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authorNeilBrown <neilb@suse.de>2012-05-21 01:27:00 +0200
committerNeilBrown <neilb@suse.de>2012-05-21 01:27:00 +0200
commit2c810cddc44d6f95cef75df3f07fc0850ff92417 (patch)
tree185b35ce06656a53327dd66343f0926aa5a910d7 /drivers/md/md.c
parentmd: using GFP_NOIO to allocate bio for flush request (diff)
downloadlinux-2c810cddc44d6f95cef75df3f07fc0850ff92417.tar.xz
linux-2c810cddc44d6f95cef75df3f07fc0850ff92417.zip
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/md.c')
-rw-r--r--drivers/md/md.c67
1 files changed, 65 insertions, 2 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 2b30ffdb81b2..44bb1d52dd4c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -607,6 +607,7 @@ void mddev_init(struct mddev *mddev)
init_waitqueue_head(&mddev->sb_wait);
init_waitqueue_head(&mddev->recovery_wait);
mddev->reshape_position = MaxSector;
+ mddev->reshape_backwards = 0;
mddev->resync_min = 0;
mddev->resync_max = MaxSector;
mddev->level = LEVEL_NONE;
@@ -1185,6 +1186,7 @@ static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev)
mddev->events = ev1;
mddev->bitmap_info.offset = 0;
mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
+ mddev->reshape_backwards = 0;
if (mddev->minor_version >= 91) {
mddev->reshape_position = sb->reshape_position;
@@ -1192,6 +1194,8 @@ static int super_90_validate(struct mddev *mddev, struct md_rdev *rdev)
mddev->new_level = sb->new_level;
mddev->new_layout = sb->new_layout;
mddev->new_chunk_sectors = sb->new_chunk >> 9;
+ if (mddev->delta_disks < 0)
+ mddev->reshape_backwards = 1;
} else {
mddev->reshape_position = MaxSector;
mddev->delta_disks = 0;
@@ -1645,7 +1649,8 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
mddev->events = ev1;
mddev->bitmap_info.offset = 0;
mddev->bitmap_info.default_offset = 1024 >> 9;
-
+ mddev->reshape_backwards = 0;
+
mddev->recovery_cp = le64_to_cpu(sb->resync_offset);
memcpy(mddev->uuid, sb->set_uuid, 16);
@@ -1662,6 +1667,11 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *rdev)
mddev->new_level = le32_to_cpu(sb->new_level);
mddev->new_layout = le32_to_cpu(sb->new_layout);
mddev->new_chunk_sectors = le32_to_cpu(sb->new_chunk);
+ if (mddev->delta_disks < 0 ||
+ (mddev->delta_disks == 0 &&
+ (le32_to_cpu(sb->feature_map)
+ & MD_FEATURE_RESHAPE_BACKWARDS)))
+ mddev->reshape_backwards = 1;
} else {
mddev->reshape_position = MaxSector;
mddev->delta_disks = 0;
@@ -1781,6 +1791,10 @@ static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
sb->delta_disks = cpu_to_le32(mddev->delta_disks);
sb->new_level = cpu_to_le32(mddev->new_level);
sb->new_chunk = cpu_to_le32(mddev->new_chunk_sectors);
+ if (mddev->delta_disks == 0 &&
+ mddev->reshape_backwards)
+ sb->feature_map
+ |= cpu_to_le32(MD_FEATURE_RESHAPE_BACKWARDS);
}
if (rdev->badblocks.count == 0)
@@ -3419,6 +3433,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
mddev->new_chunk_sectors = mddev->chunk_sectors;
mddev->raid_disks -= mddev->delta_disks;
mddev->delta_disks = 0;
+ mddev->reshape_backwards = 0;
module_put(pers->owner);
printk(KERN_WARNING "md: %s: %s would not accept array\n",
mdname(mddev), clevel);
