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md_make_request: don't touch the bio after calling make_request

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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.

Cc: <stable@kernel.org>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Chris Mason 2011-02-07 19:21:48 -05:00 committed by NeilBrown
parent c6751b2bde
commit e91ece5590
1 changed files with 7 additions and 2 deletions
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9
drivers/md/md.c
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@ -287,6 +287,7 @@ static int md_make_request(struct request_queue *q, struct bio *bio)
mddev_t *mddev = q->queuedata;
int rv;
int cpu;
unsigned int sectors;
if (mddev == NULL || mddev->pers == NULL
|| !mddev->ready) {
@ -311,12 +312,16 @@ static int md_make_request(struct request_queue *q, struct bio *bio)
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)