linux-kernel - Re: Direct IO for fat

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Message-ID: <873b5g2zq9.fsf@duaron.myhome.or.jp>
Date:	Fri, 09 Feb 2007 04:53:02 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Jan Kara <jack@...e.cz>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Direct IO for fat

Jan Kara <jack@...e.cz> writes:

>> > -> blockdev_direct_IO()
>> >   -> direct_io_worker()
>> >     -> do_direct_IO()
>> >       -> get_more_blocks()
>> > 
>> > 		create = dio->rw & WRITE;
>>   Here, create == 1.
>> 
>> > 		if (dio->lock_type == DIO_LOCKING) {
>> > 			if (dio->block_in_file < (i_size_read(dio->inode) >>
>> > 							dio->blkbits))
>> > 				create = 0;
>>   But here create was reset back to 0 - exactly because
>> dio->block_in_file > i_size...
>   Obviously, I'm blind and you're right ;) This test is not satisfied
> and so create == 1.
>   But still it would seem better to me to return 0 from fat_direct_IO()
> instead of EINVAL so that write falls back to a buffered one, instead
> returning the error...

I see. When I wrote this, I thought kernel should use DIO to write if
user sets O_DIRECT. Because the wrong alignment request isn't fallback
to buffered-write, and it's also returns EINVAL.

But I don't have strong opinion here. If anyone (you) has any request
of it, I'll not have objection to it.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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