On Thursday September 8, [EMAIL PROTECTED] wrote:
> > What happens if you then
> >  mdadm /dev/md_d0 -a /dev/sda[pqrs]
> > ??
> 
>       Getting stranger & stranger .
> 
> [EMAIL PROTECTED]:~ # mdadm /dev/md_d0 -a /dev/sda[pqrs]
> mdadm: re-added /dev/sdap
> 

Hmm.. mdadm bug.

> [EMAIL PROTECTED]:~ # cat /proc/mdstat
> Personalities : [linear] [raid0] [raid1] [raid5] [multipath] [raid6] [raid10]
> md_d0 : active raid5 sdap[36] sdc[0] sdao[40] sdan[34] sdam[33] 
> sdal[32] sdak[31] sdaj[30] sdah[29] sdag[28] sdaf[27] sdae[26] 
> sdad[25] sdac[24] sdab[23] sdaa[22] sdz[21] sdy[20] sdw[19] sdv[18] 
> sdu[17] sdt[16] sds[15] sdr[14] sdq[13] sdp[12] sdo[11] sdn[10] sdl[9] 
> sdk[8] sdj[7] sdi[6] sdh[5] sdg[4] sdf[3] sde[2](F) sdd[1]
>        1244826240 blocks level 5, 64k chunk, algorithm 2 [36/35]
> [UU_UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU]

Hmm.. obviously hot-add isn't enough to trigger the rebuild in that
kernel.


Attached are three patches.
The first two are needed by 2.6.12.5 to make sure resync happens (this
is particularly a problem for version-1 superblocks) or just upgrade
to 2.6.13.

The last fixes mdadm-v2.0 so that when you add /dev/sda[pqrs] it
actually adds all of them, and so that when you --assemble a version-1
array with spares, the spares actually get included.

NeilBrown


Status: ok

Make sure recovery happens when add_new_disk is used for hot_add

Currently if add_new_disk is used to hot-add a drive to a degraded
array, recovery doesn't start ... because we didn't tell it to.

Signed-off-by: Neil Brown <[EMAIL PROTECTED]>

### Diffstat output
 ./drivers/md/md.c |    2 ++
 1 files changed, 2 insertions(+)

diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c~current~  2005-05-31 13:40:35.000000000 +1000
+++ ./drivers/md/md.c   2005-05-31 13:40:34.000000000 +1000
@@ -2232,6 +2232,8 @@ static int add_new_disk(mddev_t * mddev,
                err = bind_rdev_to_array(rdev, mddev);
                if (err)
                        export_rdev(rdev);
+
+               set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                if (mddev->thread)
                        md_wakeup_thread(mddev->thread);
                return err;
Status: ok

Make sure resync gets started when array starts.

We weren't actually waking up the md thread after setting
MD_RECOVERY_NEEDED when assembling an array, so it is possible to
lose a race and not actually start resync.

So add a call to md_wakeup_thread, and while we are at it, remove
all the "if (mddev->thread)" guards as md_wake_thread does its own
checking.

Signed-off-by: Neil Brown <[EMAIL PROTECTED]>

### Diffstat output
 ./drivers/md/md.c |    7 +++----
 1 files changed, 3 insertions(+), 4 deletions(-)

diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c   2005-08-26 17:00:30.000000000 +1000
+++ ./drivers/md/md.c~current~  2005-08-26 17:00:39.000000000 +1000
@@ -256,8 +256,7 @@ static inline void mddev_unlock(mddev_t 
 {
        up(&mddev->reconfig_sem);
 
-       if (mddev->thread)
-               md_wakeup_thread(mddev->thread);
+       md_wakeup_thread(mddev->thread);
 }
 
 mdk_rdev_t * find_rdev_nr(mddev_t *mddev, int nr)
@@ -1726,6 +1725,7 @@ static int do_md_run(mddev_t * mddev)
        mddev->in_sync = 1;
        
        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+       md_wakeup_thread(mddev->thread);
        
        if (mddev->sb_dirty)
                md_update_sb(mddev);
@@ -2255,8 +2255,7 @@ static int add_new_disk(mddev_t * mddev,
                        export_rdev(rdev);
 
                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-               if (mddev->thread)
-                       md_wakeup_thread(mddev->thread);
+               md_wakeup_thread(mddev->thread);
                return err;
        }
 
diff ./Assemble.c~current~ ./Assemble.c
--- ./Assemble.c~current~       2005-09-05 10:55:01.000000000 +1000
+++ ./Assemble.c        2005-09-09 16:24:50.000000000 +1000
@@ -119,6 +119,7 @@ int Assemble(struct supertype *st, char 
        struct mdinfo info;
        struct mddev_ident_s ident2;
        char *avail;
+       int nextspare = 0;
        
        vers = md_get_version(mdfd);
        if (vers <= 0) {
@@ -320,6 +321,11 @@ int Assemble(struct supertype *st, char 
                        i = devcnt;
                else
                        i = devices[devcnt].raid_disk;
+               if (i+1 == 0) {
+                       if (nextspare < info.array.raid_disks)
+                               nextspare = info.array.raid_disks;
+                       i = nextspare++;
+               }
                if (i < 10000) {
                        if (i >= bestcnt) {
                                unsigned int newbestcnt = i+10;

diff ./Manage.c~current~ ./Manage.c
--- ./Manage.c~current~ 2005-09-05 10:54:55.000000000 +1000
+++ ./Manage.c  2005-09-09 16:04:12.000000000 +1000
@@ -288,7 +288,7 @@ int Manage_subdevs(char *devname, int fd
                                                if (ioctl(fd, ADD_NEW_DISK, 
&disc) == 0) {
                                                        if (verbose >= 0)
                                                                fprintf(stderr, 
Name ": re-added %s\n", dv->devname);
-                                                       return 0;
+                                                       continue;
                                                }
                                                /* fall back on normal-add */
                                        }

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