Let dm-mpath fail requests if queue_if_no_path is enabled and
request flag REQ_FAIL_IF_NO_PATH has been set. This facility will
be used in the next patch to fix a deadlock between SCSI device
removal and sd event checking.
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
---
drivers/md/dm-mpath.c | 6 ++++--
include/linux/blk_types.h | 4 ++++
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 1c97f0e..9348151 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -539,6 +539,7 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
struct multipath *m = ti->private;
int r = DM_MAPIO_REQUEUE;
size_t nr_bytes = clone ? blk_rq_bytes(clone) : blk_rq_bytes(rq);
+ bool fail_if_no_path = (clone ? : rq)->cmd_flags & REQ_FAIL_IF_NO_PATH;
struct pgpath *pgpath;
struct block_device *bdev;
struct dm_mpath_io *mpio;
@@ -549,7 +550,7 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
pgpath = choose_pgpath(m, nr_bytes);
if (!pgpath) {
- if (must_push_back_rq(m))
+ if (!fail_if_no_path && must_push_back_rq(m))
return DM_MAPIO_DELAY_REQUEUE;
return -EIO; /* Failed */
} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
@@ -1567,6 +1568,7 @@ static int do_end_io(struct multipath *m, struct request *clone,
* clone bios for it and resubmit it later.
*/
int r = DM_ENDIO_REQUEUE;
+ bool fail_if_no_path = clone->cmd_flags & REQ_FAIL_IF_NO_PATH;
if (!error && !clone->errors)
return 0; /* I/O complete */
@@ -1579,7 +1581,7 @@ static int do_end_io(struct multipath *m, struct request *clone,
if (!atomic_read(&m->nr_valid_paths)) {
if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
- if (!must_push_back_rq(m))
+ if (fail_if_no_path || !must_push_back_rq(m))
r = -EIO;
}
}
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index cd395ec..9b25728 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -189,6 +189,9 @@ enum rq_flag_bits {
__REQ_PM, /* runtime pm request */
__REQ_HASHED, /* on IO scheduler merge hash */
__REQ_MQ_INFLIGHT, /* track inflight for MQ */
+
+ __REQ_FAIL_IF_NO_PATH, /* fail if queued on dm-mpath with no paths */
+
__REQ_NR_BITS, /* stops here */
};
@@ -235,6 +238,7 @@ enum rq_flag_bits {
#define REQ_PM (1ULL << __REQ_PM)
#define REQ_HASHED (1ULL << __REQ_HASHED)
#define REQ_MQ_INFLIGHT (1ULL << __REQ_MQ_INFLIGHT)
+#define REQ_FAIL_IF_NO_PATH (1ULL << __REQ_FAIL_IF_NO_PATH)
enum req_op {
REQ_OP_READ,
--
2.10.1
--
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