From 2c810cddc44d6f95cef75df3f07fc0850ff92417 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 21 May 2012 09:27:00 +1000 Subject: [PATCH] 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 --- drivers/md/md.c | 67 +++++++++++++++++++++++++++++++++++++++++++++-- drivers/md/md.h | 1 + drivers/md/raid5.c | 23 ++++++++-------- include/linux/raid/md_p.h | 7 ++++- 4 files changed, 84 insertions(+), 14 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 2b30ffd..44bb1d5 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; } diff --git a/drivers/md/md.h b/drivers/md/md.h index 1c2063c..d51c0ca 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -262,6 +262,7 @@ struct mddev { sector_t reshape_position; int delta_disks, new_level, new_layout; int new_chunk_sectors; + int reshape_backwards; atomic_t plug_cnt; /* If device is expecting * more bios soon. 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; } } diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h index 8c0a3ad..07e05f9 100644 --- a/include/linux/raid/md_p.h +++ b/include/linux/raid/md_p.h @@ -281,10 +281,15 @@ struct mdp_superblock_1 { * active device with same 'role'. * 'recovery_offset' is also set. */ +#define MD_FEATURE_RESHAPE_BACKWARDS 32 /* Reshape doesn't change number + * of devices, but is going + * backwards anyway. + */ #define MD_FEATURE_ALL (MD_FEATURE_BITMAP_OFFSET \ |MD_FEATURE_RECOVERY_OFFSET \ |MD_FEATURE_RESHAPE_ACTIVE \ |MD_FEATURE_BAD_BLOCKS \ - |MD_FEATURE_REPLACEMENT) + |MD_FEATURE_REPLACEMENT \ + |MD_FEATURE_RESHAPE_BACKWARDS) #endif -- 2.7.4