Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754884Ab0LOPuO (ORCPT ); Wed, 15 Dec 2010 10:50:14 -0500 Received: from fxip-0047f.externet.hu ([88.209.222.127]:34983 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754811Ab0LOPuN (ORCPT ); Wed, 15 Dec 2010 10:50:13 -0500 To: akpm@linux-foundation.org CC: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm: add replace_page_cache_page() function Message-Id: From: Miklos Szeredi Date: Wed, 15 Dec 2010 16:49:58 +0100 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3787 Lines: 112 From: Miklos Szeredi This function basically does: remove_from_page_cache(old); page_cache_release(old); add_to_page_cache_locked(new); Except it does this atomically, so there's no possibility for the "add" to fail because of a race. This is used by fuse to move pages into the page cache. Signed-off-by: Miklos Szeredi --- fs/fuse/dev.c | 10 ++++------ include/linux/pagemap.h | 1 + mm/filemap.c | 41 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 46 insertions(+), 6 deletions(-) Index: linux-2.6/mm/filemap.c =================================================================== --- linux-2.6.orig/mm/filemap.c 2010-12-15 16:39:55.000000000 +0100 +++ linux-2.6/mm/filemap.c 2010-12-15 16:41:24.000000000 +0100 @@ -389,6 +389,47 @@ int filemap_write_and_wait_range(struct } EXPORT_SYMBOL(filemap_write_and_wait_range); +int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask) +{ + int error; + + VM_BUG_ON(!PageLocked(old)); + VM_BUG_ON(!PageLocked(new)); + VM_BUG_ON(new->mapping); + + error = mem_cgroup_cache_charge(new, current->mm, + gfp_mask & GFP_RECLAIM_MASK); + if (error) + goto out; + + error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM); + if (error == 0) { + struct address_space *mapping = old->mapping; + pgoff_t offset = old->index; + + page_cache_get(new); + new->mapping = mapping; + new->index = offset; + + spin_lock_irq(&mapping->tree_lock); + __remove_from_page_cache(old); + error = radix_tree_insert(&mapping->page_tree, offset, new); + BUG_ON(error); + mapping->nrpages++; + __inc_zone_page_state(new, NR_FILE_PAGES); + if (PageSwapBacked(new)) + __inc_zone_page_state(new, NR_SHMEM); + spin_unlock_irq(&mapping->tree_lock); + radix_tree_preload_end(); + mem_cgroup_uncharge_cache_page(old); + page_cache_release(old); + } else + mem_cgroup_uncharge_cache_page(new); +out: + return error; +} +EXPORT_SYMBOL_GPL(replace_page_cache_page); + /** * add_to_page_cache_locked - add a locked page to the pagecache * @page: page to add Index: linux-2.6/include/linux/pagemap.h =================================================================== --- linux-2.6.orig/include/linux/pagemap.h 2010-12-15 16:39:39.000000000 +0100 +++ linux-2.6/include/linux/pagemap.h 2010-12-15 16:41:24.000000000 +0100 @@ -457,6 +457,7 @@ int add_to_page_cache_lru(struct page *p pgoff_t index, gfp_t gfp_mask); extern void remove_from_page_cache(struct page *page); extern void __remove_from_page_cache(struct page *page); +int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask); /* * Like add_to_page_cache_locked, but used to add newly allocated pages: Index: linux-2.6/fs/fuse/dev.c =================================================================== --- linux-2.6.orig/fs/fuse/dev.c 2010-12-15 16:39:39.000000000 +0100 +++ linux-2.6/fs/fuse/dev.c 2010-12-15 16:41:24.000000000 +0100 @@ -729,14 +729,12 @@ static int fuse_try_move_page(struct fus if (WARN_ON(PageMlocked(oldpage))) goto out_fallback_unlock; - remove_from_page_cache(oldpage); - page_cache_release(oldpage); - - err = add_to_page_cache_locked(newpage, mapping, index, GFP_KERNEL); + err = replace_page_cache_page(oldpage, newpage, GFP_KERNEL); if (err) { - printk(KERN_WARNING "fuse_try_move_page: failed to add page"); - goto out_fallback_unlock; + unlock_page(newpage); + return err; } + page_cache_get(newpage); if (!(buf->flags & PIPE_BUF_FLAG_LRU)) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/