Thanks Eric and David.
I have sent out V3 patch-set which will disable access
to backup super-block unless requested by the user.
here below are some test cases and results before and
after this fix.. which finds the patch works awesome.
--------
the original problem which all this started..
mkfs.btrfs /dev/sdb -f && yes| mkfs.ext4 /dev/sdb && mount /dev/sdb /ext4
~/before/mkfs.btrfs -f /dev/sdc /dev/sdd (run twice)
~/before/mkfs.btrfs -f /dev/sdc /dev/sdd
::
ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
ERROR: unable to scan the device '/dev/sdb' - Device or resource busy
adding device /dev/sdd id 2
fs created label (null) on /dev/sdc
nodesize 4096 leafsize 4096 sectorsize 4096 size 3.11GB
after the fix.
# mkfs.btrfs -f /dev/sdc /dev/sdd
WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using
adding device /dev/sdd id 2
fs created label (null) on /dev/sdc
nodesize 4096 leafsize 4096 sectorsize 4096 size 104.98GB
Btrfs v0.20-rc1-238-g170881a-dirty
-------------
# umount /ext4
# mkfs.btrfs /dev/sdb /dev/sdc -f && wipefs /dev/sdb
There is an existing bug..
# ~/before/btrfs check /dev/sdc --repair
enabling repair mode
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sdc
UUID: e03c477d-b696-46c1-bf79-43b8b8454f11
checking extents
checking fs roots
checking root refs
btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
Aborted (core dumped)
#
and its still there even after this patch :-)
# btrfs check /dev/sdc --repair
enabling repair mode
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sdc
UUID: e03c477d-b696-46c1-bf79-43b8b8454f11
checking extents
checking fs roots
checking root refs
btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
Aborted (core dumped)
-------------------------
# mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb
without the fix
# ~/before/btrfs restore -o /dev/sdb ~/tmp
ERROR: device scan failed '/dev/sdb' - Invalid argument
ERROR: device scan failed '/dev/sdb' - Invalid argument
Root objectid is 5
with the fix
# btrfs restore -o /dev/sdb ~/tmp
No valid Btrfs found on /dev/sdb
Could not open root, trying backup super
Root objectid is 5
now I say to use sb backup 1..
# btrfs restore -u 1 -o /dev/sdb ~/tmp
Root objectid is 5
# echo $?
0
--------------
# mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb
# ~/before/btrfs check /dev/sdc --repair
enabling repair mode
ERROR: device scan failed '/dev/sdb' - Invalid argument
ERROR: device scan failed '/dev/sdb' - Invalid argument
Checking filesystem on /dev/sdc
UUID: 5dc5c663-eeea-4ec2-b8fe-170157f5d68d
checking extents
checking fs roots
checking root refs
found 28672 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 22420
file data blocks allocated: 0
referenced 0
Btrfs v0.20-rc1-235-gdd21bc1
# mkfs.btrfs /dev/sdb /dev/sdc -f && yes|mkfs.ext4 /dev/sdb
since now new code doesn't read backup SB of devid1
it hits the earlier known bug.
# btrfs check /dev/sdc --repair
enabling repair mode
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sdc
UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
checking extents
checking fs roots
checking root refs
btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
Aborted (core dumped)
So user would need to fix the devid1 first.
# btrfs check /dev/sdb --repair
enabling repair mode
No valid Btrfs found on /dev/sdb
# btrfs check -s 1 /dev/sdb --repair
using SB copy 1, bytenr 67108864
enabling repair mode
Checking filesystem on /dev/sdb
UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
checking extents
checking fs roots
checking root refs
found 28672 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 22420
file data blocks allocated: 0
referenced 0
Btrfs v0.20-rc1-238-g170881a-dirty
# btrfs check /dev/sdc --repair
enabling repair mode
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sdc
UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
checking extents
checking fs roots
checking root refs
btrfs: extent-tree.c:2553: btrfs_reserve_extent: Assertion `!(ret)' failed.
Aborted (core dumped)
Need to write back the backup SB to primary SB.
IMO when -s 1 was given it had the chance to fix
primary.. this can be fixed later.
# ./btrfs-select-super -s 1 /dev/sdb
using SB copy 1, bytenr 67108864
ERROR: device scan failed '/dev/sdb' - Invalid argument
# btrfs check /dev/sdc --repair
enabling repair mode
Checking filesystem on /dev/sdc
UUID: daa0dc6d-35b6-43ab-8333-894710a5b917
checking extents
checking fs roots
checking root refs
found 28672 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 22420
file data blocks allocated: 0
referenced 0
Btrfs v0.20-rc1-238-g170881a-dirty
---------------------------------------------------------------
I am not sure if I have a wipe -a working for btrfs,
so I would clean using dd.
# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024+64))
8+0 records in
8+0 records out
8 bytes (8 B) copied, 0.000324503 s, 24.7 kB/s
# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024*1024+64))
8+0 records in
8+0 records out
8 bytes (8 B) copied, 0.000364635 s, 21.9 kB/s
# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((256*1024*1024*1024+64))
dd: `/dev/sdb': cannot seek: Invalid argument
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.000430846 s, 0.0 kB/s
This behavior is same before and after the patch.
# btrfs check /dev/sdb
No valid Btrfs found on /dev/sdb
# btrfs check /dev/sdb -s 1
using SB copy 1, bytenr 67108864
No valid Btrfs found on /dev/sdb
# btrfs check /dev/sdb -s 2
using SB copy 2, bytenr 274877906944
No valid Btrfs found on /dev/sdb
#
------------------------
# mkfs.btrfs /dev/sdb /dev/sdc -f && mount /dev/sdc /btrfs
# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024+64))
# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((64*1024*1024+64))
# dd if=/dev/zero bs=1 count=8 of=/dev/sdb seek=$((256*1024*1024*1024+64))
# mkfs.btrfs /dev/sdb
WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using
/dev/sdb is mounted
# umount /btrfs
# mkfs.btrfs /dev/sdb
WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using
/dev/sdb appears to contain an existing filesystem (btrfs).
Use the -f option to force overwrite.
#
-------------------------
# mkfs.btrfs /dev/sdd /dev/sde -f
WARNING! - Btrfs v0.20-rc1-238-g170881a-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using
adding device /dev/sde id 2
fs created label (null) on /dev/sdd
nodesize 4096 leafsize 4096 sectorsize 4096 size 93.22GB
Btrfs v0.20-rc1-238-g170881a-dirty
# mount /dev/sde /btrfs
# umount /btrfs
# dd if=/dev/zero bs=1 count=8 of=/dev/sde seek=$((64*1024+64))
8+0 records in
8+0 records out
8 bytes (8 B) copied, 0.0149415 s, 0.5 kB/s
remove /dev/sdd
# x="0 0 3 0"
# echo "scsi remove-single-device $x" > /proc/scsi/scsi
# lsscsi
[0:0:0:0] disk Sun boot1 V1.0 /dev/sda
[0:0:2:0] disk Sun boot3 V1.0 /dev/sdc
[0:0:4:0] disk Sun boot5 V1.0 /dev/sde
[0:1:0:0] disk SEAGATE ST914602SSUN146G 0603 -
[0:1:1:0] disk SEAGATE ST914602SSUN146G 0603 -
[0:3:0:0] enclosu ADAPTEC Virtual SGPIO 0 0001 -
# btrfs check /dev/sde
No valid Btrfs found on /dev/sde
# btrfs check /dev/sde -s 1
using SB copy 1, bytenr 67108864
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sde
UUID: fa08122d-832f-4f32-87ee-58eb9380d5da
checking extents
checking fs roots
checking root refs
found 815104 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 21476
file data blocks allocated: 786432
referenced 786432
Btrfs v0.20-rc1-238-g170881a-dirty
# ./btrfs-select-super -s 1 /dev/sde
using SB copy 1, bytenr 67108864
ERROR: device scan failed '/dev/sdc' - Invalid argument
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
# btrfs check /dev/sde
warning, device 1 is missing
warning, device 1 is missing
warning devid 1 not found already
Checking filesystem on /dev/sde
UUID: fa08122d-832f-4f32-87ee-58eb9380d5da
checking extents
checking fs roots
checking root refs
found 815104 bytes used err is 0
total csum bytes: 0
total tree bytes: 28672
total fs tree bytes: 8192
btree space waste bytes: 21476
file data blocks allocated: 786432
referenced 786432
Btrfs v0.20-rc1-238-g170881a-dirty
#
---------------
Thanks, Anand
On 03/12/2013 02:16 AM, David Sterba wrote:
On Mon, Mar 11, 2013 at 10:03:46AM -0500, Eric Sandeen wrote:
IMHO, nothing should be checking the backup superblocks unless explicitly
told to.
That's the whole point I believe.
update the infrastructure, every SB access looks to the first copy
unless told by command line options.
david
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