[PATCH] btrfs: trival fix of __btrfs_set_acl error handling

[PATCH] btrfs: trival fix of __btrfs_set_acl error handling

[Sheng Yong]

* If the allocation failed, don't free to free it, even though kfree
  allows to free a NULL pointer.
* If posix_acl_to_xattr() failed, cleanup the allocation and return
  the error directly.

Signed-off-by: Sheng Yong <shengyong1@huawei.com>
---
 fs/btrfs/acl.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 9a0124a..6d01d09 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -103,18 +103,18 @@ static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
 	if (acl) {
 		size = posix_acl_xattr_size(acl->a_count);
 		value = kmalloc(size, GFP_NOFS);
-		if (!value) {
-			ret = -ENOMEM;
-			goto out;
-		}
+		if (!value)
+			return -ENOMEM;
 
 		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
-		if (ret < 0)
-			goto out;
+		if (ret < 0) {
+			kfree(value);
+			return ret;
+		}
 	}
 
 	ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
-out:
+
 	kfree(value);
 
 	if (!ret)
-- 
1.8.3.4

Re: [PATCH] btrfs: trival fix of __btrfs_set_acl error handling

[Qu Wenruo]

Sheng Yong wrote on 2015/09/08 08:46 +0000:
> * If the allocation failed, don't free to free it, even though kfree
>    allows to free a NULL pointer.
> * If posix_acl_to_xattr() failed, cleanup the allocation and return
>    the error directly.
So, what's the point?
For me, I didn't see the pros of the change.
As kfree() allow NULL pointer, why not use it?

Thanks,
Qu
>
> Signed-off-by: Sheng Yong <shengyong1@huawei.com>
> ---
>   fs/btrfs/acl.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
> index 9a0124a..6d01d09 100644
> --- a/fs/btrfs/acl.c
> +++ b/fs/btrfs/acl.c
> @@ -103,18 +103,18 @@ static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
>   	if (acl) {
>   		size = posix_acl_xattr_size(acl->a_count);
>   		value = kmalloc(size, GFP_NOFS);
> -		if (!value) {
> -			ret = -ENOMEM;
> -			goto out;
> -		}
> +		if (!value)
> +			return -ENOMEM;
>
>   		ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
> -		if (ret < 0)
> -			goto out;
> +		if (ret < 0) {
> +			kfree(value);
> +			return ret;
> +		}
>   	}
>
>   	ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
> -out:
> +
>   	kfree(value);
>
>   	if (!ret)
>

Re: [PATCH] btrfs: trival fix of __btrfs_set_acl error handling

[Sheng Yong]

Hi, Qu

On 9/8/2015 4:50 PM, Qu Wenruo wrote:
> Sheng Yong wrote on 2015/09/08 08:46 +0000:
>> * If the allocation failed, don't free to free it, even though kfree
>>    allows to free a NULL pointer.
>> * If posix_acl_to_xattr() failed, cleanup the allocation and return
>>    the error directly.
> So, what's the point?
> For me, I didn't see the pros of the change.
> As kfree() allow NULL pointer, why not use it?
In fact, there is no semantic changes. It's just because when I walk through
the code, and find there is no need to call kfree(), and could be cleaned up.
It's fine to keep as it is :)

thanks,
Sheng
> 
> Thanks,
> Qu
>>
>> Signed-off-by: Sheng Yong <shengyong1@huawei.com>
>> ---
>>   fs/btrfs/acl.c | 14 +++++++-------
>>   1 file changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
>> index 9a0124a..6d01d09 100644
>> --- a/fs/btrfs/acl.c
>> +++ b/fs/btrfs/acl.c
>> @@ -103,18 +103,18 @@ static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
>>       if (acl) {
>>           size = posix_acl_xattr_size(acl->a_count);
>>           value = kmalloc(size, GFP_NOFS);
>> -        if (!value) {
>> -            ret = -ENOMEM;
>> -            goto out;
>> -        }
>> +        if (!value)
>> +            return -ENOMEM;
>>
>>           ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
>> -        if (ret < 0)
>> -            goto out;
>> +        if (ret < 0) {
>> +            kfree(value);
>> +            return ret;
>> +        }
>>       }
>>
>>       ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
>> -out:
>> +
>>       kfree(value);
>>
>>       if (!ret)
>>
> 
> 

Re: [PATCH] btrfs: trival fix of __btrfs_set_acl error handling

[David Sterba]

On Tue, Sep 08, 2015 at 05:02:32PM +0800, Sheng Yong wrote:
> Hi, Qu
> 
> On 9/8/2015 4:50 PM, Qu Wenruo wrote:
> > Sheng Yong wrote on 2015/09/08 08:46 +0000:
> >> * If the allocation failed, don't free to free it, even though kfree
> >>    allows to free a NULL pointer.
> >> * If posix_acl_to_xattr() failed, cleanup the allocation and return
> >>    the error directly.
> > So, what's the point?
> > For me, I didn't see the pros of the change.
> > As kfree() allow NULL pointer, why not use it?
> In fact, there is no semantic changes. It's just because when I walk through
> the code, and find there is no need to call kfree(), and could be cleaned up.
> It's fine to keep as it is :)

I agree with Qu. In this case it's not performance critical and conforms
to the widely used pattern of single return point from branches.
However, the acl functions are not consistent in that respect. It's more
a matter of style that gets unified eventually.