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authorChris Mason <chris.mason@oracle.com>2011-02-07 19:21:48 -0500
committerNeilBrown <neilb@suse.de>2011-02-08 09:53:28 +1100
commite91ece5590b3c728624ab57043fc7a05069c604a (patch)
tree4c5fd4ad374caf5bd9c5f575b0a228b5cdf2f191
parentc6751b2bde477f56ceef67aa1d298ce44e8e2e23 (diff)
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: <stable@kernel.org> Signed-off-by: Chris Mason <chris.mason@oracle.com> Signed-off-by: NeilBrown <neilb@suse.de>
-rw-r--r--drivers/md/md.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1138d1053e9a..0cc30ecda4c1 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)