[PATCH 4/8] mm: cleanup add_to_page_cache_locked()

From: Kirill A. Shutemov
Date: Mon Jul 15 2013 - 06:47:44 EST


From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>

The patch makes add_to_page_cache_locked() cleaner:
- unindent most code of the function by inverting one condition;
- streamline code no-error path;
- move insert error path outside normal code path;
- call radix_tree_preload_end() earlier;

No functional changes.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
---
mm/filemap.c | 48 +++++++++++++++++++++++++-----------------------
1 file changed, 25 insertions(+), 23 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index f6fe61f..f7c4ed5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -467,32 +467,34 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
error = mem_cgroup_cache_charge(page, current->mm,
gfp_mask & GFP_RECLAIM_MASK);
if (error)
- goto out;
+ return error;

error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
- if (error == 0) {
- page_cache_get(page);
- page->mapping = mapping;
- page->index = offset;
-
- spin_lock_irq(&mapping->tree_lock);
- error = radix_tree_insert(&mapping->page_tree, offset, page);
- if (likely(!error)) {
- mapping->nrpages++;
- __inc_zone_page_state(page, NR_FILE_PAGES);
- spin_unlock_irq(&mapping->tree_lock);
- trace_mm_filemap_add_to_page_cache(page);
- } else {
- page->mapping = NULL;
- /* Leave page->index set: truncation relies upon it */
- spin_unlock_irq(&mapping->tree_lock);
- mem_cgroup_uncharge_cache_page(page);
- page_cache_release(page);
- }
- radix_tree_preload_end();
- } else
+ if (error) {
mem_cgroup_uncharge_cache_page(page);
-out:
+ return error;
+ }
+
+ page_cache_get(page);
+ page->mapping = mapping;
+ page->index = offset;
+
+ spin_lock_irq(&mapping->tree_lock);
+ error = radix_tree_insert(&mapping->page_tree, offset, page);
+ radix_tree_preload_end();
+ if (unlikely(!error))
+ goto err_insert;
+ mapping->nrpages++;
+ __inc_zone_page_state(page, NR_FILE_PAGES);
+ spin_unlock_irq(&mapping->tree_lock);
+ trace_mm_filemap_add_to_page_cache(page);
+ return 0;
+err_insert:
+ page->mapping = NULL;
+ /* Leave page->index set: truncation relies upon it */
+ spin_unlock_irq(&mapping->tree_lock);
+ mem_cgroup_uncharge_cache_page(page);
+ page_cache_release(page);
return error;
}
EXPORT_SYMBOL(add_to_page_cache_locked);
--
1.8.3.2

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