zvol_os: fix compile with blk-mq on Linux 4.x

99741bde5 accesses a cached blk-mq hardware context through the mq_hctx
field of struct request. However, this field did not exist until 5.0.
Before that, the private function blk_mq_map_queue() was used to dig it
out of broader queue context. This commit detects this situation, and
handles it with a poor-man's simulation of that function.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Ameer Hamza <ahamza@ixsystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes #16069
This commit is contained in:
Rob N 2024-04-09 04:38:49 +10:00 committed by Tony Hutter
parent 5c0fe099ec
commit 3c5f354a8c
2 changed files with 20 additions and 0 deletions

View File

@ -377,6 +377,14 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_BLK_MQ], [
(void) blk_mq_alloc_tag_set(&tag_set);
return BLK_STS_OK;
], [])
ZFS_LINUX_TEST_SRC([blk_mq_rq_hctx], [
#include <linux/blk-mq.h>
#include <linux/blkdev.h>
], [
struct request rq = {0};
struct blk_mq_hw_ctx *hctx = NULL;
rq.mq_hctx = hctx;
], [])
])
AC_DEFUN([ZFS_AC_KERNEL_BLK_MQ], [
@ -384,6 +392,13 @@ AC_DEFUN([ZFS_AC_KERNEL_BLK_MQ], [
ZFS_LINUX_TEST_RESULT([blk_mq], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_MQ, 1, [block multiqueue is available])
AC_MSG_CHECKING([whether block multiqueue hardware context is cached in struct request])
ZFS_LINUX_TEST_RESULT([blk_mq_rq_hctx], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_BLK_MQ_RQ_HCTX, 1, [block multiqueue hardware context is cached in struct request])
], [
AC_MSG_RESULT(no)
])
], [
AC_MSG_RESULT(no)
])

View File

@ -551,7 +551,12 @@ zvol_request_impl(zvol_state_t *zv, struct bio *bio, struct request *rq,
uint_t taskq_hash;
#ifdef HAVE_BLK_MQ
if (rq)
#ifdef HAVE_BLK_MQ_RQ_HCTX
blk_mq_hw_queue = rq->mq_hctx->queue_num;
#else
blk_mq_hw_queue =
rq->q->queue_hw_ctx[rq->q->mq_map[rq->cpu]]->queue_num;
#endif
#endif
taskq_hash = cityhash4((uintptr_t)zv, offset >> ZVOL_TASKQ_OFFSET_SHIFT,
blk_mq_hw_queue, 0);