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From: Christoph Hellwig <hch@lst.de>
To: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Alexander Kolesen <kolesen.a@gmail.com>,
	jfs-discussion@lists.sourceforge.net,
	Jens Axboe <jaxboe@fusionio.com>,
	rjw@sisk.pl, viro@zeniv.linux.org.uk,
	linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [Jfs-discussion] Kernel oops when accessing to mounted, but unplugged JFS
Date: Tue, 23 Nov 2010 09:37:53 +0100	[thread overview]
Message-ID: <20101123083753.GA4808@lst.de> (raw)
In-Reply-To: <1290483673.3739.5.camel@shaggy-w500>

On Mon, Nov 22, 2010 at 09:41:13PM -0600, Dave Kleikamp wrote:
> I see three potential ways to fix this.
> 
> 1. bdi_prune_sb() could set sb->s_bdi to &default_backing_dev_info
> rather than NULL
> 2. inode_to_bdi() could return &default_backing_dev_info (or
> inode->i_mapping->backing_dev_info) if sb->s_bdi is NULL.
> 3. the callers of inode_to_bdi() could check for s_bdi being NULL and
> exit gracefully.
> 
> It seems that Jens and Christoph have ideas about cleaning up the bdi
> stuff, so this may be a short-term fix.

It's a mess.  The correct fix is to never unregister a bdi that still
has a life filesystem on it.  This seems to be solved by plain removing
the unlink_gendisk call in unlink_gendisk.  Unlink_gendisk just removes
the gendisk from visibility, but it still lives on as long as we have
references to it.  We already have a bdi_destroy call in
blk_release_queue that should unregister the BDI once it's reference
count finally reaches zero.


      reply	other threads:[~2010-11-23  8:38 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20101121122008.GE4024__36829.3162588545$1290342860$gmane$org@localhost>
2010-11-21 17:57 ` Kernel oops when accessing to mounted, but unplugged JFS Andi Kleen
2010-11-22 16:22   ` [Jfs-discussion] " Dave Kleikamp
2010-11-22 21:20     ` Alexander Kolesen
2010-11-23  3:41       ` Dave Kleikamp
2010-11-23  8:37         ` Christoph Hellwig [this message]

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