Grow: fix problem with --grow --continue

If an array is being reshaped using backup space on a 'spare' device,
then
  mdadm --grow --continue
won't find it as by the time it runs, nothing looks like a spare are
more.  The spare has been added to the array, but has no data yet.

So allow reshape_prepare_fdlist to find a newly-incorporated spare and
report this so it can be used.

Reported-by: Xiao Ni <xni@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/Grow.c b/Grow.c
index a20ff3e70142b7edc141190909443d81de5099db..85de1d27f03a0a52e26b1fa5225b5da25f8a96f8 100644 (file)
--- a/Grow.c
+++ b/Grow.c
@@ -850,7 +850,8 @@ int reshape_prepare_fdlist(char *devname,
        for (sd = sra->devs; sd; sd = sd->next) {
                if (sd->disk.state & (1<<MD_DISK_FAULTY))
                        continue;
-               if (sd->disk.state & (1<<MD_DISK_SYNC)) {
+               if (sd->disk.state & (1<<MD_DISK_SYNC) &&
+                   sd->disk.raid_disk < raid_disks) {
                        char *dn = map_dev(sd->disk.major,
                                           sd->disk.minor, 1);
                        fdlist[sd->disk.raid_disk]
@@ -3184,7 +3185,7 @@ started:
        d = reshape_prepare_fdlist(devname, sra, odisks,
                                   nrdisks, blocks, backup_file,
                                   fdlist, offsets);
-       if (d < 0) {
+       if (d < odisks) {
                goto release;
        }
        if ((st->ss->manage_reshape == NULL) ||
@@ -3196,7 +3197,7 @@ started:
                                       devname);
                                pr_err(" Please provide one with \"--backup=...\"\n");
                                goto release;
-                       } else if (sra->array.spare_disks == 0) {
+                       } else if (d == odisks) {
                                pr_err("%s: Cannot grow - need a spare or backup-file to backup critical section\n", devname);
                                goto release;
                        }