Re: [PATCH 1/5] btrfs: Make async snapshot ioctl more generic

[Sage Weil <sage@newdream.net>]

Hi Li,

On Mon, 29 Nov 2010, Li Zefan wrote:
> So we don't have to add new structures as we create more ioctls
> for snapshots.
> 
> Now to create async snapshot, set BTRFS_SNAPSHOT_CREATE_ASYNC bit of
> vol_arg_v2->flags, and then call ioctl(BTRFS_IOCT_SNAP_CREATE_V2).
> 
> Note: this changes the async snapshot ioctl ABI, which was merged
> in .37 merge window, so we have to make this change into .37.

These changes all look good to me.

Thanks!
sage



> 
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
> ---
>  fs/btrfs/ioctl.c |   34 +++++++++++++++++++++-------------
>  fs/btrfs/ioctl.h |   12 ++++++++----
>  2 files changed, 29 insertions(+), 17 deletions(-)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 463d91b..d3f1a60 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -935,23 +935,31 @@ out:
>  
>  static noinline int btrfs_ioctl_snap_create(struct file *file,
>  					    void __user *arg, int subvol,
> -					    int async)
> +					    bool v2)
>  {
>  	struct btrfs_ioctl_vol_args *vol_args = NULL;
> -	struct btrfs_ioctl_async_vol_args *async_vol_args = NULL;
> +	struct btrfs_ioctl_vol_args_v2 *vol_args_v2 = NULL;
>  	char *name;
>  	u64 fd;
>  	u64 transid = 0;
> +	bool async = false;
>  	int ret;
>  
> -	if (async) {
> -		async_vol_args = memdup_user(arg, sizeof(*async_vol_args));
> -		if (IS_ERR(async_vol_args))
> -			return PTR_ERR(async_vol_args);
> +	if (v2) {
> +		vol_args_v2 = memdup_user(arg, sizeof(*vol_args_v2));
> +		if (IS_ERR(vol_args_v2))
> +			return PTR_ERR(vol_args_v2);
>  
> -		name = async_vol_args->name;
> -		fd = async_vol_args->fd;
> -		async_vol_args->name[BTRFS_SNAPSHOT_NAME_MAX] = '\0';
> +		if (vol_args_v2->flags & ~BTRFS_SNAPSHOT_CREATE_ASYNC) {
> +			ret = -EINVAL;
> +			goto out;
> +		}
> +
> +		name = vol_args_v2->name;
> +		fd = vol_args_v2->fd;
> +		vol_args_v2->name[BTRFS_SNAPSHOT_NAME_MAX] = '\0';
> +		if (vol_args_v2->flags & BTRFS_SNAPSHOT_CREATE_ASYNC)
> +			async = true;
>  	} else {
>  		vol_args = memdup_user(arg, sizeof(*vol_args));
>  		if (IS_ERR(vol_args))
> @@ -966,13 +974,13 @@ static noinline int btrfs_ioctl_snap_create(struct file *file,
>  
>  	if (!ret && async) {
>  		if (copy_to_user(arg +
> -				offsetof(struct btrfs_ioctl_async_vol_args,
> +				offsetof(struct btrfs_ioctl_vol_args_v2,
>  				transid), &transid, sizeof(transid)))
>  			return -EFAULT;
>  	}
> -
> +out:
>  	kfree(vol_args);
> -	kfree(async_vol_args);
> +	kfree(vol_args_v2);
>  
>  	return ret;
>  }
> @@ -2235,7 +2243,7 @@ long btrfs_ioctl(struct file *file, unsigned int
>  		return btrfs_ioctl_getversion(file, argp);
>  	case BTRFS_IOC_SNAP_CREATE:
>  		return btrfs_ioctl_snap_create(file, argp, 0, 0);
> -	case BTRFS_IOC_SNAP_CREATE_ASYNC:
> +	case BTRFS_IOC_SNAP_CREATE_V2:
>  		return btrfs_ioctl_snap_create(file, argp, 0, 1);
>  	case BTRFS_IOC_SUBVOL_CREATE:
>  		return btrfs_ioctl_snap_create(file, argp, 1, 0);
> diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
> index 17c99eb..bc70584 100644
> --- a/fs/btrfs/ioctl.h
> +++ b/fs/btrfs/ioctl.h
> @@ -30,10 +30,14 @@ struct btrfs_ioctl_vol_args {
>  	char name[BTRFS_PATH_NAME_MAX + 1];
>  };
>  
> -#define BTRFS_SNAPSHOT_NAME_MAX 4079
> -struct btrfs_ioctl_async_vol_args {
> +#define BTRFS_SNAPSHOT_CREATE_ASYNC	(1ULL << 0)
> +
> +#define BTRFS_SNAPSHOT_NAME_MAX 4039
> +struct btrfs_ioctl_vol_args_v2 {
>  	__s64 fd;
>  	__u64 transid;
> +	__u64 flags;
> +	__u64 unused[4];
>  	char name[BTRFS_SNAPSHOT_NAME_MAX + 1];
>  };
>  
> @@ -187,6 +191,6 @@ struct btrfs_ioctl_space_args {
>  				    struct btrfs_ioctl_space_args)
>  #define BTRFS_IOC_START_SYNC _IOR(BTRFS_IOCTL_MAGIC, 24, __u64)
>  #define BTRFS_IOC_WAIT_SYNC  _IOW(BTRFS_IOCTL_MAGIC, 22, __u64)
> -#define BTRFS_IOC_SNAP_CREATE_ASYNC _IOW(BTRFS_IOCTL_MAGIC, 23, \
> -				   struct btrfs_ioctl_async_vol_args)
> +#define BTRFS_IOC_SNAP_CREATE_V2 _IOW(BTRFS_IOCTL_MAGIC, 23, \
> +				   struct btrfs_ioctl_vol_args_v2)
>  #endif
> -- 
> 1.6.3
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
>