With "find_multipaths smart", we accept paths as valid if they are
already part of a multipath map. This patch avoids doing a full path
and device-mapper map scan for this case, speeding up "multipath -u"
considerably.
Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
Reviewed-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
---
libmultipath/sysfs.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++
libmultipath/sysfs.h | 2 ++
multipath/main.c | 9 +++++++
3 files changed, 77 insertions(+)
diff --git a/libmultipath/sysfs.c b/libmultipath/sysfs.c
index 97e09977..ee72e6a3 100644
--- a/libmultipath/sysfs.c
+++ b/libmultipath/sysfs.c
@@ -27,6 +27,7 @@
#include <string.h>
#include <dirent.h>
#include <libudev.h>
+#include <fnmatch.h>
#include "checkers.h"
#include "vector.h"
@@ -287,3 +288,68 @@ int sysfs_check_holders(char * check_devt, char * new_devt)
return 0;
}
+
+static int select_dm_devs(const struct dirent *di)
+{
+ return fnmatch("dm-*", di->d_name, FNM_FILE_NAME) == 0;
+}
+
+static void close_fd(void *arg)
+{
+ close((long)arg);
+}
+
+bool sysfs_is_multipathed(const struct path *pp)
+{
+ char pathbuf[PATH_MAX];
+ struct dirent **di;
+ int n, r, i;
+ bool found = false;
+
+ n = snprintf(pathbuf, sizeof(pathbuf), "/sys/block/%s/holders",
+ pp->dev);
+
+ if (n >= sizeof(pathbuf)) {
+ condlog(1, "%s: pathname overflow", __func__);
+ return false;
+ }
+
+ r = scandir(pathbuf, &di, select_dm_devs, alphasort);
+ if (r == 0)
+ return false;
+ else if (r < 0) {
+ condlog(1, "%s: error scanning %s", __func__, pathbuf);
+ return false;
+ }
+
+ pthread_cleanup_push(free, di);
+ for (i = 0; i < r && !found; i++) {
+ long fd;
+ int nr;
+ char uuid[6];
+
+ if (snprintf(pathbuf + n, sizeof(pathbuf) - n,
+ "/%s/dm/uuid", di[i]->d_name)
+ >= sizeof(pathbuf) - n)
+ continue;
+
+ fd = open(pathbuf, O_RDONLY);
+ if (fd == -1) {
+ condlog(1, "%s: error opening %s", __func__, pathbuf);
+ continue;
+ }
+
+ pthread_cleanup_push(close_fd, (void *)fd);
+ nr = read(fd, uuid, sizeof(uuid));
+ if (nr == sizeof(uuid) && !memcmp(uuid, "mpath-", sizeof(uuid)))
+ found = true;
+ else if (nr < 0) {
+ condlog(1, "%s: error reading from %s: %s",
+ __func__, pathbuf, strerror(errno));
+ }
+ pthread_cleanup_pop(1);
+ }
+ pthread_cleanup_pop(1);
+
+ return found;
+}
diff --git a/libmultipath/sysfs.h b/libmultipath/sysfs.h
index 75c0f9c1..9ae30b39 100644
--- a/libmultipath/sysfs.h
+++ b/libmultipath/sysfs.h
@@ -4,6 +4,7 @@
#ifndef _LIBMULTIPATH_SYSFS_H
#define _LIBMULTIPATH_SYSFS_H
+#include <stdbool.h>
ssize_t sysfs_attr_set_value(struct udev_device *dev, const char *attr_name,
const char * value, size_t value_len);
@@ -13,4 +14,5 @@ ssize_t sysfs_bin_attr_get_value(struct udev_device *dev, const char *attr_name,
unsigned char * value, size_t value_len);
int sysfs_get_size (struct path *pp, unsigned long long * size);
int sysfs_check_holders(char * check_devt, char * new_devt);
+bool sysfs_is_multipathed(const struct path *pp);
#endif
diff --git a/multipath/main.c b/multipath/main.c
index 61ba90a6..96e37a7a 100644
--- a/multipath/main.c
+++ b/multipath/main.c
@@ -593,6 +593,15 @@ configure (struct config *conf, enum mpath_cmds cmd,
if (!ignore_wwids_on(conf))
goto print_valid;
/* At this point, either r==0 or find_multipaths_on. */
+
+ /*
+ * Shortcut for find_multipaths smart:
+ * Quick check if path is already multipathed.
+ */
+ if (sysfs_is_multipathed(VECTOR_SLOT(pathvec, 0))) {
+ r = 0;
+ goto print_valid;
+ }
if (r == 0)
goto print_valid;
/* find_multipaths_on: Fall through to path detection */
--
2.16.1
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
