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blk-mq: enforce op-specific segment limits in blk_insert_cloned_request 

The block layer might merge together discard requests up until the
max_discard_segments limit is hit, but blk_insert_cloned_request checks
the segment count against max_segments regardless of the req op. This
can result in errors like the following when discards are issued through
a DM device and max_discard_segments exceeds max_segments for the queue
of the chosen underlying device.

blk_insert_cloned_request: over max segments limit. (256 > 129)

Fix this by looking at the req_op and enforcing the appropriate segment
limit - max_discard_segments for REQ_OP_DISCARDs and max_segments for
everything else.

Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230301000655.48112-1-ushankar@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Uday Shankar 2023-02-28 17:06:55 -07:00 committed by Jens Axboe
parent 326ac2c513
commit 49d2439832
3 changed files with 11 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
block/blk-merge.c
View File

@ -586,13 +586,6 @@ int __blk_rq_map_sg(struct request_queue *q, struct request *rq,
}
EXPORT_SYMBOL(__blk_rq_map_sg);
static inline unsigned int blk_rq_get_max_segments(struct request *rq)
{
if (req_op(rq) == REQ_OP_DISCARD)
return queue_max_discard_segments(rq->q);
return queue_max_segments(rq->q);
}
static inline unsigned int blk_rq_get_max_sectors(struct request *rq,
sector_t offset)
{

7
block/blk-mq.c
View File

@ -3000,6 +3000,7 @@ blk_status_t blk_insert_cloned_request(struct request *rq)
{
struct request_queue *q = rq->q;
unsigned int max_sectors = blk_queue_get_max_sectors(q, req_op(rq));
unsigned int max_segments = blk_rq_get_max_segments(rq);
blk_status_t ret;
if (blk_rq_sectors(rq) > max_sectors) {
@ -3026,9 +3027,9 @@ blk_status_t blk_insert_cloned_request(struct request *rq)
* original queue.
*/
rq->nr_phys_segments = blk_recalc_rq_segments(rq);
if (rq->nr_phys_segments > queue_max_segments(q)) {
printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n",
__func__, rq->nr_phys_segments, queue_max_segments(q));
if (rq->nr_phys_segments > max_segments) {
printk(KERN_ERR "%s: over max segments limit. (%u > %u)\n",
__func__, rq->nr_phys_segments, max_segments);
return BLK_STS_IOERR;
}

7
block/blk.h
View File

@ -156,6 +156,13 @@ static inline bool blk_discard_mergable(struct request *req)
return false;
}
static inline unsigned int blk_rq_get_max_segments(struct request *rq)
{
if (req_op(rq) == REQ_OP_DISCARD)
return queue_max_discard_segments(rq->q);
return queue_max_segments(rq->q);
}
static inline unsigned int blk_queue_get_max_sectors(struct request_queue *q,
enum req_op op)
{