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md: add ->takeover method for raid5 to be able to take over raid1

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The RAID1 must have two drives and be a suitable size to
be a multiple of a chunksize that isn't too small.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2009-03-31 14:39:39 +11:00
parent 245f46c2c2
commit d562b0c431
1 changed files with 48 additions and 0 deletions
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48
drivers/md/raid5.c
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@ -4884,6 +4884,53 @@ static void raid5_quiesce(mddev_t *mddev, int state)
}
}
static void *raid5_takeover_raid1(mddev_t *mddev)
{
int chunksect;
if (mddev->raid_disks != 2 ||
mddev->degraded > 1)
return ERR_PTR(-EINVAL);
/* Should check if there are write-behind devices? */
chunksect = 64*2; /* 64K by default */
/* The array must be an exact multiple of chunksize */
while (chunksect && (mddev->array_sectors & (chunksect-1)))
chunksect >>= 1;
if ((chunksect<<9) < STRIPE_SIZE)
/* array size does not allow a suitable chunk size */
return ERR_PTR(-EINVAL);
mddev->new_level = 5;
mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
mddev->new_chunk = chunksect << 9;
return setup_conf(mddev);
}
static void *raid5_takeover(mddev_t *mddev)
{
/* raid5 can take over:
* raid0 - if all devices are the same - make it a raid4 layout
* raid1 - if there are two drives. We need to know the chunk size
* raid4 - trivial - just use a raid4 layout.
* raid6 - Providing it is a *_6 layout
*
* For now, just do raid1
*/
if (mddev->level == 1)
return raid5_takeover_raid1(mddev);
return ERR_PTR(-EINVAL);
}
static struct mdk_personality raid5_personality;
static void *raid6_takeover(mddev_t *mddev)
@ -4975,6 +5022,7 @@ static struct mdk_personality raid5_personality =
.start_reshape = raid5_start_reshape,
#endif
.quiesce = raid5_quiesce,
.takeover = raid5_takeover,
};
static struct mdk_personality raid4_personality =