ext4: print file system UUID on mount, remount and unmount

The device names are not necessarily consistent across reboots which can
make it more difficult to identify the right file system when tracking
down issues using system logs.

Print file system UUID string on every mount, remount and unmount to
make this task easier.

This is similar to the functionality recently propsed for XFS.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Lukas Herbolt <lukas@herbolt.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20221108145042.85770-1-lczerner@redhat.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -1206,7 +1206,8 @@ static void ext4_put_super(struct super_block *sb)
 	ext4_unregister_sysfs(sb);
 
 	if (___ratelimit(&ext4_mount_msg_ratelimit, "EXT4-fs unmount"))
-		ext4_msg(sb, KERN_INFO, "unmounting filesystem.");
+		ext4_msg(sb, KERN_INFO, "unmounting filesystem %pU.",
+			 &sb->s_uuid);
 
 	ext4_unregister_li_request(sb);
 	ext4_quota_off_umount(sb);
@@ -5655,8 +5656,9 @@ static int ext4_fill_super(struct super_block *sb, struct fs_context *fc)
 		descr = "out journal";
 
 	if (___ratelimit(&ext4_mount_msg_ratelimit, "EXT4-fs mount"))
-		ext4_msg(sb, KERN_INFO, "mounted filesystem with%s. "
-			 "Quota mode: %s.", descr, ext4_quota_mode(sb));
+		ext4_msg(sb, KERN_INFO, "mounted filesystem %pU with%s. "
+			 "Quota mode: %s.", &sb->s_uuid, descr,
+			 ext4_quota_mode(sb));
 
 	/* Update the s_overhead_clusters if necessary */
 	ext4_update_overhead(sb, false);
@@ -6611,8 +6613,8 @@ static int ext4_reconfigure(struct fs_context *fc)
 	if (ret < 0)
 		return ret;
 
-	ext4_msg(sb, KERN_INFO, "re-mounted. Quota mode: %s.",
-		 ext4_quota_mode(sb));
+	ext4_msg(sb, KERN_INFO, "re-mounted %pU. Quota mode: %s.",
+		 &sb->s_uuid, ext4_quota_mode(sb));
 
 	return 0;
 }