md_make_request: don't touch the bio after calling make_request (e91ece55) · Commits · 戴 / test

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>

drivers/md/md.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -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)

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