krbd & live resize

[Loic Dachary <loic@dachary.org>]

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Hi,

This works:

lvcreate --name tmp --size 10G all
  Logical volume "tmp" created
mkfs.ext4 /dev/all/tmp
mount /dev/all/tmp /mnt
blockdev --getsize64 /dev/all/tmp
10737418240
lvextend -L+1G /dev/all/tmp
  Extending logical volume tmp to 11,00 GiB
  Logical volume tmp successfully resized
blockdev --getsize64 /dev/all/tmp
11811160064
resize2fs /dev/all/tmp 
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/all/tmp is mounted on /mnt; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/all/tmp to 2883584 (4k) blocks.
The filesystem on /dev/all/tmp is now 2883584 blocks long.

This does not work:

rbd create --size 10240 tmp
rbd info tmp
rbd image 'tmp':
	size 10240 MB in 2560 objects
	order 22 (4096 KB objects)
	block_name_prefix: rb.0.12dd.238e1f29
	format: 1
rbd map tmp
mkfs.ext4 /dev/rbd1
mount /dev/rbd1 /mnt
blockdev --getsize64 /dev/rbd1
10737418240
rbd resize --size 20000 tmp
blockdev --getsize64 /dev/rbd1
10737418240
resize2fs /dev/rbd1 
resize2fs 1.42 (29-Nov-2011)
The filesystem is already 2621440 blocks long.  Nothing to do!

It does work after umounting:

umount /mnt
blockdev --getsize64 /dev/rbd1
fsck -f /dev/rbd1
resize2fs /dev/rbd1 
resize2fs 1.42 (29-Nov-2011)
Resizing the filesystem on /dev/rbd1 to 5120000 (4k) blocks.
The filesystem on /dev/rbd1 is now 5120000 blocks long.

I assume there should be "something" in KRBD to allow for the same behavior as with LVM but I don't know enough about the kernel to be more specific. Maybe something similar to ioctl BLKRRPART ?

Cheers

-- 
Loïc Dachary, Artisan Logiciel Libre
All that is necessary for the triumph of evil is that good people do nothing.


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