Re: [PATCH] fs: create kiocb_{start,end}_write() helpers

[Jens Axboe <axboe@kernel.dk>]

On 8/15/23 11:02 AM, Jens Axboe wrote:
> On 8/15/23 10:57 AM, Amir Goldstein wrote:
>> +/**
>> + * kiocb_start_write - get write access to a superblock for async file io
>> + * @iocb: the io context we want to submit the write with
>> + *
>> + * This is a variant of file_start_write() for async io submission.
>> + * Should be matched with a call to kiocb_end_write().
>> + */
>> +static inline void kiocb_start_write(struct kiocb *iocb)
>> +{
>> +	struct inode *inode = file_inode(iocb->ki_filp);
>> +
>> +	iocb->ki_flags |= IOCB_WRITE;
>> +	if (WARN_ON_ONCE(iocb->ki_flags & IOCB_WRITE_STARTED))
>> +		return;
>> +	if (!S_ISREG(inode->i_mode))
>> +		return;
>> +	sb_start_write(inode->i_sb);
>> +	/*
>> +	 * Fool lockdep by telling it the lock got released so that it
>> +	 * doesn't complain about the held lock when we return to userspace.
>> +	 */
>> +	__sb_writers_release(inode->i_sb, SB_FREEZE_WRITE);
>> +	iocb->ki_flags |= IOCB_WRITE_STARTED;
>> +}
>> +
>> +/**
>> + * kiocb_end_write - drop write access to a superblock after async file io
>> + * @iocb: the io context we sumbitted the write with
>> + *
>> + * Should be matched with a call to kiocb_start_write().
>> + */
>> +static inline void kiocb_end_write(struct kiocb *iocb)
>> +{
>> +	struct inode *inode = file_inode(iocb->ki_filp);
>> +
>> +	if (!(iocb->ki_flags & IOCB_WRITE_STARTED))
>> +		return;
>> +	if (!S_ISREG(inode->i_mode))
>> +		return;

And how would IOCB_WRITE_STARTED ever be set, if S_ISREG() isn't true?

-- 
Jens Axboe