Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759740Ab3EGVVq (ORCPT ); Tue, 7 May 2013 17:21:46 -0400 Received: from mga09.intel.com ([134.134.136.24]:55589 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759416Ab3EGVT6 (ORCPT ); Tue, 7 May 2013 17:19:58 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,629,1363158000"; d="scan'208";a="333403561" Subject: [RFC][PATCH 2/7] make 'struct page' and swp_entry_t variants of swapcache_free(). To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mgorman@suse.de, tim.c.chen@linux.intel.com, Dave Hansen From: Dave Hansen Date: Tue, 07 May 2013 14:19:57 -0700 References: <20130507211954.9815F9D1@viggo.jf.intel.com> In-Reply-To: <20130507211954.9815F9D1@viggo.jf.intel.com> Message-Id: <20130507211957.603799B2@viggo.jf.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6857 Lines: 177 From: Dave Hansen swapcache_free() takes two arguments: void swapcache_free(swp_entry_t entry, struct page *page) Most of its callers (5/7) are from error handling paths haven't even instantiated a page, so they pass page=NULL. Both of the callers that call in with a 'struct page' create and pass in a temporary swp_entry_t. Now that we are deferring clearing page_private() until after swapcache_free() has been called, we can just create a variant that takes a 'struct page' and does the temporary variable in the helper. That leaves all the other callers doing swapcache_free(entry, NULL) so create another helper for them that makes it clear that they need only pass in a swp_entry_t. One downside here is that delete_from_swap_cache() now does an extra swap_address_space() call. But, those are pretty cheap (just some array index arithmetic). Signed-off-by: Dave Hansen --- linux.git-davehans/drivers/staging/zcache/zcache-main.c | 2 +- linux.git-davehans/include/linux/swap.h | 3 ++- linux.git-davehans/mm/shmem.c | 2 +- linux.git-davehans/mm/swap_state.c | 13 +++++-------- linux.git-davehans/mm/swapfile.c | 13 ++++++++++++- linux.git-davehans/mm/vmscan.c | 3 +-- 6 files changed, 22 insertions(+), 14 deletions(-) diff -puN drivers/staging/zcache/zcache-main.c~make-page-and-swp_entry_t-variants drivers/staging/zcache/zcache-main.c --- linux.git/drivers/staging/zcache/zcache-main.c~make-page-and-swp_entry_t-variants 2013-05-07 13:48:13.963056205 -0700 +++ linux.git-davehans/drivers/staging/zcache/zcache-main.c 2013-05-07 13:48:13.975056737 -0700 @@ -961,7 +961,7 @@ static int zcache_get_swap_cache_page(in * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - swapcache_free(entry, NULL); + swapcache_free_entry(entry); /* FIXME: is it possible to get here without err==-ENOMEM? * If not, we can dispense with the do loop, use goto retry */ } while (err != -ENOMEM); diff -puN include/linux/swap.h~make-page-and-swp_entry_t-variants include/linux/swap.h --- linux.git/include/linux/swap.h~make-page-and-swp_entry_t-variants 2013-05-07 13:48:13.964056249 -0700 +++ linux.git-davehans/include/linux/swap.h 2013-05-07 13:48:13.975056737 -0700 @@ -382,7 +382,8 @@ extern void swap_shmem_alloc(swp_entry_t extern int swap_duplicate(swp_entry_t); extern int swapcache_prepare(swp_entry_t); extern void swap_free(swp_entry_t); -extern void swapcache_free(swp_entry_t, struct page *page); +extern void swapcache_free_entry(swp_entry_t entry); +extern void swapcache_free_page_entry(struct page *page); extern int free_swap_and_cache(swp_entry_t); extern int swap_type_of(dev_t, sector_t, struct block_device **); extern unsigned int