Re: [PATCH] O_SYNC error handling fix

[Chris Mason <mason@suse.com>]

On Monday 16 January 2006 02:58, Andrew Morton wrote:
> Chris Mason <mason@suse.com> wrote:
> > If we hit errors during generic_osync_inode(),
> > generic_file_buffered_write will still return written ? written : status;
> >  This patch ensures the -EIO gets back up to userland at all times.
[ ... ]

>
> The patch does more than this.  It also changes the O_DIRECT logic and it
> also refuses to update the file position on I/O errors.

True, I can get rid of the O_DIRECT change, it was just to preserve the status 
variable for the -EIO test.

>
> Probably reasonable changes, but I'd like to have your description of why
> these changes were made please.
>

Skipping the file position update was because we are not returning the short 
write.  We want the next write to happen at the appropriate place given the 
number of bytes we've told userland went out.

>
> The patch also makes write() non-linuxy.  We normally return a short write
> on errors.  In this case I'd say that returning 0 (and not updating f_pos)
> would be appropriate?

With O_SYNC we've no way of knowing which bytes didn't make it down to the 
disk.  I can special case the -EIO check for just O_SYNC. I think that along 
with changing around the O_DIRECT bits will make us both happy?

-chris