libmultipath: implement find_multipaths_timeout

This makes the timeout for "find_multipaths smart" configurable.
If the timeout has a negative value (default), it's applied only
to "known" hardware which is either in the hwtable or in a "device" section in
multipath.conf. For typical non-multipath hardware, which is not in the
hwtable, a short timeout of 1s is used, so that boot delays caused by
pointlessly waiting e.g. for SATA devices will be minimal.

It's expected that a "reasonable" timeout value depends less on the storage
hardware itself but on other properties of the data center such as network
latencies or distances. find_multipaths_timeout is therefore just a "defaults"
section setting.

Signed-off-by: Martin Wilck <mwilck@suse.com>
Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>

diff --git a/libmultipath/config.h b/libmultipath/config.h
index c71d972..6e69a37 100644 (file)
--- a/libmultipath/config.h
+++ b/libmultipath/config.h
@@ -174,6 +174,7 @@ struct config {
        int remove_retries;
        int max_sectors_kb;
        int ghost_delay;
+       int find_multipaths_timeout;
        unsigned int version[3];
 
        char * multipath_dir;

diff --git a/libmultipath/defaults.h b/libmultipath/defaults.h
index 19ad2bf..d7b87b4 100644 (file)
--- a/libmultipath/defaults.h
+++ b/libmultipath/defaults.h
@@ -41,6 +41,8 @@
 #define DEFAULT_DISABLE_CHANGED_WWIDS 1
 #define DEFAULT_MAX_SECTORS_KB MAX_SECTORS_KB_UNDEF
 #define DEFAULT_GHOST_DELAY GHOST_DELAY_OFF
+#define DEFAULT_FIND_MULTIPATHS_TIMEOUT -10
+#define DEFAULT_UNKNOWN_FIND_MULTIPATHS_TIMEOUT 1
 
 #define DEFAULT_CHECKINT       5
 #define MAX_CHECKINT(a)                (a << 2)

diff --git a/libmultipath/dict.c b/libmultipath/dict.c
index b03197b..eda3f1f 100644 (file)
--- a/libmultipath/dict.c
+++ b/libmultipath/dict.c
@@ -491,6 +491,10 @@ declare_hw_snprint(max_sectors_kb, print_nonzero)
 declare_mp_handler(max_sectors_kb, set_int)
 declare_mp_snprint(max_sectors_kb, print_nonzero)
 
+declare_def_handler(find_multipaths_timeout, set_int)
+declare_def_snprint_defint(find_multipaths_timeout, print_int,
+                          DEFAULT_FIND_MULTIPATHS_TIMEOUT)
+
 static int
 def_config_dir_handler(struct config *conf, vector strvec)
 {
@@ -1527,6 +1531,9 @@ init_keywords(vector keywords)
        install_keyword("remove_retries", &def_remove_retries_handler, &snprint_def_remove_retries);
        install_keyword("max_sectors_kb", &def_max_sectors_kb_handler, &snprint_def_max_sectors_kb);
        install_keyword("ghost_delay", &def_ghost_delay_handler, &snprint_def_ghost_delay);
+       install_keyword("find_multipaths_timeout",
+                       &def_find_multipaths_timeout_handler,
+                       &snprint_def_find_multipaths_timeout);
        __deprecated install_keyword("default_selector", &def_selector_handler, NULL);
        __deprecated install_keyword("default_path_grouping_policy", &def_pgpolicy_handler, NULL);
        __deprecated install_keyword("default_uid_attribute", &def_uid_attribute_handler, NULL);

diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
index 2d3b7ad..627d366 100644 (file)
--- a/libmultipath/propsel.c
+++ b/libmultipath/propsel.c
@@ -953,3 +953,28 @@ out:
        condlog(3, "%s: ghost_delay = %s %s", mp->alias, buff, origin);
        return 0;
 }
+
+int select_find_multipaths_timeout(struct config *conf, struct path *pp)
+{
+       const char *origin;
+
+       pp_set_conf(find_multipaths_timeout);
+       pp_set_default(find_multipaths_timeout,
+                      DEFAULT_FIND_MULTIPATHS_TIMEOUT);
+out:
+       /*
+        * If configured value is negative, and this "unknown" hardware
+        * (no hwentry), use very small timeout to avoid delays.
+        */
+       if (pp->find_multipaths_timeout < 0) {
+               pp->find_multipaths_timeout = -pp->find_multipaths_timeout;
+               if (!pp->hwe) {
+                       pp->find_multipaths_timeout =
+                               DEFAULT_UNKNOWN_FIND_MULTIPATHS_TIMEOUT;
+                       origin = "(default for unknown hardware)";
+               }
+       }
+       condlog(3, "%s: timeout for find_multipaths \"smart\" = %ds %s",
+               pp->dev, pp->find_multipaths_timeout, origin);
+       return 0;
+}

diff --git a/libmultipath/propsel.h b/libmultipath/propsel.h
index 136f906..a022bee 100644 (file)
--- a/libmultipath/propsel.h
+++ b/libmultipath/propsel.h
@@ -8,6 +8,7 @@ int select_hwhandler (struct config *conf, struct multipath * mp);
 int select_checker(struct config *conf, struct path *pp);
 int select_getuid (struct config *conf, struct path * pp);
 int select_prio (struct config *conf, struct path * pp);
+int select_find_multipaths_timeout(struct config *conf, struct path *pp);
 int select_no_path_retry(struct config *conf, struct multipath *mp);
 int select_flush_on_last_del(struct config *conf, struct multipath *mp);
 int select_minio(struct config *conf, struct multipath *mp);

diff --git a/libmultipath/structs.h b/libmultipath/structs.h
index 1d3a34f..eb6a178 100644 (file)
--- a/libmultipath/structs.h
+++ b/libmultipath/structs.h
@@ -281,6 +281,7 @@ struct path {
        int io_err_disable_reinstate;
        int io_err_pathfail_cnt;
        int io_err_pathfail_starttime;
+       int find_multipaths_timeout;
        /* configlet pointers */
        struct hwentry * hwe;
        struct gen_path generic_path;

diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5
index 6965dac..3a34aef 100644 (file)
--- a/multipath/multipath.conf.5
+++ b/multipath/multipath.conf.5
@@ -983,6 +983,24 @@ The default is: \fBstrict\fR
 .
 .
 .TP
+.B find_multipaths_timeout
+Timeout, in seconds, to wait for additional paths after detecting the first
+one, if \fIfind_multipaths
+"smart"\fR (see above) is set. If the value is \fBpositive\fR, this timeout is used for all
+unknown, non-blacklisted devices encountered. If the value is \fBnegative\fR
+(recommended), it's only
+applied to "known" devices that have an entry in multipath's hardware table,
+either in the built-in table or in a \fIdevice\fR section; other ("unknown") devices will
+use a timeout of only 1 second to avoid booting delays. The value 0 means
+"use the built-in default". If \fIfind_multipath\fR has a value
+other than \fIsmart\fR, this option has no effect.
+.RS
+.TP
+The default is: \fB-10\fR (10s for known and 1s for unknown hardware)
+.RE
+.
+.
+.TP
 .B uxsock_timeout
 CLI receive timeout in milliseconds. For larger systems CLI commands
 might timeout before the multipathd lock is released and the CLI command