From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 1/2] vfs: Provide function to get superblock and wait
 for it to thaw
Date: Mon, 13 Feb 2012 15:24:18 +0100
Message-ID: <20120213142418.GA6478@quack.suse.cz>
References: <1328868181-16979-1-git-send-email-jack@suse.cz>
 <1328868181-16979-2-git-send-email-jack@suse.cz>
 <20120212211325.GT23916@ZenIV.linux.org.uk>
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Cc: Jan Kara <jack@suse.cz>, LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, Dave Chinner <david@fromorbit.com>,
	mpatocka@redhat.com, Eric Sandeen <sandeen@sandeen.net>
To: Al Viro <viro@ZenIV.linux.org.uk>
Return-path: <linux-kernel-owner@vger.kernel.org>
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On Sun 12-02-12 21:13:25, Al Viro wrote:
> On Fri, Feb 10, 2012 at 11:03:00AM +0100, Jan Kara wrote:
> > In quota code we need to find a superblock corresponding to a device and wait
> > for superblock to be unfrozen. However this waiting has to happen without
> > s_umount semaphore because that is required for superblock to thaw. So provide
> > a function in VFS for this to keep dances with s_umount where they belong.
> 
> Eww...  All it takes is
> struct super_block *get_super_thawed(struct block_device *bdev)
> {
>         while (1) {
>                 struct super_block *s = get_super(bdev);
>                 if (!s || s->s_frozen == SB_UNFROZEN)
>                         return s;
> 		up_read(&s->s_umount);
> 		vfs_check_frozen(s, SB_FREEZE_WRITE);
> 		put_super(s);
>         }
> }
> and there's no need of extra arguments, etc. whatsoever.  Both patches
> applied, with implementation of get_super_thawed() done as above.
  Yeah, this looks better. Thanks!

									Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR