[kpartx][libmultipath] make multipath and kpartx prefix the uuid

In order for other programs to figure out who owns the dm-devices that
are created by multipath and kpartx, this patch adds a prefix to the uuid
for all multipath and kpartx created devices.  When multipath gets the
uuid,
the prefix is stripped back off. However other programs can use the device
mapper library or dmsetup to easily check which devices were created by
multipath or kpartx.

the multipath prefix is mpath-
the kpartx prefix is part%d- where %d is the partition number.

Ben Marzinski, Redhat

diff --git a/kpartx/devmapper.c b/kpartx/devmapper.c
index 1253941..5b27487 100644 (file)
--- a/kpartx/devmapper.c
+++ b/kpartx/devmapper.c
@@ -7,6 +7,10 @@
 #include <libdevmapper.h>
 #include <ctype.h>
 #include <linux/kdev_t.h>
+#include <errno.h>
+
+#define UUID_PREFIX "part%d-"
+#define MAX_PREFIX_LEN 8
 
 extern int
 dm_prereq (char * str, int x, int y, int z)
@@ -68,9 +72,10 @@ dm_simplecmd (int task, const char *name) {
 
 extern int
 dm_addmap (int task, const char *name, const char *target,
-          const char *params, unsigned long size) {
+          const char *params, unsigned long size, const char *uuid, int part) {
        int r = 0;
        struct dm_task *dmt;
+       char *prefixed_uuid;
 
        if (!(dmt = dm_task_create (task)))
                return 0;
@@ -81,10 +86,26 @@ dm_addmap (int task, const char *name, const char *target,
        if (!dm_task_add_target (dmt, 0, size, target, params))
                goto addout;
 
+       if (task == DM_DEVICE_CREATE && uuid) {
+               prefixed_uuid = malloc(MAX_PREFIX_LEN + strlen(uuid) + 1);
+               if (!prefixed_uuid) {
+                       fprintf(stderr, "cannot create prefixed uuid : %s\n",
+                               strerror(errno));
+                       goto addout;
+               }
+               sprintf(prefixed_uuid, UUID_PREFIX "%s", part, uuid);
+               if (!dm_task_set_uuid(dmt, prefixed_uuid))
+                       goto freeout;
+       }
+
        dm_task_no_open_count(dmt);
 
        r = dm_task_run (dmt);
 
+       freeout:
+       if (prefixed_uuid)
+               free(prefixed_uuid);
+
        addout:
        dm_task_destroy (dmt);
        return r;
@@ -178,3 +199,26 @@ out:
        return ret;
 }
 
+char *
+dm_mapuuid(int major, int minor)
+{
+       struct dm_task *dmt;
+       char *tmp, *uuid = NULL;
+
+       if (!(dmt = dm_task_create(DM_DEVICE_INFO)))
+               return NULL;
+
+       dm_task_no_open_count(dmt);
+       dm_task_set_major(dmt, major);
+       dm_task_set_minor(dmt, minor);
+
+       if (!dm_task_run(dmt))
+               goto out;
+
+       tmp = dm_task_get_uuid(dmt);
+       if (tmp[0] != '\0')
+               uuid = strdup(tmp);
+out:
+       dm_task_destroy(dmt);
+       return uuid;
+}

diff --git a/kpartx/devmapper.h b/kpartx/devmapper.h
index 9607476..e20e456 100644 (file)
--- a/kpartx/devmapper.h
+++ b/kpartx/devmapper.h
@@ -1,6 +1,8 @@
 int dm_prereq (char *, int, int, int);
 int dm_simplecmd (int, const char *);
-int dm_addmap (int, const char *, const char *, const char *, unsigned long);
+int dm_addmap (int, const char *, const char *, const char *, unsigned long,
+              char *, int);
 int dm_map_present (char *);
 char * dm_mapname(int major, int minor);
 dev_t dm_get_first_dep(char *devname);
+char * dm_mapuuid(int major, int minor);

