From: Jan Kara <jack@suse.cz>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Jan Kara <jack@suse.cz>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Lino Sanfilippo <LinoSanfilippo@gmx.de>,
Miklos Szeredi <miklos@szeredi.hu>,
Paul Moore <paul@paul-moore.com>
Subject: Re: [PATCH 12/22] fsnotify: Move queueing of mark for destruction into fsnotify_put_mark()
Date: Wed, 4 Jan 2017 13:22:30 +0100 [thread overview]
Message-ID: <20170104122230.GR3780@quack2.suse.cz> (raw)
In-Reply-To: <20170104102821.GM3780@quack2.suse.cz>
On Wed 04-01-17 11:28:21, Jan Kara wrote:
> On Mon 26-12-16 16:15:23, Amir Goldstein wrote:
> > On Thu, Dec 22, 2016 at 11:15 AM, Jan Kara <jack@suse.cz> wrote:
> > > Currently we queue mark into a list of marks for destruction in
> > > __fsnotify_free_mark() and keep last mark reference dangling. After the
> > > worker waits for SRCU period, it drops the last reference to the mark
> > > which frees it. This scheme has the disadvantage that if we hold
> > > reference to mark and drop and reacquire SRCU lock, the mark can get
> > > freed immediately which is slightly inconvenient and we will need to
> > > avoid this in the future.
> > >
> > > Move to a scheme where queueing of mark into a list of marks for
> > > destruction happens when the last reference to the mark is dropped. Also
> > > drop reference to the mark held by group list already when mark is
> > > removed from that list instead of dropping it only from the destruction
> > > worker.
> > >
> >
> > The BEFORE section refers to what SRCU protects, which this patch
> > slightly changes. Can you please add to AFTER section, what is protected
> > by SRCU after this patch.
>
> Ah, the changelog is a victim of me reshuffling patches. It was written in
> a situation when mark reference did not protect from any list removal yet.
> I'll rewrite it. Thanks for noticing.
So in the end I've realized this patch needs to go before patch 10 for SRCU
guarantees to work - otherwise we could free mark under the hands of
process iterating inode list under SRCU after patch 10 and before this
patch. And then the changelog is correct. So I've just reshuffled these
patches.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2017-01-04 12:22 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-22 9:15 [PATCH 0/22] fsnotify: Avoid SRCU stalls with fanotify permission events Jan Kara
2016-12-22 9:15 ` [PATCH 01/22] fsnotify: Remove unnecessary tests when showing fdinfo Jan Kara
2016-12-22 12:59 ` Amir Goldstein
2016-12-22 15:16 ` Jan Kara
2016-12-22 15:54 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 02/22] inotify: Remove inode pointers from debug messages Jan Kara
2016-12-22 15:31 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 03/22] fanotify: Move recalculation of inode / vfsmount mask under mark_mutex Jan Kara
2016-12-22 16:27 ` Amir Goldstein
2016-12-22 17:31 ` Jan Kara
2016-12-22 19:08 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 04/22] fsnotify: Remove fsnotify_duplicate_mark() Jan Kara
2016-12-22 23:13 ` Paul Moore
2016-12-23 13:22 ` Jan Kara
2016-12-23 14:01 ` Paul Moore
2016-12-22 9:15 ` [PATCH 05/22] audit: Fix sleep in atomic Jan Kara
2016-12-22 23:18 ` Paul Moore
2016-12-23 13:24 ` Jan Kara
2016-12-23 14:17 ` Paul Moore
2016-12-26 16:33 ` Paul Moore
2017-01-02 18:21 ` Jan Kara
2017-01-03 21:11 ` Paul Moore
2017-01-03 21:11 ` Paul Moore
2017-01-04 8:50 ` Jan Kara
2017-01-05 2:14 ` Paul Moore
2016-12-22 9:15 ` [PATCH 06/22] audit: Abstract hash key handling Jan Kara
2016-12-22 23:27 ` Paul Moore
2016-12-23 13:27 ` Jan Kara
2016-12-23 14:13 ` Paul Moore
2017-01-03 17:34 ` Jan Kara
2017-01-05 2:06 ` Paul Moore
2016-12-22 9:15 ` [PATCH 07/22] fsnotify: Update comments Jan Kara
2016-12-23 4:45 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 08/22] fsnotify: Attach marks to object via dedicated head structure Jan Kara
2016-12-23 5:48 ` Amir Goldstein
2016-12-23 13:34 ` Jan Kara
2017-01-04 13:38 ` Jan Kara
2017-01-04 15:29 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 09/22] inotify: Do not drop mark reference under idr_lock Jan Kara
2016-12-23 8:04 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 10/22] fsnotify: Detach mark from object list when last reference is dropped Jan Kara
2016-12-23 10:51 ` Amir Goldstein
2016-12-23 13:42 ` Jan Kara
2016-12-22 9:15 ` [PATCH 11/22] fsnotify: Remove special handling of mark destruction on group shutdown Jan Kara
2016-12-23 12:12 ` Amir Goldstein
2016-12-23 13:31 ` Jan Kara
2016-12-22 9:15 ` [PATCH 12/22] fsnotify: Move queueing of mark for destruction into fsnotify_put_mark() Jan Kara
2016-12-26 14:15 ` Amir Goldstein
2017-01-04 10:28 ` Jan Kara
2017-01-04 12:22 ` Jan Kara [this message]
2016-12-22 9:15 ` [PATCH 13/22] fsnotify: Provide framework for dropping SRCU lock in ->handle_event Jan Kara
2016-12-26 15:01 ` Amir Goldstein
2016-12-26 15:11 ` Amir Goldstein
2017-01-04 9:03 ` Jan Kara
2017-01-04 10:50 ` Amir Goldstein
2017-01-04 11:45 ` Jan Kara
2016-12-26 18:37 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 14/22] fsnotify: Pass SRCU index into handle_event handler Jan Kara
2016-12-26 15:13 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 15/22] fanotify: Release SRCU lock when waiting for userspace response Jan Kara
2016-12-26 15:22 ` Amir Goldstein
2017-01-04 9:05 ` Jan Kara
2016-12-22 9:15 ` [PATCH 16/22] fsnotify: Remove fsnotify_set_mark_{,ignored_}mask_locked() Jan Kara
2016-12-26 16:42 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 17/22] fsnotify: Remove fsnotify_recalc_{inode|vfsmount}_mask() Jan Kara
2016-12-26 16:44 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 18/22] fsnotify: Inline fsnotify_clear_{inode|vfsmount|_mark_group() Jan Kara
2016-12-26 16:57 ` Amir Goldstein
2017-01-04 9:28 ` Jan Kara
2016-12-22 9:15 ` [PATCH 19/22] fsnotify: Remove fsnotify_find_{inode|vfsmount}_mark() Jan Kara
2016-12-26 17:14 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 20/22] fsnotify: Drop inode_mark.c Jan Kara
2016-12-26 17:15 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 21/22] fsnotify: Add group pointer in fsnotify_init_mark() Jan Kara
2016-12-26 17:34 ` Amir Goldstein
2016-12-22 9:15 ` [PATCH 22/22] fsnotify: Move ->free_mark callback to fsnotify_ops Jan Kara
2016-12-26 17:39 ` Amir Goldstein
2016-12-22 20:58 ` [PATCH 0/22] fsnotify: Avoid SRCU stalls with fanotify permission events Paul Moore
2016-12-22 21:05 ` Amir Goldstein
2016-12-22 23:04 ` Paul Moore
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