[dm-devel] [PATCH] libmultipath: Use existing user friendly name if possible
Stewart, Sean
Sean.Stewart at netapp.com
Fri Mar 28 21:01:14 UTC 2014
When a system is booted to the SAN, a condition can occur where one
user friendly name is given to a disk during boot, but multipathd tries
to allocate a different one after boot. If the second alias is already
used by another device, multipathd can't rename it. Multipathd then has
incorrect information about the alias/wwid relationships, which can
result in paths being added to the wrong map.
This patch works around this problem by first trying to use the alias
already bound to a device during boot. If the bindings file has that
alias bound to a different device, it'll auto generate a new alias to
rename it to.
The alias prioritization is:
1. multipath.conf per-device alias
2. Currently bound alias
3. New auto-generated alias
4. wwid
Signed-off-by: Sean Stewart <sean.stewart at netapp.com>
Reviewed-by: Shiva Krishna Merla <shivakrishna.merla at netapp.com>
---
libmultipath/alias.c | 64 +++++++++++++++++++++++++++++++++++++++++++---
libmultipath/alias.h | 2 ++
libmultipath/propsel.c | 32 +++++++++++++++--------
libmultipath/structs_vec.c | 15 +++++++++++
4 files changed, 100 insertions(+), 13 deletions(-)
diff --git a/libmultipath/alias.c b/libmultipath/alias.c
index ab15185..008396e 100644
--- a/libmultipath/alias.c
+++ b/libmultipath/alias.c
@@ -145,7 +145,7 @@ lookup_binding(FILE *f, char *map_wwid, char **map_alias, char *prefix)
}
static int
-rlookup_binding(FILE *f, char *buff, char *map_alias)
+rlookup_binding(FILE *f, char *buff, char *map_alias, char *prefix)
{
char line[LINE_MAX];
unsigned int line_nr = 0;
@@ -164,7 +164,7 @@ rlookup_binding(FILE *f, char *buff, char *map_alias)
alias = strtok(line, " \t");
if (!alias) /* blank line */
continue;
- curr_id = scan_devname(alias, NULL); /* TBD: Why this call? */
+ curr_id = scan_devname(alias, prefix);
if (curr_id >= id)
id = curr_id + 1;
wwid = strtok(NULL, " \t");
@@ -188,6 +188,11 @@ rlookup_binding(FILE *f, char *buff, char *map_alias)
}
}
condlog(3, "No matching alias [%s] in bindings file.", map_alias);
+
+ /* Get the theoretical id for this map alias.
+ * Used by use_existing_alias
+ */
+ id = scan_devname(map_alias, prefix);
return id;
}
@@ -237,6 +242,59 @@ allocate_binding(int fd, char *wwid, int id, char *prefix)
}
char *
+use_existing_alias (char *wwid, char *file, char *alias_old,
+ char *prefix, int bindings_read_only)
+{
+ char *alias = NULL;
+ int id = 0;
+ int fd, can_write;
+ char buff[WWID_SIZE];
+ FILE *f;
+
+ fd = open_file(file, &can_write, BINDINGS_FILE_HEADER);
+ if (fd < 0)
+ return NULL;
+
+ f = fdopen(fd, "r");
+ if (!f) {
+ condlog(0, "cannot fdopen on bindings file descriptor");
+ close(fd);
+ return NULL;
+ }
+ /* lookup the binding. if it exsists, the wwid will be in buff
+ * either way, id contains the id for the alias
+ */
+ id = rlookup_binding(f , buff, alias_old, prefix);
+ if (id < 0)
+ goto out;
+
+ if (strlen(buff) > 0) {
+ /* if buff is our wwid, it's already
+ * allocated correctly
+ */
+ if (strcmp(buff, wwid) == 0)
+ alias = STRDUP(alias_old);
+ else {
+ alias = NULL;
