commit: e91ece5590b3c728624ab57043fc7a05069c604a From: Chris Mason <[email protected]> Date: Mon, 7 Feb 2011 19:21:48 -0500 Subject: [PATCH] md_make_request: don't touch the bio after calling make_request
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: <[email protected]> Signed-off-by: Chris Mason <[email protected]> Signed-off-by: NeilBrown <[email protected]> --- drivers/md/md.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 1138d10..0cc30ec 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -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) _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
