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

From: Li Zefan <lizf@cn.fujitsu.com>
To: Sage Weil <sage@newdream.net>
Cc: chris.mason@oracle.com, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 1/5] btrfs: Make async snapshot ioctl more generic
Date: Wed, 08 Dec 2010 09:09:12 +0800	[thread overview]
Message-ID: <4CFEDAB8.6040109@cn.fujitsu.com> (raw)
In-Reply-To: <Pine.LNX.4.64.1012071057230.29827@cobra.newdream.net>

03:04, Sage Weil wrote:
> Hi Chris,
> 
> Is this ioctl change destined for 2.6.37?  If it (or something similar) 
> looks good it should probably be merged (independent of the rest of the 
> series) this time around before we're stuck with the current version.
> 

I'm going to post a revised patchset today or tomorrow. Thanks!

btw, is there a typo?

#define BTRFS_IOC_SPACE_INFO _IOWR(BTRFS_IOCTL_MAGIC, 20, \
                                    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)

It seems we should have given 21 to START_SYNC ioctl.

> Thanks-
> sage
> 
> 
> 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.
>>
>> 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
>>
>> --