[dm-devel] Re: DM configuration
Kiyoshi Ueda
k-ueda at ct.jp.nec.com
Wed Oct 12 00:17:45 UTC 2005
Hi Christophe,
Thank you for your comments.
On Fri, 07 Oct 2005 22:54:09 +0200, Christophe Varoqui <christophe.varoqui at free.fr> wrote:
> > This patch adds 'no_path_retry' option to multipathd.
> >
> > o no_path_retry = "fail" is equal to 'fail_if_no_path'.
> > (i.e. I/O to the no-path map will immediately fail.)
> >
> > o no_path_retry = "queue" is equal to 'queue_if_no_path'.
> > (i.e. I/O to the no-path map will be queued until any path comes up.)
> >
> > o If no_path_retry = <n> where n is positive number,
> > then multipathd will set queue_if_no_path to the map,
> > and if the all paths are down, multipathd will turn the feature
> > off to fail_if_no_path after the checker tries <n> times for each
> > paths in the map.
> >
> > Multipathd re-writes queue_if_no_path feature parameter in the map,
> > if this option is specified. But by default, this patch doesn't
> > change current multipathd behaviour.
> > So this patch don't break any existing configuration.
> >
> Interesting. Is this patched reviewed (besides me) and agreed on ?
> Does the "no_path_retry" option name raise consensus ?
The patch has gotten internal review only.
I hope to get further review from people in dm-devel including
the naming of the option.
> > # Multipathd has "features" option, with which user can directly specify
> > # a feature parameter of the table (e.g. features="1 queue_if_no_path").
> > # However, no_path_retry could be considered as smarter replacement for it.
> >
> I have no objection phasing out the "features" option, in favor of a
> more "deterministic" solution. If you care to submit a patch.
OK.
I extended the scope of the "no_path_retry" option to the multipath
command so that we can phase out the "features" option, because
the multipath command also sees the "features" option.
And fixed some bugs of the patch.
o Initialization issue of retry_tick.
o Missing status update of retry_tick in waiteventloop and reconfigure.
The new patch is below.
This patch doesn't change current behavior of multipath command by default.
The "no_path_option" option overrides the "features" option.
diff -rup git/libmultipath/config.h retry/libmultipath/config.h
--- git/libmultipath/config.h 2005-09-28 12:32:02.000000000 -0400
+++ retry/libmultipath/config.h 2005-10-10 10:41:27.000000000 -0400
@@ -33,6 +33,7 @@ struct mpentry {
int pgpolicy;
int pgfailback;
int rr_weight;
+ int no_path_retry;
char * wwid;
char * selector;
@@ -56,6 +57,7 @@ struct config {
int pgfailback;
int remove;
int rr_weight;
+ int no_path_retry;
char * dev;
char * udev_dir;
diff -rup git/libmultipath/devmapper.c retry/libmultipath/devmapper.c
--- git/libmultipath/devmapper.c 2005-10-04 12:20:03.000000000 -0400
+++ retry/libmultipath/devmapper.c 2005-10-10 12:04:24.000000000 -0400
@@ -490,6 +490,41 @@ out:
return r;
}
+int
+dm_queue_if_no_path(char *mapname, int enable)
+{
+ int r = 1;
+ struct dm_task *dmt;
+ char *str;
