mm: allow for outstanding swap writeback accounting
authorSeth Jennings <sjenning@linux.vnet.ibm.com>
Mon, 29 Apr 2013 22:08:35 +0000 (15:08 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 29 Apr 2013 22:54:38 +0000 (15:54 -0700)
commit1eec6702a80e04416d528846a5ff2122484d95ec
treeead36835b194b3253cef6c4391489fef6a574575
parent2f772e6cadf8ad8fca38927b17e6be028be669f5
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 <sjenning@linux.vnet.ibm.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/swap.h
mm/page_io.c