Re: [PATCH RFC] __bd_forget should wait for inodes using the mapping

[Chris Mason <mason@suse.com>]

On Fri, 2004-06-18 at 11:15, viro@parcelfarce.linux.theplanet.co.uk
wrote:
> On Fri, Jun 18, 2004 at 10:47:11AM -0400, Chris Mason wrote:
> > During writeback, we need to answer the question: "are there dirty pages
> > attached to this inode", and the only way to answer it is via the
> > address space.
> > 
> > If bdev inodes don't want other inodes using their address space, they
> > shouldn't be setting the i_mapping on other inodes.  Since they are, the
> > bdev code needs to be aware that someone else might be using it.
> 
> Scheduled for 2.7.1; for now users of ->i_mapping (the fewer of them remain,
> the better) have to be aware of bdev.
> 
> And yes, ->i_mapping flips on "normal" bdev inodes will go away - we set
> ->f_mapping on open directly.

Fair enough, I'll cook up some code to bump the inode->bdev->bd_inode
i_count in __sync_single_inode  It won't be pretty either though, I'll
have to drop the inode_lock so that some function can take the bdev_lock
to safely use inode->i_bdev.

-chris