Re: [RFC PATCH 2/2] f2fs: introduce lost+found feature

[Chao Yu <chao@kernel.org>]

On 2018/2/6 12:31, Sheng Yong wrote:
> Introduce lost+found feature. The lost+found is a directory which saves

Nitpick, lost_found feature...

Needs to add /sys/fs/f2fs/features/lost_found sysfs entry, and show
'lost_found' in /sys/fs/f2fs/<dev>/features.

Thanks,

> unreachable files. If f2fsck finds a file which has no parent, or the
> parent is removed by f2fsck, the file will be placed in lost+found
> directory.
> 
> According fscrypt policy, lost+found could not be encrypted. As a
> result, the root directory cannot be encrypted. So if lost+found
> feature is enabled, let's avoid to encrypt root directory.
> 
> Signed-off-by: Sheng Yong <shengyong1@huawei.com>
> ---
>  fs/f2fs/f2fs.h  |  2 ++
>  fs/f2fs/super.c | 12 ++++++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index a60d56a96f9b..d9c9be6ea5d5 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -125,6 +125,7 @@ struct f2fs_mount_info {
>  #define F2FS_FEATURE_FLEXIBLE_INLINE_XATTR	0x0040
>  #define F2FS_FEATURE_QUOTA_INO		0x0080
>  #define F2FS_FEATURE_INODE_CRTIME	0x0100
> +#define F2FS_FEATURE_LOST_FOUND		0x0200
>  
>  #define F2FS_HAS_FEATURE(sb, mask)					\
>  	((F2FS_SB(sb)->raw_super->feature & cpu_to_le32(mask)) != 0)
> @@ -3186,6 +3187,7 @@ F2FS_FEATURE_FUNCS(inode_chksum, INODE_CHKSUM);
>  F2FS_FEATURE_FUNCS(flexible_inline_xattr, FLEXIBLE_INLINE_XATTR);
>  F2FS_FEATURE_FUNCS(quota_ino, QUOTA_INO);
>  F2FS_FEATURE_FUNCS(inode_crtime, INODE_CRTIME);
> +F2FS_FEATURE_FUNCS(lost_found, LOST_FOUND);
>  
>  #ifdef CONFIG_BLK_DEV_ZONED
>  static inline int get_blkz_type(struct f2fs_sb_info *sbi,
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index b39ab55ab1b5..5f536e878d21 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1797,6 +1797,18 @@ static int f2fs_get_context(struct inode *inode, void *ctx, size_t len)
>  static int f2fs_set_context(struct inode *inode, const void *ctx, size_t len,
>  							void *fs_data)
>  {
> +	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> +
> +	/*
> +	 * Encrypting the root directory is not allowed because f2fsck
> +	 * expects lost+found directory to exist and remain unencrypted
> +	 * if LOST_FOUND feature is enabled.
> +	 *
> +	 */
> +	if (f2fs_sb_has_lost_found(sbi->sb) &&
> +			inode->i_ino == F2FS_ROOT_INO(sbi))
> +		return -EPERM;
> +
>  	return f2fs_setxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
>  				F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
>  				ctx, len, fs_data, XATTR_CREATE);
> 

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