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Message-Id: <1277981359-10717-1-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Date:	Thu,  1 Jul 2010 19:49:16 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	axboe@...nel.dk
Cc:	snitzer@...hat.com, hch@....de, James.Bottomley@...e.de,
	linux-scsi@...r.kernel.org, dm-devel@...hat.com,
	fujita.tomonori@....ntt.co.jp, linux-kernel@...r.kernel.org

This patchset fixes page leak issue in discard commands with unprep
facility that James posted:

http://marc.info/?l=linux-scsi&m=127791727508214&w=2

The 1/3 patch adds unprep facility to the block layer (identical to
what James posted).

The 2/3 patch frees a page for discard commands by using the unprep
facility. James' original patch doesn't work since it accesses to
rq->bio in q->unprep_rq_fn. We hit oops since q->unprep_rq_fn is
called when all the data buffer (req->bio and scsi_data_buffer) in the
request is freed.

I use rq->buffer to keep track of an allocated page as the block layer
sets rq->buffer to the address of bio's page. scsi-ml (and llds) don't
use rq->buffer (rq->buffer is set to NULL). So I can't say that I like
it lots. Any other way to do that?

The 3/3 path just removes the dead code.

This is against Jens' for-2.6.36.

The git tree is also available:

git://git.kernel.org/pub/scm/linux/kernel/git/tomo/linux-2.6-misc.git unprep

I'll update the discard FS request conversion on the top of this soon. But this can be applied independently (and fixes the memory leak).

=
 block/blk-core.c        |   25 +++++++++++++++++++++++++
 block/blk-settings.c    |   17 +++++++++++++++++
 drivers/scsi/scsi_lib.c |    2 +-
 drivers/scsi/sd.c       |   25 +++++++++++++++----------
 include/linux/blkdev.h  |    4 ++++
 5 files changed, 62 insertions(+), 11 deletions(-)

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