[PATCH V5 5/7] ublk_drv: support UBLK_F_USER_RECOVERY_REISSUE

ZiyangZhang
2022-09-22T06:18:20Z

UBLK_F_USER_RECOVERY_REISSUE implies that:
With a dying ubq_daemon, ublk_drv let monitor_work requeues rq issued to
userspace(ublksrv) before the ubq_daemon is dying.

UBLK_F_USER_RECOVERY_REISSUE is designed for backends which:
(1) tolerate double-write since ublk_drv may issue the same rq
twice.
(2) does not let frontend users get I/O error, such as read-only FS
and VM backend.

Signed-off-by: ZiyangZhang <ZiyangZhang@linux.alibaba.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
---
drivers/block/ublk_drv.c | 22 ++++++++++++++++++----
include/uapi/linux/ublk_cmd.h | 2 ++
2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 888ad16c5dd8..3977869d2bc4 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -50,7 +50,8 @@
#define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY \
| UBLK_F_URING_CMD_COMP_IN_TASK \
| UBLK_F_NEED_GET_DATA \
- | UBLK_F_USER_RECOVERY)
+ | UBLK_F_USER_RECOVERY \
+ | UBLK_F_USER_RECOVERY_REISSUE)

/* All UBLK_PARAM_TYPE_* should be included here */
#define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD)
@@ -325,6 +326,15 @@ static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
PAGE_SIZE);
}

+static inline bool ublk_queue_can_use_recovery_reissue(
+ struct ublk_queue *ubq)
+{
+ if ((ubq->flags & UBLK_F_USER_RECOVERY) &&
+ (ubq->flags & UBLK_F_USER_RECOVERY_REISSUE))
+ return true;
+ return false;
+}
+
static inline bool ublk_queue_can_use_recovery(
struct ublk_queue *ubq)
{
@@ -629,13 +639,17 @@ static void ublk_complete_rq(struct request *req)
* Also aborting may not be started yet, keep in mind that one failed
* request may be issued by block layer again.
*/
-static void __ublk_fail_req(struct ublk_io *io, struct request *req)
+static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
+ struct request *req)
{
WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);

if (!(io->flags & UBLK_IO_FLAG_ABORTED)) {
io->flags |= UBLK_IO_FLAG_ABORTED;
- blk_mq_end_request(req, BLK_STS_IOERR);
+ if (ublk_queue_can_use_recovery_reissue(ubq))
+ blk_mq_requeue_request(req, false);
+ else
+ blk_mq_end_request(req, BLK_STS_IOERR);
}
}

@@ -973,7 +987,7 @@ static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
*/
rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);
if (rq)
- __ublk_fail_req(io, rq);
+ __ublk_fail_req(ubq, io, rq);
}
}
ublk_put_device(ub);
diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
index 340ff14bde49..332370628757 100644
--- a/include/uapi/linux/ublk_cmd.h
+++ b/include/uapi/linux/ublk_cmd.h
@@ -76,6 +76,8 @@

#define UBLK_F_USER_RECOVERY (1UL << 3)

+#define UBLK_F_USER_RECOVERY_REISSUE (1UL << 4)
+
/* device state */
#define UBLK_S_DEV_DEAD 0
#define UBLK_S_DEV_LIVE 1
--
2.27.0