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authorNeilBrown <neilb@suse.de>2012-05-21 09:27:00 +1000
committerNeilBrown <neilb@suse.de>2012-05-21 09:27:00 +1000
commit2c810cddc44d6f95cef75df3f07fc0850ff92417 (patch)
tree185b35ce06656a53327dd66343f0926aa5a910d7 /drivers/md/raid5.c
parentb5e1b8cee7ad58a15d2fa79bcd7946acb592602d (diff)
downloadop-kernel-dev-2c810cddc44d6f95cef75df3f07fc0850ff92417.zip
op-kernel-dev-2c810cddc44d6f95cef75df3f07fc0850ff92417.tar.gz
md: allow a reshape operation to be reversed.
Currently a reshape operation always progresses from the start of the array to the end unless the number of devices is being reduced, in which case it progressed in the opposite direction. To reverse a partial reshape which changes the number of devices you can stop the array and re-assemble with the raid-disks numbers reversed and it will undo. However for a reshape that does not change the number of devices it is not possible to reverse the reshape in the middle - you have to wait until it completes. So add a 'reshape_direction' attribute with is either 'forwards' or 'backwards' and can be explicitly set when delta_disks is zero. This will become more important when we allow the data_offset to change in a reshape. Then the explicit statement of what direction is being used will be more useful. This can be enabled in raid5 trivially as it already supports reverse reshape and just needs to use a different trigger to request it. Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md/raid5.c')
-rw-r--r--drivers/md/raid5.c23
1 files changed, 12 insertions, 11 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f351422..0abbd34 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3970,13 +3970,13 @@ static void make_request(struct mddev *mddev, struct bio * bi)
* to check again.
*/
spin_lock_irq(&conf->device_lock);
- if (mddev->delta_disks < 0
+ if (mddev->reshape_backwards
? logical_sector < conf->reshape_progress
: logical_sector >= conf->reshape_progress) {
disks = conf->previous_raid_disks;
previous = 1;
} else {
- if (mddev->delta_disks < 0
+ if (mddev->reshape_backwards
? logical_sector < conf->reshape_safe
: logical_sector >= conf->reshape_safe) {
spin_unlock_irq(&conf->device_lock);
@@ -4009,7 +4009,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
*/
int must_retry = 0;
spin_lock_irq(&conf->device_lock);
- if (mddev->delta_disks < 0
+ if (mddev->reshape_backwards
? logical_sector >= conf->reshape_progress
: logical_sector < conf->reshape_progress)
/* mismatch, need to try again */
@@ -4108,11 +4108,11 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
if (sector_nr == 0) {
/* If restarting in the middle, skip the initial sectors */
- if (mddev->delta_disks < 0 &&
+ if (mddev->reshape_backwards &&
conf->reshape_progress < raid5_size(mddev, 0, 0)) {
sector_nr = raid5_size(mddev, 0, 0)
- conf->reshape_progress;
- } else if (mddev->delta_disks >= 0 &&
+ } else if (!mddev->reshape_backwards &&
conf->reshape_progress > 0)
sector_nr = conf->reshape_progress;
sector_div(sector_nr, new_data_disks);
@@ -4147,7 +4147,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
sector_div(readpos, data_disks);
safepos = conf->reshape_safe;
sector_div(safepos, data_disks);
- if (mddev->delta_disks < 0) {
+ if (mddev->reshape_backwards) {
writepos -= min_t(sector_t, reshape_sectors, writepos);
readpos += reshape_sectors;
safepos += reshape_sectors;
@@ -4174,7 +4174,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
* Maybe that number should be configurable, but I'm not sure it is
* worth it.... maybe it could be a multiple of safemode_delay???
*/
- if ((mddev->delta_disks < 0
+ if ((mddev->reshape_backwards
? (safepos > writepos && readpos < writepos)
: (safepos < writepos && readpos > writepos)) ||
time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
@@ -4195,7 +4195,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
sysfs_notify(&mddev->kobj, NULL, "sync_completed");
}
- if (mddev->delta_disks < 0) {
+ if (mddev->reshape_backwards) {
BUG_ON(conf->reshape_progress == 0);
stripe_addr = writepos;
BUG_ON((mddev->dev_sectors &
@@ -4239,7 +4239,7 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
list_add(&sh->lru, &stripes);
}
spin_lock_irq(&conf->device_lock);
- if (mddev->delta_disks < 0)
+ if (mddev->reshape_backwards)
conf->reshape_progress -= reshape_sectors * new_data_disks;
else
conf->reshape_progress += reshape_sectors * new_data_disks;
@@ -5008,7 +5008,7 @@ static int run(struct mddev *mddev)
mdname(mddev));
return -EINVAL;
}
- } else if (mddev->delta_disks < 0
+ } else if (mddev->reshape_backwards
? (here_new * mddev->new_chunk_sectors <=
here_old * mddev->chunk_sectors)
: (here_new * mddev->new_chunk_sectors >=
@@ -5535,7 +5535,7 @@ static int raid5_start_reshape(struct mddev *mddev)
conf->chunk_sectors = mddev->new_chunk_sectors;
conf->prev_algo = conf->algorithm;
conf->algorithm = mddev->new_layout;
- if (mddev->delta_disks < 0)
+ if (mddev->reshape_backwards)
conf->reshape_progress = raid5_size(mddev, 0, 0);
else
conf->reshape_progress = 0;
@@ -5663,6 +5663,7 @@ static void raid5_finish_reshape(struct mddev *mddev)
mddev->chunk_sectors = conf->chunk_sectors;
mddev->reshape_position = MaxSector;
mddev->delta_disks = 0;
+ mddev->reshape_backwards = 0;
}
}
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