Assemble: allow an array undergoing reshape to be started without backup file

Though not having the proper backup file can cause data corruption, it
is not enough to justify not being able to start the array at all.
So allow "--invalid-backup" to be specified which says "just continue
even if a backup cannot be restored".

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/Assemble.c b/Assemble.c
index dc5ddd5c6af2d4d502dca5d10685a7b0d445e14b..ac489e8741c82af3c3f7fe36361a1cc81a3161ef 100644 (file)
--- a/Assemble.c
+++ b/Assemble.c
@@ -133,7 +133,8 @@ static int ident_matches(struct mddev_ident *ident,
 
 int Assemble(struct supertype *st, char *mddev,
             struct mddev_ident *ident,
-            struct mddev_dev *devlist, char *backup_file,
+            struct mddev_dev *devlist,
+            char *backup_file, int invalid_backup,
             int readonly, int runstop,
             char *update, char *homehost, int require_homehost,
             int verbose, int force)
@@ -1097,8 +1098,16 @@ int Assemble(struct supertype *st, char *mddev,
                        } else
                                fdlist[i] = -1;
                }
-               if (!err)
-                       err = Grow_restart(st, content, fdlist, bestcnt, backup_file, verbose > 0);
+               if (!err) {
+                       err = Grow_restart(st, content, fdlist, bestcnt,
+                                          backup_file, verbose > 0);
+                       if (err && invalid_backup) {
+                               if (verbose > 0)
+                                       fprintf(stderr, Name ": continuing"
+                                               " without restoring backup\n");
+                               err = 0;
+                       }
+               }
                while (i>0) {
                        i--;
                        if (fdlist[i]>=0) close(fdlist[i]);

diff --git a/Grow.c b/Grow.c
index 13c60288112c57a91956dff9a4ad74b62e78f8b1..0515cfa13cd3141d0e7c92919e61e44a48462692 100644 (file)
--- a/Grow.c
+++ b/Grow.c
@@ -2665,6 +2665,11 @@ int Grow_continue(int mdfd, struct supertype *st, struct mdinfo *info,
        bsb.devstart2 = blocks;
 
        backup_fd = open(backup_file, O_RDWR|O_CREAT, S_IRUSR | S_IWUSR);
+       if (backup_fd < 0) {
+               fprintf(stderr, Name ": Cannot open backup file %s\n",
+                       backup_file ?: "- no backup-file given");
+               return 1;
+       }
        backup_list[0] = backup_fd;
        backup_offsets[0] = 8 * 512;
        fds = malloc(odisks * sizeof(fds[0]));

diff --git a/ReadMe.c b/ReadMe.c
index 5dae87aae7c719ab2985345d6faa59975da337de..5714849293a766b18d2ef26242f02dadbb7a9c18 100644 (file)
--- a/ReadMe.c
+++ b/ReadMe.c
@@ -190,6 +190,7 @@ struct option long_options[] = {
 
     /* For Grow */
     {"backup-file", 1,0, BackupFile},
+    {"invalid-backup",0,0,InvalidBackup},
     {"array-size", 1, 0, 'Z'},
 
     /* For Incremental */

diff --git a/mdadm.8.in b/mdadm.8.in
index 4fc943963fc1f8ef68c3ca838ceba60371200457..8a75e256662f2d4fc144655f5976506913ec542a 100644 (file)
--- a/mdadm.8.in
+++ b/mdadm.8.in
@@ -884,13 +884,24 @@ bitmap, there is no need to specify this when assembling the array.
 .BR \-\-backup\-file=
 If
 .B \-\-backup\-file
-was used to grow the number of raid-devices in a RAID5, and the system
-crashed during the critical section, then the same
+was used while reshaping an array (e.g. changing number of devices or
+chunk size) and the system crashed during the critical section, then the same
 .B \-\-backup\-file
 must be presented to
 .B \-\-assemble
 to allow possibly corrupted data to be restored.
 
