Re: [RFC PATCH v1 11/18] xfs: add async buffered write support

[Stefan Roesch <shr@fb.com>]

On 4/26/22 3:56 PM, Dave Chinner wrote:
> On Tue, Apr 26, 2022 at 10:43:28AM -0700, Stefan Roesch wrote:
>> This adds the async buffered write support to XFS. For async buffered
>> write requests, the request will return -EAGAIN if the ilock cannot be
>> obtained immediately.
>>
>> Signed-off-by: Stefan Roesch <shr@fb.com>
>> ---
>>  fs/xfs/xfs_file.c | 10 ++++++----
>>  1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
>> index 6f9da1059e8b..49d54b939502 100644
>> --- a/fs/xfs/xfs_file.c
>> +++ b/fs/xfs/xfs_file.c
>> @@ -739,12 +739,14 @@ xfs_file_buffered_write(
>>  	bool			cleared_space = false;
>>  	int			iolock;
>>  
>> -	if (iocb->ki_flags & IOCB_NOWAIT)
>> -		return -EOPNOTSUPP;
>> -
>>  write_retry:
>>  	iolock = XFS_IOLOCK_EXCL;
>> -	xfs_ilock(ip, iolock);
>> +	if (iocb->ki_flags & IOCB_NOWAIT) {
>> +		if (!xfs_ilock_nowait(ip, iolock))
>> +			return -EAGAIN;
>> +	} else {
>> +		xfs_ilock(ip, iolock);
>> +	}
> 
> xfs_ilock_iocb().
> 

The helper xfs_ilock_iocb cannot be used as it hardcoded to use iocb->ki_filp to
get a pointer to the xfs_inode. However here we need to use iocb->ki_filp->f_mapping->host.
I'll split off new helper for this in the next version of the patch.

> -Dave.
>