+
+ if (enable)
+ str = "queue_if_no_path\n";
+ else
+ str = "fail_if_no_path\n";
+
+ if (!(dmt = dm_task_create(DM_DEVICE_TARGET_MSG)))
+ return 1;
+
+ if (!dm_task_set_name(dmt, mapname))
+ goto out;
+
+ if (!dm_task_set_sector(dmt, 0))
+ goto out;
+
+ if (!dm_task_set_message(dmt, str))
+ goto out;
+
+ dm_task_no_open_count(dmt);
+
+ if (!dm_task_run(dmt))
+ goto out;
+
+ r = 0;
+out:
+ dm_task_destroy(dmt);
+ return r;
+}
+
static int
dm_groupmsg (char * msg, char * mapname, int index)
{
diff -rup git/libmultipath/devmapper.h retry/libmultipath/devmapper.h
--- git/libmultipath/devmapper.h 2005-09-30 14:13:49.000000000 -0400
+++ retry/libmultipath/devmapper.h 2005-10-05 18:39:58.000000000 -0400
@@ -10,6 +10,7 @@ int dm_flush_map (char *, char *);
int dm_flush_maps (char *);
int dm_fail_path(char * mapname, char * path);
int dm_reinstate(char * mapname, char * path);
+int dm_queue_if_no_path(char *mapname, int enable);
int dm_switchgroup(char * mapname, int index);
int dm_enablegroup(char * mapname, int index);
int dm_disablegroup(char * mapname, int index);
diff -rup git/libmultipath/dict.c retry/libmultipath/dict.c
--- git/libmultipath/dict.c 2005-09-28 12:32:02.000000000 -0400
+++ retry/libmultipath/dict.c 2005-10-10 10:52:18.000000000 -0400
@@ -171,6 +171,26 @@ default_failback_handler(vector strvec)
return 0;
}
+static int
+def_no_path_retry_handler(vector strvec)
+{
+ char * buff;
+
+ buff = set_value(strvec);
+ if (!buff)
+ return 1;
+
+ if (!strncmp(buff, "fail", 4) || !strncmp(buff, "0", 1))
+ conf->no_path_retry = NO_PATH_RETRY_FAIL;
+ else if (!strncmp(buff, "queue", 5))
+ conf->no_path_retry = NO_PATH_RETRY_QUEUE;
+ else if ((conf->no_path_retry = atoi(buff)) < 1)
+ conf->no_path_retry = NO_PATH_RETRY_UNDEF;
+
+ FREE(buff);
+ return 0;
+}
+
/*
* blacklist block handlers
*/
@@ -579,6 +599,30 @@ mp_weight_handler(vector strvec)
return 0;
}
+static int
+mp_no_path_retry_handler(vector strvec)
+{
+ struct mpentry *mpe = VECTOR_LAST_SLOT(conf->mptable);
+ char *buff;
+
+ if (!mpe)
+ return 1;
+
+ buff = set_value(strvec);
+ if (!buff)
+ return 1;
+
+ if (!strncmp(buff, "fail", 4) || !strncmp(buff, "0", 1))
+ mpe->no_path_retry = NO_PATH_RETRY_FAIL;
+ else if (!strncmp(buff, "queue", 5))
+ mpe->no_path_retry = NO_PATH_RETRY_QUEUE;
+ else if ((mpe->no_path_retry = atoi(buff)) < 1)
+ mpe->no_path_retry = NO_PATH_RETRY_UNDEF;
+
+ FREE(buff);
+ return 0;
+}
+
vector
init_keywords(void)
{
@@ -596,6 +640,7 @@ init_keywords(void)
install_keyword("failback", &default_failback_handler);
install_keyword("rr_min_io", &def_minio_handler);
install_keyword("rr_weight", &def_weight_handler);
+ install_keyword("no_path_retry", &def_no_path_retry_handler);
install_keyword_root("devnode_blacklist", &blacklist_handler);
install_keyword("devnode", &ble_handler);
@@ -626,6 +671,7 @@ init_keywords(void)
install_keyword("path_selector", &mp_selector_handler);
install_keyword("failback", &mp_failback_handler);
install_keyword("rr_weight", &mp_weight_handler);
