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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: viro@zeniv.linux.org.uk, bart.vanassche@wdc.com,
	ming.lei@redhat.com, tytso@mit.edu, darrick.wong@oracle.com,
	jikos@kernel.org, pavel@ucw.cz, len.brown@intel.com,
	linux-fsdevel@vger.kernel.org, boris.ostrovsky@oracle.com,
	jgross@suse.com, todd.e.brandt@linux.intel.com,
	nborisov@suse.com, jack@suse.cz, martin.petersen@oracle.com,
	ONeukum@suse.com, oleksandr@natalenko.name,
	oleg.b.antonyan@gmail.com, yu.chen.surf@gmail.com,
	dan.j.williams@intel.com, linux-pm@vger.kernel.org,
	linux-block@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 00/11] fs: use freeze_fs on suspend/hibernate
Date: Wed, 13 Dec 2017 02:09:49 +0100
Message-ID: <7282138.2afjHhBgNp@aspire.rjw.lan> (raw)
In-Reply-To: <20171129232356.28296-1-mcgrof@kernel.org>

On Thursday, November 30, 2017 12:23:45 AM CET Luis R. Rodriguez wrote:
> This is a followup from the original RFC which proposed to start
> to kill kthread freezing all together [0]. Instead of going straight
> out to the jugular for kthread freezing this series only addresses
> killing freezer calls on filesystems which implement freeze_fs, after
> we let the kernel freeze these filesystems for us on suspend.
> 
> This approach puts on a slow but steady path towards the original goal
> though. Each subsystem could look for similar solutions. Even with
> filesystems we're not all done yet, after this we'll still have to
> decide what to do about filesystems which do not implement freeze_fs().
> 
> Motivation and problem:
> 
> kthreads have some semantics for freezing, which helps the kernel
> freeze them when a system is going to suspend or hibernation. These
> semantics are not well defined though, and it actually turns out
> pretty hard to get it right.
> 
> Without a proper solution suspend and hibernation are fragile on filesystems,
> it can easily break suspend and fixing such issues are in no way trivial [1]
> [2].
> 
> Proposed solution:
> 
> Instead of fixing such semantics and trying to get all filesystems to do it
> right, we can easily do away with all freezing calls if the filesystem
> implements a proper freeze_fs() callback. The following 9 filesystems have
> freeze_fs() implemented as such we can let the kernel issue the callback upon
> suspend and thaw on resume automatically on our behalf.
> 
>   o xfs
>   o reiserfs
>   o nilfs2
>   o jfs
>   o f2fs
>   o ext4
>   o ext2
>   o btrfs
> 
> Of these, the following have freezer helpers, which can then be removed
> after the kernel automaticaly calls freeze_fs for us on suspend:
> 
>   o xfs
>   o nilfs2
>   o jfs
>   o f2fs
>   o ext4
> 
> I've tested this on a system with ext4 and XFS, and have let 0-day go at
> without issues. I have branches availabe for linux-next [3] and Linus'
> latest tree [4].
> 
> Further testing, thoughts, reviews, flames are all equally appreciated.
> 
> [0] https://lkml.kernel.org/r/20171003185313.1017-1-mcgrof@kernel.org
> [1] https://bugzilla.suse.com/show_bug.cgi?id=1043449
> [2] https://lkml.kernel.org/r/20171113103139.GA18936@yu-chen.sh.intel.com
> [3] https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux-next.git/log/?h=20171129-fs-freeze-cleanup
> [4] https://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux.git/log/?h=20171129-fs-freeze-cleanup
> 
> Luis R. Rodriguez (11):
>   fs: provide unlocked helper for freeze_super()
>   fs: provide unlocked helper thaw_super()
>   fs: add frozen sb state helpers
>   fs: distinguish between user initiated freeze and kernel initiated
>     freeze
>   fs: add iterate_supers_excl() and iterate_supers_reverse_excl()
>   fs: freeze on suspend and thaw on resume
>   xfs: remove not needed freezing calls
>   ext4: remove not needed freezing calls
>   f2fs: remove not needed freezing calls
>   nilfs2: remove not needed freezing calls
>   jfs: remove not needed freezing calls
> 
>  fs/ext4/ext4_jbd2.c    |   2 +-
>  fs/ext4/super.c        |   2 -
>  fs/f2fs/gc.c           |   5 +-
>  fs/f2fs/segment.c      |   6 +-
>  fs/jfs/jfs_logmgr.c    |  11 +-
>  fs/jfs/jfs_txnmgr.c    |  31 ++---
>  fs/nilfs2/segment.c    |  48 ++++----
>  fs/super.c             | 320 ++++++++++++++++++++++++++++++++++++++++---------
>  fs/xfs/xfs_trans.c     |   2 +-
>  fs/xfs/xfs_trans_ail.c |   7 +-
>  include/linux/fs.h     |  63 +++++++++-
>  kernel/power/process.c |  15 ++-
>  12 files changed, 378 insertions(+), 134 deletions(-)
> 

