From: Jonathan Brassow Device-mapper mirroring currently takes a best effort approach to recovery - failures during mirror synchronization are completely ignored. This means that regions are marked 'in-sync' and 'clean' and removed from the hash list. Future reads and writes that query the region will incorrectly interpret the region as in-sync. This patch handles failures during the recovery process. If a failure occurs, the region is marked as 'not-in-sync' (aka RH_NOSYNC) and added to a new list 'failed_recovered_regions'. Regions on the 'failed_recovered_regions' list are not marked as 'clean' upon removal from the list. Furthermore, if the DM_RAID1_HANDLE_ERRORS flag is set, the region is marked as 'not-in-sync'. This action prevents any future read-balancing from choosing an invalid device because of the 'not-in-sync' status. If "handle_errors" is not specified when creating a mirror (leaving the DM_RAID1_HANDLE_ERRORS flag unset), failures will be ignored exactly as they would be without this patch. This is to preserve backwards compatibility with user-space tools, such as 'pvmove'. However, since future read-balancing policies will rely on the correct sync status of a region, a user must choose "handle_errors" when using read-balancing. Signed-off-by: Jonathan Brassow Signed-off-by: Alasdair G Kergon --- drivers/md/dm-raid1.c | 44 +++++++++++++++++++++++++++++++++++++++++--- 1 files changed, 41 insertions(+), 3 deletions(-) Index: linux/drivers/md/dm-raid1.c =================================================================== --- linux.orig/drivers/md/dm-raid1.c 2007-07-12 17:04:04.000000000 +0100 +++ linux/drivers/md/dm-raid1.c 2007-07-12 17:04:06.000000000 +0100 @@ -24,6 +24,7 @@ #define DM_IO_PAGES 64 #define DM_RAID1_HANDLE_ERRORS 0x01 +#define errors_handled(p) ((p)->features & DM_RAID1_HANDLE_ERRORS) static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped); @@ -85,6 +86,7 @@ struct region_hash { struct list_head clean_regions; struct list_head quiesced_regions; struct list_head recovered_regions; + struct list_head failed_recovered_regions; }; enum { @@ -204,6 +206,7 @@ static int rh_init(struct region_hash *r INIT_LIST_HEAD(&rh->clean_regions); INIT_LIST_HEAD(&rh->quiesced_regions); INIT_LIST_HEAD(&rh->recovered_regions); + INIT_LIST_HEAD(&rh->failed_recovered_regions); rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS, sizeof(struct region)); @@ -368,6 +371,7 @@ static void rh_update_states(struct regi LIST_HEAD(clean); LIST_HEAD(recovered); + LIST_HEAD(failed_recovered); /* * Quickly grab the lists. @@ -389,6 +393,15 @@ static void rh_update_states(struct regi list_for_each_entry (reg, &recovered, list) list_del(®->hash_list); } + + if (!list_empty(&rh->failed_recovered_regions)) { + list_splice(&rh->failed_recovered_regions, &failed_recovered); + INIT_LIST_HEAD(&rh->failed_recovered_regions); + + list_for_each_entry(reg, &failed_recovered, list) + list_del(®->hash_list); + } + spin_unlock(&rh->region_lock); write_unlock_irq(&rh->hash_lock); @@ -403,6 +416,11 @@ static void rh_update_states(struct regi mempool_free(reg, rh->region_pool); } + list_for_each_entry_safe(reg, next, &failed_recovered, list) { + complete_resync_work(reg, errors_handled(rh->ms) ? 0 : 1); + mempool_free(reg, rh->region_pool); + } + list_for_each_entry_safe(reg, next, &clean, list) { rh->log->type->clear_region(rh->log, reg->key); mempool_free(reg, rh->region_pool); @@ -555,13 +573,17 @@ static struct region *rh_recovery_start( return reg; } -/* FIXME: success ignored for now */ static void rh_recovery_end(struct region *reg, int success) { struct region_hash *rh = reg->rh; spin_lock_irq(&rh->region_lock); - list_add(®->list, ®->rh->recovered_regions); + if (success) + list_add(®->list, ®->rh->recovered_regions); + else { + reg->state = RH_NOSYNC; + list_add(®->list, ®->rh->failed_recovered_regions); + } spin_unlock_irq(&rh->region_lock); wake(rh->ms); @@ -633,7 +655,14 @@ static void recovery_complete(int read_e { struct region *reg = (struct region *) context; - /* FIXME: better error handling */ + if (read_err) + /* Read error means the failure of default mirror. */ + DMERR_LIMIT("Unable to read primary mirror during recovery"); + + if (write_err) + DMERR_LIMIT("Write error during recovery (error = 0x%x)", + write_err); + rh_recovery_end(reg, !(read_err || write_err)); } @@ -1145,6 +1174,15 @@ static int mirror_ctr(struct dm_target * argv += args_used; argc -= args_used; + /* + * Any read-balancing addition depends on the + * DM_RAID1_HANDLE_ERRORS flag being present. + * This is because the decision to balance depends + * on the sync state of a region. If the above + * flag is not present, we ignore errors; and + * the sync state may be inaccurate. + */ + if (argc) { ti->error = "Too many mirror arguments"; free_context(ms, ti, ms->nr_mirrors);