This is a note to let you know that I've just added the patch titled
md_make_request: don't touch the bio after calling make_request
to the 2.6.36-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
md_make_request-don-t-touch-the-bio-after-calling-make_request.patch
and it can be found in the queue-2.6.36 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From e91ece5590b3c728624ab57043fc7a05069c604a Mon Sep 17 00:00:00 2001
From: Chris Mason <[email protected]>
Date: Mon, 7 Feb 2011 19:21:48 -0500
Subject: md_make_request: don't touch the bio after calling make_request
From: Chris Mason <[email protected]>
commit e91ece5590b3c728624ab57043fc7a05069c604a upstream.
md_make_request was calling bio_sectors() for part_stat_add
after it was calling the make_request function. This is
bad because the make_request function can free the bio and
because the bi_size field can change around.
The fix here was suggested by Jens Axboe. It saves the
sector count before the make_request call. I hit this
with CONFIG_DEBUG_PAGEALLOC turned on while trying to break
his pretty fusionio card.
Signed-off-by: Chris Mason <[email protected]>
Signed-off-by: NeilBrown <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/md/md.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -220,6 +220,7 @@ static int md_make_request(struct reques
mddev_t *mddev = q->queuedata;
int rv;
int cpu;
+ unsigned int sectors;
if (mddev == NULL || mddev->pers == NULL
|| !mddev->ready) {
@@ -244,12 +245,16 @@ static int md_make_request(struct reques
atomic_inc(&mddev->active_io);
rcu_read_unlock();
+ /*
+ * save the sectors now since our bio can
+ * go away inside make_request
+ */
+ sectors = bio_sectors(bio);
rv = mddev->pers->make_request(mddev, bio);
cpu = part_stat_lock();
part_stat_inc(cpu, &mddev->gendisk->part0, ios[rw]);
- part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw],
- bio_sectors(bio));
+ part_stat_add(cpu, &mddev->gendisk->part0, sectors[rw], sectors);
part_stat_unlock();
if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.36/md_make_request-don-t-touch-the-bio-after-calling-make_request.patch
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