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md: allow reshape_position for md arrays to be set via sysfs
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"reshape_position" records how much progress has been made on a "reshape"
(adding drives, changing layout or chunksize).

When it is set, the number of drives, layout and chunksize can have
two possible values, an old an a new.

So allow these different values to be visible, and allow both old and new to
be set: Set the old ones first, then the reshape_position, then the new
values.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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NeilBrown authored and Linus Torvalds committed May 9, 2007
1 parent 42b9beb commit 08a02ec
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72 changes: 44 additions & 28 deletions Documentation/md.txt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -178,6 +178,21 @@ All md devices contain:
The size should be at least PAGE_SIZE (4k) and should be a power
of 2. This can only be set while assembling an array

layout
The "layout" for the array for the particular level. This is
simply a number that is interpretted differently by different
levels. It can be written while assembling an array.

reshape_position
This is either "none" or a sector number within the devices of
the array where "reshape" is up to. If this is set, the three
attributes mentioned above (raid_disks, chunk_size, layout) can
potentially have 2 values, an old and a new value. If these
values differ, reading the attribute returns
new (old)
and writing will effect the 'new' value, leaving the 'old'
unchanged.

component_size
For arrays with data redundancy (i.e. not raid0, linear, faulty,
multipath), all components must be the same size - or at least
Expand All @@ -193,11 +208,6 @@ All md devices contain:
1.2 (newer format in varying locations) or "none" indicating that
the kernel isn't managing metadata at all.

layout
The "layout" for the array for the particular level. This is
simply a number that is interpretted differently by different
levels. It can be written while assembling an array.

resync_start
The point at which resync should start. If no resync is needed,
this will be a very large number. At array creation it will
Expand Down Expand Up @@ -259,29 +269,6 @@ All md devices contain:
like active, but no writes have been seen for a while (safe_mode_delay).


sync_speed_min
sync_speed_max
This are similar to /proc/sys/dev/raid/speed_limit_{min,max}
however they only apply to the particular array.
If no value has been written to these, of if the word 'system'
is written, then the system-wide value is used. If a value,
in kibibytes-per-second is written, then it is used.
When the files are read, they show the currently active value
followed by "(local)" or "(system)" depending on whether it is
a locally set or system-wide value.

sync_completed
This shows the number of sectors that have been completed of
whatever the current sync_action is, followed by the number of
sectors in total that could need to be processed. The two
numbers are separated by a '/' thus effectively showing one
value, a fraction of the process that is complete.

sync_speed
This shows the current actual speed, in K/sec, of the current
sync_action. It is averaged over the last 30 seconds.


As component devices are added to an md array, they appear in the 'md'
directory as new directories named
dev-XXX
Expand Down Expand Up @@ -412,6 +399,35 @@ also have
Note that the numbers are 'bit' numbers, not 'block' numbers.
They should be scaled by the bitmap_chunksize.

sync_speed_min
sync_speed_max
This are similar to /proc/sys/dev/raid/speed_limit_{min,max}
however they only apply to the particular array.
If no value has been written to these, of if the word 'system'
is written, then the system-wide value is used. If a value,
in kibibytes-per-second is written, then it is used.
When the files are read, they show the currently active value
followed by "(local)" or "(system)" depending on whether it is
a locally set or system-wide value.

sync_completed
This shows the number of sectors that have been completed of
whatever the current sync_action is, followed by the number of
sectors in total that could need to be processed. The two
numbers are separated by a '/' thus effectively showing one
value, a fraction of the process that is complete.

sync_speed
This shows the current actual speed, in K/sec, of the current
sync_action. It is averaged over the last 30 seconds.

suspend_lo
suspend_hi
The two values, given as numbers of sectors, indicate a range
within the array where IO will be blocked. This is currently
only supported for raid4/5/6.


Each active md device may also have attributes specific to the
personality module that manages it.
These are specific to the implementation of the module and could
Expand Down
70 changes: 63 additions & 7 deletions drivers/md/md.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -274,6 +274,7 @@ static mddev_t * mddev_find(dev_t unit)
atomic_set(&new->active, 1);
spin_lock_init(&new->write_lock);
init_waitqueue_head(&new->sb_wait);
new->reshape_position = MaxSector;

new->queue = blk_alloc_queue(GFP_KERNEL);
if (!new->queue) {
Expand Down Expand Up @@ -2242,6 +2243,10 @@ static ssize_t
layout_show(mddev_t *mddev, char *page)
{
/* just a number, not meaningful for all levels */
if (mddev->reshape_position != MaxSector &&
mddev->layout != mddev->new_layout)
return sprintf(page, "%d (%d)\n",
mddev->new_layout, mddev->layout);
return sprintf(page, "%d\n", mddev->layout);
}

