btrfs-progs: Detect compressed extent without csum

Patches can be fetch from github:
https://github.com/adam900710/btrfs-progs/tree/compress_nodatasum

It's based on v4.16 stable branch.

James Harvey from mail list reports a strange kernel panic, whichs show obviously kernel memory corruption, while after btrfs decompression failure.

It turns out that, some compressed extent get corrupted on-disk, while the inode has NODATASUM set, there is no csum to prevent corrupted mirror being used.

Although the root cause should be buggy lzo implementation, it still shows that btrfs is not following the behavior defined in btrfs(5):

Note
If nodatacow or nodatasum are enabled, compression is disabled.

So at least make btrfs check to detect such problem.

Qu Wenruo (3):
btrfs-progs: check/lowmem: Add checks for compressed extent without
csum
btrfs-progs: check/original: Add checks for compressed extent without
csum
btrfs-progs: fsck-tests: Add test case for detecting compressed extent
without csum

 check/main.c                                  |  10 ++++++--
 check/mode-lowmem.c                           |  18 +++++++++++++
 .../compressed_extent_without_csum.raw.xz     | Bin 0 -> 21996 bytes
 .../032-compressed-nodatasum/test.sh          |  24 ++++++++++++++++++
 4 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 tests/fsck-tests/032-compressed-nodatasum/compressed_extent_without_csum.raw.xz
 create mode 100755 tests/fsck-tests/032-compressed-nodatasum/test.sh

2.17.0