diff --git a/kpartx/kpartx.c b/kpartx/kpartx.c
index 2198302..0ee0cb3 100644 (file)
--- a/kpartx/kpartx.c
+++ b/kpartx/kpartx.c
@@ -192,6 +192,7 @@ main(int argc, char **argv){
        char partname[PARTNAME_SIZE], params[PARTNAME_SIZE + 16];
        char * loopdev = NULL;
        char * delim = NULL;
+       char *uuid = NULL;
        int loopro = 0;
        int hotplug = 0;
        struct stat buf;
@@ -284,11 +285,6 @@ main(int argc, char **argv){
        }
 
        if (S_ISREG (buf.st_mode)) {
-               loopdev = malloc(LO_NAME_SIZE * sizeof(char));
-               
-               if (!loopdev)
-                       exit(1);
-
                /* already looped file ? */
                loopdev = find_loop_by_file(device);
 
@@ -313,6 +309,13 @@ main(int argc, char **argv){
        }
        
        off = find_devname_offset(device);
+
+       if (!loopdev)
+               uuid = dm_mapuuid((unsigned int)MAJOR(buf.st_rdev),
+                                 (unsigned int)MINOR(buf.st_rdev));
+       if (!uuid)
+               uuid = device + off;
+               
        fd = open(device, O_RDONLY);
 
        if (fd == -1) {
@@ -420,7 +423,7 @@ main(int argc, char **argv){
                                        DM_DEVICE_RELOAD : DM_DEVICE_CREATE);
 
                                dm_addmap(op, partname, DM_TARGET, params,
-                                         slices[j].size);
+                                         slices[j].size, uuid, j+1);
 
                                if (op == DM_DEVICE_RELOAD)
                                        dm_simplecmd(DM_DEVICE_RESUME,

diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index 0abdb88..c0765ae 100644 (file)
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -11,6 +11,7 @@
 #include <ctype.h>
 #include <linux/kdev_t.h>
 #include <unistd.h>
+#include <errno.h>
 
 #include <checkers.h>
 
@@ -23,6 +24,10 @@
 #define MAX_WAIT 5
 #define LOOPS_PER_SEC 5
 
+#define UUID_PREFIX "mpath-"
+#define UUID_PREFIX_LEN 6
+
+
 static void
 dm_dummy_log (int level, const char *file, int line, const char *f, ...)
 {
@@ -113,6 +118,7 @@ dm_addmap (int task, const char *name, const char *target,
           const char *params, unsigned long long size, const char *uuid) {
        int r = 0;
        struct dm_task *dmt;
+       char *prefixed_uuid = NULL;
 
        if (!(dmt = dm_task_create (task)))
                return 0;
@@ -123,13 +129,26 @@ dm_addmap (int task, const char *name, const char *target,
        if (!dm_task_add_target (dmt, 0, size, target, params))
                goto addout;
 
-       if (uuid && !dm_task_set_uuid(dmt, uuid))
-               goto addout;
+       if (uuid){
+               prefixed_uuid = MALLOC(UUID_PREFIX_LEN + strlen(uuid) + 1);
+               if (!prefixed_uuid) {
+                       condlog(0, "cannot create prefixed uuid : %s\n",
+                               strerror(errno));
+                       goto addout;
+               }
+               sprintf(prefixed_uuid, UUID_PREFIX "%s", uuid);
+               if (!dm_task_set_uuid(dmt, prefixed_uuid))
+                       goto freeout;
+       }
 
        dm_task_no_open_count(dmt);
 
        r = dm_task_run (dmt);
 
+       freeout:
+       if (prefixed_uuid)
+               free(prefixed_uuid);
+
        addout:
        dm_task_destroy (dmt);
        return r;
@@ -215,8 +234,12 @@ dm_get_uuid(char *name, char *uuid)
                 goto uuidout;
 
        uuidtmp = dm_task_get_uuid(dmt);
-       if (uuidtmp)
-               strcpy(uuid, uuidtmp);
+       if (uuidtmp) {
+               if (!strncmp(uuidtmp, UUID_PREFIX, UUID_PREFIX_LEN))
+                       strcpy(uuid, uuidtmp + UUID_PREFIX_LEN);
+               else
+                       strcpy(uuid, uuidtmp);
+       }
        else
                uuid[0] = '\0';