libmount: add support for ID=

This patch add support for a new tag. The tag is based on udev block
device ID (see /dev/disk/by-id). The usual use-case is to use
WWN for this purpose, for example

  # mount ID=wwn-0x50026b724b09a1ff /mnt

Note that ID is not strictly defined and udevd generates various IDs
also for HW where WWN is undefined. This is reason why introduce ID=
seems better and more generic than more restrictive WWN=.

Addresses: https://github.com/karelzak/util-linux/issues/1008
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libblkid/src/evaluate.c b/libblkid/src/evaluate.c
index 8ba8bd5f372b3a87c96af6634388caa4aa544b87..710eac95663487c67e66c06772fbf494c10060f9 100644 (file)
--- a/libblkid/src/evaluate.c
+++ b/libblkid/src/evaluate.c
@@ -59,6 +59,9 @@ static int verify_tag(const char *devname, const char *name, const char *value)
        const char *data;
        int errsv = 0;
 
+       if (strcmp(token, "ID") == 0)
+               return 0; /* non-content tag */
+
        pr = blkid_new_probe();
        if (!pr)
                return -1;
@@ -149,6 +152,8 @@ static char *evaluate_by_udev(const char *token, const char *value, int uevent)
                strcpy(dev, _PATH_DEV_BYPARTLABEL "/");
        else if (!strcmp(token, "PARTUUID"))
                strcpy(dev, _PATH_DEV_BYPARTUUID "/");
+       else if (!strcmp(token, "ID"))
+               strcpy(dev, _PATH_DEV_BYID "/");
        else {
                DBG(EVALUATE, ul_debug("unsupported token %s", token));
                return NULL;    /* unsupported tag */

diff --git a/libmount/src/utils.c b/libmount/src/utils.c
index 6be7a72c0a6cd01600581ccb169da9e9de0b95d5..92829ebb01f267fb70e92dc835ccf407d289f178 100644 (file)
--- a/libmount/src/utils.c
+++ b/libmount/src/utils.c
@@ -72,6 +72,7 @@ int is_file_empty(const char *name)
 int mnt_valid_tagname(const char *tagname)
 {
        if (tagname && *tagname && (
+           strcmp("ID", tagname) == 0 ||
            strcmp("UUID", tagname) == 0 ||
            strcmp("LABEL", tagname) == 0 ||
            strcmp("PARTUUID", tagname) == 0 ||

diff --git a/sys-utils/mount.8 b/sys-utils/mount.8
index f1d114cb338ab99a8affa8f7b46fd258a45bfb93..082fa1719e34c7f62ad26dc1afa38931e0f941c2 100644 (file)
--- a/sys-utils/mount.8
+++ b/sys-utils/mount.8
@@ -177,6 +177,14 @@ PARTUUID=\fIuuid\fR
 Partition universally unique identifier.  This identifier is independent on
 filesystem and does not change by mkfs or mkswap operations  It's supported
 for example for GUID Partition Tables (GPT).
+.TP
+ID=\fIid\fR
+Hardware block device ID as generated by udevd.  This identifier is usually
+based on WWN (unique storage identifier) and assigned by the hardware
+manufacturer.  See \fBls /dev/disk/by-id\fR for more details, this directory
+and running udevd is required.  This identifier is not recommended for generic
+use as the identifier is not strictly defined and it depends on udev, udev rules
+and hardware.
 .RE
 .sp
 The command \fBlsblk \-\-fs\fR provides an overview of filesystems, LABELs and UUIDs
@@ -189,7 +197,7 @@ unique, especially if you move, share or copy the device.  Use
 to verify that the UUIDs are really unique in your system.
 
 The recommended setup is to use tags (e.g.\& \fBUUID=\fIuuid\fR) rather than
-.I /dev/disk/by-{label,uuid,partuuid,partlabel}
+.I /dev/disk/by-{label,uuid,id,partuuid,partlabel}
 udev symlinks in the
 .I /etc/fstab
 file.  Tags are
@@ -301,7 +309,7 @@ program does not read the
 .I /etc/fstab
 file if both
 .I device
-(or LABEL, UUID, PARTUUID or PARTLABEL) and
+(or LABEL, UUID, ID, PARTUUID or PARTLABEL) and
 .I dir
 are specified.  For example, to mount device
 .BR foo " at " /dir :

diff --git a/sys-utils/mount.c b/sys-utils/mount.c
index 49d3beb0d51d485279d8e301374f5d584ade0ab1..a87833eee381b4122e61eb4c3fbc6eaa1c44903d 100644 (file)
--- a/sys-utils/mount.c
+++ b/sys-utils/mount.c
@@ -493,7 +493,8 @@ static void __attribute__((__noreturn__)) usage(void)
        " LABEL=<label>           specifies device by filesystem label\n"
        " UUID=<uuid>             specifies device by filesystem UUID\n"
        " PARTLABEL=<label>       specifies device by partition label\n"
-       " PARTUUID=<uuid>         specifies device by partition UUID\n"));
+       " PARTUUID=<uuid>         specifies device by partition UUID\n"
+       " ID=<id>                 specifies device by udev hardware ID\n"));
 
        fprintf(out, _(
        " <device>                specifies device by path\n"