+ install_keyword("no_path_retry", &mp_no_path_retry_handler);
install_sublevel_end();
return keywords;
diff -rup git/libmultipath/propsel.c retry/libmultipath/propsel.c
--- git/libmultipath/propsel.c 2005-09-28 12:32:02.000000000 -0400
+++ retry/libmultipath/propsel.c 2005-10-10 10:52:42.000000000 -0400
@@ -201,3 +201,22 @@ select_getprio (struct path * pp)
return 0;
}
+extern int
+select_no_path_retry(struct multipath *mp)
+{
+ if (mp->mpe && mp->mpe->no_path_retry != NO_PATH_RETRY_UNDEF) {
+ mp->no_path_retry = mp->mpe->no_path_retry;
+ condlog(3, "no_path_retry = %i (controler setting)",
+ mp->no_path_retry);
+ return 0;
+ }
+ if (conf->no_path_retry != NO_PATH_RETRY_UNDEF) {
+ mp->no_path_retry = conf->no_path_retry;
+ condlog(3, "no_path_retry = %i (config file default)",
+ mp->no_path_retry);
+ return 0;
+ }
+ mp->no_path_retry = NO_PATH_RETRY_UNDEF;
+ condlog(3, "no_path_retry = NONE (internal default)");
+ return 0;
+}
diff -rup git/libmultipath/propsel.h retry/libmultipath/propsel.h
--- git/libmultipath/propsel.h 2005-08-29 09:41:06.000000000 -0400
+++ retry/libmultipath/propsel.h 2005-10-05 18:46:21.000000000 -0400
@@ -8,4 +8,4 @@ int select_hwhandler (struct multipath *
int select_checkfn(struct path *pp);
int select_getuid (struct path * pp);
int select_getprio (struct path * pp);
-
+int select_no_path_retry(struct multipath *mp);
diff -rup git/libmultipath/structs.h retry/libmultipath/structs.h
--- git/libmultipath/structs.h 2005-10-04 12:20:03.000000000 -0400
+++ retry/libmultipath/structs.h 2005-10-05 18:51:01.000000000 -0400
@@ -14,6 +14,10 @@
#define SCSI_PRODUCT_SIZE 17
#define SCSI_REV_SIZE 5
+#define NO_PATH_RETRY_UNDEF 0
+#define NO_PATH_RETRY_FAIL -1
+#define NO_PATH_RETRY_QUEUE -2
+
enum free_path_switch {
KEEP_PATHS,
FREE_PATHS
@@ -115,6 +119,9 @@ struct multipath {
int pgfailback;
int failback_tick;
int rr_weight;
+ int nr_active; /* current available(= not known as failed) paths */
+ int no_path_retry; /* number of retries after all paths are down */
+ int retry_tick; /* remaining times for retries */
unsigned long long size;
vector paths;
vector pg;
diff -rup git/multipath/main.c retry/multipath/main.c
--- git/multipath/main.c 2005-10-04 12:20:03.000000000 -0400
+++ retry/multipath/main.c 2005-10-11 19:09:33.000000000 -0400
@@ -393,6 +393,7 @@ setup_map (struct multipath * mpp)
select_features(mpp);
select_hwhandler(mpp);
select_rr_weight(mpp);
+ select_no_path_retry(mpp);
/*
* apply selected grouping policy to valid paths
@@ -577,6 +578,12 @@ reinstate_paths (struct multipath * mpp)
return 0;
}
+/*
+ * Return value:
+ * 0: DM_DEVICE_CREATE or DM_DEVICE_RELOAD failed, or dry_run mode.
+ * 1: DM_DEVICE_CREATE or DM_DEVICE_RELOAD succeeded.
+ * 2: Map is already existing.
+ */
static int
domap (struct multipath * mpp)
{
@@ -592,7 +599,7 @@ domap (struct multipath * mpp)
switch (mpp->action) {
case ACT_NOTHING:
- return 0;
+ return 2;
case ACT_SWITCHPG:
dm_switchgroup(mpp->alias, mpp->nextpg);
@@ -602,7 +609,7 @@ domap (struct multipath * mpp)
* retry.