+ condlog(0, "alias %s already bound to wwid %s, cannot reuse",
+ alias_old, buff);
+ }
+ goto out;
+ }
+
+ /* allocate the existing alias in the bindings file */
+ if (can_write && id && !bindings_read_only) {
+ alias = allocate_binding(fd, wwid, id, prefix);
+ condlog(0, "Allocated existing binding [%s] for WWID [%s]",
+ alias, wwid);
+ }
+
+out:
+ fclose(f);
+ return alias;
+}
+
+char *
get_user_friendly_alias(char *wwid, char *file, char *prefix,
int bindings_read_only)
{
@@ -305,7 +363,7 @@ get_user_friendly_wwid(char *alias, char *buff, char *file)
return -1;
}
- rlookup_binding(f, buff, alias);
+ rlookup_binding(f, buff, alias, NULL);
if (!strlen(buff)) {
fclose(f);
return -1;
diff --git a/libmultipath/alias.h b/libmultipath/alias.h
index 8ddd0b5..9cb3e8f 100644
--- a/libmultipath/alias.h
+++ b/libmultipath/alias.h
@@ -10,3 +10,5 @@
char *get_user_friendly_alias(char *wwid, char *file, char *prefix,
int bindings_readonly);
int get_user_friendly_wwid(char *alias, char *buff, char *file);
+char *use_existing_alias (char *wwid, char *file, char *alias_old,
+ char *prefix, int bindings_read_only);
diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
index 7b7944d..2859e3e 100644
--- a/libmultipath/propsel.c
+++ b/libmultipath/propsel.c
@@ -253,19 +253,31 @@ want_user_friendly_names(struct multipath * mp)
extern int
select_alias (struct multipath * mp)
{
- if (mp->mpe && mp->mpe->alias)
+ if (mp->mpe && mp->mpe->alias) {
mp->alias = STRDUP(mp->mpe->alias);
- else {
- mp->alias = NULL;
- if (want_user_friendly_names(mp)) {
- select_alias_prefix(mp);
- mp->alias = get_user_friendly_alias(mp->wwid,
- conf->bindings_file, mp->alias_prefix, conf->bindings_read_only);
- }
- if (mp->alias == NULL)
- mp->alias = STRDUP(mp->wwid);
+ goto out;
}
+ mp->alias = NULL;
+ if (!want_user_friendly_names(mp))
+ goto out;
+
+ select_alias_prefix(mp);
+
+ if (strlen(mp->alias_old) > 0) {
+ mp->alias = use_existing_alias(mp->wwid, conf->bindings_file,
+ mp->alias_old, mp->alias_prefix,
+ conf->bindings_read_only);
+ memset (mp->alias_old, 0, WWID_SIZE);
+ }
+
+ if (mp->alias == NULL)
+ mp->alias = get_user_friendly_alias(mp->wwid,
+ conf->bindings_file, mp->alias_prefix, conf->bindings_read_only);
+out:
+ if (mp->alias == NULL)
+ mp->alias = STRDUP(mp->wwid);
+
return mp->alias ? 0 : 1;
}
diff --git a/libmultipath/structs_vec.c b/libmultipath/structs_vec.c
index 76c7e02..8cdbe3d 100644
--- a/libmultipath/structs_vec.c
+++ b/libmultipath/structs_vec.c
@@ -403,6 +403,20 @@ out:
return NULL;
}
+static void
+find_existing_alias (struct multipath * mpp,
+ struct vectors *vecs)
+{
+ struct multipath * mp;
+ int i;
+
+ vector_foreach_slot (vecs->mpvec, mp, i)
+ if (strcmp(mp->wwid, mpp->wwid) == 0) {
+ strncpy(mpp->alias_old, mp->alias, WWID_SIZE);
+ return;
+ }
+}
+
extern struct multipath *
add_map_with_path (struct vectors * vecs,
struct path * pp, int add_vec)
@@ -416,6 +430,7 @@ add_map_with_path (struct vectors * vecs,
mpp->hwe = pp->hwe;
strcpy(mpp->wwid, pp->wwid);
+ find_existing_alias(mpp, vecs);
if (select_alias(mpp))
goto out;
mpp->size = pp->size;
--
1.8.3.1
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