GFS2: Expose UUID via sysfs/uevent

Since we have a UUID, we ought to expose it to the user via sysfs
and uevents. We already have the fs name in both of these places
(a combination of the lock proto and lock table name) so if we add
the UUID as well, we have a full set.

For older filesystems (i.e. those created before mkfs.gfs2 was writing
UUIDs by default) the sysfs file will appear zero length, and no UUID
env var will be added to the uevents.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index 3f29bd224ba146c3ce3360f38d38b4aac16496f0..980a0864ca6ce39df5968114b01d21e089dcc10d 100644 (file)
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -470,6 +470,7 @@ struct gfs2_sb_host {
 
        char sb_lockproto[GFS2_LOCKNAME_LEN];
        char sb_locktable[GFS2_LOCKNAME_LEN];
+       u8 sb_uuid[16];
 };
 
 /*

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index e502b379a4dab7ecc0f81c2c04966ac983669069..804ca7273a496aac3601046d6d3026eab8ccfa48 100644 (file)
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -234,6 +234,7 @@ static void gfs2_sb_in(struct gfs2_sb_host *sb, const void *buf)
 
        memcpy(sb->sb_lockproto, str->sb_lockproto, GFS2_LOCKNAME_LEN);
        memcpy(sb->sb_locktable, str->sb_locktable, GFS2_LOCKNAME_LEN);
+       memcpy(sb->sb_uuid, str->sb_uuid, 16);
 }
 
 /**

diff --git a/fs/gfs2/sys.c b/fs/gfs2/sys.c
index a78997ea50373c13a0c0870c276f70d4e6602e26..4d284d14980b8ef4641ce78ba291dfb30a4298f7 100644 (file)
--- a/fs/gfs2/sys.c
+++ b/fs/gfs2/sys.c
@@ -36,6 +36,30 @@ static ssize_t fsname_show(struct gfs2_sbd *sdp, char *buf)
        return snprintf(buf, PAGE_SIZE, "%s\n", sdp->sd_fsname);
 }
 
+static int gfs2_uuid_valid(const u8 *uuid)
+{
+       int i;
+
+       for (i = 0; i < 16; i++) {
+               if (uuid[i])
+                       return 1;
+       }
+       return 0;
+}
+
+static ssize_t uuid_show(struct gfs2_sbd *sdp, char *buf)
+{
+       const u8 *uuid = sdp->sd_sb.sb_uuid;
+       buf[0] = '\0';
+       if (!gfs2_uuid_valid(uuid))
+               return 0;
+       return snprintf(buf, PAGE_SIZE, "%02X%02X%02X%02X-%02X%02X-"
+                       "%02X%02X-%02X%02X-%02X%02X%02X%02X%02X%02X\n",
+                       uuid[0], uuid[1], uuid[2], uuid[3], uuid[4], uuid[5],
+                       uuid[6], uuid[7], uuid[8], uuid[9], uuid[10], uuid[11],
+                       uuid[12], uuid[13], uuid[14], uuid[15]);
+}
+
 static ssize_t freeze_show(struct gfs2_sbd *sdp, char *buf)
 {
        unsigned int count;
@@ -158,6 +182,7 @@ static struct gfs2_attr gfs2_attr_##name = __ATTR(name, mode, show, store)
 
 GFS2_ATTR(id,                  0444, id_show,       NULL);
 GFS2_ATTR(fsname,              0444, fsname_show,   NULL);
+GFS2_ATTR(uuid,                0444, uuid_show,     NULL);
 GFS2_ATTR(freeze,              0644, freeze_show,   freeze_store);
 GFS2_ATTR(withdraw,            0644, withdraw_show, withdraw_store);
 GFS2_ATTR(statfs_sync,         0200, NULL,          statfs_sync_store);
@@ -168,6 +193,7 @@ GFS2_ATTR(quota_refresh_group, 0200, NULL,          quota_refresh_group_store);
 static struct attribute *gfs2_attrs[] = {
        &gfs2_attr_id.attr,
        &gfs2_attr_fsname.attr,
+       &gfs2_attr_uuid.attr,
        &gfs2_attr_freeze.attr,
        &gfs2_attr_withdraw.attr,
        &gfs2_attr_statfs_sync.attr,
@@ -598,12 +624,23 @@ void gfs2_sys_fs_del(struct gfs2_sbd *sdp)
        kobject_put(&sdp->sd_kobj);
 }
 
+
 static int gfs2_uevent(struct kset *kset, struct kobject *kobj,
                       struct kobj_uevent_env *env)
 {
        struct gfs2_sbd *sdp = container_of(kobj, struct gfs2_sbd, sd_kobj);
+       const u8 *uuid = sdp->sd_sb.sb_uuid;
+
        add_uevent_var(env, "LOCKTABLE=%s", sdp->sd_table_name);
        add_uevent_var(env, "LOCKPROTO=%s", sdp->sd_proto_name);
+       if (gfs2_uuid_valid(uuid)) {
+               add_uevent_var(env, "UUID=%02X%02X%02X%02X-%02X%02X-%02X%02X-"
+                              "%02X%02X-%02X%02X%02X%02X%02X%02X",
+                              uuid[0], uuid[1], uuid[2], uuid[3], uuid[4],
+                              uuid[5], uuid[6], uuid[7], uuid[8], uuid[9],
+                              uuid[10], uuid[11], uuid[12], uuid[13],
+                              uuid[14], uuid[15]);
+       }
        return 0;
 }