Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753271Ab2KUA5m (ORCPT ); Tue, 20 Nov 2012 19:57:42 -0500 Received: from cantor2.suse.de ([195.135.220.15]:54520 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752511Ab2KUA5l (ORCPT ); Tue, 20 Nov 2012 19:57:41 -0500 Date: Wed, 21 Nov 2012 01:57:39 +0100 From: Jan Kara To: Jeff Moyer Cc: Jan Kara , "Darrick J. Wong" , axboe@kernel.dk, tytso@mit.edu, david@fromorbit.com, bpm@sgi.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, hch@infradead.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com Subject: Re: [PATCH 9/9] blkdev: Fix up AIO+DIO+O_SYNC to do the sync part correctly Message-ID: <20121121005739.GD10507@quack.suse.cz> References: <20121120074116.24645.36369.stgit@blackbox.djwong.org> <20121120075115.25270.62451.stgit@blackbox.djwong.org> <20121120101559.GC1408@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3109 Lines: 72 On Tue 20-11-12 15:47:54, Jeff Moyer wrote: > Jan Kara writes: > > > On Mon 19-11-12 23:51:15, Darrick J. Wong wrote: > >> 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); > > This should be folded into the original patch introducing the > > s_dio_flush_wq. And please add a comment before this line saying that block > > devices need a dereference exactly like this... Otherwise the patch looks > > good so you can add: > > Reviewed-by: Jan Kara > > When you say, "This," do you mean that one change, or the whole patch? I meant the whole patch after that hung is folded ;) Honza -- Jan Kara SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/