btrfs/15[78]: Use proper helper to get both devid and physical offset for corruption

btrfs/15[78]: Use proper helper to get both devid and physical offset for corruption

[BUG]
When using btrfs-progs v5.4, btrfs/157 and btrfs/158 will fail:

btrfs/157 1s ... - output mismatch (see xfstests/results//btrfs/157.out.bad)
    --- tests/btrfs/157.out 2018-09-16 21:30:48.505104287 +0100
    +++ xfstests/results//btrfs/157.out.bad
2019-12-10 15:35:43.112390076 +0000
    @@ -1,9 +1,9 @@
     QA output created by 157
     wrote 131072/131072 bytes at offset 0
     XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
    -wrote 65536/65536 bytes at offset 9437184
    +wrote 65536/65536 bytes at offset 22020096
     XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
    -wrote 65536/65536 bytes at offset 9437184
    ...
    (Run 'diff -u xfstests/tests/btrfs/157.out xfstests/results//btrfs/157.out.bad'  to see the entire diff)
btrfs/158 2s ... - output mismatch (see xfstests/results//btrfs/158.out.bad)
    --- tests/btrfs/158.out 2018-09-16 21:30:48.505104287 +0100
    +++ xfstests/results//btrfs/158.out.bad
2019-12-10 15:35:44.844388521 +0000
    @@ -1,9 +1,9 @@
     QA output created by 158
     wrote 131072/131072 bytes at offset 0
     XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
    -wrote 65536/65536 bytes at offset 9437184
    +wrote 65536/65536 bytes at offset 22020096
     XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
    -wrote 65536/65536 bytes at offset 9437184
    ...
    (Run 'diff -u xfstests/tests/btrfs/158.out xfstests/results//btrfs/158.out.bad'  to see the entire diff)

[CAUSE]
This two tests use physical offset as golden output, while mkfs.btrfs
can do whatever it likes to arrange its chunk layout, thus physical
offset is never reliable.

And btrfs-progs commit c501c9e3b816 ("btrfs-progs: mkfs: match devid
order to the stripe index") just changed the layout.

So the output mismatch and failed.

[FIX]
In fact, that btrfs-progs commit not only changed offset, but also the
device sequence.

So we can't just simply remove the physical offset, but also need to use
proper helper to get both devid (as its device path) and physical offset
for corruption.

As long as mkfs.btrfs still uses sequential devid, these tests should
handle future chunk layout change without problem.

Reported-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>