> From: Bob Liu [mailto:lliubbo@xxxxxxxxx] > Sent: Monday, April 01, 2013 9:50 PM > To: akpm@xxxxxxxxxxxxxxxxxxxx > Cc: linux-mm@xxxxxxxxx; minchan@xxxxxxxxxx; sjenning@xxxxxxxxxxxxxxxxxx; rcj@xxxxxxxxxxxxxxxxxx; > ngupta@xxxxxxxxxx; konrad.wilk@xxxxxxxxxx; dan.magenheimer@xxxxxxxxxx; Bob Liu > Subject: [PATCH 1/2] mm: break up swap_writepage() for frontswap backends > > From: Seth Jennings <sjenning@xxxxxxxxxxxxxxxxxx> > > 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 <minchan@xxxxxxxxxx> > Signed-off-by: Seth Jennings <sjenning@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx> Reviewed-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> > --- > 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@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href