linux-kernel - Re: [PATCH] deadlock with suspend and quotas

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.64.1111290746230.10352@hs20-bc2-1.build.redhat.com>
Date:	Tue, 29 Nov 2011 07:54:28 -0500 (EST)
From:	Mikulas Patocka <mpatocka@...hat.com>
To:	Jan Kara <jack@...e.cz>
cc:	Valerie Aurora <val@...consulting.com>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	dm-devel@...hat.com,
	Christopher Chaltain <christopher.chaltain@...onical.com>,
	esandeen@...hat.com, Surbhi Palande <csurbhi@...il.com>
Subject: Re: [PATCH] deadlock with suspend and quotas

> > This is technically impossible to achieve on ext2, fat or other 
> > non-transactional filesystems. These filesystems have no locks around code 
> > paths that set data or inodes dirty. And you still need working sync for 
> > ext2. So the best thing to do in sync is to wait until the filesystem is 
> > unfrozen.
>   Then suspend is effectively unsupported on the filesystem and should
> return EOPNOTSUPP? At least that's what I'd expect...
> 
> 									Honza
> -- 
> Jan Kara <jack@...e.cz>
> SUSE Labs, CR

LVM uses suspend every time it changes layout of the logical volume. For 
example when it converts to/from mirrored format, extends/shrinks the 
volume, moves the volume to a different disk, takes a snapshots, merges a 
snapshot back, on mirror or multipath failover.

For most of these actions (except taking a snapshot) it is irrelevant if 
there are dirty data in the filesystem cache or not while it is suspended. 
So there is no point in banning suspend on ext2. If you banned it, you 
couldn't use ext2 on LVM at all.

Mikulas
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/