mm: cleanup add_to_page_cache_locked()

Make 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@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 25 insertions, 23 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index e3b6fc8c0b7b..1e6aec4a2d2e 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_maybe_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);