Expand All @@ -2250,13 +2255,16 @@ layout_store(mddev_t *mddev, const char *buf, size_t len)
{
char *e;
unsigned long n = simple_strtoul(buf, &e, 10);
if (mddev->pers)
return -EBUSY;

if (!*buf || (*e && *e != '\n'))
return -EINVAL;

mddev->layout = n;
if (mddev->pers)
return -EBUSY;
if (mddev->reshape_position != MaxSector)
mddev->new_layout = n;
else
mddev->layout = n;
return len;
}
static struct md_sysfs_entry md_layout =
Expand All @@ -2268,6 +2276,10 @@ raid_disks_show(mddev_t *mddev, char *page)
{
if (mddev->raid_disks == 0)
return 0;
if (mddev->reshape_position != MaxSector &&
mddev->delta_disks != 0)
return sprintf(page, "%d (%d)\n", mddev->raid_disks,
mddev->raid_disks - mddev->delta_disks);
return sprintf(page, "%d\n", mddev->raid_disks);
}

Expand All @@ -2285,7 +2297,11 @@ raid_disks_store(mddev_t *mddev, const char *buf, size_t len)

if (mddev->pers)
rv = update_raid_disks(mddev, n);
else
else if (mddev->reshape_position != MaxSector) {
int olddisks = mddev->raid_disks - mddev->delta_disks;
mddev->delta_disks = n - olddisks;
mddev->raid_disks = n;
} else
mddev->raid_disks = n;
return rv ? rv : len;
}
Expand All @@ -2295,6 +2311,10 @@ __ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);
static ssize_t
chunk_size_show(mddev_t *mddev, char *page)
{
if (mddev->reshape_position != MaxSector &&
mddev->chunk_size != mddev->new_chunk)
return sprintf(page, "%d (%d)\n", mddev->new_chunk,
mddev->chunk_size);
return sprintf(page, "%d\n", mddev->chunk_size);
}

Expand All @@ -2305,12 +2325,15 @@ chunk_size_store(mddev_t *mddev, const char *buf, size_t len)
char *e;
unsigned long n = simple_strtoul(buf, &e, 10);

if (mddev->pers)
return -EBUSY;
if (!*buf || (*e && *e != '\n'))
return -EINVAL;

mddev->chunk_size = n;
if (mddev->pers)
return -EBUSY;
else if (mddev->reshape_position != MaxSector)
mddev->new_chunk = n;
else
mddev->chunk_size = n;
return len;
}
static struct md_sysfs_entry md_chunk_size =
Expand Down Expand Up @@ -2896,6 +2919,37 @@ suspend_hi_store(mddev_t *mddev, const char *buf, size_t len)
static struct md_sysfs_entry md_suspend_hi =
__ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);

static ssize_t
reshape_position_show(mddev_t *mddev, char *page)
{
if (mddev->reshape_position != MaxSector)
return sprintf(page, "%llu\n",
(unsigned long long)mddev->reshape_position);
strcpy(page, "none\n");
return 5;
}

static ssize_t
reshape_position_store(mddev_t *mddev, const char *buf, size_t len)
{
char *e;
unsigned long long new = simple_strtoull(buf, &e, 10);
if (mddev->pers)
return -EBUSY;
if (buf == e || (*e && *e != '\n'))
return -EINVAL;
mddev->reshape_position = new;
mddev->delta_disks = 0;
mddev->new_level = mddev->level;
mddev->new_layout = mddev->layout;
mddev->new_chunk = mddev->chunk_size;
return len;
}

static struct md_sysfs_entry md_reshape_position =
__ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
reshape_position_store);


static struct attribute *md_default_attrs[] = {
&md_level.attr,
Expand All @@ -2908,6 +2962,7 @@ static struct attribute *md_default_attrs[] = {
&md_new_device.attr,
&md_safe_delay.attr,
&md_array_state.attr,
&md_reshape_position.attr,
NULL,
};

Expand Down Expand Up @@ -3446,6 +3501,7 @@ static int do_md_stop(mddev_t * mddev, int mode)
mddev->size = 0;
mddev->raid_disks = 0;
mddev->recovery_cp = 0;
mddev->reshape_position = MaxSector;

} else if (mddev->pers)
printk(KERN_INFO "md: %s switched to read-only mode.\n",
Expand Down

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