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From: Jan Kara <jack@suse.cz>
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, rjw@rjwysocki.net, 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 03/11] fs: add frozen sb state helpers
Date: Thu, 30 Nov 2017 18:13:10 +0100
Message-ID: <20171130171310.GG28180@quack2.suse.cz> (raw)
In-Reply-To: <20171129232356.28296-4-mcgrof@kernel.org>

On Wed 29-11-17 15:23:48, Luis R. Rodriguez wrote:
> The question of whether or not a superblock is frozen needs to be
> augmented in the future to account for differences between a user
> initiated freeze and a kernel initiated freeze done automatically
> on behalf of the kernel.
> 
> Provide helpers so that these can be used instead so that we don't
> have to expand checks later in these same call sites as we expand
> the definition of a frozen superblock.
> 
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>

So helpers are fine but...

> +/**
> + * sb_is_frozen_by_user - is superblock frozen by a user call
> + * @sb: the super to check
> + *
> + * Returns true if the super freeze was initiated by userspace, for instance,
> + * an ioctl call.
> + */
> +static inline bool sb_is_frozen_by_user(struct super_block *sb)
> +{
> +	return sb->s_writers.frozen == SB_FREEZE_COMPLETE;
> +}

... I dislike the _by_user() suffix as there may be different places that
call freeze_super() (e.g. device mapper does this during some operations).
Clearly we need to distinguish "by system suspend" and "the other" cases.
So please make this clear in the naming.

In fact, what might be a cleaner solution is to introduce a 'freeze_count'
for superblock freezing (we already do have this for block devices). Then
you don't need to differentiate these two cases - but you'd still need to
properly handle cleanup if freezing of all superblocks fails in the middle.
So I'm not 100% this works out nicely in the end. But it's certainly worth
a consideration.

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-29 23:23 [PATCH 00/11] fs: use freeze_fs on suspend/hibernate 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 [this message]
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
2017-12-19 16:50   ` Luis R. Rodriguez

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