[PATCH 0/2] btrfs-progs: check: avoid false alerts for --check-data-csum on RAID56

[Qu Wenruo <wqu@suse.com>]

There is a long existing bug that btrfs-progs doesn't really support
rebuilding its data using RAID56 P/Q.

This means any read with mirror_num > 1 for RAID56 won't work, and will
just return the P/Q raw data directly.

The RAID56 ability in btrfs-progs is only for data write.

This will cause tons of false alerts for "btrfs check
--check-data-csum", making it useless as an offline to verify RAID56
data.

The proper fix will need way more code modification (btrfs-fuse supports
that, so I believe it's possible).

But for now, let's just disable mirror_num > 1 read repair for progs.

Qu Wenruo (2):
  btrfs-progs: avoid checking wrong RAID5/6 P/Q data
  btrfs-progs: tests/fsck: add test case for data csum check on raid5

 kernel-shared/disk-io.c                       |  7 +++++
 kernel-shared/volumes.c                       | 10 +++---
 .../056-raid56-false-alerts/test.sh           | 31 +++++++++++++++++++
 3 files changed, 44 insertions(+), 4 deletions(-)
 create mode 100755 tests/fsck-tests/056-raid56-false-alerts/test.sh

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2.35.1