On Wed, Sep 29, 2010 at 02:18:08PM +0200, Jan Kara wrote:
On Wed 29-09-10 10:19:36, Christoph Hellwig wrote:
> ---
> From: Christoph Hellwig <hch(a)lst.de>
> Subject: [PATCH] writeback: always use sb->s_bdi for writeback purposes
>
...
> The one exception for now is the block device filesystem which really
> wants different writeback contexts for it's different (internal) inodes
> to handle the writeout more efficiently. For now we do this with
> a hack in fs-writeback.c because we're so late in the cycle, but in
> the future I plan to replace this with a superblock method that allows
> for multiple writeback contexts per filesystem.
Another exception I know about is mtd_inodefs filesystem
(drivers/mtd/mtdchar.c).
No, it's not. MTD only has three different backing_dev_info instances
which have different flags in the mapping-relevant portion of the
backing_dev.
So at least here you'd need also add a similar exception for
"mtd_inodefs".
No. For one thing we don't need any exception for correctnes alone -
even the block device variant would work fine with the default case.
But for mtd specificly we don't need an exception for performance either
given that there are no per-device bdis in mtd.