[f2fs-dev] [PATCH v2] f2fs: Prevent swap file in LFS mode

[f2fs-dev] [PATCH v2] f2fs: Prevent swap file in LFS mode

[Shin'ichiro Kawasaki]

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@wdc.com>
Cc: stable@vger.kernel.org # v5.10+
---
 fs/f2fs/data.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 96f1a354f89f..285302d009aa 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -4050,6 +4050,12 @@ static int f2fs_swap_activate(struct swap_info_struct *sis, struct file *file,
 	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;
-- 
2.30.2



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Re: [f2fs-dev] [PATCH v2] f2fs: Prevent swap file in LFS mode

[Chao Yu]

On 2021/5/10 19:24, Shin'ichiro Kawasaki wrote:
> 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@wdc.com>
> Cc: stable@vger.kernel.org # v5.10

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,




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