[PATCH 008 of 11] md: Allow a linear array to have drives added while active.

NeilBrown
2006-05-01T05:31:59Z

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./drivers/md/linear.c | 74 ++++++++++++++++++++++++++++++++++--------
./drivers/md/md.c | 15 +++++++-
./include/linux/raid/linear.h | 2 +
3 files changed, 76 insertions(+), 15 deletions(-)

diff ./drivers/md/linear.c~current~ ./drivers/md/linear.c
--- ./drivers/md/linear.c~current~ 2006-05-01 15:09:20.000000000 +1000
+++ ./drivers/md/linear.c 2006-05-01 15:13:14.000000000 +1000
@@ -111,7 +111,7 @@ static int linear_issue_flush(request_qu
return ret;
}

-static int linear_run (mddev_t *mddev)
+static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
{
linear_conf_t *conf;
dev_info_t **table;
@@ -121,20 +121,21 @@ static int linear_run (mddev_t *mddev)
sector_t curr_offset;
struct list_head *tmp;

- conf = kzalloc (sizeof (*conf) + mddev->raid_disks*sizeof(dev_info_t),
+ conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
GFP_KERNEL);
if (!conf)
- goto out;
+ return NULL;
+
mddev->private = conf;

cnt = 0;
- mddev->array_size = 0;
+ conf->array_size = 0;

ITERATE_RDEV(mddev,rdev,tmp) {
int j = rdev->raid_disk;
dev_info_t *disk = conf->disks + j;

- if (j < 0 || j > mddev->raid_disks || disk->rdev) {
+ if (j < 0 || j > raid_disks || disk->rdev) {
printk("linear: disk numbering problem. Aborting!\n");
goto out;
}
@@ -152,11 +153,11 @@ static int linear_run (mddev_t *mddev)
blk_queue_max_sectors(mddev->queue, PAGE_SIZE>>9);

disk->size = rdev->size;
- mddev->array_size += rdev->size;
+ conf->array_size += rdev->size;

cnt++;
}
- if (cnt != mddev->raid_disks) {
+ if (cnt != raid_disks) {
printk("linear: not enough drives present. Aborting!\n");
goto out;
}
@@ -200,7 +201,7 @@ static int linear_run (mddev_t *mddev)
unsigned round;
unsigned long base;

- sz = mddev->array_size >> conf->preshift;
+ sz = conf->array_size >> conf->preshift;
sz += 1; /* force round-up */
base = conf->hash_spacing >> conf->preshift;
round = sector_div(sz, base);
@@ -247,14 +248,56 @@ static int linear_run (mddev_t *mddev)

BUG_ON(table - conf->hash_table > nb_zone);

+ return conf;
+
+out:
+ kfree(conf);
+ return NULL;
+}
+
+static int linear_run (mddev_t *mddev)
+{
+ linear_conf_t *conf;
+
+ conf = linear_conf(mddev, mddev->raid_disks);
+
+ if (!conf)
+ return 1;
+ mddev->private = conf;
+ mddev->array_size = conf->array_size;
+
blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
mddev->queue->unplug_fn = linear_unplug;
mddev->queue->issue_flush_fn = linear_issue_flush;
return 0;
+}

-out:
- kfree(conf);
- return 1;
+static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
+{
+ /* Adding a drive to a linear array allows the array to grow.
+ * It is permitted if the new drive has a matching superblock
+ * already on it, with raid_disk equal to raid_disks.
+ * It is achieved by creating a new linear_private_data structure
+ * and swapping it in in-place of the current one.
+ * The current one is never freed until the array is stopped.
+ * This avoids races.
+ */
+ linear_conf_t *newconf;
+
+ if (rdev->raid_disk != mddev->raid_disks)
+ return -EINVAL;
+
+ newconf = linear_conf(mddev,mddev->raid_disks+1);
+
+ if (!newconf)
+ return -ENOMEM;
+
+ newconf->prev = mddev_to_conf(mddev);
+ mddev->private = newconf;
+ mddev->raid_disks++;
+ mddev->array_size = newconf->array_size;
+ set_capacity(mddev->gendisk, mddev->array_size << 1);
+ return 0;
}

static int linear_stop (mddev_t *mddev)
@@ -262,8 +305,12 @@ static int linear_stop (mddev_t *mddev)
linear_conf_t *conf = mddev_to_conf(mddev);

blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
- kfree(conf->hash_table);
- kfree(conf);
+ do {
+ linear_conf_t *t = conf->prev;
+ kfree(conf->hash_table);
+ kfree(conf);
+ conf = t;
+ } while (conf);

return 0;
}
@@ -360,6 +407,7 @@ static struct mdk_personality linear_per
.run = linear_run,
.stop = linear_stop,
.status = linear_status,
+ .hot_add_disk = linear_add,
};

static int __init linear_init (void)

diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c~current~ 2006-05-01 15:12:34.000000000 +1000
+++ ./drivers/md/md.c 2006-05-01 15:13:14.000000000 +1000
@@ -807,8 +807,8 @@ static int super_90_validate(mddev_t *md

if (desc->state & (1<<MD_DISK_FAULTY))
set_bit(Faulty, &rdev->flags);
- else if (desc->state & (1<<MD_DISK_SYNC) &&
- desc->raid_disk < mddev->raid_disks) {
+ else if (desc->state & (1<<MD_DISK_SYNC) /* &&
+ desc->raid_disk < mddev->raid_disks */) {
set_bit(In_sync, &rdev->flags);
rdev->raid_disk = desc->raid_disk;
}
@@ -3346,6 +3346,17 @@ static int add_new_disk(mddev_t * mddev,

rdev->raid_disk = -1;
err = bind_rdev_to_array(rdev, mddev);
+ if (!err && !mddev->pers->hot_remove_disk) {
+ /* If there is hot_add_disk but no hot_remove_disk
+ * then added disks for geometry changes,
+ * and should be added immediately.
+ */
+ super_types[mddev->major_version].
+ validate_super(mddev, rdev);
+ err = mddev->pers->hot_add_disk(mddev, rdev);
+ if (err)
+ unbind_rdev_from_array(rdev);
+ }
if (err)
export_rdev(rdev);

diff ./include/linux/raid/linear.h~current~ ./include/linux/raid/linear.h
--- ./include/linux/raid/linear.h~current~ 2006-05-01 15:09:20.000000000 +1000
+++ ./include/linux/raid/linear.h 2006-05-01 15:13:14.000000000 +1000
@@ -13,8 +13,10 @@ typedef struct dev_info dev_info_t;

struct linear_private_data
{
+ struct linear_private_data *prev; /* earlier version */
dev_info_t **hash_table;
sector_t hash_spacing;
+ sector_t array_size;
int preshift; /* shift before dividing by hash_spacing */
dev_info_t disks[0];
};