[Bug 1377142] Re: Bcache doesn't allow full unregistering without rebooting
Kick In
pierre-andre.morey at canonical.com
Fri Oct 3 12:55:14 UTC 2014
** Description changed:
If you create a bcache device, you can't reuse all your disk/partitions
without a reboot.
You can reproduce the case this way:
start a vm with 2 disks (caching must be bigger or equal to the backing
cf bug :1377130) and an iso of utopic desktop amd64
create the bcache device:
- make-bcache --writeback --discard -C /dev/sda -B
- /dev/sdb
-
- UUID: b245150d-cfbe-4f90-836a-343e0e1a4c55
- Set UUID: c990a31a-f531-4231-9603-d40230dc6504
- version: 0
- nbuckets: 16384
- block_size: 1
- bucket_size: 1024
- nr_in_set: 1
- nr_this_dev: 0
- first_bucket: 1
- UUID: cc31e0bb-db29-4115-a1b2-e9ff54e5f127
- Set UUID: c990a31a-f531-4231-9603-d40230dc6504
- version: 1
- block_size: 1
- data_offset: 16
-
- ******************************
- command:
- lsblk
-
- result:
- NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
- sda 8:0 0 8G 0 disk
- └─bcache0 251:0 0 16G 0 disk
- sdb 8:16 0 16G 0 disk
- └─bcache0 251:0 0 16G 0 disk
- sr0 11:0 1 1,1G 0 rom /cdrom
- loop0 7:0 0 1,1G 1 loop /rofs
- ******************************
+ make-bcache --writeback --discard -C /dev/sda -B /dev/sdb
+
+ UUID: b245150d-cfbe-4f90-836a-343e0e1a4c55
+ Set UUID: c990a31a-f531-4231-9603-d40230dc6504
+ version: 0
+ nbuckets: 16384
+ block_size: 1
+ bucket_size: 1024
+ nr_in_set: 1
+ nr_this_dev: 0
+ first_bucket: 1
+ UUID: cc31e0bb-db29-4115-a1b2-e9ff54e5f127
+ Set UUID: c990a31a-f531-4231-9603-d40230dc6504
+ version: 1
+ block_size: 1
+ data_offset: 16
+
+ ******************************
+ command:
+ lsblk
+
+ result:
+ NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
+ sda 8:0 0 8G 0 disk
+ └─bcache0 251:0 0 16G 0 disk
+ sdb 8:16 0 16G 0 disk
+ └─bcache0 251:0 0 16G 0 disk
+ sr0 11:0 1 1,1G 0 rom /cdrom
+ loop0 7:0 0 1,1G 1 loop /rofs
+ ******************************
All is good
- lsmod | grep bcache:
- bcache 227884 3
+ lsmod | grep bcache:
+ bcache 227884 3
format the bcache device:
- ******************************
- command:
- mkfs.ext4 /dev/bcache0
-
- result:
- Rejet des blocs de périphérique : 4096/4194302 complété
- Creating filesystem with 4194302 4k blocks and 1048576 inodes
- Filesystem UUID: 587d2249-3eaf-4590-a00d-42939f257e99
- Superblocs de secours stockés sur les blocs :
- 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
- 4096000
-
- Allocation des tables de groupe : 0/128 complété
- Écriture des tables d'i-noeuds : 0/128 complété
- Création du journal (32768 blocs) : complété
- Écriture des superblocs et de l'information de comptabilité du système de
- fichiers : 0/128 2/128 complété
-
- ******************************
+ ******************************
+ command:
+ mkfs.ext4 /dev/bcache0
+
+ result:
+ Rejet des blocs de périphérique : 4096/4194302 complété
+ Creating filesystem with 4194302 4k blocks and 1048576 inodes
+ Filesystem UUID: 587d2249-3eaf-4590-a00d-42939f257e99
+ Superblocs de secours stockés sur les blocs :
+ 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
+ 4096000
+
+ Allocation des tables de groupe : 0/128 complété
+ Écriture des tables d'i-noeuds : 0/128 complété
+ Création du journal (32768 blocs) : complété
+ Écriture des superblocs et de l'information de comptabilité du système de
