FAILED: patch "[PATCH] f2fs: force out-place update for all writes on compressed file" failed to apply to 6.6-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x a64a3fec11e77a3a0dc0009bdc58b925e45a1bb4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107052913-failed-6.6-a64a3fec11e7@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From a64a3fec11e77a3a0dc0009bdc58b925e45a1bb4 Mon Sep 17 00:00:00 2001
From: Jiucheng Xu <jiucheng.xu@amlogic.com>
Date: Mon, 7 Sep 2026 19:35:42 +0800
Subject: [PATCH] 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>
---
 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 bc53ac21efeee..22de00754678c 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2914,10 +2914,12 @@ 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 */
-- 
2.53.0