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| author | Karel Zak <kzak@redhat.com> | 2009-04-27 15:00:58 +0200 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2009-05-02 22:39:20 -0400 |
| commit | 46f3eeca59a1fc8233790bbed604e4634e0f3fbe (patch) | |
| tree | f951927ee1aa18dcfd627a78b03912cf8b9916d4 /lib/blkid/devname.c | |
| parent | 4271e23942bdc60e1fa6c0b26bc666a94a8b3e1d (diff) | |
| download | e2fsprogs-46f3eeca59a1fc8233790bbed604e4634e0f3fbe.tar.gz | |
blkid: use /sys/block/dm-<N>/dm/name
The Linux kernel (since 2.6.29, patch 784aae735d9b0bba3f8b9faef4c8b30df3bf0128)
exports the real DM device names in /sys/block/<ptname>/dm/name.
The sysfs based solution is nicer and faster than scan for devno in
/dev/mapper/.
CC: Milan Broz <mbroz@redhat.com>
Signed-off-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'lib/blkid/devname.c')
| -rw-r--r-- | lib/blkid/devname.c | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/lib/blkid/devname.c b/lib/blkid/devname.c index ec19a2e8..b151354d 100644 --- a/lib/blkid/devname.c +++ b/lib/blkid/devname.c @@ -153,6 +153,30 @@ static int is_dm_leaf(const char *devname) } /* + * Since 2.6.29 (patch 784aae735d9b0bba3f8b9faef4c8b30df3bf0128) kernel sysfs + * provides the real DM device names in /sys/block/<ptname>/dm/name + */ +static char *get_dm_name(const char *ptname) +{ + FILE *f; + size_t sz; + char path[256], name[256], *res = NULL; + + snprintf(path, sizeof(path), "/sys/block/%s/dm/name", ptname); + if ((f = fopen(path, "r")) == NULL) + return NULL; + + /* read "<name>\n" from sysfs */ + if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) { + name[sz - 1] = '\0'; + snprintf(path, sizeof(path), "/dev/mapper/%s", name); + res = blkid_strdup(path); + } + fclose(f); + return res; +} + +/* * Probe a single block device to add to the device cache. */ static void probe_one(blkid_cache cache, const char *ptname, @@ -183,7 +207,9 @@ static void probe_one(blkid_cache cache, const char *ptname, * to standard /dev/mapper/<name>. */ if (!strncmp(ptname, "dm-", 3) && isdigit(ptname[3])) { - blkid__scan_dir("/dev/mapper", devno, 0, &devname); + devname = get_dm_name(ptname); + if (!devname) + blkid__scan_dir("/dev/mapper", devno, 0, &devname); if (devname) goto get_dev; } @@ -211,6 +237,8 @@ static void probe_one(blkid_cache cache, const char *ptname, } /* Do a short-cut scan of /dev/mapper first */ if (!devname) + devname = get_dm_name(ptname); + if (!devname) blkid__scan_dir("/dev/mapper", devno, 0, &devname); if (!devname) { devname = blkid_devno_to_devname(devno); |