Hi,
When one request is dispatched to LLD via dm-rq, if the result is
BLK_STS_*RESOURCE, dm-rq will free the request. However, LLD may allocate
private data for this request, so this way will cause memory leak.
Add .cleanup_rq() callback and implement it in SCSI for fixing the issue,
since SCSI is the only driver which allocates private requst data in
.queue_rq() path.
Another use case of this callback is to free the request and re-submit
bios during cpu hotplug when the hctx is dead, see the following link:
https://lore.kernel.org/linux-block/f122e8f2-5ede-2d83-9ca0-bc713ce66d01@hu…
V2:
- run .cleanup_rq() in blk_mq_free_request(), as suggested by Mike
Ming Lei (2):
blk-mq: add callback of .cleanup_rq
scsi: implement .cleanup_rq callback
block/blk-mq.c | 3 +++
drivers/scsi/scsi_lib.c | 28 ++++++++++++++++++++--------
include/linux/blk-mq.h | 7 +++++++
3 files changed, 30 insertions(+), 8 deletions(-)
Cc: Ewan D. Milne <emilne(a)redhat.com>
Cc: Bart Van Assche <bvanassche(a)acm.org>
Cc: Hannes Reinecke <hare(a)suse.com>
Cc: Christoph Hellwig <hch(a)lst.de>
Cc: Mike Snitzer <snitzer(a)redhat.com>
Cc: dm-devel(a)redhat.com
Cc: <stable(a)vger.kernel.org>
Fixes: 396eaf21ee17 ("blk-mq: improve DM's blk-mq IO merging via blk_insert_cloned_request feedback")
--
2.20.1