[dm-devel] [PATCH v3] dm mpath: add feature flag to control call to blk_abort_queue
Mike Snitzer
snitzer at redhat.com
Thu Nov 18 15:48:37 UTC 2010
Add 'features' member to 'struct multipath' and introduce
MPF_ABORT_QUEUE as the first feature flag. If "abort_queue_on_fail"
is provided during mpath device configuration the MPF_ABORT_QUEUE
feature flag will be set and blk_abort_queue() will be called during
path failure to allow for lower latency path failures.
But this feature has been disabled by default due to a race (between
blk_abort_queue and scsi_request_fn) that can lead to list corruption,
from: https://www.redhat.com/archives/dm-devel/2010-November/msg00085.html
"the cmd gets blk_abort_queued/timedout run on it and the scsi eh
somehow is able to complete and run scsi_queue_insert while
scsi_request_fn is still trying to process the request."
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
Cc: Mike Anderson <andmike at linux.vnet.ibm.com>
Cc: Mike Christie <michaelc at cs.wisc.edu>
---
drivers/md/dm-mpath.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
Index: linux-2.6/drivers/md/dm-mpath.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-mpath.c
+++ linux-2.6/drivers/md/dm-mpath.c
@@ -56,8 +56,14 @@ struct priority_group {
struct list_head pgpaths;
};
+/*
+ * Bits for the m->features
+ */
+#define MPF_ABORT_QUEUE 0
+
/* Multipath context */
struct multipath {
+ unsigned long features;
struct list_head list;
struct dm_target *ti;
@@ -146,7 +152,8 @@ static void deactivate_path(struct work_
struct pgpath *pgpath =
container_of(work, struct pgpath, deactivate_path);
- blk_abort_queue(pgpath->path.dev->bdev->bd_disk->queue);
+ if (test_bit(MPF_ABORT_QUEUE, &pgpath->pg->m->features))
+ blk_abort_queue(pgpath->path.dev->bdev->bd_disk->queue);
}
static struct priority_group *alloc_priority_group(void)
@@ -813,6 +820,11 @@ static int parse_features(struct arg_set
continue;
}
+ if (!strnicmp(param_name, MESG_STR("abort_queue_on_fail"))) {
+ set_bit(MPF_ABORT_QUEUE, &m->features);
+ continue;
+ }
+
if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
(argc >= 1)) {
r = read_param(_params + 1, shift(as),
@@ -1382,11 +1394,14 @@ static int multipath_status(struct dm_ta
DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count);
else {
DMEMIT("%u ", m->queue_if_no_path +
- (m->pg_init_retries > 0) * 2);
+ (m->pg_init_retries > 0) * 2 +
+ test_bit(MPF_ABORT_QUEUE, &m->features));
if (m->queue_if_no_path)
DMEMIT("queue_if_no_path ");
if (m->pg_init_retries)
DMEMIT("pg_init_retries %u ", m->pg_init_retries);
+ if (test_bit(MPF_ABORT_QUEUE, &m->features))
+ DMEMIT("abort_queue_on_fail ");
}
if (!m->hw_handler_name || type == STATUSTYPE_INFO)
@@ -1655,7 +1670,7 @@ out:
*---------------------------------------------------------------*/
static struct target_type multipath_target = {
.name = "multipath",
- .version = {1, 1, 1},
+ .version = {1, 2, 0},
.module = THIS_MODULE,
.ctr = multipath_ctr,
.dtr = multipath_dtr,
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