From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH v3] fs: Invalidate the cache for a parent block-device if
 fsync() is called for a partition
Date: Thu, 26 Jan 2012 16:45:34 -0500
Message-ID: <20120126214534.GA9319@infradead.org>
References: <4F213E1A.4060808@redhat.com>
 <1327584802-14298-1-git-send-email-ndevos@redhat.com>
 <20120126134051.6add3cd2.akpm@linux-foundation.org>
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Cc: Niels de Vos <ndevos@redhat.com>, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
	Mikulas Patocka <mpatocka@redhat.com>,
	Jeff Moyer <jmoyer@redhat.com>,
	"Bryn M. Reeves" <bmr@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
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On Thu, Jan 26, 2012 at 01:40:51PM -0800, Andrew Morton wrote:
> The Right Thing To Do here is to make the kernel behave logically and
> predictably, then modify the userspace tools.  But if we're modifying
> the userspace tools then we would just change userspace to issue a
> BLKFLSBUF to /dev/sda and leave the kernel alone.

The right fix is to make partition and whole disk access coherent,
which is fairly simply:

 - create the block device inode/mapping per gendisk, and only reference
   count it per block_device
 - make sure blkdev_get_block(s) applies the correct offset if used on
   partitions