*/
reinstate_paths(mpp);
- return 0;
+ return 2;
case ACT_CREATE:
r = dm_addmap(DM_DEVICE_CREATE, mpp->alias, DEFAULT_TARGET,
@@ -726,7 +733,12 @@ coalesce_paths (vector curmp, vector pat
condlog(3, "action set to %i", mpp->action);
- domap(mpp);
+ if (domap(mpp) && mpp->no_path_retry != NO_PATH_RETRY_UNDEF) {
+ if (mpp->no_path_retry == NO_PATH_RETRY_FAIL)
+ dm_queue_if_no_path(mpp->alias, 0);
+ else
+ dm_queue_if_no_path(mpp->alias, 1);
+ }
drop_multipath(curmp, mpp->wwid, KEEP_PATHS);
free_multipath(mpp, KEEP_PATHS);
}
diff -rup git/multipath.conf.annotated retry/multipath.conf.annotated
--- git/multipath.conf.annotated 2005-09-28 12:32:02.000000000 -0400
+++ retry/multipath.conf.annotated 2005-10-10 10:55:58.000000000 -0400
@@ -99,6 +99,17 @@
# # default : immediate
# #
# failback manual
+#
+# #
+# # name : no_path_retry
+# # scope : multipath & multipathd
+# # desc : tell the number of retries until disable queueing, or
+# # "fail" means immediate failure (no queueing),
+# # "queue" means never stop queueing
+# # values : queue|fail|n (>0)
+# # default : (null)
+# #
+# #no_path_retry queue
#}
#
##
@@ -177,6 +188,17 @@
# # default : immediate
# #
# failback manual
+#
+# #
+# # name : no_path_retry
+# # scope : multipath & multipathd
+# # desc : tell the number of retries until disable queueing, or
+# # "fail" means immediate failure (no queueing),
+# # "queue" means never stop queueing
+# # values : queue|fail|n (>0)
+# # default : (null)
+# #
+# #no_path_retry queue
# }
# multipath {
# wwid 1DEC_____321816758474
diff -rup git/multipathd/main.c retry/multipathd/main.c
--- git/multipathd/main.c 2005-09-28 12:32:02.000000000 -0400
+++ retry/multipathd/main.c 2005-10-11 19:39:39.000000000 -0400
@@ -209,6 +209,85 @@ set_multipath_wwid (struct multipath * m
}
static int
+pathcount (struct multipath *mpp, int state)
+{
+ struct pathgroup *pgp;
+ struct path *pp;
+ int i, j;
+ int count = 0;
+
+ vector_foreach_slot (mpp->pg, pgp, i)
+ vector_foreach_slot (pgp->paths, pp, j)
+ if (pp->state == state)
+ count++;
+ return count;
+}
+
+/*
+ * mpp->no_path_retry:
+ * -2 (QUEUE) : queue_if_no_path enabled, never turned off
+ * -1 (FAIL) : fail_if_no_path
+ * 0 (UNDEF) : nothing
+ * >0 : queue_if_no_path enabled, turned off after polling n times
+ */
+static void
+update_queue_mode_del_path(struct multipath *mpp)
+{
+ if (--mpp->nr_active == 0 && mpp->no_path_retry > 0) {
+ /*
+ * Enter retry mode.
+ * meaning of +1: retry_tick may be decremented in
+ * checkerloop before starting retry.
+ */
+ mpp->retry_tick = mpp->no_path_retry * conf->checkint + 1;
+ condlog(1, "%s: Entering recovery mode: max_retries=%d",
+ mpp->alias, mpp->no_path_retry);
+ }
+ condlog(2, "%s: remaining active paths: %d", mpp->alias, mpp->nr_active);
+}
+
+static void
+update_queue_mode_add_path(struct multipath *mpp)
+{
+ if (mpp->nr_active++ == 0 && mpp->no_path_retry > 0) {
+ /* come back to normal mode from retry mode */
+ mpp->retry_tick = 0;
+ dm_queue_if_no_path(mpp->alias, 1);
+ condlog(2, "%s: queue_if_no_path enabled", mpp->alias);
