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From: "Stephen C. Tweedie" <sct@redhat.com>
To: Zoltan Menyhart <Zoltan.Menyhart@bull.net>
Cc: Jan Kara <jack@suse.cz>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Stephen Tweedie <sct@redhat.com>
Subject: Re: [PATCH] Change ll_rw_block() calls in JBD
Date: Fri, 19 May 2006 16:05:27 +0100	[thread overview]
Message-ID: <1148051127.5156.28.camel@sisko.sctweedie.blueyonder.co.uk> (raw)
In-Reply-To: <446DBB31.6010101@bull.net>

Hi,

On Fri, 2006-05-19 at 14:33 +0200, Zoltan Menyhart wrote:

> >   For two of the above comments: Under memory pressure data buffers can
> > be written out earlier and then released by __journal_try_to_free_buffer()
> > as they are not dirty any more. The above checks protect us against this.
> 
> Assume "bh" has been set free in the mean time.
> Assume it is now used for another transaction (maybe for another file system).

I don't follow --- we already have a refcount to the bh, how can it be
reused?  We took the j_list_lock first, then looked up the jh on this
transaction's sync data list, then did the get_bh() without dropping
j_list_lock; so by the time we take the refcount, the j_list_lock
ensures it cannot have come off this transaction.  And subsequently, the
refcount prevents reuse.

--Stephen



  reply	other threads:[~2006-05-19 15:05 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-18  8:25 [PATCH] Change ll_rw_block() calls in JBD Zoltan Menyhart
2006-05-18 13:45 ` Jan Kara
2006-05-18 15:11   ` Zoltan Menyhart
2006-05-18 22:25     ` Stephen C. Tweedie
2006-05-19 10:01       ` Zoltan Menyhart
2006-05-19 12:26         ` Stephen C. Tweedie
2006-05-19  1:30     ` Jan Kara
2006-05-19 12:33       ` Zoltan Menyhart
2006-05-19 15:05         ` Stephen C. Tweedie [this message]
2006-05-19 15:06   ` Stephen C. Tweedie
2006-05-24 17:33     ` Jan Kara
2006-05-30 15:36       ` Zoltan Menyhart
2006-05-30 16:40         ` Jan Kara
2006-05-23 16:01   ` Zoltan Menyhart
2006-05-24  9:14   ` Zoltan Menyhart
2006-05-24 17:18     ` Jan Kara
     [not found]   ` <447F13B3.6050505@bull.net>
     [not found]     ` <20060601162751.GH26933@atrey.karlin.mff.cuni.cz>
     [not found]       ` <44801E16.3040300@bull.net>
     [not found]         ` <20060602134923.GA1644@atrey.karlin.mff.cuni.cz>
2006-06-20 16:33           ` Zoltan Menyhart
2006-06-21  0:09             ` Jan Kara
  -- strict thread matches above, loose matches on Subject: below --
2005-07-11 15:52 Jan Kara

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