@@ -3492,6 +3507,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
mddev->layout = mddev->new_layout;
mddev->chunk_sectors = mddev->new_chunk_sectors;
mddev->delta_disks = 0;
+ mddev->reshape_backwards = 0;
mddev->degraded = 0;
if (mddev->pers->sync_request == NULL) {
/* this is now an array without redundancy, so
@@ -3585,6 +3601,7 @@ raid_disks_store(struct mddev *mddev, const char *buf, size_t len)
int olddisks = mddev->raid_disks - mddev->delta_disks;
mddev->delta_disks = n - olddisks;
mddev->raid_disks = n;
+ mddev->reshape_backwards = (mddev->delta_disks < 0);
} else
mddev->raid_disks = n;
return rv ? rv : len;
@@ -4436,6 +4453,7 @@ reshape_position_store(struct mddev *mddev, const char *buf, size_t len)
return -EINVAL;
mddev->reshape_position = new;
mddev->delta_disks = 0;
+ mddev->reshape_backwards = 0;
mddev->new_level = mddev->level;
mddev->new_layout = mddev->layout;
mddev->new_chunk_sectors = mddev->chunk_sectors;
@@ -4447,6 +4465,42 @@ __ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
reshape_position_store);
static ssize_t
+reshape_direction_show(struct mddev *mddev, char *page)
+{
+ return sprintf(page, "%s\n",
+ mddev->reshape_backwards ? "backwards" : "forwards");
+}
+
+static ssize_t
+reshape_direction_store(struct mddev *mddev, const char *buf, size_t len)
+{
+ int backwards = 0;
+ if (cmd_match(buf, "forwards"))
+ backwards = 0;
+ else if (cmd_match(buf, "backwards"))
+ backwards = 1;
+ else
+ return -EINVAL;
+ if (mddev->reshape_backwards == backwards)
+ return len;
+
+ /* check if we are allowed to change */
+ if (mddev->delta_disks)
+ return -EBUSY;
+
+ if (mddev->persistent &&
+ mddev->major_version == 0)
+ return -EINVAL;
+
+ mddev->reshape_backwards = backwards;
+ return len;
+}
+
+static struct md_sysfs_entry md_reshape_direction =
+__ATTR(reshape_direction, S_IRUGO|S_IWUSR, reshape_direction_show,
+ reshape_direction_store);
+
+static ssize_t
array_size_show(struct mddev *mddev, char *page)
{
if (mddev->external_size)
@@ -4501,6 +4555,7 @@ static struct attribute *md_default_attrs[] = {
&md_safe_delay.attr,
&md_array_state.attr,
&md_reshape_position.attr,
+ &md_reshape_direction.attr,
&md_array_size.attr,
&max_corr_read_errors.attr,
NULL,
@@ -5064,6 +5119,7 @@ static void md_clean(struct mddev *mddev)
mddev->events = 0;
mddev->can_decrease_events = 0;
mddev->delta_disks = 0;
+ mddev->reshape_backwards = 0;
mddev->new_level = LEVEL_NONE;
mddev->new_layout = 0;
mddev->new_chunk_sectors = 0;
@@ -5888,6 +5944,7 @@ static int set_array_info(struct mddev * mddev, mdu_array_info_t *info)
mddev->new_chunk_sectors = mddev->chunk_sectors;
mddev->new_layout = mddev->layout;
mddev->delta_disks = 0;
+ mddev->reshape_backwards = 0;
return 0;
}
@@ -5953,10 +6010,16 @@ static int update_raid_disks(struct mddev *mddev, int raid_disks)
if (mddev->sync_thread || mddev->reshape_position != MaxSector)
return -EBUSY;
mddev->delta_disks = raid_disks - mddev->raid_disks;
+ if (mddev->delta_disks < 0)
+ mddev->reshape_backwards = 1;
+ else if (mddev->delta_disks > 0)
+ mddev->reshape_backwards = 0;
rv = mddev->pers->check_reshape(mddev);
- if (rv < 0)
+ if (rv < 0) {
mddev->delta_disks = 0;
+ mddev->reshape_backwards = 0;
+ }
return rv;
}