shmem_add_to_page_cache() has three callsites, but only one of them
wants the radix_tree_preload() (an exceptional entry guarantees that
the radix tree node is present in the other cases), and only that site
can achieve mem_cgroup_uncharge_cache_page() (PageSwapCache makes it a
no-op in the other cases). We did it this way originally to reflect
add_to_page_cache_locked(); but it's confusing now, so move the
radix_tree preloading and mem_cgroup uncharging to that one caller.
Signed-off-by: Hugh Dickins <hu...@google.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hir...@jp.fujitsu.com>
Cc: Michal Hocko <mho...@suse.cz>
---
This is just a cleanup: I'd prefer it to go in along with the fix 2/3,
but it can be delayed to v3.6 if you prefer.
mm/shmem.c | 58 ++++++++++++++++++++++++---------------------------
1 file changed, 28 insertions(+), 30 deletions(-)
--- 3.5-rc6+/mm/shmem.c 2012-07-07 19:20:52.026952048 -0700
+++ linux/mm/shmem.c 2012-07-07 19:21:44.342952082 -0700
@@ -288,40 +288,31 @@ static int shmem_add_to_page_cache(struc
struct address_space *mapping,
pgoff_t index, gfp_t gfp, void *expected)
{
- int error = 0;
+ int error;
VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(!PageSwapBacked(page));
+ page_cache_get(page);
+ page->mapping = mapping;
+ page->index = index;
+
+ spin_lock_irq(&mapping->tree_lock);
if (!expected)
- error = radix_tree_preload(gfp & GFP_RECLAIM_MASK);
+ error = radix_tree_insert(&mapping->page_tree, index, page);
+ else
+ error = shmem_radix_tree_replace(mapping, index, expected,
+ page);
if (!error) {
- page_cache_get(page);
- page->mapping = mapping;
- page->index = index;
-
- spin_lock_irq(&mapping->tree_lock);
- if (!expected)
- error = radix_tree_insert(&mapping->page_tree,
- index, page);
- else
- error = shmem_radix_tree_replace(mapping, index,
- expected, page);
- if (!error) {
- mapping->nrpages++;
- __inc_zone_page_state(page, NR_FILE_PAGES);
- __inc_zone_page_state(page, NR_SHMEM);
- spin_unlock_irq(&mapping->tree_lock);
- } else {
- page->mapping = NULL;
- spin_unlock_irq(&mapping->tree_lock);
- page_cache_release(page);
- }
- if (!expected)
- radix_tree_preload_end();
+ mapping->nrpages++;
+ __inc_zone_page_state(page, NR_FILE_PAGES);
+ __inc_zone_page_state(page, NR_SHMEM);
+ spin_unlock_irq(&mapping->tree_lock);
+ } else {
+ page->mapping = NULL;
+ spin_unlock_irq(&mapping->tree_lock);
+ page_cache_release(page);
}
- if (error)
- mem_cgroup_uncharge_cache_page(page);
return error;
}
@@ -1202,11 +1193,18 @@ repeat:
__set_page_locked(page);
error = mem_cgroup_cache_charge(page, current->mm,
gfp & GFP_RECLAIM_MASK);
- if (!error)
- error = shmem_add_to_page_cache(page, mapping, index,
- gfp, NULL);
if (error)
goto decused;
+ error = radix_tree_preload(gfp & GFP_RECLAIM_MASK);
+ if (!error) {
+ error = shmem_add_to_page_cache(page, mapping, index,
+ gfp, NULL);
+ radix_tree_preload_end();
+ }
+ if (error) {
+ mem_cgroup_uncharge_cache_page(page);
+ goto decused;
+ }
lru_cache_add_anon(page);
spin_lock(&info->lock);
--
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