From: Dave Hansen <dave.han...@linux.intel.com>
swapcache_free() takes two arguments:
void swapcache_free(swp_entry_t entry, struct page *page)
Most of its callers (5/7) are from error handling paths haven't even
instantiated a page, so they pass page=NULL. Both of the callers
that call in with a 'struct page' create and pass in a temporary
swp_entry_t.
Now that we are deferring clearing page_private() until after
swapcache_free() has been called, we can just create a variant
that takes a 'struct page' and does the temporary variable in
the helper.
That leaves all the other callers doing
swapcache_free(entry, NULL)
so create another helper for them that makes it clear that they
need only pass in a swp_entry_t.
One downside here is that delete_from_swap_cache() now does
an extra swap_address_space() call. But, those are pretty
cheap (just some array index arithmetic).
Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
---
linux.git-davehans/drivers/staging/zcache/zcache-main.c | 2 +-
linux.git-davehans/include/linux/swap.h | 3 ++-
linux.git-davehans/mm/shmem.c | 2 +-
linux.git-davehans/mm/swap_state.c | 13 +++++--------
linux.git-davehans/mm/swapfile.c | 13 ++++++++++++-
linux.git-davehans/mm/vmscan.c | 3 +--
6 files changed, 22 insertions(+), 14 deletions(-)
diff -puN
drivers/staging/zcache/zcache-main.c~make-page-and-swp_entry_t-variants
drivers/staging/zcache/zcache-main.c
---
linux.git/drivers/staging/zcache/zcache-main.c~make-page-and-swp_entry_t-variants
2013-05-07 13:48:13.963056205 -0700
+++ linux.git-davehans/drivers/staging/zcache/zcache-main.c 2013-05-07
13:48:13.975056737 -0700
@@ -961,7 +961,7 @@ static int zcache_get_swap_cache_page(in
* add_to_swap_cache() doesn't return -EEXIST, so we can safely
* clear SWAP_HAS_CACHE flag.
*/
- swapcache_free(entry, NULL);
+ swapcache_free_entry(entry);
/* FIXME: is it possible to get here without err==-ENOMEM?
* If not, we can dispense with the do loop, use goto retry */
} while (err != -ENOMEM);
diff -puN include/linux/swap.h~make-page-and-swp_entry_t-variants
include/linux/swap.h
--- linux.git/include/linux/swap.h~make-page-and-swp_entry_t-variants
2013-05-07 13:48:13.964056249 -0700
+++ linux.git-davehans/include/linux/swap.h 2013-05-07 13:48:13.975056737
-0700
@@ -382,7 +382,8 @@ extern void swap_shmem_alloc(swp_entry_t
extern int swap_duplicate(swp_entry_t);
extern int swapcache_prepare(swp_entry_t);
extern void swap_free(swp_entry_t);
-extern void swapcache_free(swp_entry_t, struct page *page);
+extern void swapcache_free_entry(swp_entry_t entry);
+extern void swapcache_free_page_entry(struct page *page);
extern int free_swap_and_cache(swp_entry_t);
extern int swap_type_of(dev_t, sector_t, struct block_device **);
extern unsigned int count_swap_pages(int, int);
diff -puN mm/shmem.c~make-page-and-swp_entry_t-variants mm/shmem.c
--- linux.git/mm/shmem.c~make-page-and-swp_entry_t-variants 2013-05-07
13:48:13.966056339 -0700
+++ linux.git-davehans/mm/shmem.c 2013-05-07 13:48:13.976056781 -0700
@@ -871,7 +871,7 @@ static int shmem_writepage(struct page *
}
mutex_unlock(&shmem_swaplist_mutex);
- swapcache_free(swap, NULL);
+ swapcache_free_entry(swap);
redirty:
set_page_dirty(page);
if (wbc->for_reclaim)
diff -puN mm/swapfile.c~make-page-and-swp_entry_t-variants mm/swapfile.c
--- linux.git/mm/swapfile.c~make-page-and-swp_entry_t-variants 2013-05-07
13:48:13.968056427 -0700
+++ linux.git-davehans/mm/swapfile.c 2013-05-07 13:48:13.977056825 -0700
@@ -637,7 +637,7 @@ void swap_free(swp_entry_t entry)
/*
* Called after dropping swapcache to decrease refcnt to swap entries.
*/
-void swapcache_free(swp_entry_t entry, struct page *page)
+static void __swapcache_free(swp_entry_t entry, struct page *page)
{
struct swap_info_struct *p;
unsigned char count;
@@ -651,6 +651,17 @@ void swapcache_free(swp_entry_t entry, s
}
}
+void swapcache_free_entry(swp_entry_t entry)
+{
+ __swapcache_free(entry, NULL);
+}
+
+void swapcache_free_page_entry(struct page *page)
+{
+ swp_entry_t entry = { .val = page_private(page) };
+ __swapcache_free(entry, page);
+}
+
/*
* How many references to page are currently swapped out?
* This does not give an exact answer when swap count is continued,
diff -puN mm/swap_state.c~make-page-and-swp_entry_t-variants mm/swap_state.c
--- linux.git/mm/swap_state.c~make-page-and-swp_entry_t-variants
2013-05-07 13:48:13.969056471 -0700
+++ linux.git-davehans/mm/swap_state.c 2013-05-07 13:48:13.978056869 -0700
@@ -172,7 +172,7 @@ int add_to_swap(struct page *page, struc
if (unlikely(PageTransHuge(page)))
if (unlikely(split_huge_page_to_list(page, list))) {
- swapcache_free(entry, NULL);
+ swapcache_free_entry(entry);
return 0;
}
@@ -198,7 +198,7 @@ int add_to_swap(struct page *page, struc
* add_to_swap_cache() doesn't return -EEXIST, so we can safely
* clear SWAP_HAS_CACHE flag.
*/
- swapcache_free(entry, NULL);
+ swapcache_free_entry(entry);
return 0;
}
}
@@ -211,17 +211,14 @@ int add_to_swap(struct page *page, struc
*/
void delete_from_swap_cache(struct page *page)
{
- swp_entry_t entry;
struct address_space *address_space;
- entry.val = page_private(page);
-
- address_space = swap_address_space(entry);
+ address_space = page_mapping(page);
spin_lock_irq(&address_space->tree_lock);
__delete_from_swap_cache(page);
spin_unlock_irq(&address_space->tree_lock);
- swapcache_free(entry, page);
+ swapcache_free_page_entry(page);
set_page_private(page, 0);
ClearPageSwapCache(page);
page_cache_release(page);
@@ -365,7 +362,7 @@ struct page *read_swap_cache_async(swp_e
* add_to_swap_cache() doesn't return -EEXIST, so we can safely
* clear SWAP_HAS_CACHE flag.
*/
- swapcache_free(entry, NULL);
+ swapcache_free_entry(entry);
} while (err != -ENOMEM);
if (new_page)
diff -puN mm/vmscan.c~make-page-and-swp_entry_t-variants mm/vmscan.c
--- linux.git/mm/vmscan.c~make-page-and-swp_entry_t-variants 2013-05-07
13:48:13.971056559 -0700
+++ linux.git-davehans/mm/vmscan.c 2013-05-07 13:48:13.979056913 -0700
@@ -490,10 +490,9 @@ static int __remove_mapping(struct addre
}
if (PageSwapCache(page)) {
- swp_entry_t swap = { .val = page_private(page) };
__delete_from_swap_cache(page);
spin_unlock_irq(&mapping->tree_lock);
- swapcache_free(swap, page);
+ swapcache_free_page_entry(page);
set_page_private(page, 0);
ClearPageSwapCache(page);
} else {
_
--
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