mm: allow for outstanding swap writeback accounting

To prevent flooding the swap device with writebacks, frontswap backends
need to count and limit the number of outstanding writebacks.  The
incrementing of the counter can be done before the call to
__swap_writepage().  However, the caller must receive a notification
when the writeback completes in order to decrement the counter.

To achieve this functionality, this patch modifies __swap_writepage() to
take the bio completion callback function as an argument.

end_swap_bio_write(), the normal bio completion function, is also made
non-static so that code doing the accounting can call it after the
accounting is done.

There should be no behavioural change to existing code.

Signed-off-by: Seth Jennings <[email protected]>
Signed-off-by: Bob Liu <[email protected]>
Acked-by: Minchan Kim <[email protected]>
Reviewed-by: Dan Magenheimer <[email protected]>
Cc: Konrad Rzeszutek Wilk <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions