linux-kernel - Re: [PATCH 15/13] sysfs: Protect sysfs_refresh

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Date:	Sat, 07 Nov 2009 11:26:52 +0900
From:	Tejun Heo <tj@...nel.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Greg Kroah-Hartman <gregkh@...e.de>,
	Kay Sievers <kay.sievers@...y.org>, Greg KH <greg@...ah.com>,
	linux-kernel@...r.kernel.org,
	Cornelia Huck <cornelia.huck@...ibm.com>,
	linux-fsdevel@...r.kernel.org,
	Eric Dumazet <eric.dumazet@...il.com>,
	Benjamin LaHaise <bcrl@...et.ca>,
	Serge Hallyn <serue@...ibm.com>
Subject: Re: [PATCH 15/13] sysfs: Protect sysfs_refresh_inode with inode mutex.

Eric W. Biederman wrote:
> In general everything that writes to vfs inodes holds the
> inode mutex, so hold the inode mutex over sysfs_refresh_inode.
> The sysfs data structures don't need this but it looks like the
> vfs might.
> 
> Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>

Acked-by: Tejun Heo <tj@...nel.org>

Sidenote: Hmmm... Originally, sysfs completely depended on vfs locking
but with sysfs_dirent separation, the tree structure itself and some
attributes went under the protection of sysfs_mutex while leaving more
vfs oriented fields under vfs locking.  This patchset makes sysfs
lazier so it can't depend on any vfs layer locking.  I think you've
converted all necessary places while removing dependency on
dentry/inode from update operations but it might be a good idea to do
a audit pass over how fields are being protected now.

Thanks for your patience.

-- 
tejun
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