Re: [PATCH 1/3] bdi: Use parent filesystem BDI for inodes notcapable of writeback

From: Jan Kara
Date: Tue Jul 27 2010 - 14:02:05 EST


On Tue 27-07-10 13:27:31, Christoph Hellwig wrote:
> On Tue, Jul 27, 2010 at 07:24:38PM +0200, Jan Kara wrote:
> > Always returning inode->i_sb->s_bdi wouldn't be a right thing IMHO.
> > That would file inode for /dev/sda to BDI list of tmpfs mounted on /dev/
> > which isn't what you want...
>
> It shouldn't. Block device nodes are on the bdev filesystems, and
Ok, so inode->i_sb->s_bdi will actually point to noop_backing_dev_info
as set by set_anon_super(). Or am I completely out?

> we twist the file->mapping pointer so that all the low-level read/write
> code always deals with the bdev fs inode, and not the device node
> filesystem.
Yes, I know this but I fail to see how this influences where </dev/sda's
inode>->i_sb->s_bdi ends up...

Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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