Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756919Ab0LBDIS (ORCPT ); Wed, 1 Dec 2010 22:08:18 -0500 Received: from mx2.netapp.com ([216.240.18.37]:28482 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756546Ab0LBDIP (ORCPT ); Wed, 1 Dec 2010 22:08:15 -0500 X-IronPort-AV: E=Sophos;i="4.59,285,1288594800"; d="scan'208";a="489804694" From: Trond Myklebust To: Linus Torvalds , Nick Bowler Cc: Linux Kernel Mailing List , linux-nfs@vger.kernel.org, Andrew Morton , Hugh Dickins , Nick Piggin , Rik van Riel , Christoph Hellwig , Al Viro Subject: [PATCH v3 2/3] Call the filesystem back whenever a page is removed from the page cache Date: Wed, 1 Dec 2010 22:08:04 -0500 Message-Id: <1291259285-26803-3-git-send-email-Trond.Myklebust@netapp.com> X-Mailer: git-send-email 1.7.3.2 In-Reply-To: <1291259285-26803-2-git-send-email-Trond.Myklebust@netapp.com> References: <1291259285-26803-1-git-send-email-Trond.Myklebust@netapp.com> <1291259285-26803-2-git-send-email-Trond.Myklebust@netapp.com> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6353 Lines: 169 From: Linus Torvalds NFS needs to be able to release objects that are stored in the page cache once the page itself is no longer visible from the page cache. This patch adds a callback to the address space operations that allows filesystems to perform page cleanups once the page has been removed from the page cache. Original patch by: Linus Torvalds [trondmy: cover the cases of invalidate_inode_pages2() and truncate_inode_pages()] Signed-off-by: Trond Myklebust --- Documentation/filesystems/Locking | 7 ++++++- Documentation/filesystems/vfs.txt | 7 +++++++ include/linux/fs.h | 1 + mm/truncate.c | 8 ++++++++ mm/vmscan.c | 11 +++++++++++ 5 files changed, 33 insertions(+), 1 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index a91f308..b6426f1 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -173,12 +173,13 @@ prototypes: sector_t (*bmap)(struct address_space *, sector_t); int (*invalidatepage) (struct page *, unsigned long); int (*releasepage) (struct page *, int); + void (*freepage)(struct page *); int (*direct_IO)(int, struct kiocb *, const struct iovec *iov, loff_t offset, unsigned long nr_segs); int (*launder_page) (struct page *); locking rules: - All except set_page_dirty may block + All except set_page_dirty and freepage may block BKL PageLocked(page) i_mutex writepage: no yes, unlocks (see below) @@ -193,6 +194,7 @@ perform_write: no n/a yes bmap: no invalidatepage: no yes releasepage: no yes +freepage: no yes direct_IO: no launder_page: no yes @@ -288,6 +290,9 @@ buffers from the page in preparation for freeing it. It returns zero to indicate that the buffers are (or may be) freeable. If ->releasepage is zero, the kernel assumes that the fs has no private interest in the buffers. + ->freepage() is called when the kernel is done dropping the page +from the page cache. + ->launder_page() may be called prior to releasing a page if it is still found to be dirty. It returns zero if the page was successfully cleaned, or an error value if not. Note that in order to prevent the page diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index ed7e5ef..3b14a55 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -534,6 +534,7 @@ struct address_space_operations { sector_t (*bmap)(struct address_space *, sector_t); int (*invalidatepage) (struct page *, unsigned long); int (*releasepage) (struct page *, int); + void (*freepage)(struct page *); ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov, loff_t offset, unsigned long nr_segs); struct page* (*get_xip_page)(struct address_space *, sector_t, @@ -679,6 +680,12 @@ struct address_space_operations { need to ensure this. Possibly it can clear the PageUptodate bit if it cannot free private data yet. + freepage: freepage is called once the page is no longer visible in + the page cache in order to allow the cleanup of any private + data. Since it may be called by the memory reclaimer, it + should not assume that the original address_space mapping still + exists, and it should not block. + direct_IO: called by the generic read/write routines to perform direct_IO - that is IO requests which bypass the page cache and transfer data directly between the storage and the diff --git a/include/linux/fs.h b/include/linux/fs.h index c9e06cc..090f0ea 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -602,6 +602,7 @@ struct address_space_operations { sector_t (*bmap)(struct address_space *, sector_t); void (*invalidatepage) (struct page *, unsigned long); int (*releasepage) (struct page *, gfp_t); + void (*freepage)(struct page *); ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov, loff_t offset, unsigned long nr_segs); int (*get_xip_mem)(struct address_space *, pgoff_t, int, diff --git a/mm/truncate.c b/mm/truncate.c index ba887bf..76ab2a8 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -108,6 +108,10 @@ truncate_complete_page(struct address_space *mapping, struct page *page) clear_page_mlock(page); remove_from_page_cache(page); ClearPageMappedToDisk(page); + + if (mapping->a_ops->freepage) + mapping->a_ops->freepage(page); + page_cache_release(page); /* pagecache ref */ return 0; } @@ -390,6 +394,10 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page) __remove_from_page_cache(page); spin_unlock_irq(&mapping->tree_lock); mem_cgroup_uncharge_cache_page(page); + + if (mapping->a_ops->freepage) + mapping->a_ops->freepage(page); + page_cache_release(page); /* pagecache ref */ return 1; failed: diff --git a/mm/vmscan.c b/mm/vmscan.c index d31d7ce..9e218e7 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -454,6 +454,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page) BUG_ON(!PageLocked(page)); BUG_ON(mapping != page_mapping(page)); + preempt_disable(); spin_lock_irq(&mapping->tree_lock); /* * The non racy check for a busy page. @@ -492,10 +493,19 @@ static int __remove_mapping(struct address_space *mapping, struct page *page) swp_entry_t swap = { .val = page_private(page) }; __delete_from_swap_cache(page); spin_unlock_irq(&mapping->tree_lock); + preempt_enable(); swapcache_free(swap, page); } else { + void (*freepage)(struct page *); + + freepage = mapping->a_ops->freepage; + __remove_from_page_cache(page); spin_unlock_irq(&mapping->tree_lock); + if (freepage != NULL) + freepage(page); + preempt_enable(); + mem_cgroup_uncharge_cache_page(page); } @@ -503,6 +513,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page) cannot_free: spin_unlock_irq(&mapping->tree_lock); + preempt_enable(); return 0; } -- 1.7.3.2 -- 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/