Re: [PATCH] libxfs: don't return cnt as failure from XFS_BUF_SET_PTR

[Eric Sandeen <sandeen@redhat.com>]

On 2/22/18 3:46 PM, Darrick J. Wong wrote:
> On Thu, Feb 22, 2018 at 03:33:04PM -0600, Eric Sandeen wrote:
>> We must not get here very often, because any test of an error
>> from XFS_BUF_SET_PTR will fail because it  returns whatever
>> is sent in as cnt.  Fix the macro to return 0 so that
>> "error = XFS_BUF_SET_PTR()" works as expected.
>>
>> Should probably make this xfs_buf_associate_memory() to be
>> more like kernelspace, but for now just fix up the bug.
>>
>> Found this via xfs_logprint failing for no good reason.
>>
>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>> ---
>>
>> diff --git a/libxfs/libxfs_io.h b/libxfs/libxfs_io.h
>> index 81d2804..0ae7a28 100644
>> --- a/libxfs/libxfs_io.h
>> +++ b/libxfs/libxfs_io.h
>> @@ -105,6 +105,7 @@ enum xfs_buf_flags_t {	/* b_flags bits */
>>  #define XFS_BUF_SET_PTR(bp,p,cnt)	({	\
>>  	(bp)->b_addr = (char *)(p);		\
>>  	XFS_BUF_SET_COUNT(bp,cnt);		\
>> +	0;					\
> 
> There are only two callers of this macro and it's not exported to
> xfslibs headers, so why not just fix them not to care about the return
> value?

because it marginally matches kernel code ... *shrug* I'd rather
have libxlog diverge less from kernel, not more, overall.

-Eric