Commit 8bb93aac authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds

[PATCH] md: expose md metadata format in sysfs

Allow it to be set to a particular version, or 'none'.
Signed-off-by: default avatarNeil Brown <>
Acked-by: Greg Kroah-Hartman's avatarGreg KH <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent a35b0d69
......@@ -183,6 +183,12 @@ All md devices contain:
the array if the personality supports it (raid1, raid5, raid6),
and if the component drives are large enough.
This indicates the format that is being used to record metadata
about the array. It can be 0.90 (traditional format), 1.0, 1.1,
1.2 (newer format in varying locations) or "none" indicating that
the kernel isn't managing metadata at all.
As component devices are added to an md array, they appear in the 'md'
directory as new directories named
......@@ -1857,6 +1857,54 @@ size_store(mddev_t *mddev, const char *buf, size_t len)
static struct md_sysfs_entry md_size =
__ATTR(component_size, 0644, size_show, size_store);
/* Metdata version.
* This is either 'none' for arrays with externally managed metadata,
* or N.M for internally known formats
static ssize_t
metadata_show(mddev_t *mddev, char *page)
if (mddev->persistent)
return sprintf(page, "%d.%d\n",
mddev->major_version, mddev->minor_version);
return sprintf(page, "none\n");
static ssize_t
metadata_store(mddev_t *mddev, const char *buf, size_t len)
int major, minor;
char *e;
if (!list_empty(&mddev->disks))
return -EBUSY;
if (cmd_match(buf, "none")) {
mddev->persistent = 0;
mddev->major_version = 0;
mddev->minor_version = 90;
return len;
major = simple_strtoul(buf, &e, 10);
if (e==buf || *e != '.')
return -EINVAL;
buf = e+1;
minor = simple_strtoul(buf, &e, 10);
if (e==buf || *e != '\n')
return -EINVAL;
if (major >= sizeof(super_types)/sizeof(super_types[0]) ||
super_types[major].name == NULL)
return -ENOENT;
mddev->major_version = major;
mddev->minor_version = minor;
mddev->persistent = 1;
return len;
static struct md_sysfs_entry md_metadata =
__ATTR(metadata_version, 0644, metadata_show, metadata_store);
static ssize_t
action_show(mddev_t *mddev, char *page)
......@@ -1926,6 +1974,7 @@ static struct attribute *md_default_attrs[] = {
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