+ fichiers : 0/128 2/128 complété
+
+ ******************************
Now mount it:
- mount /dev/bcache0 /mnt/
- mkdir /mnt/test_dir
- touch /mnt/test_file
+ mount /dev/bcache0 /mnt/
+ mkdir /mnt/test_dir
+ touch /mnt/test_file
state of: /sys/fs/bcache/
- ls /sys/fs/bcache/
-
- c990a31a-f531-4231-9603-d40230dc6504
- register
- register_quiet
+ ls /sys/fs/bcache/
+
+ c990a31a-f531-4231-9603-d40230dc6504
+ register
+ register_quiet
bcache-super-show /dev/sda
- sb.magic ok
- sb.first_sector 8 [match]
- sb.csum E6A8D9AC496B0B04 [match]
- sb.version 3 [cache device]
-
- dev.label (empty)
- dev.uuid b245150d-cfbe-4f90-836a-343e0e1a4c55
- dev.sectors_per_block 1
- dev.sectors_per_bucket 1024
- dev.cache.first_sector 1024
- dev.cache.cache_sectors 16776192
- dev.cache.total_sectors 16777216
- dev.cache.ordered yes
- dev.cache.discard yes
- dev.cache.pos 0
- dev.cache.replacement 0 [lru]
-
- cset.uuid c990a31a-f531-4231-9603-d40230dc6504
- ******************************
+ sb.magic ok
+ sb.first_sector 8 [match]
+ sb.csum E6A8D9AC496B0B04 [match]
+ sb.version 3 [cache device]
+
+ dev.label (empty)
+ dev.uuid b245150d-cfbe-4f90-836a-343e0e1a4c55
+ dev.sectors_per_block 1
+ dev.sectors_per_bucket 1024
+ dev.cache.first_sector 1024
+ dev.cache.cache_sectors 16776192
+ dev.cache.total_sectors 16777216
+ dev.cache.ordered yes
+ dev.cache.discard yes
+ dev.cache.pos 0
+ dev.cache.replacement 0 [lru]
+
+ cset.uuid c990a31a-f531-4231-9603-d40230dc6504
+ ******************************
bcache-super-show -f /dev/sdb
- sb.magic ok
- sb.first_sector 8 [match]
- sb.csum 9600B159F36A67DD [match]
- sb.version 1 [backing device]
-
- dev.label (empty)
- dev.uuid cc31e0bb-db29-4115-a1b2-e9ff54e5f127
- dev.sectors_per_block 1
- dev.sectors_per_bucket 1024
- dev.data.first_sector 16
- dev.data.cache_mode 1 [writeback]
- dev.data.cache_state 2 [dirty]
-
- cset.uuid c990a31a-f531-4231-9603-d40230dc6504
- ******************************
+ sb.magic ok
+ sb.first_sector 8 [match]
+ sb.csum 9600B159F36A67DD [match]
+ sb.version 1 [backing device]
+
+ dev.label (empty)
+ dev.uuid cc31e0bb-db29-4115-a1b2-e9ff54e5f127
+ dev.sectors_per_block 1
+ dev.sectors_per_bucket 1024
+ dev.data.first_sector 16
+ dev.data.cache_mode 1 [writeback]
+ dev.data.cache_state 2 [dirty]
+
+ cset.uuid c990a31a-f531-4231-9603-d40230dc6504
+ ******************************
mount:
- /dev/bcache0 on /mnt type ext4 (rw)
+ /dev/bcache0 on /mnt type ext4 (rw)
we will unregister the bcache:
- echo 1 /sys/fs/bcache/c990a31a-f531-4231-9603-d40230dc6504/unregister
-
+ echo 1 /sys/fs/bcache/c990a31a-f531-4231-9603-d40230dc6504/unregister
check the content of /sys/fs/bcache
- ls /sys/fs/bcache/
-
- register
- register_quiet
+ ls /sys/fs/bcache/
+
+ register
+ register_quiet
So bcache is unregistered, but status of /dev/sda:
- bcache-super-show -f /dev/sda
- sb.magic ok
- sb.first_sector 8 [match]
- sb.csum E6A8D9AC496B0B04 [match]
- sb.version 3 [cache device]
-
- dev.label (empty)
- dev.uuid b245150d-cfbe-4f90-836a-343e0e1a4c55
- dev.sectors_per_block 1
- dev.sectors_per_bucket 1024
- dev.cache.first_sector 1024
- dev.cache.cache_sectors 16776192
- dev.cache.total_sectors 16777216
- dev.cache.ordered yes
- dev.cache.discard yes
- dev.cache.pos 0
- dev.cache.replacement 0 [lru]
