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Anand Jain 4ebdad0512 btrfs: fix replace of seed device
[ Upstream commit c6a5d954950c5031444173ad2195efc163afcac9 ]

If you replace a seed device in a sprouted fs, it appears to have
successfully replaced the seed device, but if you look closely, it
didn't.  Here is an example.

  $ mkfs.btrfs /dev/sda
  $ btrfstune -S1 /dev/sda
  $ mount /dev/sda /btrfs
  $ btrfs device add /dev/sdb /btrfs
  $ umount /btrfs
  $ btrfs device scan --forget
  $ mount -o device=/dev/sda /dev/sdb /btrfs
  $ btrfs replace start -f /dev/sda /dev/sdc /btrfs
  $ echo $?
  0

  BTRFS info (device sdb): dev_replace from /dev/sda (devid 1) to /dev/sdc started
  BTRFS info (device sdb): dev_replace from /dev/sda (devid 1) to /dev/sdc finished

  $ btrfs fi show
  Label: none  uuid: ab2c88b7-be81-4a7e-9849-c3666e7f9f4f
	  Total devices 2 FS bytes used 256.00KiB
	  devid    1 size 3.00GiB used 520.00MiB path /dev/sdc
	  devid    2 size 3.00GiB used 896.00MiB path /dev/sdb

  Label: none  uuid: 10bd3202-0415-43af-96a8-d5409f310a7e
	  Total devices 1 FS bytes used 128.00KiB
	  devid    1 size 3.00GiB used 536.00MiB path /dev/sda

So as per the replace start command and kernel log replace was successful.
Now let's try to clean mount.

  $ umount /btrfs
  $ btrfs device scan --forget

  $ mount -o device=/dev/sdc /dev/sdb /btrfs
  mount: /btrfs: wrong fs type, bad option, bad superblock on /dev/sdb, missing codepage or helper program, or other error.

  [  636.157517] BTRFS error (device sdc): failed to read chunk tree: -2
  [  636.180177] BTRFS error (device sdc): open_ctree failed

That's because per dev items it is still looking for the original seed
device.

 $ btrfs inspect-internal dump-tree -d /dev/sdb

	item 0 key (DEV_ITEMS DEV_ITEM 1) itemoff 16185 itemsize 98
		devid 1 total_bytes 3221225472 bytes_used 545259520
		io_align 4096 io_width 4096 sector_size 4096 type 0
		generation 6 start_offset 0 dev_group 0
		seek_speed 0 bandwidth 0
		uuid 59368f50-9af2-4b17-91da-8a783cc418d4  <--- seed uuid
		fsid 10bd3202-0415-43af-96a8-d5409f310a7e  <--- seed fsid
	item 1 key (DEV_ITEMS DEV_ITEM 2) itemoff 16087 itemsize 98
		devid 2 total_bytes 3221225472 bytes_used 939524096
		io_align 4096 io_width 4096 sector_size 4096 type 0
		generation 0 start_offset 0 dev_group 0
		seek_speed 0 bandwidth 0
		uuid 56a0a6bc-4630-4998-8daf-3c3030c4256a  <- sprout uuid
		fsid ab2c88b7-be81-4a7e-9849-c3666e7f9f4f <- sprout fsid

But the replaced target has the following uuid+fsid in its superblock
which doesn't match with the expected uuid+fsid in its devitem.

  $ btrfs in dump-super /dev/sdc | egrep '^generation|dev_item.uuid|dev_item.fsid|devid'
  generation	20
  dev_item.uuid	59368f50-9af2-4b17-91da-8a783cc418d4
  dev_item.fsid	ab2c88b7-be81-4a7e-9849-c3666e7f9f4f [match]
  dev_item.devid	1

So if you provide the original seed device the mount shall be
successful.  Which so long happening in the test case btrfs/163.

  $ btrfs device scan --forget
  $ mount -o device=/dev/sda /dev/sdb /btrfs

Fix in this patch:
If a seed is not sprouted then there is no replacement of it, because of
its read-only filesystem with a read-only device. Similarly, in the case
of a sprouted filesystem, the seed device is still read only. So, mark
it as you can't replace a seed device, you can only add a new device and
then delete the seed device. If replace is attempted then returns
-EINVAL.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-11-05 11:43:19 +01:00
arch ARC: [dts] fix the errors detected by dtbs_check 2020-11-05 11:43:19 +01:00
block block: ratelimit handle_bad_sector() message 2020-10-29 09:58:01 +01:00
certs
crypto crypto: algif_skcipher - EBUSY on aio should be an error 2020-10-29 09:57:30 +01:00
Documentation media: videodev2.h: RGB BT2020 and HSV are always full range 2020-11-05 11:43:15 +01:00
drivers drm/amd/display: HDMI remote sink need mode validation for Linux 2020-11-05 11:43:19 +01:00
fs btrfs: fix replace of seed device 2020-11-05 11:43:19 +01:00
include usb: typec: tcpm: During PR_SWAP, source caps should be sent only after tSwapSourceStart 2020-11-05 11:43:15 +01:00
init printk: reduce LOG_BUF_SHIFT range for H8300 2020-11-05 11:43:16 +01:00
ipc
kernel bpf: Permit map_ptr arithmetic with opcode add and offset 0 2020-11-05 11:43:17 +01:00
lib lib/crc32.c: fix trivial typo in preprocessor condition 2020-10-29 09:57:52 +01:00
LICENSES
mm mm/page_owner: change split_page_owner to take a count 2020-10-29 09:57:52 +01:00
net SUNRPC: Mitigate cond_resched() in xprt_transmit() 2020-11-05 11:43:18 +01:00
samples samples/bpf: Fix possible deadlock in xdpsock 2020-11-05 11:43:17 +01:00
scripts scripts/setlocalversion: make git describe output more reliable 2020-11-01 12:01:01 +01:00
security evm: Check size of security.evm before using it 2020-11-01 12:01:05 +01:00
sound ALSA: hda/ca0132 - Add new quirk ID for SoundBlaster AE-7. 2020-10-29 09:58:09 +01:00
tools selftests/bpf: Define string const as global for test_sysctl_prog.c 2020-11-05 11:43:17 +01:00
usr
virt KVM: arm64: Assume write fault on S1PTW permission fault on instruction fetch 2020-10-01 13:18:25 +02:00
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.cocciconfig
.get_maintainer.ignore
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MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.74 2020-11-01 12:01:07 +01:00
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