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>

diff --git a/mm/filemap.c b/mm/filemap.c
index e3b6fc8..1e6aec4 100644 (file)
--- 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);