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Date: Sun, 16 Dec 2001 17:17:33 +0900
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From: GOTO Masanori <gotom@debian.org>
To: Andrew Morton <akpm@zip.com.au>
Cc: Suresh Gopalakrishnan <gsuresh@cs.rutgers.edu>,
        linux-kernel@vger.kernel.org, Andrea Arcangeli <andrea@suse.de>,
        gotom@debian.org
Subject: Re: O_DIRECT wierd behavior..
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At Sat, 15 Dec 2001 21:59:06 -0800,
Andrew Morton wrote:
> Then the kernel screws up the error handling, and ends up
> setting the file size to -EINVAL (ie: rather large).
> 
> 1: We're testing `written >= 0', but it is unsigned (!).  In two
>    places.
> 
>    This one, IMO is a gcc shortcoming.  The compiler is capable of warning
>    about expressions which always evaluate to true or false in `if' statements,
>    but turning this on also enables lots of things you don't want it to warn about.
>    gcc needs to provide finer control of its warning capabilities.  I patched
>    gcc-2.7.2.3 to do this ages back and it was very useful.
>
> 2: If generic_osync_inode() returns an error, we fail to report it.  In
>    two places.
>
> Here's a quick fix.  It needs a review.
> 
> --- linux-2.4.17-rc1/mm/filemap.c	Thu Dec 13 14:07:55 2001
> +++ linux-akpm/mm/filemap.c	Sat Dec 15 21:52:06 2001
> @@ -3038,8 +3038,11 @@ unlock:
>  	/* For now, when the user asks for O_SYNC, we'll actually
>  	 * provide O_DSYNC. */
>  	if (status >= 0) {
> -		if ((file->f_flags & O_SYNC) || IS_SYNC(inode))
> +		if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
>  			status = generic_osync_inode(inode, OSYNC_METADATA|OSYNC_DATA);
> +			if (status < 0)
> +				written = 0;	/* Return the right thing */
> +		}
>  	}

Right. If generic_osync_inode returns error, it must be needed. 
This patch seems ok than my patch...

-- gotom
-
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