[PATCH v4 03/10] scsi: core: Support failing requests while recovering

Bart Van Assche
2022-10-18T20:30:43Z

The current behavior for SCSI commands submitted while error recovery
is ongoing is to retry command submission after error recovery has
finished. See also the scsi_host_in_recovery() check in
scsi_host_queue_ready(). Add support for failing SCSI commands while
host recovery is in progress. This functionality will be used to fix a
deadlock in the UFS driver.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
drivers/scsi/scsi_lib.c | 8 +++++---
include/scsi/scsi_cmnd.h | 3 ++-
2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index fa96d3cfdfa3..ec890865abae 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1341,9 +1341,6 @@ static inline int scsi_host_queue_ready(struct request_queue *q,
struct scsi_device *sdev,
struct scsi_cmnd *cmd)
{
- if (scsi_host_in_recovery(shost))
- return 0;
-
if (atomic_read(&shost->host_blocked) > 0) {
if (scsi_host_busy(shost) > 0)
goto starved;
@@ -1732,6 +1729,11 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
ret = BLK_STS_RESOURCE;
if (!scsi_target_queue_ready(shost, sdev))
goto out_put_budget;
+ if (unlikely(scsi_host_in_recovery(shost))) {
+ if (cmd->flags & SCMD_FAIL_IF_RECOVERING)
+ ret = BLK_STS_OFFLINE;
+ goto out_dec_target_busy;
+ }
if (!scsi_host_queue_ready(q, shost, sdev, cmd))
goto out_dec_target_busy;

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 7d3622db38ed..c2cb5f69635c 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -52,8 +52,9 @@ struct scsi_pointer {
#define SCMD_TAGGED (1 << 0)
#define SCMD_INITIALIZED (1 << 1)
#define SCMD_LAST (1 << 2)
+#define SCMD_FAIL_IF_RECOVERING (1 << 4)
/* flags preserved across unprep / reprep */
-#define SCMD_PRESERVED_FLAGS (SCMD_INITIALIZED)
+#define SCMD_PRESERVED_FLAGS (SCMD_INITIALIZED | SCMD_FAIL_IF_RECOVERING)

/* for scmd->state */
#define SCMD_STATE_COMPLETE 0