+ condlog(1, "%s: Recovered to normal mode", mpp->alias);
+ }
+ condlog(2, "%s: remaining active paths: %d", mpp->alias, mpp->nr_active);
+}
+
+static void
+set_no_path_retry(struct multipath *mpp)
+{
+ mpp->retry_tick = 0;
+ mpp->nr_active = pathcount(mpp, PATH_UP);
+ select_no_path_retry(mpp);
+
+ switch (mpp->no_path_retry) {
+ case NO_PATH_RETRY_UNDEF:
+ break;
+ case NO_PATH_RETRY_FAIL:
+ dm_queue_if_no_path(mpp->alias, 0);
+ break;
+ case NO_PATH_RETRY_QUEUE:
+ dm_queue_if_no_path(mpp->alias, 1);
+ break;
+ default:
+ dm_queue_if_no_path(mpp->alias, 1);
+ if (mpp->nr_active == 0) {
+ /* Enter retry mode */
+ mpp->retry_tick = mpp->no_path_retry * conf->checkint;
+ condlog(1, "%s: Entering recovery mode: max_retries=%d",
+ mpp->alias, mpp->no_path_retry);
+ }
+ break;
+ }
+}
+
+static int
setup_multipath (struct vectors * vecs, struct multipath * mpp)
{
int i;
@@ -222,6 +301,7 @@ setup_multipath (struct vectors * vecs,
set_paths_owner(vecs, mpp);
select_pgfailback(mpp);
+ set_no_path_retry(mpp);
return 0;
out:
@@ -308,6 +388,7 @@ update_multipath (struct vectors *vecs,
if (pp->state != PATH_DOWN) {
condlog(2, "%s: mark as failed", pp->dev_t);
pp->state = PATH_DOWN;
+ update_queue_mode_del_path(pp->mpp);
/*
* if opportune,
@@ -690,6 +771,10 @@ uev_remove_path (char * devname, struct
condlog(3, "%s: not in pathvec");
return 1;
}
+
+ if (pp->mpp && pp->state == PATH_UP)
+ update_queue_mode_del_path(pp->mpp);
+
condlog(2, "remove %s path checker", devname);
i = find_slot(vecs->pathvec, (void *)pp);
vector_del_slot(vecs->pathvec, i);
@@ -817,6 +902,7 @@ reconfigure (struct vectors * vecs)
vector_foreach_slot (vecs->mpvec, mpp, i) {
mpp->mpe = find_mpe(mpp->wwid);
set_paths_owner(vecs, mpp);
+ set_no_path_retry(mpp);
}
vector_foreach_slot (vecs->pathvec, pp, i) {
select_checkfn(pp);
@@ -983,6 +1069,7 @@ fail_path (struct path * pp)
pp->dev_t, pp->mpp->alias);
dm_fail_path(pp->mpp->alias, pp->dev_t);
+ update_queue_mode_del_path(pp->mpp);
}
/*
@@ -991,11 +1078,14 @@ fail_path (struct path * pp)
static void
reinstate_path (struct path * pp)
{
- if (pp->mpp) {
- if (dm_reinstate(pp->mpp->alias, pp->dev_t))
- condlog(0, "%s: reinstate failed", pp->dev_t);
- else
- condlog(2, "%s: reinstated", pp->dev_t);
+ if (!pp->mpp)
+ return;
+
+ if (dm_reinstate(pp->mpp->alias, pp->dev_t))
+ condlog(0, "%s: reinstate failed", pp->dev_t);
+ else {
+ condlog(2, "%s: reinstated", pp->dev_t);
+ update_queue_mode_add_path(pp->mpp);
}
}
@@ -1056,6 +1146,23 @@ defered_failback_tick (vector mpvec)
}
}
+static void
+retry_count_tick(vector mpvec)
+{
+ struct multipath *mpp;
+ int i;
+
+ vector_foreach_slot (mpvec, mpp, i) {
+ if (mpp->retry_tick) {
+ condlog(4, "%s: Retrying.. No active path", mpp->alias);
+ if(--mpp->retry_tick == 0) {
+ dm_queue_if_no_path(mpp->alias, 0);
+ condlog(2, "%s: Disable queueing", mpp->alias);
+ }
+ }
+ }
+}
+
static void *
checkerloop (void *ap)
{
@@ -1201,6 +1308,7 @@ checkerloop (void *ap)
}
}
defered_failback_tick(vecs->mpvec);
+ retry_count_tick(vecs->mpvec);
if (count)
count--;
Regards,
Kiyoshi Ueda
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