dm raid1: report fault status

This patch adds extra information to the mirror status output, so that
it can be determined which device(s) have failed.  For each mirror device,
a character is printed indicating the most severe error encountered.  The
characters are:
 *    A => Alive - No failures
 *    D => Dead - A write failure occurred leaving mirror out-of-sync
 *    S => Sync - A sychronization failure occurred, mirror out-of-sync
 *    R => Read - A read failure occurred, mirror data unaffected
This allows userspace to properly reconfigure the mirror set.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 36 insertions, 8 deletions

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 38efa7071dd7..edc057f5cdcc 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -1781,29 +1781,57 @@ static void mirror_resume(struct dm_target *ti)
         rh_start_recovery(&ms->rh);
 }
 
+/*
+ * device_status_char
+ * @m: mirror device/leg we want the status of
+ *
+ * We return one character representing the most severe error
+ * we have encountered.
+ *    A => Alive - No failures
+ *    D => Dead - A write failure occurred leaving mirror out-of-sync
+ *    S => Sync - A sychronization failure occurred, mirror out-of-sync
+ *    R => Read - A read failure occurred, mirror data unaffected
+ *
+ * Returns: <char>
+ */
+static char device_status_char(struct mirror *m)
+{
+        if (!atomic_read(&(m->error_count)))
+                return 'A';
+
+        return (test_bit(DM_RAID1_WRITE_ERROR, &(m->error_type))) ? 'D' :
+                (test_bit(DM_RAID1_SYNC_ERROR, &(m->error_type))) ? 'S' :
+                (test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U';
+}
+
+
 static int mirror_status(struct dm_target *ti, status_type_t type,
                          char *result, unsigned int maxlen)
 {
         unsigned int m, sz = 0;
         struct mirror_set *ms = (struct mirror_set *) ti->private;
+        struct dirty_log *log = ms->rh.log;
+        char buffer[ms->nr_mirrors + 1];
 
         switch (type) {
         case STATUSTYPE_INFO:
                 DMEMIT("%d ", ms->nr_mirrors);
-                for (m = 0; m < ms->nr_mirrors; m++)
+                for (m = 0; m < ms->nr_mirrors; m++) {
                         DMEMIT("%s ", ms->mirror[m].dev->name);
+                        buffer[m] = device_status_char(&(ms->mirror[m]));
+                }
+                buffer[m] = '\0';
 
-                DMEMIT("%llu/%llu 0 ",
-                        (unsigned long long)ms->rh.log->type->
-                                get_sync_count(ms->rh.log),
-                        (unsigned long long)ms->nr_regions);
+                DMEMIT("%llu/%llu 1 %s ",
+                      (unsigned long long)log->type->get_sync_count(ms->rh.log),
+                      (unsigned long long)ms->nr_regions, buffer);
 
-                sz += ms->rh.log->type->status(ms->rh.log, type, result+sz, maxlen-sz);
+                sz += log->type->status(ms->rh.log, type, result+sz, maxlen-sz);
 
                 break;
 
         case STATUSTYPE_TABLE:
-                sz = ms->rh.log->type->status(ms->rh.log, type, result, maxlen);
+                sz = log->type->status(ms->rh.log, type, result, maxlen);
 
                 DMEMIT("%d", ms->nr_mirrors);
                 for (m = 0; m < ms->nr_mirrors; m++)
@@ -1819,7 +1847,7 @@ static int mirror_status(struct dm_target *ti, status_type_t type,
 
 static struct target_type mirror_target = {
         .name    = "mirror",
-        .version = {1, 0, 3},
+        .version = {1, 0, 20},
         .module  = THIS_MODULE,
         .ctr     = mirror_ctr,
         .dtr     = mirror_dtr,