- Add kern.geom.mirror.disconnect_on_failure sysctl/tunnable (default to 1

  to preserve currect behaviour). When set to 0, components are not
  disconnected - gmirror will try to still use them (only first error will
  be logged). This is helpful when we have two broken components, but in
  different places, so actually all data is available.
  Such buggy component will be visible in 'gmirror list' output with flag
  BROKEN.
- Never disconnect the last valid component. If we detect errors there we
  will just pass them up. This wasn't reasonable to deny access to the
  whole provider because of one broken sector.

Prodded by:	ru
MFC after:	3 days

2 files changed, 47 insertions, 10 deletions

diff --git a/sys/geom/mirror/g_mirror.c b/sys/geom/mirror/g_mirror.c
index f5929a4..4edd9af 100644
--- a/sys/geom/mirror/g_mirror.c
+++ b/sys/geom/mirror/g_mirror.c
@@ -70,6 +70,11 @@ static u_int g_mirror_syncs_per_sec = 1000;
 SYSCTL_UINT(_kern_geom_mirror, OID_AUTO, syncs_per_sec, CTLFLAG_RW,
     &g_mirror_syncs_per_sec, 0,
     "Number of synchronizations requests per second");
+static u_int g_mirror_disconnect_on_failure = 1;
+TUNABLE_INT("kern.geom.mirror.disconnect_on_failure",
+    &g_mirror_disconnect_on_failure);
+SYSCTL_UINT(_kern_geom_mirror, OID_AUTO, disconnect_on_failure, CTLFLAG_RW,
+    &g_mirror_disconnect_on_failure, 0, "Disconnect component on I/O failure.");
 
 #define	MSLEEP(ident, mtx, priority, wmesg, timeout)	do {		\
 	G_MIRROR_DEBUG(4, "%s: Sleeping %p.", __func__, (ident));	\
@@ -625,9 +630,23 @@ g_mirror_write_metadata(struct g_mirror_disk *disk,
 	g_topology_lock();
 	free(sector, M_MIRROR);
 	if (error != 0) {
-		disk->d_softc->sc_bump_id |= G_MIRROR_BUMP_GENID;
-		g_mirror_event_send(disk, G_MIRROR_DISK_STATE_DISCONNECTED,
-		    G_MIRROR_EVENT_DONTWAIT);
+		if ((disk->d_flags & G_MIRROR_DISK_FLAG_BROKEN) == 0) {
+			disk->d_flags |= G_MIRROR_DISK_FLAG_BROKEN;
+			G_MIRROR_DEBUG(0, "Cannot write metadata on %s "
+			    "(device=%s, error=%d).",
+			    g_mirror_get_diskname(disk), sc->sc_name, error);
+		} else {
+			G_MIRROR_DEBUG(1, "Cannot write metadata on %s "
+			    "(device=%s, error=%d).",
+			    g_mirror_get_diskname(disk), sc->sc_name, error);
+		}
+		if (g_mirror_disconnect_on_failure &&
+		    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) > 1) {
+			sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
+			g_mirror_event_send(disk,
+			    G_MIRROR_DISK_STATE_DISCONNECTED,
+			    G_MIRROR_EVENT_DONTWAIT);
+		}
 	}
 	return (error);
 }
@@ -884,13 +903,25 @@ g_mirror_regular_request(struct bio *bp)
 	} else if (bp->bio_error != 0) {
 		if (pbp->bio_error == 0)
 			pbp->bio_error = bp->bio_error;
-		G_MIRROR_LOGREQ(0, bp, "Request failed (error=%d).",
-		    bp->bio_error);
 		if (disk != NULL) {
-			sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
-			g_mirror_event_send(disk,
-			    G_MIRROR_DISK_STATE_DISCONNECTED,
-			    G_MIRROR_EVENT_DONTWAIT);
+			if ((disk->d_flags & G_MIRROR_DISK_FLAG_BROKEN) == 0) {
+				disk->d_flags |= G_MIRROR_DISK_FLAG_BROKEN;
+				G_MIRROR_LOGREQ(0, bp,
+				    "Request failed (error=%d).",
+				    bp->bio_error);
+			} else {
+				G_MIRROR_LOGREQ(1, bp,
+				    "Request failed (error=%d).",
+				    bp->bio_error);
+			}
+			if (g_mirror_disconnect_on_failure &&
+			    g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) > 1)
+			{
+				sc->sc_bump_id |= G_MIRROR_BUMP_GENID;
+				g_mirror_event_send(disk,
+				    G_MIRROR_DISK_STATE_DISCONNECTED,
+				    G_MIRROR_EVENT_DONTWAIT);
+			}
 		}
 		switch (pbp->bio_cmd) {
 		case BIO_DELETE:
@@ -904,7 +935,11 @@ g_mirror_regular_request(struct bio *bp)
 
 	switch (pbp->bio_cmd) {
 	case BIO_READ:
-		if (pbp->bio_children == pbp->bio_inbed) {
+		if (pbp->bio_inbed < pbp->bio_children)
+			break;
+		if (g_mirror_ndisks(sc, G_MIRROR_DISK_STATE_ACTIVE) == 1)
+			g_io_deliver(pbp, pbp->bio_error);
+		else {
 			pbp->bio_error = 0;
 			mtx_lock(&sc->sc_queue_mtx);
 			bioq_disksort(&sc->sc_queue, pbp);
@@ -2739,6 +2774,7 @@ g_mirror_dumpconf(struct sbuf *sb, const char *indent, struct g_geom *gp,
 			ADD_FLAG(G_MIRROR_DISK_FLAG_SYNCHRONIZING,
 			    "SYNCHRONIZING");
 			ADD_FLAG(G_MIRROR_DISK_FLAG_FORCE_SYNC, "FORCE_SYNC");
+			ADD_FLAG(G_MIRROR_DISK_FLAG_BROKEN, "BROKEN");
 #undef	ADD_FLAG
 		}
 		sbuf_printf(sb, "</Flags>\n");
diff --git a/sys/geom/mirror/g_mirror.h b/sys/geom/mirror/g_mirror.h
index 35d84b4..1e13e5a 100644
--- a/sys/geom/mirror/g_mirror.h
+++ b/sys/geom/mirror/g_mirror.h
@@ -57,6 +57,7 @@
 #define	G_MIRROR_DISK_FLAG_FORCE_SYNC		0x0000000000000004ULL
 #define	G_MIRROR_DISK_FLAG_INACTIVE		0x0000000000000008ULL
 #define	G_MIRROR_DISK_FLAG_HARDCODED		0x0000000000000010ULL
+#define	G_MIRROR_DISK_FLAG_BROKEN		0x0000000000000020ULL
 #define	G_MIRROR_DISK_FLAG_MASK		(G_MIRROR_DISK_FLAG_DIRTY |	\
 					 G_MIRROR_DISK_FLAG_SYNCHRONIZING | \
 					 G_MIRROR_DISK_FLAG_FORCE_SYNC | \