From: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
Tahsin Erdogan <tahsin-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>,
Jens Axboe <axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>,
Nauman Rafique <nauman-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Jan Kara <jack-IBi9RG/b67k@public.gmane.org>
Subject: Re: [PATCH block/for-linus] writeback: flush inode cgroup wb switches instead of pinning super_block
Date: Mon, 29 Feb 2016 22:21:19 +0100 [thread overview]
Message-ID: <20160229212119.GH6174@quack.suse.cz> (raw)
In-Reply-To: <20160229210800.GY3965-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
On Mon 29-02-16 16:08:00, Tejun Heo wrote:
> On Mon, Feb 29, 2016 at 09:06:15PM +0000, Al Viro wrote:
> > > Hmmm? The flushing is done after shrink_dcache_for_umount() and
> > > sync_filesystems(). Aren't inodes supposed to stay clean after that?
> >
> > s/shrink_dcache_for_umount/fsnotify_unmount_inodes/ - sorry.
>
> Is that allowed to dirty indoes and initiate writebacks again, after
> sync_filesystems() is done? That sounds weird but it's trivial to
> move cgroup_writeback_umount() below that if so.
Hardly, but generally it is true that filesystem may still dirty something
(e.g. from outstanding workqueue work, but most likely some special "system
inodes" may still become dirty) until ->put_super() is finished.
Anyway, to make this foolproof, I'd just avoid queueing any new switching
work after S_ACTIVE is cleared on the superblock and flush the workqueue just
before evict_inodes() call.
Honza
--
Jan Kara <jack-IBi9RG/b67k@public.gmane.org>
SUSE Labs, CR
WARNING: multiple messages have this Message-ID (diff)
From: Jan Kara <jack@suse.cz>
To: Tejun Heo <tj@kernel.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>,
Tahsin Erdogan <tahsin@google.com>, Jan Kara <jack@suse.cz>,
Jens Axboe <axboe@kernel.dk>,
cgroups@vger.kernel.org, "Theodore Ts'o" <tytso@mit.edu>,
Nauman Rafique <nauman@google.com>,
linux-kernel@vger.kernel.org, Jan Kara <jack@suse.com>
Subject: Re: [PATCH block/for-linus] writeback: flush inode cgroup wb switches instead of pinning super_block
Date: Mon, 29 Feb 2016 22:21:19 +0100 [thread overview]
Message-ID: <20160229212119.GH6174@quack.suse.cz> (raw)
In-Reply-To: <20160229210800.GY3965@htj.duckdns.org>
On Mon 29-02-16 16:08:00, Tejun Heo wrote:
> On Mon, Feb 29, 2016 at 09:06:15PM +0000, Al Viro wrote:
> > > Hmmm? The flushing is done after shrink_dcache_for_umount() and
> > > sync_filesystems(). Aren't inodes supposed to stay clean after that?
> >
> > s/shrink_dcache_for_umount/fsnotify_unmount_inodes/ - sorry.
>
> Is that allowed to dirty indoes and initiate writebacks again, after
> sync_filesystems() is done? That sounds weird but it's trivial to
> move cgroup_writeback_umount() below that if so.
Hardly, but generally it is true that filesystem may still dirty something
(e.g. from outstanding workqueue work, but most likely some special "system
inodes" may still become dirty) until ->put_super() is finished.
