9pfs: fix filesystem to wait for stable page writeback

9pfs: fix filesystem to wait for stable page writeback

Fix up the ->page_mkwrite handler to provide stable page writes if necessary.

Signed-off-by: Darrick J. Wong <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Artem Bityutskiy <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Steven Whitehouse <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Eric Van Hensbergen <[email protected]>
Cc: Ron Minnich <[email protected]>
Cc: Latchesar Ionkov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>