dm raid: add region_size parameter
Allow the user to specify the region_size.
Ensures that the supplied value meets md's constraints, viz. the number of
regions does not exceed 2^21.
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/Documentation/device-mapper/dm-raid.txt b/Documentation/device-mapper/dm-raid.txt
index 4f9dd3c..be4419a 100644
--- a/Documentation/device-mapper/dm-raid.txt
+++ b/Documentation/device-mapper/dm-raid.txt
@@ -52,6 +52,10 @@
[max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
[max_write_behind <sectors>] See '-write-behind=' (man mdadm)
[stripe_cache <sectors>] Stripe cache size (higher RAIDs only)
+ [region_size <sectors>]
+ The region_size multiplied by the number of regions is the
+ logical size of the array. The bitmap records the device
+ synchronisation state for each region.
<#raid_devs>: The number of devices composing the array.
Each device consists of two entries. The first is the device
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index d4e95b2..a8a1915 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -52,7 +52,7 @@
#define DMPF_MAX_RECOVERY_RATE 0x20
#define DMPF_MAX_WRITE_BEHIND 0x40
#define DMPF_STRIPE_CACHE 0x80
-
+#define DMPF_REGION_SIZE 0X100
struct raid_set {
struct dm_target *ti;
@@ -237,6 +237,67 @@
}
/*
+ * validate_region_size
+ * @rs
+ * @region_size: region size in sectors. If 0, pick a size (4MiB default).
+ *
+ * Set rs->md.bitmap_info.chunksize (which really refers to 'region size').
+ * Ensure that (ti->len/region_size < 2^21) - required by MD bitmap.
+ *
+ * Returns: 0 on success, -EINVAL on failure.
+ */
+static int validate_region_size(struct raid_set *rs, unsigned long region_size)
+{
+ unsigned long min_region_size = rs->ti->len / (1 << 21);
+
+ if (!region_size) {
+ /*
+ * Choose a reasonable default. All figures in sectors.
+ */
+ if (min_region_size > (1 << 13)) {
+ DMINFO("Choosing default region size of %lu sectors",
+ region_size);
+ region_size = min_region_size;
+ } else {
+ DMINFO("Choosing default region size of 4MiB");
+ region_size = 1 << 13; /* sectors */
+ }
+ } else {
+ /*
+ * Validate user-supplied value.
+ */
+ if (region_size > rs->ti->len) {
+ rs->ti->error = "Supplied region size is too large";
+ return -EINVAL;
+ }
+
+ if (region_size < min_region_size) {
+ DMERR("Supplied region_size (%lu sectors) below minimum (%lu)",
+ region_size, min_region_size);
+ rs->ti->error = "Supplied region size is too small";
+ return -EINVAL;
+ }
+
+ if (!is_power_of_2(region_size)) {
+ rs->ti->error = "Region size is not a power of 2";
+ return -EINVAL;
+ }
+
+ if (region_size < rs->md.chunk_sectors) {
+ rs->ti->error = "Region size is smaller than the chunk size";
+ return -EINVAL;
+ }
+ }
+
+ /*
+ * Convert sectors to bytes.
+ */
+ rs->md.bitmap_info.chunksize = (region_size << 9);
+
+ return 0;
+}
+
+/*
* Possible arguments are...
* RAID456:
* <chunk_size> [optional_args]
@@ -249,12 +310,13 @@
* [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
* [max_write_behind <sectors>] See '-write-behind=' (man mdadm)
* [stripe_cache <sectors>] Stripe cache size for higher RAIDs
+ * [region_size <sectors>] Defines granularity of bitmap
*/
static int parse_raid_params(struct raid_set *rs, char **argv,
unsigned num_raid_params)
{
unsigned i, rebuild_cnt = 0;
- unsigned long value;
+ unsigned long value, region_size = 0;
char *key;
/*
@@ -365,6 +427,9 @@
return -EINVAL;
}
rs->md.sync_speed_max = (int)value;
+ } else if (!strcasecmp(key, "region_size")) {
+ rs->print_flags |= DMPF_REGION_SIZE;
+ region_size = value;
} else {
DMERR("Unable to parse RAID parameter: %s", key);
rs->ti->error = "Unable to parse RAID parameters";
@@ -372,6 +437,14 @@
}
}
+ if (validate_region_size(rs, region_size))
+ return -EINVAL;
+
+ if (rs->md.chunk_sectors)
+ rs->ti->split_io = rs->md.chunk_sectors;
+ else
+ rs->ti->split_io = region_size;
+
/* Assume there are no metadata devices until the drives are parsed */
rs->md.persistent = 0;
rs->md.external = 1;
@@ -469,7 +542,6 @@
goto bad;
INIT_WORK(&rs->md.event_work, do_table_event);
- ti->split_io = rs->md.chunk_sectors;
ti->private = rs;
mutex_lock(&rs->md.reconfig_mutex);
@@ -596,6 +668,10 @@
conf ? conf->max_nr_stripes * 2 : 0);
}
+ if (rs->print_flags & DMPF_REGION_SIZE)
+ DMEMIT(" region_size %lu",
+ rs->md.bitmap_info.chunksize >> 9);
+
DMEMIT(" %d", rs->md.raid_disks);
for (i = 0; i < rs->md.raid_disks; i++) {
DMEMIT(" -"); /* metadata device */