dm raid1: keep issuing IO after leg failure

Currently if there is a leg failure, the bio will be put into the hold
list until userspace does a remove/replace on the leg.  Doing so in a
cluster config (clvmd) is problematic because there may be a temporary
path failure that results in cluster raid1 remove/replace.  Such
recovery takes a long time due to a full resync.

Update dm-raid1 to optionally ignore these failures so bios continue
being issued without interrupton.  To enable this feature userspace
must pass "keep_log" when creating the dm-raid1 device.

Signed-off-by: Lidong Zhong <lzhong@suse.com>
Tested-by: Liuhua Wang <lwang@suse.com>
Acked-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 743fa9bbae9eaafeb5e2fb7063319622e4987861..d83696bf403ba0dc9d80603ba94281887ee4f1e5 100644 (file)
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -23,8 +23,10 @@
 
 #define MAX_RECOVERY 1 /* Maximum number of regions recovered in parallel. */
 
-#define DM_RAID1_HANDLE_ERRORS 0x01
+#define DM_RAID1_HANDLE_ERRORS 0x01
+#define DM_RAID1_KEEP_LOG      0x02
 #define errors_handled(p)      ((p)->features & DM_RAID1_HANDLE_ERRORS)
+#define keep_log(p)            ((p)->features & DM_RAID1_KEEP_LOG)
 
 static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped);
 
@@ -229,7 +231,7 @@ static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type)
        if (m != get_default_mirror(ms))
                goto out;
 
-       if (!ms->in_sync) {
+       if (!ms->in_sync && !keep_log(ms)) {
                /*
                 * Better to issue requests to same failing device
                 * than to risk returning corrupt data.
@@ -370,6 +372,17 @@ static int recover(struct mirror_set *ms, struct dm_region *reg)
        return r;
 }
 
+static void reset_ms_flags(struct mirror_set *ms)
+{
+       unsigned int m;
+
+       ms->leg_failure = 0;
+       for (m = 0; m < ms->nr_mirrors; m++) {
+               atomic_set(&(ms->mirror[m].error_count), 0);
+               ms->mirror[m].error_type = 0;
+       }
+}
+
 static void do_recovery(struct mirror_set *ms)
 {
        struct dm_region *reg;
@@ -398,6 +411,7 @@ static void do_recovery(struct mirror_set *ms)
                /* the sync is complete */
                dm_table_event(ms->ti->table);
                ms->in_sync = 1;
+               reset_ms_flags(ms);
        }
 }
 
@@ -759,7 +773,7 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
                dm_rh_delay(ms->rh, bio);
 
        while ((bio = bio_list_pop(&nosync))) {
-               if (unlikely(ms->leg_failure) && errors_handled(ms)) {
+               if (unlikely(ms->leg_failure) && errors_handled(ms) && !keep_log(ms)) {
                        spin_lock_irq(&ms->lock);
                        bio_list_add(&ms->failures, bio);
                        spin_unlock_irq(&ms->lock);
@@ -803,15 +817,21 @@ static void do_failures(struct mirror_set *ms, struct bio_list *failures)
 
                /*
                 * If all the legs are dead, fail the I/O.
-                * If we have been told to handle errors, hold the bio
-                * and wait for userspace to deal with the problem.
+                * If the device has failed and keep_log is enabled,
+                * fail the I/O.
+                *
+                * If we have been told to handle errors, and keep_log
+                * isn't enabled, hold the bio and wait for userspace to
+                * deal with the problem.
+                *
                 * Otherwise pretend that the I/O succeeded. (This would
                 * be wrong if the failed leg returned after reboot and
                 * got replicated back to the good legs.)
                 */
-               if (!get_valid_mirror(ms))
+
+               if (unlikely(!get_valid_mirror(ms) || (keep_log(ms) && ms->log_failure)))
                        bio_endio(bio, -EIO);
-               else if (errors_handled(ms))
+               else if (errors_handled(ms) && !keep_log(ms))
                        hold_bio(ms, bio);
                else
                        bio_endio(bio, 0);
@@ -987,6 +1007,7 @@ static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
        unsigned num_features;
        struct dm_target *ti = ms->ti;
        char dummy;
+       int i;
 
        *args_used = 0;
 
@@ -1007,15 +1028,25 @@ static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
                return -EINVAL;
        }
 
-       if (!strcmp("handle_errors", argv[0]))
-               ms->features |= DM_RAID1_HANDLE_ERRORS;
-       else {
-               ti->error = "Unrecognised feature requested";
+       for (i = 0; i < num_features; i++) {
+               if (!strcmp("handle_errors", argv[0]))
+                       ms->features |= DM_RAID1_HANDLE_ERRORS;
+               else if (!strcmp("keep_log", argv[0]))
+                       ms->features |= DM_RAID1_KEEP_LOG;
+               else {
+                       ti->error = "Unrecognised feature requested";
+                       return -EINVAL;
+               }
+
+               argc--;
+               argv++;
+               (*args_used)++;
+       }
+       if (!errors_handled(ms) && keep_log(ms)) {
+               ti->error = "keep_log feature requires the handle_errors feature";
                return -EINVAL;
        }
 
-       (*args_used)++;
-
        return 0;
 }
 
@@ -1029,7 +1060,7 @@ static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
  * log_type is "core" or "disk"
  * #log_params is between 1 and 3
  *
- * If present, features must be "handle_errors".
+ * If present, supported features are "handle_errors" and "keep_log".
  */
 static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
@@ -1363,6 +1394,7 @@ static void mirror_status(struct dm_target *ti, status_type_t type,
                          unsigned status_flags, char *result, unsigned maxlen)
 {
        unsigned int m, sz = 0;
+       int num_feature_args = 0;
        struct mirror_set *ms = (struct mirror_set *) ti->private;
        struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
        char buffer[ms->nr_mirrors + 1];
@@ -1392,8 +1424,17 @@ static void mirror_status(struct dm_target *ti, status_type_t type,
                        DMEMIT(" %s %llu", ms->mirror[m].dev->name,
                               (unsigned long long)ms->mirror[m].offset);
 
-               if (ms->features & DM_RAID1_HANDLE_ERRORS)
-                       DMEMIT(" 1 handle_errors");
+               num_feature_args += !!errors_handled(ms);
+               num_feature_args += !!keep_log(ms);
+               if (num_feature_args) {
+                       DMEMIT(" %d", num_feature_args);
+                       if (errors_handled(ms))
+                               DMEMIT(" handle_errors");
+                       if (keep_log(ms))
+                               DMEMIT(" keep_log");
+               }
+
+               break;
        }
 }
 
@@ -1413,7 +1454,7 @@ static int mirror_iterate_devices(struct dm_target *ti,
 
 static struct target_type mirror_target = {
        .name    = "mirror",
-       .version = {1, 13, 2},
+       .version = {1, 14, 0},
        .module  = THIS_MODULE,
        .ctr     = mirror_ctr,
        .dtr     = mirror_dtr,