linux-kernel - [PATCH 5.12 079/700] f2fs: Prevent swap file in LFS mode

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Date:   Mon, 12 Jul 2021 08:02:42 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Shinichiro Kawasaki <shinichiro.kawasaki@....com>,
        Chao Yu <yuchao0@...wei.com>, Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH 5.12 079/700] f2fs: Prevent swap file in LFS mode

From: Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>

commit d927ccfccb009ede24448d69c08b12e7c8a6979b upstream.

The kernel writes to swap files on f2fs directly without the assistance
of the filesystem. This direct write by kernel can be non-sequential
even when the f2fs is in LFS mode. Such non-sequential write conflicts
with the LFS semantics. Especially when f2fs is set up on zoned block
devices, the non-sequential write causes unaligned write command errors.

To avoid the non-sequential writes to swap files, prevent swap file
activation when the filesystem is in LFS mode.

Fixes: 4969c06a0d83 ("f2fs: support swap file w/ DIO")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>
Cc: stable@...r.kernel.org # v5.10+
Reviewed-by: Chao Yu <yuchao0@...wei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/f2fs/data.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -3971,6 +3971,12 @@ static int f2fs_swap_activate(struct swa
 	if (f2fs_readonly(F2FS_I_SB(inode)->sb))
 		return -EROFS;
 
+	if (f2fs_lfs_mode(F2FS_I_SB(inode))) {
+		f2fs_err(F2FS_I_SB(inode),
+			"Swapfile not supported in LFS mode");
+		return -EINVAL;
+	}
+
 	ret = f2fs_convert_inline_inode(inode);
 	if (ret)
 		return ret;