Re: [RFC PATCH 0/6] Do not call ->writepage[s] from direct reclaim and use a_ops->writepages() where possible

Christoph Hellwig
2010-06-15T16:35:51Z

On Tue, Jun 15, 2010 at 05:30:44PM +0100, Mel Gorman wrote:
> After grepping through fs/, it was only xfs and btrfs that I saw were
> specfically disabling writepage from reclaim context.

ext4 doesn't specificly disable writeback from reclaim context, but
in a rather convoluted way disabled basically all writeback through
->writepage. The only thing allowed is overwrites of already allocated
blocks.

In addition to that reiserfs also frefuses to write back pages
from reclaim context if they require a transaction, which is the case
if the file was written to through mmap.