+.TP
+.BR \-\-invalid\-backup
+If the file needed for the above option is not available for any
+reason an empty file can be given together with this option to
+indicate that the backup file is invalid.  In this case the data that
+was being rearranged at the time of the crash could be irrecoverably
+lost, but the rest of the array may still be recoverable.  This option
+should only be used as a last resort if there is no way to recover the
+backup file.
+
+
 .TP
 .BR \-U ", " \-\-update=
 Update the superblock on each device while assembling the array.  The

diff --git a/mdadm.c b/mdadm.c
index ea518f1520f76c29328f285e03e8df94a7986441..c5acd43e29043f29b84c0bd827789e8207fd41ae 100644 (file)
--- a/mdadm.c
+++ b/mdadm.c
@@ -60,6 +60,7 @@ int main(int argc, char *argv[])
        int bitmap_fd = -1;
        char *bitmap_file = NULL;
        char *backup_file = NULL;
+       int invalid_backup = 0;
        int bitmap_chunk = UnSet;
        int SparcAdjust = 0;
        struct mddev_dev *devlist = NULL;
@@ -945,6 +946,13 @@ int main(int argc, char *argv[])
                        backup_file = optarg;
                        continue;
 
+               case O(ASSEMBLE, InvalidBackup):
+                       /* Acknowledge that the backupfile is invalid, but ask
+                        * to continue anyway
+                        */
+                       invalid_backup = 1;
+                       continue;
+
                case O(BUILD,'b'):
                case O(BUILD,Bitmap):
                case O(CREATE,'b'):
@@ -1180,14 +1188,14 @@ int main(int argc, char *argv[])
                                if (array_ident->autof == 0)
                                        array_ident->autof = autof;
                                rv |= Assemble(ss, devlist->devname, array_ident,
-                                              NULL, backup_file,
+                                              NULL, backup_file, invalid_backup,
                                               readonly, runstop, update,
                                               homehost, require_homehost,
                                               verbose-quiet, force);
                        }
                } else if (!scan)
                        rv = Assemble(ss, devlist->devname, &ident,
-                                     devlist->next, backup_file,
+                                     devlist->next, backup_file, invalid_backup,
                                      readonly, runstop, update,
                                      homehost, require_homehost,
                                      verbose-quiet, force);
@@ -1211,7 +1219,7 @@ int main(int argc, char *argv[])
                                if (array_ident->autof == 0)
                                        array_ident->autof = autof;
                                rv |= Assemble(ss, dv->devname, array_ident,
-                                              NULL, backup_file,
+                                              NULL, backup_file, invalid_backup,
                                               readonly, runstop, update,
                                               homehost, require_homehost,
                                               verbose-quiet, force);
@@ -1252,7 +1260,7 @@ int main(int argc, char *argv[])
                                
                                        r = Assemble(ss, a->devname,
                                                     a,
-                                                    NULL, NULL,
+                                                    NULL, NULL, 0,
                                                     readonly, runstop, NULL,
                                                     homehost, require_homehost,
                                                     verbose-quiet, force);
@@ -1279,7 +1287,7 @@ int main(int argc, char *argv[])
                                        do {
                                                rv2 = Assemble(ss, NULL,
                                                               &ident,
-                                                              devlist, NULL,
+                                                              devlist, NULL, 0,
                                                               readonly, runstop, NULL,
                                                               homehost, require_homehost,
                                                               verbose-quiet, force);
@@ -1301,12 +1309,15 @@ int main(int argc, char *argv[])
                                        do {
                                                acnt = 0;
                                                do {
-                                                       rv2 = Assemble(ss, NULL,
-                                                                      &ident,
-                                                                      NULL, NULL,
-                                                                      readonly, runstop, "homehost",
-                                                                      homehost, require_homehost,
-                                                                      verbose-quiet, force);
+                                                       rv2 = Assemble(
+                                                               ss, NULL,
+                                                               &ident,
+                                                               NULL, NULL, 0,
+                                                               readonly, runstop,
+                                                               "homehost",
+                                                               homehost,
+                                                               require_homehost,
+                                                               verbose-quiet, force);
                                                        if (rv2==0) {
                                                                cnt++;
                                                                acnt++;

diff --git a/mdadm.h b/mdadm.h
index 91afe160c32a5b1871c15ce1b688eb2489295225..a0126eb5cc3993c87144daf99a96b483fa4a1831 100644 (file)
--- a/mdadm.h
+++ b/mdadm.h
@@ -310,6 +310,7 @@ enum special_options {
        Fork,
        Bitmap,
        RebuildMapOpt,
+       InvalidBackup,
 };
 
 /* structures read from config file */
@@ -967,7 +968,8 @@ extern int Grow_continue(int mdfd, struct supertype *st,
 
 extern int Assemble(struct supertype *st, char *mddev,
                    struct mddev_ident *ident,
-                   struct mddev_dev *devlist, char *backup_file,
+                   struct mddev_dev *devlist,
+                   char *backup_file, int invalid_backup,
                    int readonly, int runstop,
                    char *update, char *homehost, int require_homehost,
                    int verbose, int force);