From 02e7c5b75cd4ad5176441add156389c71dab6e3a Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Mon, 22 Nov 2010 19:35:25 +1100
Subject: [PATCH] Assemble - avoid including wayward devices.

If a device - typically in a mirrored set - is assembled independently
of the other devices, and then attempted to be brought back into the
set it could contain inconsistent data.  It should not be included.

So detect this situation by ensuring that the 'most recent' device is
believed to be active by every other device.  If a device is wayward,
it will only consider fellow wayward devices to be active and will
think all others are failed or missing.

This patch only fixes --assemble, not --incremental

Signed-off-by: NeilBrown <neilb@suse.de>
---
 Assemble.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/Assemble.c b/Assemble.c
index d23c130..f66a21b 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -145,6 +145,7 @@ int Assemble(struct supertype *st, char *mddev,
 			       */
 		struct mdinfo i;
 	} *devices;
+	char *devmap;
 	int *best = NULL; /* indexed by raid_disk */
 	int bestcnt = 0;
 	int devcnt = 0;
@@ -603,6 +604,7 @@ int Assemble(struct supertype *st, char *mddev,
 	bitmap_done = 0;
 	content->update_private = NULL;
 	devices = malloc(num_devs * sizeof(*devices));
+	devmap = calloc(num_devs * content->array.raid_disks, 1);
 	for (tmpdev = devlist; tmpdev; tmpdev=tmpdev->next) if (tmpdev->used == 1) {
 		char *devname = tmpdev->devname;
 		struct stat stb;
@@ -640,9 +642,10 @@ int Assemble(struct supertype *st, char *mddev,
 					close(dfd);
 				close(mdfd);
 				free(devices);
+				free(devmap);
 				return 1;
 			}
-			tst->ss->getinfo_super(tst, content, NULL);
+			tst->ss->getinfo_super(tst, content, devmap + devcnt * content->array.raid_disks);
 
 			memcpy(content->uuid, ident->uuid, 16);
 			strcpy(content->name, ident->name);
@@ -665,6 +668,7 @@ int Assemble(struct supertype *st, char *mddev,
 				close(mdfd);
 				close(dfd);
 				free(devices);
+				free(devmap);
 				return 1;
 			}
 			if (strcmp(update, "uuid")==0 &&
@@ -703,9 +707,10 @@ int Assemble(struct supertype *st, char *mddev,
 					close(dfd);
 				close(mdfd);
 				free(devices);
+				free(devmap);
 				return 1;
 			}
-			tst->ss->getinfo_super(tst, content, NULL);
+			tst->ss->getinfo_super(tst, content, devmap + devcnt * content->array.raid_disks);
 			tst->ss->free_super(tst);
 			close(dfd);
 		}
@@ -776,6 +781,7 @@ int Assemble(struct supertype *st, char *mddev,
 					);
 				close(mdfd);
 				free(devices);
+				free(devmap);
 				return 1;
 			}
 			if (best[i] == -1
@@ -795,6 +801,7 @@ int Assemble(struct supertype *st, char *mddev,
 			st->ss->free_super(st);
 		close(mdfd);
 		free(devices);
+		free(devmap);
 		return 1;
 	}
 
@@ -828,6 +835,19 @@ int Assemble(struct supertype *st, char *mddev,
 					sparecnt++;
 				continue;
 			}
+		/* If this devices thinks that 'most_recent' has failed, then
+		 * we must reject this device.
+		 */
+		if (j != most_recent &&
+		    content->array.raid_disks > 0 &&
+		    devices[most_recent].i.disk.raid_disk >= 0 &&
+		    devmap[j * content->array.raid_disks + devices[most_recent].i.disk.raid_disk] == 0) {
+			if (verbose > -1)
+				fprintf(stderr, Name ": ignoring %s as it reports %s as failed\n",
+					devices[j].devname, devices[most_recent].devname);
+			best[i] = -1;
+			continue;
+		}
 		if (devices[j].i.events+event_margin >=
 		    devices[most_recent].i.events) {
 			devices[j].uptodate = 1;
@@ -841,6 +861,7 @@ int Assemble(struct supertype *st, char *mddev,
 				sparecnt++;
 		}
 	}
+	free(devmap);
 	while (force && !enough(content->array.level, content->array.raid_disks,
 				content->array.layout, 1,
 				avail, okcnt)) {