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

[Jiucheng Xu via B4 Relay]

From: Jiucheng Xu <jiucheng.xu@xxxxxxxxxxx>

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.

Signed-off-by: Jiucheng Xu <jiucheng.xu@xxxxxxxxxxx>
---
- Link to v1: https://lore.kernel.org/r/20260826-origin-dev-v1-1-c21271a82100@xxxxxxxxxxx
---
 fs/f2fs/data.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 6ae0eb37d20f96ed51a8124f59ba90dabf632fb5..aaeea561dcd30681b9b37f2f6f0493ed58ec2fe0 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2973,10 +2973,12 @@ bool f2fs_should_update_outplace(struct inode *inode, struct f2fs_io_info *fio)
 		return true;
 	if (f2fs_used_in_atomic_write(inode))
 		return true;
-	/* rewrite low ratio compress data w/ OPU mode to avoid fragmentation */
-	if (f2fs_compressed_file(inode) &&
-		F2FS_OPTION(sbi).compress_mode == COMPR_MODE_USER &&
-		is_inode_flag_set(inode, FI_ENABLE_COMPRESS))
+	/*
+	 * rewrite low ratio compress data w/ OPU mode to avoid fragmentation.
+	 * If IO comes from compressed write path and fallback to raw write,
+	 * force out‑place to prevent metadata‑data inconsistency.
+	 */
+	if (f2fs_compressed_file(inode))
 		return true;
 
 	/* swap file is migrating in aligned write mode */

---
base-commit: 0a1703eba23707e3b2edfa2a2329352e7abc0ffa
change-id: 20260818-origin-dev-0e8c63e2145a

Best regards,
-- 
Jiucheng Xu <jiucheng.xu@xxxxxxxxxxx>