From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jan Kara <jack@suse.cz>
Cc: akpm@linux-foundation.org, fabf@skynet.be,
mm-commits@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: Elevated i_writecount doesn't guarantee ->release to be called
Date: Thu, 29 Jan 2015 17:35:33 +0000 [thread overview]
Message-ID: <20150129173532.GF29656@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20150129124630.GB11635@quack.suse.cz>
On Thu, Jan 29, 2015 at 01:46:30PM +0100, Jan Kara wrote:
> Thanks for pointing this out. You made me at look where exactly is
> get_write_access() called and there are even places where we call it
> without having file descriptor at all (e.g. truncate path). So ext3, ext4,
> udf, and gfs2 are racy. If we race, results aren't that bad (we just keep
> preallocated blocks in the inode) but still it would be nice to fix.
>
> Obviously we could maintain a private writecount in ->open() method but it
> would seem a bit sad to do that for this mostly theoretical issue. Maybe we
> just verify whether preallocation is truncated when evicting inode from
> memory and if not, do it there. It's not perfect but even with current racy
> solution noone noticed in practice.
The trouble with doing that on inode eviction is that we might have done
r/o remount by then, so any metadata writes are unexpected at that point...
next prev parent reply other threads:[~2015-01-29 17:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <54c95874.1pbbCloLAl3wWsPR%akpm@linux-foundation.org>
[not found] ` <20150128224534.GB29656@ZenIV.linux.org.uk>
2015-01-29 12:46 ` Elevated i_writecount doesn't guarantee ->release to be called Jan Kara
2015-01-29 16:47 ` Fabian Frederick
2015-01-29 16:57 ` Jan Kara
2015-01-29 17:35 ` Al Viro [this message]
2015-01-30 5:33 ` Fabian Frederick
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