md: make merge_bvec_fn more robust in face of personality changes.
There is no locking around calls to merge_bvec_fn(), so
it is possible that calls which coincide with a level (or personality)
change could go wrong.
So create a central dispatch point for these functions and use
rcu_read_lock().
If the array is suspended, reject any merge that can be rejected.
If not, we know it is safe to call the function.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 502a908..2d4a2cc 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4170,11 +4170,10 @@
/* We want read requests to align with chunks where possible,
* but write requests don't need to.
*/
-static int raid5_mergeable_bvec(struct request_queue *q,
+static int raid5_mergeable_bvec(struct mddev *mddev,
struct bvec_merge_data *bvm,
struct bio_vec *biovec)
{
- struct mddev *mddev = q->queuedata;
sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
int max;
unsigned int chunk_sectors = mddev->chunk_sectors;
@@ -6237,8 +6236,6 @@
if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
- blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
-
chunk_size = mddev->chunk_sectors << 9;
blk_queue_io_min(mddev->queue, chunk_size);
blk_queue_io_opt(mddev->queue, chunk_size *
@@ -7113,6 +7110,7 @@
.quiesce = raid5_quiesce,
.takeover = raid6_takeover,
.congested = raid5_congested,
+ .mergeable_bvec = raid5_mergeable_bvec,
};
static struct md_personality raid5_personality =
{
@@ -7136,6 +7134,7 @@
.quiesce = raid5_quiesce,
.takeover = raid5_takeover,
.congested = raid5_congested,
+ .mergeable_bvec = raid5_mergeable_bvec,
};
static struct md_personality raid4_personality =
@@ -7160,6 +7159,7 @@
.quiesce = raid5_quiesce,
.takeover = raid4_takeover,
.congested = raid5_congested,
+ .mergeable_bvec = raid5_mergeable_bvec,
};
static int __init raid5_init(void)