-
- cset.uuid
- c990a31a-f531-4231-9603-d40230dc6504
-
-
- command:
- bcache-super-show -f /dev/sdb
-
- result:
- sb.magic ok
- sb.first_sector 8 [match]
- sb.csum D41799F794675FA8 [match]
- sb.version 1 [backing device]
-
- dev.label (empty)
- dev.uuid cc31e0bb-db29-4115-a1b2-e9ff54e5f127
- dev.sectors_per_block 1
- dev.sectors_per_bucket 1024
- dev.data.first_sector 16
- dev.data.cache_mode 1 [writeback]
- dev.data.cache_state 0 [detached]
-
- cset.uuid 00000000-0000-0000-0000-000000000000
- ******************************
+ bcache-super-show -f /dev/sda
+ sb.magic ok
+ sb.first_sector 8 [match]
+ sb.csum E6A8D9AC496B0B04 [match]
+ sb.version 3 [cache device]
+
+ dev.label (empty)
+ dev.uuid b245150d-cfbe-4f90-836a-343e0e1a4c55
+ dev.sectors_per_block 1
+ dev.sectors_per_bucket 1024
+ dev.cache.first_sector 1024
+ dev.cache.cache_sectors 16776192
+ dev.cache.total_sectors 16777216
+ dev.cache.ordered yes
+ dev.cache.discard yes
+ dev.cache.pos 0
+ dev.cache.replacement 0 [lru]
+
+ cset.uuid c990a31a-f531-4231-9603-d40230dc6504
+
+ command:
+ bcache-super-show -f /dev/sdb
+
+ result:
+ sb.magic ok
+ sb.first_sector 8 [match]
+ sb.csum D41799F794675FA8 [match]
+ sb.version 1 [backing device]
+
+ dev.label (empty)
+ dev.uuid cc31e0bb-db29-4115-a1b2-e9ff54e5f127
+ dev.sectors_per_block 1
+ dev.sectors_per_bucket 1024
+ dev.data.first_sector 16
+ dev.data.cache_mode 1 [writeback]
+ dev.data.cache_state 0 [detached]
+
+ cset.uuid 00000000-0000-0000-0000-000000000000
+ ******************************
Maybe I'm wrong, but I would expect the cahing device to be 000000000ed
not the backing device, as we may still want to use the data on it.
But data is still accessible on the mount point.
- So we wipe /dev/sda now:
- ******************************
- command:
- wipefs -a /dev/sda
-
- result:
- /dev/sda: 16 bytes were erased at offset 0x00001018 (bcache): c6 85 73 f6 4e 1a 45 ca 82 65 f5 7f 48 ba 6d 81
- ******************************
+ So we wipe /dev/sda now:
+ ******************************
+ command:
+ wipefs -a /dev/sda
+
+ result:
+ /dev/sda: 16 bytes were erased at offset 0x00001018 (bcache): c6 85 73 f6 4e 1a 45 ca 82 65 f5 7f 48 ba 6d 81
+ ******************************
mount:
- /dev/bcache0 on /mnt type ext4 (rw)
+ /dev/bcache0 on /mnt type ext4 (rw)
data still there:
- ******************************
- command:
- ls /mnt/
-
- result:
- lost+found
- test_dir
- test_file
- ******************************
-
- ******************************
- command:
- lsblk
-
- result:
- NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
- sda 8:0 0 8G 0 disk
- sdb 8:16 0 16G 0 disk
- └─bcache0 251:0 0 16G 0 disk /mnt
- sr0 11:0 1 1,1G 0 rom /cdrom
- loop0 7:0 0 1,1G 1 loop /rofs
- ******************************
+ ******************************
+ command:
+ ls /mnt/
+
+ result:
+ lost+found
+ test_dir
+ test_file
+ ******************************
+
+ ******************************
+ command:
+ lsblk
+
+ result:
+ NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
+ sda 8:0 0 8G 0 disk
+ sdb 8:16 0 16G 0 disk
+ └─bcache0 251:0 0 16G 0 disk /mnt
+ sr0 11:0 1 1,1G 0 rom /cdrom
+ loop0 7:0 0 1,1G 1 loop /rofs
+ ******************************
Ok now we can backup our data if we need to, next, we will umount:
- umount /mnt/
+ umount /mnt/
ok no errors.
