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authorJonathan Brassow <jbrassow@redhat.com>2007-07-12 17:29:04 +0100
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-12 15:01:08 -0700
commitf44db678edcc6f4c2779ac43f63f0b9dfa28b724 (patch)
treebbd835d00ca6ed0805c5c7331ebc5dd7978d299c /drivers/md
parentd0d444c7d48c14d59f665887c758fde248f1cb37 (diff)
downloadop-kernel-dev-f44db678edcc6f4c2779ac43f63f0b9dfa28b724.zip
op-kernel-dev-f44db678edcc6f4c2779ac43f63f0b9dfa28b724.tar.gz
dm raid1: handle resync failures
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 <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-raid1.c44
1 files changed, 41 insertions, 3 deletions
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 04dce7a..dee4221 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -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 *rh, struct mirror_set *ms,
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 region_hash *rh)
LIST_HEAD(clean);
LIST_HEAD(recovered);
+ LIST_HEAD(failed_recovered);
/*
* Quickly grab the lists.
@@ -389,6 +393,15 @@ static void rh_update_states(struct region_hash *rh)
list_for_each_entry (reg, &recovered, list)
list_del(&reg->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(&reg->hash_list);
+ }
+
spin_unlock(&rh->region_lock);
write_unlock_irq(&rh->hash_lock);
@@ -403,6 +416,11 @@ static void rh_update_states(struct region_hash *rh)
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(struct region_hash *rh)
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(&reg->list, &reg->rh->recovered_regions);
+ if (success)
+ list_add(&reg->list, &reg->rh->recovered_regions);
+ else {
+ reg->state = RH_NOSYNC;
+ list_add(&reg->list, &reg->rh->failed_recovered_regions);
+ }
spin_unlock_irq(&rh->region_lock);
wake(rh->ms);
@@ -633,7 +655,14 @@ static void recovery_complete(int read_err, unsigned int write_err,
{
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 *ti, unsigned int argc, char **argv)
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);
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