From: Matthew Bobrowski <mbobrowski@mbobrowski.org>
To: Jan Kara <jack@suse.cz>
Cc: "Theodore Y. Ts'o" <tytso@mit.edu>,
adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org,
linux-fsdevel@vger.kernel.org, hch@infradead.org,
david@fromorbit.com, darrick.wong@oracle.com
Subject: Re: [PATCH v5 00/12] ext4: port direct I/O to iomap infrastructure
Date: Wed, 23 Oct 2019 13:35:19 +1100 [thread overview]
Message-ID: <20191023023519.GA16505@bobrowski> (raw)
In-Reply-To: <20191021194330.GJ25184@quack2.suse.cz>
On Mon, Oct 21, 2019 at 09:43:30PM +0200, Jan Kara wrote:
> On Mon 21-10-19 09:31:12, Theodore Y. Ts'o wrote:
> > Hi Matthew, thanks for your work on this patch series!
> >
> > I applied it against 4c3, and ran a quick test run on it, and found
> > the following locking problem. To reproduce:
> >
> > kvm-xfstests -c nojournal generic/113
> >
> > generic/113 [09:27:19][ 5.841937] run fstests generic/113 at 2019-10-21 09:27:19
> > [ 7.959477]
> > [ 7.959798] ============================================
> > [ 7.960518] WARNING: possible recursive locking detected
> > [ 7.961225] 5.4.0-rc3-xfstests-00012-g7fe6ea084e48 #1238 Not tainted
> > [ 7.961991] --------------------------------------------
> > [ 7.962569] aio-stress/1516 is trying to acquire lock:
> > [ 7.963129] ffff9fd4791148c8 (&sb->s_type->i_mutex_key#12){++++}, at: __generic_file_fsync+0x3e/0xb0
> > [ 7.964109]
> > [ 7.964109] but task is already holding lock:
> > [ 7.964740] ffff9fd4791148c8 (&sb->s_type->i_mutex_key#12){++++}, at: ext4_dio_write_iter+0x15b/0x430
>
> This is going to be a tricky one. With iomap, the inode locking is handled
> by the filesystem while calling generic_write_sync() is done by
> iomap_dio_rw(). I would really prefer to avoid tweaking iomap_dio_rw() not
> to call generic_write_sync(). So we need to remove inode_lock from
> __generic_file_fsync() (used from ext4_sync_file()). This locking is mostly
> for legacy purposes and we don't need this in ext4 AFAICT - but removing
> the lock from __generic_file_fsync() would mean auditing all legacy
> filesystems that use this to make sure flushing inode & its metadata buffer
> list while it is possibly changing cannot result in something unexpected. I
> don't want to clutter this series with it so we are left with
> reimplementing __generic_file_fsync() inside ext4 without inode_lock. Not
> too bad but not great either. Thoughts?
So, I just looked at this on my lunch break and I think the simplest approach
would be to just transfer the necessary chunks of code from within
__generic_file_fsync() into ext4_sync_file() for !journal cases, minus the
inode lock, and minus calling into __generic_file_fsync(). I don't forsee this
causing any issues, but feel free to correct me if I'm wrong.
If this is deemed to be OK, then I will go ahead and include this as a
separate patch in my series.
--<M>--
next prev parent reply other threads:[~2019-10-23 2:35 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-21 9:17 [PATCH v5 00/12] ext4: port direct I/O to iomap infrastructure Matthew Bobrowski
2019-10-21 9:17 ` [PATCH v5 01/12] ext4: move set iomap routines into separate helper ext4_set_iomap() Matthew Bobrowski
2019-10-21 13:23 ` Jan Kara
2019-10-23 6:31 ` Ritesh Harjani
2019-10-23 10:14 ` Matthew Bobrowski
2019-10-21 9:17 ` [PATCH v5 02/12] ext4: iomap that extends beyond EOF should be marked dirty Matthew Bobrowski
2019-10-21 13:28 ` Jan Kara
2019-10-22 1:49 ` Matthew Bobrowski
2019-10-23 6:35 ` Ritesh Harjani
2019-10-23 10:20 ` Matthew Bobrowski
2019-10-21 9:18 ` [PATCH v5 03/12] ext4: split IOMAP_WRITE branch in ext4_iomap_begin() into helper Matthew Bobrowski
2019-10-21 13:31 ` Jan Kara
2019-10-23 6:37 ` Ritesh Harjani
2019-10-21 9:18 ` [PATCH v5 04/12] ext4: introduce new callback for IOMAP_REPORT Matthew Bobrowski
2019-10-21 13:37 ` Jan Kara
2019-10-22 1:55 ` Matthew Bobrowski
2019-10-23 6:39 ` Ritesh Harjani
2019-10-23 10:35 ` Matthew Bobrowski
2019-10-21 9:18 ` [PATCH v5 05/12] iomap: Allow forcing of waiting for running DIO in iomap_dio_rw() mbobrowski
2019-10-24 1:41 ` Christoph Hellwig
2019-10-24 11:17 ` Matthew Bobrowski
2019-10-21 9:18 ` [PATCH v5 06/12] xfs: Use iomap_dio_rw_wait() mbobrowski
2019-10-21 13:38 ` Jan Kara
2019-10-21 9:18 ` [PATCH v5 07/12] ext4: introduce direct I/O read using iomap infrastructure Matthew Bobrowski
2019-10-21 13:41 ` Jan Kara
2019-10-22 1:58 ` Matthew Bobrowski
2019-10-23 6:40 ` Ritesh Harjani
2019-10-21 9:18 ` [PATCH v5 08/12] ext4: update direct I/O read to do trylock in IOCB_NOWAIT cases Matthew Bobrowski
2019-10-21 13:48 ` Jan Kara
2019-10-22 2:04 ` Matthew Bobrowski
2019-10-22 7:50 ` Jan Kara
2019-10-23 6:51 ` Ritesh Harjani
2019-10-21 9:18 ` [PATCH v5 09/12] ext4: move inode extension/truncate code out from ->iomap_end() callback Matthew Bobrowski
2019-10-21 13:53 ` Jan Kara
2019-10-22 2:07 ` Matthew Bobrowski
2019-10-21 9:20 ` [PATCH v5 12/12] ext4: introduce direct I/O write using iomap infrastructure Matthew Bobrowski
2019-10-21 16:18 ` Jan Kara
2019-10-22 3:02 ` Matthew Bobrowski
2019-10-22 7:55 ` Jan Kara
2019-10-21 9:20 ` [PATCH v5 11/12] ext4: reorder map->m_flags checks in ext4_set_iomap() Matthew Bobrowski
2019-10-21 9:20 ` [PATCH v5 10/12] ext4: move inode extension check out from ext4_iomap_alloc() Matthew Bobrowski
2019-10-21 13:31 ` [PATCH v5 00/12] ext4: port direct I/O to iomap infrastructure Theodore Y. Ts'o
2019-10-21 19:43 ` Jan Kara
2019-10-21 22:38 ` Dave Chinner
2019-10-22 8:01 ` Jan Kara
2019-10-23 2:35 ` Matthew Bobrowski [this message]
2019-10-23 10:01 ` Jan Kara
2019-10-23 10:11 ` Matthew Bobrowski
2019-10-24 1:58 ` Christoph Hellwig
2019-10-24 11:09 ` Matthew Bobrowski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191023023519.GA16505@bobrowski \
--to=mbobrowski@mbobrowski.org \
--cc=adilger.kernel@dilger.ca \
--cc=darrick.wong@oracle.com \
--cc=david@fromorbit.com \
--cc=hch@infradead.org \
--cc=jack@suse.cz \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.