- lsblk:
- NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
- sda 8:0 0 8G 0 disk
- sdb 8:16 0 16G 0 disk
- └─bcache0 251:0 0 16G 0 disk
- sr0 11:0 1 1,1G 0 rom /cdrom
- loop0 7:0 0 1,1G 1 loop /rofs
- ******************************
+ lsblk:
+ NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
+ sda 8:0 0 8G 0 disk
+ sdb 8:16 0 16G 0 disk
+ └─bcache0 251:0 0 16G 0 disk
+ sr0 11:0 1 1,1G 0 rom /cdrom
+ loop0 7:0 0 1,1G 1 loop /rofs
+ ******************************
bcache0 is still there, ok, but how to delete to unregister it
definitively?
- ls /sys/fs/bcache/
-
- result:
- register
- register_quiet
- **************
-
- lsmod
-
- result:
- Module Size Used by
- bcache 227884 1
+ ls /sys/fs/bcache/
+
+ result:
+ register
+ register_quiet
+ **************
+
+ lsmod
+
+ result:
+ Module Size Used by
+ bcache 227884 1
we can't wipefs -a /dev/sdb, device is in use, so we reboot machine (NOT
OK)
- in the vm:
- ls /sys/fs/bcache/
-
- result:
- register
- register_quiet
+ in the vm:
+ ls /sys/fs/bcache/
+
+ result:
+ register
+ register_quiet
update packages and reinstall bcache-tools:
- bcache-super-show -f /dev/sda
-
- result:
- Invalid superblock (bad magic)
- sb.magic bad magic
-
- bcache-super-show -f /dev/sdb
-
- result:
- sb.magic ok
- sb.first_sector 8 [match]
- sb.csum D41799F794675FA8 [match]
- sb.version 1 [backing device]
-
- dev.label (empty)
- dev.uuid cc31e0bb-db29-4115-a1b2-e9ff54e5f127
- dev.sectors_per_block 1
- dev.sectors_per_bucket 1024
- dev.data.first_sector 16
- dev.data.cache_mode 1 [writeback]
- dev.data.cache_state 0 [detached]
-
- cset.uuid
- 00000000-0000-0000-0000-000000000000
+ bcache-super-show -f /dev/sda
+
+ result:
+ Invalid superblock (bad magic)
+ sb.magic bad magic
+
+ bcache-super-show -f /dev/sdb
+
+ result:
+ sb.magic ok
+ sb.first_sector 8 [match]
+ sb.csum D41799F794675FA8 [match]
+ sb.version 1 [backing device]
+
+ dev.label (empty)
+ dev.uuid cc31e0bb-db29-4115-a1b2-e9ff54e5f127
+ dev.sectors_per_block 1
+ dev.sectors_per_bucket 1024
+ dev.data.first_sector 16
+ dev.data.cache_mode 1 [writeback]
+ dev.data.cache_state 0 [detached]
+
+ cset.uuid 00000000-0000-0000-0000-000000000000
Now we can wipe /dev/sdb because we rebooted, and bcache don't use the device anymore:
- wipefs -a /dev/sdb
-
- result:
- /dev/sdb: 16 bytes were erased at offset 0x00001018 (bcache): c6 85 73 f6 4e 1a 45 ca 82 65 f5 7f 48 ba 6d 81
-
- **********************************************************
-
- Now I can re-use my device, but I needed a reboot. Maybe we must also
- have better bcache management tools also.
+ wipefs -a /dev/sdb
+
+ result:
+ /dev/sdb: 16 bytes were erased at offset 0x00001018 (bcache): c6 85 73 f6 4e 1a 45 ca 82 65 f5 7f 48 ba 6d 81
+
+ **********************************************************
+
+ Now I can re-use my device, but I needed a reboot. Maybe we also must
+ have better bcache management tools.
--
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https://bugs.launchpad.net/bugs/1377142
Title:
Bcache doesn't allow full unregistering without rebooting
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