Resubmitting the patch with 2 changes:
1. pg_init_delay_secs was used inconsistently (jiffies and seconds).
Fixed the problem
2. Moved the #define to dm_mpath.c from scsi_dh.h
-----------------------
From: Chandra Seetharaman <sekharan@xxxxxxxxxx>
SCSI Device Handlers return SCSI_DH_IMM_RETRY if we could retry
immediately and SCSI_DH_RETRY in cases where it is better to retry
after some delay.
Currently we retry immediately irrespective of SCSI_DH_IMM_RETRY and
SCSI_DH_RETRY. This patch adds a user configurable attribute
pg_init_delay_secs which specifies the number of seconds to delay
before retrying scsi_dh_activate, when it returned SCSI_DH_RETRY.
Default for this attribute is set to 2 seconds.
Signed-off-by: Nikanth Karthikesan <knikanth@xxxxxxx>
Signed-off-by: Chandra Seetharaman <sekharan@xxxxxxxxxx>
---
drivers/md/dm-mpath.c | 44 +++++++++++++++++++++++++++++++++++---------
1 file changed, 35 insertions(+), 9 deletions(-)
Index: linux-2.6.29/drivers/md/dm-mpath.c
===================================================================
--- linux-2.6.29.orig/drivers/md/dm-mpath.c
+++ linux-2.6.29/drivers/md/dm-mpath.c
@@ -24,6 +24,7 @@
#define DM_MSG_PREFIX "multipath"
#define MESG_STR(x) x, sizeof(x)
+#define DM_PG_INIT_RETRY_DELAY 2
/* Path properties */
struct pgpath {
@@ -35,7 +36,7 @@ struct pgpath {
struct dm_path path;
struct work_struct deactivate_path;
- struct work_struct activate_path;
+ struct delayed_work activate_path;
};
#define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
@@ -69,6 +70,7 @@ struct multipath {
struct list_head priority_groups;
unsigned pg_init_required; /* pg_init needs calling? */
unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
+ unsigned pg_init_delay; /* To delay or not to delay */
unsigned nr_valid_paths; /* Total number of usable paths */
struct pgpath *current_pgpath;
@@ -81,6 +83,7 @@ struct multipath {
unsigned saved_queue_if_no_path;/* Saved state during suspension */
unsigned pg_init_retries; /* Number of times to retry pg_init */
unsigned pg_init_count; /* Number of times pg_init called */
+ unsigned pg_init_delay_secs; /* Delay in seconds before retry */
struct work_struct process_queued_ios;
struct bio_list queued_ios;
@@ -127,7 +130,7 @@ static struct pgpath *alloc_pgpath(void)
if (pgpath) {
pgpath->is_active = 1;
INIT_WORK(&pgpath->deactivate_path, deactivate_path);
- INIT_WORK(&pgpath->activate_path, activate_path);
+ INIT_DELAYED_WORK(&pgpath->activate_path, activate_path);
}
return pgpath;
@@ -195,6 +198,7 @@ static struct multipath *alloc_multipath
INIT_LIST_HEAD(&m->priority_groups);
spin_lock_init(&m->lock);
m->queue_io = 1;
+ m->pg_init_delay_secs = DM_PG_INIT_RETRY_DELAY;
INIT_WORK(&m->process_queued_ios, process_queued_ios);
INIT_WORK(&m->trigger_event, trigger_event);
m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
@@ -443,9 +447,12 @@ static void process_queued_ios(struct wo
m->pg_init_count++;
m->pg_init_required = 0;
list_for_each_entry(tmp, &pgpath->pg->pgpaths, list) {
- queue_work(kmpath_handlerd, &tmp->activate_path);
+ queue_delayed_work(kmpath_handlerd, &tmp->activate_path,
+ m->pg_init_delay ?
+ m->pg_init_delay_secs * HZ : 0);
m->pg_init_in_progress++;
}
+ m->pg_init_delay = 0;
}
out:
spin_unlock_irqrestore(&m->lock, flags);
@@ -714,8 +721,9 @@ static int parse_features(struct arg_set
const char *param_name;
static struct param _params[] = {
- {0, 3, "invalid number of feature args"},
+ {0, 5, "invalid number of feature args"},
{1, 50, "pg_init_retries must be between 1 and 50"},
+ {1, 50, "pg_init_delay_secs must be between 1 and 50"},
};
r = read_param(_params, shift(as), &argc, &ti->error);
@@ -742,6 +750,14 @@ static int parse_features(struct arg_set
continue;
}
+ if (!strnicmp(param_name, MESG_STR("pg_init_delay_secs")) &&
+ (argc >= 1)) {
+ r = read_param(_params + 1, shift(as),
+ &m->pg_init_delay_secs, &ti->error);
+ argc--;
+ continue;
+ }
+
ti->error = "Unrecognised multipath feature request";
r = -EINVAL;
} while (argc && !r);
@@ -919,7 +935,7 @@ static int reinstate_path(struct pgpath
queue_work(kmultipathd, &m->process_queued_ios);
} else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
m->pg_init_in_progress++;
- queue_work(kmpath_handlerd, &pgpath->activate_path);
+ queue_delayed_work(kmpath_handlerd, &pgpath->activate_path, 0);
}
dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
@@ -1053,6 +1069,7 @@ static void pg_init_done(struct dm_path
struct priority_group *pg = pgpath->pg;
struct multipath *m = pg->m;
unsigned long flags;
+ unsigned int delay = 0;
/* device or driver problems */
switch (errors) {
@@ -1077,8 +1094,11 @@ static void pg_init_done(struct dm_path
*/
bypass_pg(m, pg, 1);
break;
- /* TODO: For SCSI_DH_RETRY we should wait a couple seconds */
+ /*
+ * For SCSI_DH_RETRY we wait before retrying.
+ */
case SCSI_DH_RETRY:
+ delay = 1;
case SCSI_DH_IMM_RETRY:
case SCSI_DH_RES_TEMP_UNAVAIL:
if (pg_init_limit_reached(m, pgpath))
@@ -1107,8 +1127,10 @@ static void pg_init_done(struct dm_path
}
m->pg_init_in_progress--;
- if (!m->pg_init_in_progress)
+ if (!m->pg_init_in_progress) {
+ m->pg_init_delay = delay;
queue_work(kmultipathd, &m->process_queued_ios);
+ }
spin_unlock_irqrestore(&m->lock, flags);
}
@@ -1116,7 +1138,7 @@ static void activate_path(struct work_st
{
int ret;
struct pgpath *pgpath =
- container_of(work, struct pgpath, activate_path);
+ container_of(work, struct pgpath, activate_path.work);
ret = scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev));
pg_init_done(&pgpath->path, ret);
@@ -1252,11 +1274,15 @@ 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 +
+ (m->pg_init_delay_secs !=
+ DM_PG_INIT_RETRY_DELAY) * 2);
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 (m->pg_init_delay_secs != DM_PG_INIT_RETRY_DELAY)
+ DMEMIT("pg_init_delay_secs %u ", m->pg_init_delay_secs);
}
if (!m->hw_handler_name || type == STATUSTYPE_INFO)
