diff options
| author | Seth Jennings <sjenning@linux.vnet.ibm.com> | 2013-04-29 15:08:34 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-04-29 15:54:38 -0700 |
| commit | 2f772e6cadf8ad8fca38927b17e6be028be669f5 (patch) | |
| tree | 5eac4cfd72c6e8e9b4d48ad7463cdf1a8b97f7b4 | |
| parent | e8420a8ece80b3fe810415ecf061d54ca7fab266 (diff) | |
mm: break up swap_writepage() for frontswap backends
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.
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>
| -rw-r--r-- | include/linux/swap.h | 2 | ||||
| -rw-r--r-- | mm/page_io.c | 14 | ||||
| -rw-r--r-- | 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 2818a123f3e..76f6c3b3123 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 78eee32ee48..8e6bcf176cf 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 7efcf152592..fe43fd5578c 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; |