From: Jeff Moyer <jmoyer@redhat.com>
To: Jan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
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 2/9] ext4: honor the O_SYNC flag for aysnchronous direct I/O requests
Date: Tue, 20 Nov 2012 15:02:15 -0500 [thread overview]
Message-ID: <x49sj84hwl4.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <20121120100751.GB1408@quack.suse.cz> (Jan Kara's message of "Tue, 20 Nov 2012 11:07:51 +0100")
Jan Kara <jack@suse.cz> writes:
>> @@ -1279,6 +1280,9 @@ struct ext4_sb_info {
>> /* workqueue for dio unwritten */
>> struct workqueue_struct *dio_unwritten_wq;
>>
>> + /* workqueue for aio+dio+o_sync disk cache flushing */
>> + struct workqueue_struct *aio_dio_flush_wq;
>> +
> Umm, I'm not completely decided whether we really need a separate
> workqueue. But it doesn't cost too much so I guess it makes some sense -
> fsync() is rather heavy so syncing won't starve extent conversion...
I'm assuming you'd like me to convert the names from flush to fsync,
yes?
>> +
>> + /*
>> + * If we are running in nojournal mode, just flush the disk
>> + * cache and return.
>> + */
>> + if (!journal)
>> + return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_NOIO, NULL);
> And this is wrong as well - you need to do work similar to what
> ext4_sync_file() does. Actually it would be *much* better if these two
> sites used the same helper function. Which also poses an interesting
> question about locking - do we need i_mutex or not? Forcing a transaction
> commit is definitely OK without it, similarly as grabbing transaction ids
> from inode or ext4_should_journal_data() test. __sync_inode() call seems
> to be OK without i_mutex as well so I believe we can just get rid of it
> (getting i_mutex from the workqueue is a locking nightmare we don't want to
> return to).
Just to be clear, are you saying you would like me to remove the
mutex_lock/unlock pair from ext4_sync_file? (I had already factored out
the common code between this new code path and the fsync path in my tree.)
>> @@ -149,8 +209,11 @@ void ext4_add_complete_io(ext4_io_end_t *io_end)
>> struct workqueue_struct *wq;
>> unsigned long flags;
>>
>> - BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
>> - wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
>> + BUG_ON(!ext4_io_end_deferred(io_end));
>> + if (io_end->flag & EXT4_IO_END_UNWRITTEN)
>> + wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
>> + else
>> + wq = EXT4_SB(io_end->inode->i_sb)->aio_dio_flush_wq;
> Umm, I'd prefer if we used aio_dio_flush_wq when EXT4_IO_END_NEEDS_SYNC
> is set. That way slow syncing works will be always offloaded to a separate
> workqueue.
OK.
Thanks!
Jeff
next prev parent reply other threads:[~2012-11-20 20:02 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-20 7:41 [PATCH v1 0/9] fs: fix up AIO+DIO+O_SYNC to actually do the sync part Darrick J. Wong
2012-11-20 7:41 ` [PATCH 1/9] vfs: Handle O_SYNC AIO DIO in generic code properly Darrick J. Wong
2012-11-21 10:08 ` Christoph Hellwig
2012-11-21 16:58 ` Jeff Moyer
2012-11-21 18:29 ` Christoph Hellwig
2012-11-21 18:38 ` Jeff Moyer
2012-11-21 21:37 ` Jan Kara
2012-11-21 23:09 ` Jeffrey Ellis
2012-11-20 7:41 ` [PATCH 2/9] ext4: honor the O_SYNC flag for aysnchronous direct I/O requests Darrick J. Wong
2012-11-20 10:07 ` Jan Kara
2012-11-20 20:02 ` Jeff Moyer [this message]
2012-11-21 0:56 ` Jan Kara
2012-11-21 14:09 ` Jeff Moyer
2012-11-21 16:54 ` Jan Kara
2012-11-20 7:41 ` [PATCH 3/9] xfs: factor out everything but the filemap_write_and_wait from xfs_file_fsync Darrick J. Wong
2012-11-20 10:47 ` Dave Chinner
2012-11-21 10:09 ` Christoph Hellwig
2012-11-21 14:10 ` Jeff Moyer
2012-11-20 7:51 ` [PATCH 7/9] ocfs2: Use generic handlers of O_SYNC AIO DIO Darrick J. Wong
2012-11-21 19:32 ` Joel Becker
2012-11-20 7:51 ` [PATCH 5/9] btrfs: " Darrick J. Wong
2012-11-20 7:51 ` [PATCH 6/9] gfs2: " Darrick J. Wong
2012-11-20 7:51 ` [PATCH 4/9] xfs: honor the O_SYNC flag for aysnchronous direct I/O requests Darrick J. Wong
2012-11-20 10:24 ` Jan Kara
2012-11-20 11:20 ` Dave Chinner
2012-11-20 19:42 ` Jeff Moyer
2012-11-20 20:08 ` Dave Chinner
2012-11-20 7:51 ` [PATCH 8/9] filemap: don't call generic_write_sync for -EIOCBQUEUED Darrick J. Wong
2012-11-20 7:51 ` [PATCH 9/9] blkdev: Fix up AIO+DIO+O_SYNC to do the sync part correctly Darrick J. Wong
2012-11-20 10:15 ` Jan Kara
2012-11-20 20:47 ` Jeff Moyer
2012-11-21 0:57 ` Jan Kara
2012-11-20 8:38 ` [PATCH v1 0/9] fs: fix up AIO+DIO+O_SYNC to actually do the sync part Darrick J. Wong
2012-11-20 14:23 ` Jeff Moyer
2012-11-20 18:57 ` Darrick J. Wong
2012-11-20 19:05 ` Jeff Moyer
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