Re: [RFC PATCH v4 16/17] xfs: Add async buffered write support

[Stefan Roesch <shr@fb.com>]

On 5/22/22 8:35 AM, Darrick J. Wong wrote:
> On Fri, May 20, 2022 at 11:36:45AM -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.
>>
>> This splits off a new helper xfs_ilock_inode from the existing helper
>> xfs_ilock_iocb so it can be used for this function. The exising helper
>> cannot be used as it hardcoded the inode to be used.
>>
>> Signed-off-by: Stefan Roesch <shr@fb.com>
>> ---
>>  fs/xfs/xfs_file.c | 32 +++++++++++++++-----------------
>>  1 file changed, 15 insertions(+), 17 deletions(-)
>>
>> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
>> index 793918c83755..ad3175b7d366 100644
>> --- a/fs/xfs/xfs_file.c
>> +++ b/fs/xfs/xfs_file.c
>> @@ -190,14 +190,13 @@ xfs_file_fsync(
>>  	return error;
>>  }
>>  
>> -static int
>> -xfs_ilock_iocb(
>> -	struct kiocb		*iocb,
>> +static inline int
>> +xfs_ilock_xfs_inode(
> 
> A couple of nitpicky things:
> 
> "ilock" is shorthand for "inode lock", which means this name expands to
> "xfs inode lock xfs inode", which is redundant.  Seeing as the whole
> point of this function is to take a particular inode lock with a
> particular set of IOCB flags, just leave the name as it was.
> 

Renamed xfs_ilock_xfs_inode()n back to xfs_ilock_iocb().

>> +	struct xfs_inode	*ip,
>> +	int			flags,
> 
> "iocb_flags", not "flags", to reinforce what kind of flags are supposed
> to be passed in here.
> 

Renamed flags parameter to iocb_flags in function xfs_ilock_iocb().

> --D
> 
>>  	unsigned int		lock_mode)
>>  {
>> -	struct xfs_inode	*ip = XFS_I(file_inode(iocb->ki_filp));
>> -
>> -	if (iocb->ki_flags & IOCB_NOWAIT) {
>> +	if (flags & IOCB_NOWAIT) {
>>  		if (!xfs_ilock_nowait(ip, lock_mode))
>>  			return -EAGAIN;
>>  	} else {
>> @@ -222,7 +221,7 @@ xfs_file_dio_read(
>>  
>>  	file_accessed(iocb->ki_filp);
>>  
>> -	ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
>> +	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, XFS_IOLOCK_SHARED);
>>  	if (ret)
>>  		return ret;
>>  	ret = iomap_dio_rw(iocb, to, &xfs_read_iomap_ops, NULL, 0, 0);
>> @@ -244,7 +243,7 @@ xfs_file_dax_read(
>>  	if (!iov_iter_count(to))
>>  		return 0; /* skip atime */
>>  
>> -	ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
>> +	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, XFS_IOLOCK_SHARED);
>>  	if (ret)
>>  		return ret;
>>  	ret = dax_iomap_rw(iocb, to, &xfs_read_iomap_ops);
>> @@ -264,7 +263,7 @@ xfs_file_buffered_read(
>>  
>>  	trace_xfs_file_buffered_read(iocb, to);
>>  
>> -	ret = xfs_ilock_iocb(iocb, XFS_IOLOCK_SHARED);
>> +	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, XFS_IOLOCK_SHARED);
>>  	if (ret)
>>  		return ret;
>>  	ret = generic_file_read_iter(iocb, to);
>> @@ -343,7 +342,7 @@ xfs_file_write_checks(
>>  	if (*iolock == XFS_IOLOCK_SHARED && !IS_NOSEC(inode)) {
>>  		xfs_iunlock(ip, *iolock);
>>  		*iolock = XFS_IOLOCK_EXCL;
>> -		error = xfs_ilock_iocb(iocb, *iolock);
>> +		error = xfs_ilock_xfs_inode(ip, iocb->ki_flags, *iolock);
>>  		if (error) {
>>  			*iolock = 0;
>>  			return error;
>> @@ -516,7 +515,7 @@ xfs_file_dio_write_aligned(
>>  	int			iolock = XFS_IOLOCK_SHARED;
>>  	ssize_t			ret;
>>  
>> -	ret = xfs_ilock_iocb(iocb, iolock);
>> +	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, iolock);
>>  	if (ret)
>>  		return ret;
>>  	ret = xfs_file_write_checks(iocb, from, &iolock);
>> @@ -583,7 +582,7 @@ xfs_file_dio_write_unaligned(
>>  		flags = IOMAP_DIO_FORCE_WAIT;
>>  	}
>>  
>> -	ret = xfs_ilock_iocb(iocb, iolock);
>> +	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, iolock);
>>  	if (ret)
>>  		return ret;
>>  
>> @@ -659,7 +658,7 @@ xfs_file_dax_write(
>>  	ssize_t			ret, error = 0;
>>  	loff_t			pos;
>>  
>> -	ret = xfs_ilock_iocb(iocb, iolock);
>> +	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, iolock);
>>  	if (ret)
>>  		return ret;
>>  	ret = xfs_file_write_checks(iocb, from, &iolock);
>> @@ -702,12 +701,11 @@ 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);
>> +	ret = xfs_ilock_xfs_inode(ip, iocb->ki_flags, iolock);
>> +	if (ret)
>> +		return ret;
>>  
>>  	ret = xfs_file_write_checks(iocb, from, &iolock);
>>  	if (ret)
>> -- 
>> 2.30.2
>>