From: Fengguang Wu Subject: [PATCH] clear PAGECACHE_TAG_DIRTY for truncated pages Date: Fri, 1 Feb 2008 20:18:47 +0800 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Peter Zijlstra , Michael Rubin , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Andrew Morton Return-path: Content-Disposition: inline Message-Id: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org The `truncated' page in block_write_full_page()/nobh_writepage() may stick for a long time. For example, ext2_rmdir() will set i_size to 0, and then the dir inode and its pages may hang around because of being referenced by some process. To produce this situation: In terminal 1: $ mkdir hi; cd hi $ sleep 1h; cd .. In terminal 2: $ rmdir hi The dir 'hi' is deleted in terminal 2 while still being referenced by the shell(as working dir) in terminal 1. The deleted inode 'hi' with its dirty-and-truncated page will stay for 1 hour, during which the pdflush will retry the page _at least_ once every 5s. So clear PAGECACHE_TAG_DIRTY to prevent pdflush from retrying on it. Tested-by: Joerg Platte Cc: Peter Zijlstra Cc: Michael Rubin Signed-off-by: Fengguang Wu --- fs/buffer.c | 16 ++++++++++++++++ 1 files changed, 16 insertions(+) --- linux-mm.orig/fs/buffer.c +++ linux-mm/fs/buffer.c @@ -2631,7 +2631,13 @@ int nobh_writepage(struct page *page, ge if (page->mapping->a_ops->invalidatepage) page->mapping->a_ops->invalidatepage(page, offset); #endif + /* + * Clear PAGECACHE_TAG_DIRTY to stop pdflush from retrying. + * Read block_write_full_page() for more details. + */ + set_page_writeback(page); unlock_page(page); + end_page_writeback(page); return 0; /* don't care */ } @@ -2826,7 +2832,17 @@ int block_write_full_page(struct page *p * freeable here, so the page does not leak. */ do_invalidatepage(page, 0); + /* + * Clear PAGECACHE_TAG_DIRTY to stop pdflush from retrying. + * + * Some truncated pages may hang around for long time. + * For example, ext2_rmdir() will set i_size to 0, and then + * keep the pages as long as the dir is still referenced(as + * the working dir of some process). + */ + set_page_writeback(page); unlock_page(page); + end_page_writeback(page); return 0; /* don't care */ }