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Date: Fri, 30 Nov 2001 02:37:22 -0500 (EST)
From: Alexander Viro <viro@math.psu.edu>
To: Jens Axboe <axboe@suse.de>
cc: Jeff Garzik <jgarzik@mandrakesoft.com>,
        Linus Torvalds <torvalds@transmeta.com>,
        Linux-Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: PATCH 2.5.1.4: fix rd.c build
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On Fri, 30 Nov 2001, Jens Axboe wrote:

> On Fri, Nov 30 2001, Alexander Viro wrote:
> > 
> > 
> > On Fri, 30 Nov 2001, Jens Axboe wrote:
> > 
> > > Actually, this is not even enough if rd receives a multi page bio.
> > > Something like this should work, untested.
> > > 
> > > @@ -237,9 +238,9 @@
> > >  	err = -EIO;
> > 
> > Make it err = 0...
> 
> Explain

Think what happens if you have all these pages in page cache.  Already.
Returning -EIO is hardly a good idea in that case.  Look through the
loop - we assign err in the body only if we have to allocate a new
page.

Notice that any bh brings the page in.  I.e. for smaller-than-page ones
you are going to have a lot of fun...

>From -pre2:

@@ -227,19 +227,18 @@
        commit_write: ramdisk_commit_write,
 };
 
-static int rd_blkdev_pagecache_IO(int rw, struct buffer_head * sbh, int minor)
+static int rd_blkdev_pagecache_IO(int rw, struct bio *sbh, int minor)
 {
        struct address_space * mapping;
        unsigned long index;
        int offset, size, err;
 
        err = -EIO;
-       err = 0;
        mapping = rd_bdev[minor]->bd_inode->i_mapping;

Sure, one of these assignments had to go away.  You'd picked the wrong one,
though...

-
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