[PATCH] remove PF_SYNC

current->flags:PF_SYNC was a hack I added because I didn't want to
change all ->writepage implementations.

It's foul.  And it means that if someone happens to run direct page
reclaim within the context of (say) sys_sync, the writepage invokations
from the VM will be treated as "data integrity" operations, not "memory
cleansing" operations, which would cause latency.

So the patch removes PF_SYNC and adds an extra arg to a_ops->writepage.
 It is the `writeback_control' structure which contains the full context
information about why writepage was called.

The initial version of this patch just passed in a bare `int sync', but
the XFS team need more info so they can perform writearound from within
page reclaim.

The patch also adds writeback_control.for_reclaim, so writepage
implementations can inspect that to work out the call context rather
than peeking at current->flags:PF_MEMALLOC.

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index afbb9474f25b..bd133801c3e0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -278,7 +278,7 @@ struct address_space;
 struct writeback_control;
 
 struct address_space_operations {
-	int (*writepage)(struct page *);
+	int (*writepage)(struct page *page, struct writeback_control *wbc);
 	int (*readpage)(struct file *, struct page *);
 	int (*sync_page)(struct page *);