Commit 6ea9c07c authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: cause md/raid1 to "repack" working devices when number of drives is changed

i.e.  missing or failed drives are moved to the end of the list.  The means
a 3 drive md array with the first drive missing can be shrunk to a two
drive array.  Currently that isn't possible.

Also, the "last_used" device number might be out-of-range after the number
of devices is reduced, so we set it to 0.

Signed-off-by: default avatarNeil Brown <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 58a60643
......@@ -1349,17 +1349,26 @@ static int raid1_reshape(mddev_t *mddev, int raid_disks)
* We allocate a new r1bio_pool if we can.
* Then raise a device barrier and wait until all IO stops.
* Then resize conf->mirrors and swap in the new r1bio pool.
* At the same time, we "pack" the devices so that all the missing
* devices have the higher raid_disk numbers.
mempool_t *newpool, *oldpool;
struct pool_info *newpoolinfo;
mirror_info_t *newmirrors;
conf_t *conf = mddev_to_conf(mddev);
int cnt;
int d;
int d, d2;
for (d= raid_disks; d < conf->raid_disks; d++)
if (conf->mirrors[d].rdev)
if (raid_disks < conf->raid_disks) {
for (d= 0; d < conf->raid_disks; d++)
if (conf->mirrors[d].rdev)
if (cnt > raid_disks)
return -EBUSY;
newpoolinfo = kmalloc(sizeof(*newpoolinfo), GFP_KERNEL);
if (!newpoolinfo)
......@@ -1390,8 +1399,12 @@ static int raid1_reshape(mddev_t *mddev, int raid_disks)
/* ok, everything is stopped */
oldpool = conf->r1bio_pool;
conf->r1bio_pool = newpool;
for (d=0; d < raid_disks && d < conf->raid_disks; d++)
newmirrors[d] = conf->mirrors[d];
for (d=d2=0; d < conf->raid_disks; d++)
if (conf->mirrors[d].rdev) {
conf->mirrors[d].rdev->raid_disk = d2;
newmirrors[d2++].rdev = conf->mirrors[d].rdev;
conf->mirrors = newmirrors;
......@@ -1400,6 +1413,7 @@ static int raid1_reshape(mddev_t *mddev, int raid_disks)
mddev->degraded += (raid_disks - conf->raid_disks);
conf->raid_disks = mddev->raid_disks = raid_disks;
conf->last_used = 0; /* just make sure it is in-range */
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