f2fs: force out-place update for all writes on compressed file

For compressed file, compressed write may fail and fall back to raw
write.

-Thread A                                         - Thread B
  - f2fs_write_multi_pages                          - f2fs_down_write(&sbi->cp_rwsem);
   - f2fs_write_compressed_pages                    - ...
    - f2fs_trylock_op                               - ...
     - f2fs_down_read_trylock(&sbi->cp_rwsem);      - ...
   - f2fs_write_raw_pages                           - ...

Thread B acquires the lock first, which causes Thread A to fail lock
acquisition and fall back to raw-data write.
IPU_FORCE is enabled on small-capacity storage devices (< 16GB),
so f2fs_write_raw_pages() overwrites the original compressed data
in-place.

The in-memory node has been updated with raw-data addresses, while the
node metadata stored on eMMC still remains in compressed state.
If a power-cut occurs before the node is flushed to disk, on-disk
inconsistency arises: disk data is raw, yet metadata treats it as a
compressed cluster, leading to decompression failure.

To eliminate this risk completely, force out-place update for all
write operations on compressed file.

Cc: stable@kernel.org
Fixes: 4c8ff7095bef ("f2fs: support data compression")
Signed-off-by: Jiucheng Xu <jiucheng.xu@amlogic.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

0 files changed, 0 insertions, 0 deletions