I'm assuming an update of this to be posted due to the comments from Jan
on patch [3/11] and patch [7/11] probably.

Is there anything else that needs to be addressed?

Thanks,
Rafael

  parent reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-29 23:23 Luis R. Rodriguez
2017-11-29 23:23 ` [PATCH 01/11] fs: provide unlocked helper for freeze_super() Luis R. Rodriguez
2017-11-30 16:58   ` Jan Kara
2017-11-29 23:23 ` [PATCH 02/11] fs: provide unlocked helper thaw_super() Luis R. Rodriguez
2017-11-30 16:59   ` Jan Kara
2017-11-29 23:23 ` [PATCH 03/11] fs: add frozen sb state helpers Luis R. Rodriguez
2017-11-30 17:13   ` Jan Kara
2017-11-30 19:05     ` Luis R. Rodriguez
2017-12-01 11:47       ` Jan Kara
2017-12-01 21:13         ` Luis R. Rodriguez
2017-12-21 11:03           ` Jan Kara
2018-04-18  0:59             ` Luis R. Rodriguez
2018-04-18 10:12               ` Jan Kara
2018-04-20 18:49               ` Luis R. Rodriguez
2018-04-21 23:53                 ` Jan Kara
2018-04-22  1:22                   ` Luis R. Rodriguez
2018-04-22  2:53     ` Luis R. Rodriguez
2017-11-29 23:23 ` [PATCH 04/11] fs: distinguish between user initiated freeze and kernel initiated freeze Luis R. Rodriguez
2017-11-29 23:23 ` [PATCH 05/11] fs: add iterate_supers_excl() and iterate_supers_reverse_excl() Luis R. Rodriguez
2017-11-29 23:48   ` Rafael J. Wysocki
2017-11-30  0:22     ` Luis R. Rodriguez
2017-11-30  1:34     ` Dave Chinner
2017-11-30  1:40       ` Rafael J. Wysocki
2017-11-30 16:57   ` Jan Kara
2017-11-29 23:23 ` [PATCH 06/11] fs: freeze on suspend and thaw on resume Luis R. Rodriguez
2017-11-29 23:23 ` [PATCH 07/11] xfs: remove not needed freezing calls Luis R. Rodriguez
2017-11-30 16:21   ` Jan Kara
2017-11-30 20:32     ` Rafael J. Wysocki
2017-11-30 23:30       ` Dave Chinner
2017-11-30 23:40         ` Rafael J. Wysocki
2017-11-29 23:23 ` [PATCH 08/11] ext4: " Luis R. Rodriguez
2017-11-29 23:23 ` [PATCH 09/11] f2fs: " Luis R. Rodriguez
2017-11-29 23:23 ` [PATCH 10/11] nilfs2: " Luis R. Rodriguez
2017-11-29 23:23 ` [PATCH 11/11] jfs: " Luis R. Rodriguez
2017-11-30 16:36 ` [PATCH 00/11] fs: use freeze_fs on suspend/hibernate Yu Chen
2017-11-30 16:41   ` Jiri Kosina
2017-11-30 16:50     ` Yu Chen
2017-12-01 19:05     ` Jeff Layton
2017-12-01 21:51       ` Dave Chinner
2017-11-30 17:01 ` Bart Van Assche
2017-11-30 19:42   ` Luis R. Rodriguez
2017-11-30 20:53     ` Bart Van Assche
2017-11-30 21:03       ` Dave Chinner
2017-11-30 21:51 ` Pavel Machek
2017-12-01  0:44   ` Luis R. Rodriguez
2017-12-13  1:09 ` Rafael J. Wysocki [this message]
2017-12-19 16:50   ` Luis R. Rodriguez

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