Re: [f2fs-dev] [PATCH] f2fs: add ioctl to expose current features

[Chao Yu <chao@kernel.org>]

On 2017/7/22 4:11, Jaegeuk Kim wrote:
> This patch adds an ioctl to provide feature information to user.
> For exapmle, SQLite can use this ioctl to detect whether f2fs support atomic
> write or not.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

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

Thanks,

> ---
>  fs/f2fs/f2fs.h |  2 ++
>  fs/f2fs/file.c | 13 +++++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index e06d4e4b4579..5c46a462b56e 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -112,6 +112,7 @@ struct f2fs_mount_info {
>  
>  #define F2FS_FEATURE_ENCRYPT	0x0001
>  #define F2FS_FEATURE_BLKZONED	0x0002
> +#define F2FS_FEATURE_ATOMIC_WRITE 0x0004
>  
>  #define F2FS_HAS_FEATURE(sb, mask)					\
>  	((F2FS_SB(sb)->raw_super->feature & cpu_to_le32(mask)) != 0)
> @@ -308,6 +309,7 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
>  						struct f2fs_flush_device)
>  #define F2FS_IOC_GARBAGE_COLLECT_RANGE	_IOW(F2FS_IOCTL_MAGIC, 11,	\
>  						struct f2fs_gc_range)
> +#define	F2FS_IOC_GET_FEATURES		_IOR(F2FS_IOCTL_MAGIC, 12, __u32)
>  
>  #define F2FS_IOC_SET_ENCRYPTION_POLICY	FS_IOC_SET_ENCRYPTION_POLICY
>  #define F2FS_IOC_GET_ENCRYPTION_POLICY	FS_IOC_GET_ENCRYPTION_POLICY
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 2706130c261b..0e07b5b18cfa 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -2384,6 +2384,16 @@ static int f2fs_ioc_flush_device(struct file *filp, unsigned long arg)
>  	return ret;
>  }
>  
> +static int f2fs_ioc_get_features(struct file *filp, unsigned long arg)
> +{
> +	struct inode *inode = file_inode(filp);
> +	u32 sb_feature = le32_to_cpu(F2FS_I_SB(inode)->raw_super->feature);
> +
> +	/* Must validate to set it with SQLite behavior in Android. */
> +	sb_feature |= F2FS_FEATURE_ATOMIC_WRITE;
> +
> +	return put_user(sb_feature, (u32 __user *)arg);
> +}
>  
>  long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  {
> @@ -2426,6 +2436,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  		return f2fs_ioc_move_range(filp, arg);
>  	case F2FS_IOC_FLUSH_DEVICE:
>  		return f2fs_ioc_flush_device(filp, arg);
> +	case F2FS_IOC_GET_FEATURES:
> +		return f2fs_ioc_get_features(filp, arg);
>  	default:
>  		return -ENOTTY;
>  	}
> @@ -2491,6 +2503,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>  	case F2FS_IOC_DEFRAGMENT:
>  	case F2FS_IOC_MOVE_RANGE:
>  	case F2FS_IOC_FLUSH_DEVICE:
> +	case F2FS_IOC_GET_FEATURES:
>  		break;
>  	default:
>  		return -ENOIOCTLCMD;
>