From ec164d07aa771370c7c24c1fa7f7692ad30f01cb Mon Sep 17 00:00:00 2001 From: Sebastian Parschauer Date: Tue, 28 Jul 2020 12:01:39 +0200 Subject: [PATCH] md: register new md sysfs file 'uuid' read-only Report the UUID of the MD array in the following format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx This is useful if you don't want to wait for udev to identify array. And it is also easy for script to monitor it with the format. Signed-off-by: Sebastian Parschauer [Guoqing: mention the change in md.rst] Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu --- Documentation/admin-guide/md.rst | 4 ++++ drivers/md/md.c | 9 +++++++++ 2 files changed, 13 insertions(+) diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst index d973d469ffc4..cc8781b96b4d 100644 --- a/Documentation/admin-guide/md.rst +++ b/Documentation/admin-guide/md.rst @@ -426,6 +426,10 @@ All md devices contain: The accepted values when writing to this file are ``ppl`` and ``resync``, used to enable and disable PPL. + uuid + This indicates the UUID of the array in the following format: + xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx + As component devices are added to an md array, they appear in the ``md`` directory as new directories named:: diff --git a/drivers/md/md.c b/drivers/md/md.c index 5e8f772ab117..5116d29b74e1 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4252,6 +4252,14 @@ out_unlock: static struct md_sysfs_entry md_raid_disks = __ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store); +static ssize_t +uuid_show(struct mddev *mddev, char *page) +{ + return sprintf(page, "%pU\n", mddev->uuid); +} +static struct md_sysfs_entry md_uuid = +__ATTR(uuid, S_IRUGO, uuid_show, NULL); + static ssize_t chunk_size_show(struct mddev *mddev, char *page) { @@ -5508,6 +5516,7 @@ static struct attribute *md_default_attrs[] = { &md_level.attr, &md_layout.attr, &md_raid_disks.attr, + &md_uuid.attr, &md_chunk_size.attr, &md_size.attr, &md_resync_start.attr,