On 10/26/2010 12:54 AM, Neil Brown wrote:
On Tue, 26 Oct 2010 00:26:33 -0700
Dan Williams<dan.j.williams@xxxxxxxxx> wrote:
On 10/25/2010 10:35 PM, Neil Brown wrote:
On Fri, 22 Oct 2010 11:03:59 -0700
Dan Williams<dan.j.williams@xxxxxxxxx> wrote:
We mark the disk in-sync, and also need to init ->recovery_offset lest
we confuse older versions of mdadm that don't consider this case at
assembly (i.e. that when growing we assume the disk is insync).
mdadm: /dev/md0 assembled from 3 drives and 1 rebuilding - not enough to start the array.
Cc:<stable@xxxxxxxxxx>
Signed-off-by: Dan Williams<dan.j.williams@xxxxxxxxx>
---
drivers/md/raid5.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9e8ecd5..f8a27d4 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5580,6 +5580,7 @@ static int raid5_start_reshape(mddev_t *mddev)
if (raid5_add_disk(mddev, rdev) == 0) {
char nm[20];
if (rdev->raid_disk>= conf->previous_raid_disks) {
+ rdev->recovery_offset = MaxSector;
set_bit(In_sync,&rdev->flags);
added_devices++;
} else
Sorry, but I'm not getting this one....
rdev->recovery_offset is only ever used when In_sync is clear. So it makes
no sense to give it a value when In_sync is set.
Maybe there are some places where we clear In_sync that need to have
recovery_offset set to zero, but it isn't obvious to me that that would
explain your symptom.
Can you give a bit more detail of the problem you are seeing please?
mdadm -A an array growing raid disks by more than max_degraded.
Here is the related mdadm fix, but I figured it was worhtwhile to also
address this in the kernel for the corner case of new kernel + old mdadm.
commit 156a33719d956fe90cbb1625b13beb52a0d6fd87
Author: Dan Williams<dan.j.williams@xxxxxxxxx>
Date: Mon Jul 12 12:03:13 2010 -0700
Assemble: fix assembly in the delta_disks> max_degraded case
Incremental assembly works on such an array because the kernel sees the
disk as in-sync and that the array is reshaping. Teach Assemble() the
same assumptions.
This is only needed on kernels that do not initialize ->recovery_offset
when activating spares for reshape.
Signed-off-by: Dan Williams<dan.j.williams@xxxxxxxxx>
diff --git a/Assemble.c b/Assemble.c
index afd4e60..409f0d7 100644
--- a/Assemble.c
+++ b/Assemble.c
@@ -804,7 +804,9 @@ int Assemble(struct supertype *st, char *mddev,
devices[most_recent].i.events) {
devices[j].uptodate = 1;
if (i< content->array.raid_disks) {
- if (devices[j].i.recovery_start == MaxSector) {
+ if (devices[j].i.recovery_start == MaxSector ||
+ (content->reshape_active&&
+ j>= content->array.raid_disks - content->delta_disks)) {
okcnt++;
avail[i]=1;
} else
--
Dan
I think the issue here is probably that the metadata handler isn't setting
recovery_start "properly" for devices that are in-sync just as far as the
the current reshape has progressed.
I really don't think the kernel has anything to do with it as it doesn't
report any recovery_start value at all when the device is 'in_sync'.
This was a few months back, but it looks like I looked at the mdadm fix
and thought I could derive a kernel fix, but yes, the real problem is in
the mdadm metadata handler.
So I think this patch is wrong
The kernel patch, not the mdadm patch.
and you need to fix the getinfo_super method
to set recovery_start to MaxSector when the device is a new device in an
array being reshaped.
Could that make sense?
Yes, I can push this fix down to super1.c to avoid:
# mdadm -A /dev/md1 /dev/loop[0-3]
mdadm: /dev/md1 assembled from 3 drives and 1 rebuilding - not enough
to start the array.
--
Dan
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