dm raid1: add handle_errors feature flag

This patch adds the ability to specify desired features in the mirror
constructor/mapping table.

The first feature of interest is "handle_errors".  Currently, mirroring will
ignore any I/O errors from the devices.  Subsequent patches will check for
this flag and handle the errors.  If flag/feature is not present, mirror will
do nothing - maintaining backwards compatibility.

Signed-off-by: Jonathan E Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 63 insertions, 2 deletions

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index cb3f318a3692..2a3e2f80aa4b 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -22,6 +22,8 @@
 
 #define DM_MSG_PREFIX "raid1"
 
+#define DM_RAID1_HANDLE_ERRORS 0x01
+
 static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped);
 
 /*-----------------------------------------------------------------
@@ -118,6 +120,7 @@ struct mirror_set {
         struct list_head list;
         struct region_hash rh;
         struct kcopyd_client *kcopyd_client;
+        uint64_t features;
 
         spinlock_t lock;        /* protects the next two lists */
         struct bio_list reads;
@@ -1010,14 +1013,54 @@ static struct dirty_log *create_dirty_log(struct dm_target *ti,
         return dl;
 }
 
+static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
+                          unsigned *args_used)
+{
+        unsigned num_features;
+        struct dm_target *ti = ms->ti;
+
+        *args_used = 0;
+
+        if (!argc)
+                return 0;
+
+        if (sscanf(argv[0], "%u", &num_features) != 1) {
+                ti->error = "Invalid number of features";
+                return -EINVAL;
+        }
+
+        argc--;
+        argv++;
+        (*args_used)++;
+
+        if (num_features > argc) {
+                ti->error = "Not enough arguments to support feature count";
+                return -EINVAL;
+        }
+
+        if (!strcmp("handle_errors", argv[0]))
+                ms->features |= DM_RAID1_HANDLE_ERRORS;
+        else {
+                ti->error = "Unrecognised feature requested";
+                return -EINVAL;
+        }
+
+        (*args_used)++;
+
+        return 0;
+}
+
 /*
  * Construct a mirror mapping:
  *
  * log_type #log_params <log_params>
  * #mirrors [mirror_path offset]{2,}
+ * [#features <features>]
  *
  * log_type is "core" or "disk"
  * #log_params is between 1 and 3
+ *
+ * If present, features must be "handle_errors".
  */
 #define DM_IO_PAGES 64
 static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
@@ -1043,8 +1086,8 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
         argv++, argc--;
 
-        if (argc != nr_mirrors * 2) {
-                ti->error = "Wrong number of mirror arguments";
+        if (argc < nr_mirrors * 2) {
+                ti->error = "Too few mirror arguments";
                 dm_destroy_dirty_log(dl);
                 return -EINVAL;
         }
@@ -1077,6 +1120,21 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         }
         INIT_WORK(&ms->kmirrord_work, do_mirror);
 
+        r = parse_features(ms, argc, argv, &args_used);
+        if (r) {
+                free_context(ms, ti, ms->nr_mirrors);
+                return r;
+        }
+
+        argv += args_used;
+        argc -= args_used;
+
+        if (argc) {
+                ti->error = "Too many mirror arguments";
+                free_context(ms, ti, ms->nr_mirrors);
+                return -EINVAL;
+        }
+
         r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
         if (r) {
                 destroy_workqueue(ms->kmirrord_wq);
@@ -1230,6 +1288,9 @@ static int mirror_status(struct dm_target *ti, status_type_t type,
                 for (m = 0; m < ms->nr_mirrors; m++)
                         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");
         }
 
         return 0;