uevent_can_discard: optimize devpath check
authorMartin Wilck <mwilck@suse.com>
Wed, 1 Mar 2017 17:22:19 +0000 (18:22 +0100)
committerChristophe Varoqui <christophe.varoqui@opensvc.com>
Thu, 16 Mar 2017 06:42:16 +0000 (07:42 +0100)
This uses roughly 10% cycles of the sscanf-based implementation.

Improves: ee8888f0 "multipath-tools: improve processing efficiency..."
Signed-off-by: Martin Wilck <mwilck@suse.com>
libmultipath/uevent.c

index 6e2527b..367e129 100644 (file)
@@ -143,26 +143,35 @@ uevent_need_merge(void)
        return need_merge;
 }
 
+static bool
+uevent_can_discard_by_devpath(const char *devpath)
+{
+       static const char BLOCK[] = "/block/";
+       const char *tmp = strstr(devpath, BLOCK);
+
+       if (tmp == NULL) {
+               condlog(4, "no /block/ in '%s'", devpath);
+               return true;
+       }
+       tmp += sizeof(BLOCK) - 1;
+       if (*tmp == '\0')
+               /* just ".../block/" - discard */
+               return true;
+       /*
+        * If there are more path elements after ".../block/xyz",
+        * it's a partition - discard it; but don't discard ".../block/sda/".
+        */
+       tmp = strchr(tmp, '/');
+       return tmp != NULL && *(tmp + 1) != '\0';
+}
+
 bool
 uevent_can_discard(struct uevent *uev)
 {
-       char *tmp;
-       char a[11], b[11];
        struct config * conf;
 
-       /*
-        * keep only block devices, discard partitions
-        */
-       tmp = strstr(uev->devpath, "/block/");
-       if (tmp == NULL){
-               condlog(4, "no /block/ in '%s'", uev->devpath);
+       if (uevent_can_discard_by_devpath(uev->devpath))
                return true;
-       }
-       if (sscanf(tmp, "/block/%10s", a) != 1 ||
-           sscanf(tmp, "/block/%10[^/]/%10s", a, b) == 2) {
-               condlog(4, "discard event on %s", uev->devpath);
-               return true;
-       }
 
        /* 
         * do not filter dm devices by devnode