count_swap_pages(int, int); diff -puN mm/shmem.c~make-page-and-swp_entry_t-variants mm/shmem.c --- linux.git/mm/shmem.c~make-page-and-swp_entry_t-variants 2013-05-07 13:48:13.966056339 -0700 +++ linux.git-davehans/mm/shmem.c 2013-05-07 13:48:13.976056781 -0700 @@ -871,7 +871,7 @@ static int shmem_writepage(struct page * } mutex_unlock(&shmem_swaplist_mutex); - swapcache_free(swap, NULL); + swapcache_free_entry(swap); redirty: set_page_dirty(page); if (wbc->for_reclaim) diff -puN mm/swapfile.c~make-page-and-swp_entry_t-variants mm/swapfile.c --- linux.git/mm/swapfile.c~make-page-and-swp_entry_t-variants 2013-05-07 13:48:13.968056427 -0700 +++ linux.git-davehans/mm/swapfile.c 2013-05-07 13:48:13.977056825 -0700 @@ -637,7 +637,7 @@ void swap_free(swp_entry_t entry) /* * Called after dropping swapcache to decrease refcnt to swap entries. */ -void swapcache_free(swp_entry_t entry, struct page *page) +static void __swapcache_free(swp_entry_t entry, struct page *page) { struct swap_info_struct *p; unsigned char count; @@ -651,6 +651,17 @@ void swapcache_free(swp_entry_t entry, s } } +void swapcache_free_entry(swp_entry_t entry) +{ + __swapcache_free(entry, NULL); +} + +void swapcache_free_page_entry(struct page *page) +{ + swp_entry_t entry = { .val = page_private(page) }; + __swapcache_free(entry, page); +} + /* * How many references to page are currently swapped out? * This does not give an exact answer when swap count is continued, diff -puN mm/swap_state.c~make-page-and-swp_entry_t-variants mm/swap_state.c --- linux.git/mm/swap_state.c~make-page-and-swp_entry_t-variants 2013-05-07 13:48:13.969056471 -0700 +++ linux.git-davehans/mm/swap_state.c 2013-05-07 13:48:13.978056869 -0700 @@ -172,7 +172,7 @@ int add_to_swap(struct page *page, struc if (unlikely(PageTransHuge(page))) if (unlikely(split_huge_page_to_list(page, list))) { - swapcache_free(entry, NULL); + swapcache_free_entry(entry); return 0; } @@ -198,7 +198,7 @@ int add_to_swap(struct page *page, struc * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - swapcache_free(entry, NULL); + swapcache_free_entry(entry); return 0; } } @@ -211,17 +211,14 @@ int add_to_swap(struct page *page, struc */ void delete_from_swap_cache(struct page *page) { - swp_entry_t entry; struct address_space *address_space; - entry.val = page_private(page); - - address_space = swap_address_space(entry); + address_space = page_mapping(page); spin_lock_irq(&address_space->tree_lock); __delete_from_swap_cache(page); spin_unlock_irq(&address_space->tree_lock); - swapcache_free(entry, page); + swapcache_free_page_entry(page); set_page_private(page, 0); ClearPageSwapCache(page); page_cache_release(page); @@ -365,7 +362,7 @@ struct page *read_swap_cache_async(swp_e * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ - swapcache_free(entry, NULL); + swapcache_free_entry(entry); } while (err != -ENOMEM); if (new_page) diff -puN mm/vmscan.c~make-page-and-swp_entry_t-variants mm/vmscan.c --- linux.git/mm/vmscan.c~make-page-and-swp_entry_t-variants 2013-05-07 13:48:13.971056559 -0700 +++ linux.git-davehans/mm/vmscan.c 2013-05-07 13:48:13.979056913 -0700 @@ -490,10 +490,9 @@ static int __remove_mapping(struct addre } if (PageSwapCache(page)) { - swp_entry_t swap = { .val = page_private(page) }; __delete_from_swap_cache(page); spin_unlock_irq(&mapping->tree_lock); - swapcache_free(swap, page); + swapcache_free_page_entry(page); set_page_private(page, 0); ClearPageSwapCache(page); } else { _ -- 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/