blkid: use /dev/mapper/<name> rather than /dev/dm-<N>

The libblkid (since v1.41.1) returns private device-mapper names (e.g.
/dev/dm-0). It's because the probe_one() function scans /dev before
/dev/mapper.

brw-rw---- 1 root disk 253, 0 2009-04-27 13:41 /dev/dm-0
brw-rw---- 1 root disk 253, 0 2009-04-27 13:41 /dev/mapper/TestVolGroup-TestLogVolume

Old version:
  # blkid -t LABEL="TEST-LABEL" -o device
  /dev/dm-0

Fixed version:
  # blkid -t LABEL="TEST-LABEL" -o device
  /dev/mapper/TestVolGroup-TestLogVolume

Addresses-Red-Hat-Bug: #497259
Signed-off-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/blkid/devname.c b/lib/blkid/devname.c
index 8553e9f3eb593ab4ff85e7ef34b607a655ef8bf7..ec19a2e853ba4eb7b49cfaab8e0980e330917693 100644 (file)
--- a/lib/blkid/devname.c
+++ b/lib/blkid/devname.c
@@ -179,6 +179,15 @@ static void probe_one(blkid_cache cache, const char *ptname,
        if (dev && dev->bid_devno == devno)
                goto set_pri;
 
+       /* Try to translate private device-mapper dm-<N> names
+        * to standard /dev/mapper/<name>.
+        */
+       if (!strncmp(ptname, "dm-", 3) && isdigit(ptname[3])) {
+               blkid__scan_dir("/dev/mapper", devno, 0, &devname);
+               if (devname)
+                       goto get_dev;
+       }
+
        /*
         * Take a quick look at /dev/ptname for the device number.  We check
         * all of the likely device directories.  If we don't find it, or if
@@ -197,7 +206,7 @@ static void probe_one(blkid_cache cache, const char *ptname,
                if (stat(device, &st) == 0 && S_ISBLK(st.st_mode) &&
                    st.st_rdev == devno) {
                        devname = blkid_strdup(device);
-                       break;
+                       goto get_dev;
                }
        }
        /* Do a short-cut scan of /dev/mapper first */
@@ -208,9 +217,9 @@ static void probe_one(blkid_cache cache, const char *ptname,
                if (!devname)
                        return;
        }
+get_dev:
        dev = blkid_get_dev(cache, devname, BLKID_DEV_NORMAL);
        free(devname);
-
 set_pri:
        if (dev) {
                if (pri)