Anyway, to make this foolproof, I'd just avoid queueing any new switching
work after S_ACTIVE is cleared on the superblock and flush the workqueue just
before evict_inodes() call.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2016-02-29 21:21 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-12 19:32 [BUG] cgroup writeback crash Tahsin Erdogan
[not found] ` <CAAeU0aNCq7LGODvVGRU-oU_o-6enii5ey0p1c26D1ZzYwkDc5A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-02-15 21:00 ` Tejun Heo
[not found] ` <20160215210047.GN3965-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-02-16 7:56 ` Tahsin Erdogan
[not found] ` <CAAeU0aNAd1Ra6LXmWwq8row4MD_BpVHiSXOwHx07m86UWREvHw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-02-16 18:24 ` [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Tejun Heo
2016-02-16 18:24 ` Tejun Heo
[not found] ` <20160216182457.GO3741-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-02-16 18:34 ` Jens Axboe
2016-02-16 18:34 ` Jens Axboe
2016-02-17 20:57 ` Jan Kara
2016-02-17 20:57 ` Jan Kara
[not found] ` <20160217205721.GE14140-+0h/O2h83AeN3ZZ/Hiejyg@public.gmane.org>
2016-02-17 21:07 ` Tejun Heo
2016-02-17 21:07 ` Tejun Heo
2016-02-17 22:30 ` Jan Kara
2016-02-17 22:41 ` Tahsin Erdogan
[not found] ` <CAAeU0aOvSwPbLPU0=20D1RExNj8VsbB38hUnyso2L8xNSQC0XA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-02-17 23:02 ` Tejun Heo
2016-02-17 23:02 ` Tejun Heo
2016-02-18 9:55 ` Jan Kara
[not found] ` <20160218095538.GA4338-+0h/O2h83AeN3ZZ/Hiejyg@public.gmane.org>
2016-02-18 13:00 ` Tejun Heo
2016-02-18 13:00 ` Tejun Heo
2016-02-18 13:20 ` Jan Kara
2016-02-19 20:18 ` Al Viro
2016-02-19 20:51 ` Tejun Heo
[not found] ` <20160219205147.GN13177-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-02-19 21:58 ` Al Viro
2016-02-19 21:58 ` Al Viro
[not found] ` <20160219215811.GA17997-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2016-02-19 22:15 ` Tejun Heo
2016-02-19 22:15 ` Tejun Heo
2016-02-19 22:26 ` Al Viro
[not found] ` <20160219222609.GC17997-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2016-02-28 21:53 ` Tejun Heo
2016-02-28 21:53 ` Tejun Heo
[not found] ` <20160217230231.GC6479-qYNAdHglDFBN0TnZuCh8vA@public.gmane.org>
2016-02-29 20:47 ` [PATCH block/for-linus] writeback: flush inode cgroup wb switches instead of pinning super_block Tejun Heo
2016-02-29 20:47 ` Tejun Heo
[not found] ` <20160229204724.GV3965-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-02-29 20:54 ` Al Viro
2016-02-29 20:54 ` Al Viro
[not found] ` <20160229205428.GB17997-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2016-02-29 20:58 ` Tejun Heo
2016-02-29 20:58 ` Tejun Heo
[not found] ` <20160229205837.GX3965-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-02-29 21:06 ` Al Viro
2016-02-29 21:06 ` Al Viro
[not found] ` <20160229210614.GC17997-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2016-02-29 21:08 ` Tejun Heo
2016-02-29 21:08 ` Tejun Heo
[not found] ` <20160229210800.GY3965-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org>
2016-02-29 21:21 ` Jan Kara [this message]
2016-02-29 21:21 ` Jan Kara
2016-02-29 23:28 ` [PATCH v2 " Tejun Heo
2016-02-29 23:28 ` Tejun Heo
2016-03-01 9:20 ` Jan Kara
2016-03-01 17:46 ` Jens Axboe
[not found] ` <56D5D592.2020800-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>
2016-03-01 17:50 ` Tejun Heo
2016-03-01 17:50 ` Tejun Heo
[not found] ` <CAOS58YO5vTBnM561np7gpXKGQELrT169bYqmcfvAvsquBJK5yw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-02 10:29 ` Jan Kara
2016-03-02 10:29 ` Jan Kara
2016-03-01 13:39 ` [PATCH " Tahsin Erdogan
2016-02-18 10:12 ` [PATCH block/for-4.5-fixes] writeback: keep superblock pinned during cgroup writeback association switches Nikolay Borisov
2016-02-18 10:12 ` Nikolay Borisov
2016-02-18 12:57 ` Tejun Heo
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