path: root/mm
diff options
authorSeth Jennings <sjenning@linux.vnet.ibm.com>2013-04-29 15:08:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-29 15:54:38 -0700
commit1eec6702a80e04416d528846a5ff2122484d95ec (patch)
treeead36835b194b3253cef6c4391489fef6a574575 /mm
parent2f772e6cadf8ad8fca38927b17e6be028be669f5 (diff)
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>
Diffstat (limited to 'mm')
1 files changed, 5 insertions, 4 deletions
diff --git a/mm/page_io.c b/mm/page_io.c
index 8e6bcf176cf..8e0e5c0e7cd 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -42,7 +42,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags,
return bio;
-static void end_swap_bio_write(struct bio *bio, int err)
+void end_swap_bio_write(struct bio *bio, int err)
const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
struct page *page = bio->bi_io_vec[0].bv_page;
@@ -197,12 +197,13 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
goto out;
- ret = __swap_writepage(page, wbc);
+ ret = __swap_writepage(page, wbc, end_swap_bio_write);
return ret;
-int __swap_writepage(struct page *page, struct writeback_control *wbc)
+int __swap_writepage(struct page *page, struct writeback_control *wbc,
+ void (*end_write_func)(struct bio *, int))
struct bio *bio;
int ret = 0, rw = WRITE;
@@ -234,7 +235,7 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc)
return ret;
- bio = get_swap_bio(GFP_NOIO, page, end_swap_bio_write);
+ bio = get_swap_bio(GFP_NOIO, page, end_write_func);
if (bio == NULL) {