From: Jan Kara <jack@suse.cz>
To: tytso@mit.edu
Cc: linux-fsdevel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: Lazytime feature bugs
Date: Tue, 24 Feb 2015 19:31:03 +0100 [thread overview]
Message-ID: <20150224183103.GA13024@quack.suse.cz> (raw)
In-Reply-To: <20150218131931.GA10424@quack.suse.cz>
Hello,
any reaction here?
Honza
On Wed 18-02-15 14:19:31, Jan Kara wrote:
> I had a look at what got merged as a lazytime series from Ted and I have
> found a couple of issues (I think I've pointed them out in my emails back
> in November but admittedly things were somewhat confused back then since
> Ted was submitting new versions pretty fast). Anyway here are the issues
> I've found in the merged code:
>
> 1) Inode that gets periodically dirtied with I_DIRTY_PAGES, cleaned and
> dirtied again will have inode with updated timestamps never written due
> to age since inode->dirtied_when gets reset on each redirtying with
> I_DIRTY_PAGES.
> 2) The code won't maintain time ordering of b_dirty_time list by
> inode->dirtied_when - this happens because requeue_inode() moves inode
> at the head of the b_dirty_time list but inodes in b_io list from which
> we move are no longer ordered by dirtied_when (due to that list being
> combined from several lists and also because we sort the list by
> superblock). As a result terminating logic in move_expired_inodes() may
> terminate the scan too early for b_dirty_time list.
> 3) This is mostly cosmetic currently but is a potential landmine for
> future: If you dirty with I_DIRTY_PAGES | I_DIRTY_TIME inode gets filed
> to b_dirty_time list instead of b_dirty list.
> 4) Another mostly cosmetic issue: move_expired_inodes() should use
> work->for_sync instead of work->reason == WB_REASON_SYNC (work->reason is
> there only for tracing purposes).
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2015-02-24 18:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-18 13:19 Lazytime feature bugs Jan Kara
2015-02-24 18:31 ` Jan Kara [this message]
2015-02-24 18:58 ` Linus Torvalds
2015-02-25 14:52 ` Theodore Ts'o
2015-02-25 16:25 ` Jan Kara
2015-02-26 4:33 ` Theodore Ts'o
2015-02-26 8:34 ` Jan Kara
2015-02-26 13:45 ` Theodore Ts'o
2015-02-26 14:38 ` Jan Kara
2015-02-26 19:27 ` Theodore Ts'o
2015-03-02 8:29 ` Jan Kara
2015-03-07 5:34 ` [PATCH] fs: make sure the timestamps for lazytime inodes eventually get written Theodore Ts'o
2015-03-08 10:06 ` Jan Kara
2015-03-08 19:06 ` Theodore Ts'o
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