[PATCH 004 of 5] md: Allow reshape_position for md arrays to be set via sysfs.


"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@xxxxxxx>

### Diffstat output
./Documentation/md.txt | 72 +++++++++++++++++++++++++++++--------------------
./drivers/md/md.c | 70 ++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 107 insertions(+), 35 deletions(-)

diff .prev/Documentation/md.txt ./Documentation/md.txt
--- .prev/Documentation/md.txt 2007-05-07 15:38:13.000000000 +1000
+++ ./Documentation/md.txt 2007-05-07 15:49:01.000000000 +1000
@@ -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
@@ -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
@@ -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
@@ -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

diff .prev/drivers/md/md.c ./drivers/md/md.c
--- .prev/drivers/md/md.c 2007-05-07 14:57:41.000000000 +1000
+++ ./drivers/md/md.c 2007-05-07 15:18:16.000000000 +1000
@@ -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) {
@@ -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);
}

@@ -2250,13 +2255,16 @@ layout_store(mddev_t *mddev, const char
{
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 =
@@ -2268,6 +2276,10 @@ raid_disks_show(mddev_t *mddev, char *pa
{
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);
}

@@ -2285,7 +2297,11 @@ raid_disks_store(mddev_t *mddev, const c

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;
}
@@ -2295,6 +2311,10 @@ __ATTR(raid_disks, S_IRUGO|S_IWUSR, raid
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);
}

@@ -2305,12 +2325,15 @@ chunk_size_store(mddev_t *mddev, const c
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 =
@@ -2896,6 +2919,37 @@ suspend_hi_store(mddev_t *mddev, const c
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,
@@ -2908,6 +2962,7 @@ static struct attribute *md_default_attr
&md_new_device.attr,
&md_safe_delay.attr,
&md_array_state.attr,
+ &md_reshape_position.attr,
NULL,
};

@@ -3446,6 +3501,7 @@ static int do_md_stop(mddev_t * mddev, i
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",
-
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