From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx105.postini.com [74.125.245.105]) by kanga.kvack.org (Postfix) with SMTP id C13746B0006 for ; Mon, 1 Apr 2013 23:50:06 -0400 (EDT) Received: by mail-pa0-f49.google.com with SMTP id kp14so52263pab.22 for ; Mon, 01 Apr 2013 20:50:06 -0700 (PDT) From: Bob Liu Subject: [PATCH 1/2] mm: break up swap_writepage() for frontswap backends Date: Tue, 2 Apr 2013 11:50:00 +0800 Message-Id: <1364874600-878-1-git-send-email-bob.liu@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, minchan@kernel.org, sjenning@linux.vnet.ibm.com, rcj@linux.vnet.ibm.com, ngupta@vflare.org, konrad.wilk@oracle.com, dan.magenheimer@oracle.com, Bob Liu From: Seth Jennings swap_writepage() is currently where frontswap hooks into the swap write path to capture pages with the frontswap_store() function. However, if a frontswap backend wants to "resume" the writeback of a page to the swap device, it can't call swap_writepage() as the page will simply reenter the backend. This patch separates swap_writepage() into a top and bottom half, the bottom half named __swap_writepage() to allow a frontswap backend, like zswap, to resume writeback beyond the frontswap_store() hook. __add_to_swap_cache() is also made non-static so that the page for which writeback is to be resumed can be added to the swap cache. Acked-by: Minchan Kim Signed-off-by: Seth Jennings Signed-off-by: Bob Liu --- include/linux/swap.h | 2 ++ mm/page_io.c | 14 +++++++++++--- mm/swap_state.c | 2 +- 3 files changed, 14 insertions(+), 4 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 2818a12..76f6c3b 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -330,6 +330,7 @@ static inline void mem_cgroup_uncharge_swap(swp_entry_t ent) /* linux/mm/page_io.c */ extern int swap_readpage(struct page *); extern int swap_writepage(struct page *page, struct writeback_control *wbc); +extern int __swap_writepage(struct page *page, struct writeback_control *wbc); extern int swap_set_page_dirty(struct page *page); extern void end_swap_bio_read(struct bio *bio, int err); @@ -345,6 +346,7 @@ extern unsigned long total_swapcache_pages(void); extern void show_swap_cache_info(void); extern int add_to_swap(struct page *); extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t); +extern int __add_to_swap_cache(struct page *page, swp_entry_t entry); extern void __delete_from_swap_cache(struct page *); extern void delete_from_swap_cache(struct page *); extern void free_page_and_swap_cache(struct page *); diff --git a/mm/page_io.c b/mm/page_io.c index 78eee32..8e6bcf1 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -185,9 +185,7 @@ bad_bmap: */ int swap_writepage(struct page *page, struct writeback_control *wbc) { - struct bio *bio; - int ret = 0, rw = WRITE; - struct swap_info_struct *sis = page_swap_info(page); + int ret = 0; if (try_to_free_swap(page)) { unlock_page(page); @@ -199,6 +197,16 @@ int swap_writepage(struct page *page, struct writeback_control *wbc) end_page_writeback(page); goto out; } + ret = __swap_writepage(page, wbc); +out: + return ret; +} + +int __swap_writepage(struct page *page, struct writeback_control *wbc) +{ + struct bio *bio; + int ret = 0, rw = WRITE; + struct swap_info_struct *sis = page_swap_info(page); if (sis->flags & SWP_FILE) { struct kiocb kiocb; diff --git a/mm/swap_state.c b/mm/swap_state.c index 7efcf15..fe43fd5 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -78,7 +78,7 @@ void show_swap_cache_info(void) * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space, * but sets SwapCache flag and private instead of mapping and index. */ -static int __add_to_swap_cache(struct page *page, swp_entry_t entry) +int __add_to_swap_cache(struct page *page, swp_entry_t entry) { int error; struct address_space *address_space; -- 1.7.10.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org