Re: [RFC PATCH v3 01/18] block: Add check for async buffered writes to generic_write_checks

Stefan Roesch
2022-05-20T18:24:20Z

On 5/19/22 1:17 AM, Christoph Hellwig wrote:
> On Wed, May 18, 2022 at 04:36:52PM -0700, Stefan Roesch wrote:
>> @@ -1633,7 +1633,9 @@ int generic_write_checks_count(struct kiocb *iocb, loff_t *count)
>> if (iocb->ki_flags & IOCB_APPEND)
>> iocb->ki_pos = i_size_read(inode);
>>
>> - if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags & IOCB_DIRECT))
>> + if ((iocb->ki_flags & IOCB_NOWAIT) &&
>> + !((iocb->ki_flags & IOCB_DIRECT) ||
>> + (file->f_mode & FMODE_BUF_WASYNC)))
>
> This is some really odd indentation. I'd expect something like:
>
> if ((iocb->ki_flags & IOCB_NOWAIT) &&
> !((iocb->ki_flags & IOCB_DIRECT) ||
> (file->f_mode & FMODE_BUF_WASYNC)))
>

I reformatted the above code for the next version.

>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index bbde95387a23..3b479d02e210 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -177,6 +177,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
>> /* File supports async buffered reads */
>> #define FMODE_BUF_RASYNC ((__force fmode_t)0x40000000)
>>
>> +/* File supports async nowait buffered writes */
>> +#define FMODE_BUF_WASYNC ((__force fmode_t)0x80000000)
>
> This is the last available flag in fmode_t.
>
> At some point we should probably move the static capabilities to
> a member of file_operations.