices, use the DIO_SYNC_WRITES flag so that flushes are issued /after/ the write completes, not before. Note, however, that for block devices, the DIO setup code ensures that a flush wq is attached to the superblock of the bdevfs filesystem, not the filesystem that the device node happens to reside in. This means that unlike regular files, iocb->ki_filp->f_mapping->host->i_sb != inode->i_sb. Therefore, adjust Jeff's earlier patch to keep the pointer use consistent and avoid a NULL deref. Signed-off-by: Darrick J. Wong --- fs/block_dev.c | 5 +++-- fs/direct-io.c | 3 ++- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 1a1e5e3..05ff33a 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -235,7 +235,8 @@ blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, struct inode *inode = file->f_mapping->host; return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset, - nr_segs, blkdev_get_blocks, NULL, NULL, 0); + nr_segs, blkdev_get_blocks, NULL, NULL, + DIO_SYNC_WRITES); } int __sync_blockdev(struct block_device *bdev, int wait) @@ -1631,7 +1632,7 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov, percpu_down_read(&bdev->bd_block_size_semaphore); ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); - if (ret > 0 || ret == -EIOCBQUEUED) { + if (ret > 0) { ssize_t err; err = generic_write_sync(file, pos, ret); diff --git a/fs/direct-io.c b/fs/direct-io.c index b7391d4..c626c43 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -258,7 +258,8 @@ void generic_dio_end_io(struct kiocb *iocb, loff_t offset, ssize_t bytes, work->ret = ret; work->offset = offset; work->len = bytes; - queue_work(inode->i_sb->s_dio_flush_wq, &work->work); + queue_work(iocb->ki_filp->f_mapping->host->i_sb->s_dio_flush_wq, + &work->work); } else { aio_complete(iocb, ret, 0); inode_dio_done(inode);