linux-kernel - [PATCH] f2fs: fix to avoid atomicity corruption of atomic file

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Message-Id: <20250314120651.443184-1-youngjin.gil@samsung.com>
Date: Fri, 14 Mar 2025 21:06:51 +0900
From: Yeongjin Gil <youngjin.gil@...sung.com>
To: jaegeuk@...nel.org, chao@...nel.org, daehojeong@...gle.com,
	linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Cc: sj1557.seo@...sung.com, s_min.jeong@...sung.com, Yeongjin Gil
	<youngjin.gil@...sung.com>
Subject: [PATCH] f2fs: fix to avoid atomicity corruption of atomic file

In the case of the following call stack for an atomic file,
FI_DIRTY_INODE is set, but FI_ATOMIC_DIRTIED is not subsequently set.

f2fs_file_write_iter
  f2fs_map_blocks
    f2fs_reserve_new_blocks
      inc_valid_block_count
        __mark_inode_dirty(dquot)
          f2fs_dirty_inode

If FI_ATOMIC_DIRTIED is not set, atomic file can encounter corruption
due to a mismatch between old file size and new data.

To resolve this issue, I changed to set FI_ATOMIC_DIRTIED when
FI_DIRTY_INODE is set. This ensures that FI_DIRTY_INODE, which was
previously cleared by the Writeback thread during the commit atomic, is
set and i_size is updated.

Fixes: fccaa81de87e ("f2fs: prevent atomic file from being dirtied before commit")
Reviewed-by: Sungjong Seo <sj1557.seo@...sung.com>
Reviewed-by: Sunmin Jeong <s_min.jeong@...sung.com>
Signed-off-by: Yeongjin Gil <youngjin.gil@...sung.com>
---
 fs/f2fs/inode.c | 4 +---
 fs/f2fs/super.c | 4 ++++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index aa2f41696a88..83f862578fc8 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -34,10 +34,8 @@ void f2fs_mark_inode_dirty_sync(struct inode *inode, bool sync)
 	if (f2fs_inode_dirtied(inode, sync))
 		return;
 
-	if (f2fs_is_atomic_file(inode)) {
-		set_inode_flag(inode, FI_ATOMIC_DIRTIED);
+	if (f2fs_is_atomic_file(inode))
 		return;
-	}
 
 	mark_inode_dirty_sync(inode);
 }
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 397df271885c..c08d52c6467a 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1534,6 +1534,10 @@ int f2fs_inode_dirtied(struct inode *inode, bool sync)
 		inc_page_count(sbi, F2FS_DIRTY_IMETA);
 	}
 	spin_unlock(&sbi->inode_lock[DIRTY_META]);
+
+	if (!ret && f2fs_is_atomic_file(inode))
+		set_inode_flag(inode, FI_ATOMIC_DIRTIED);
+
 	return ret;
 }
 
-- 
2.34.1