From patchwork Thu Dec 20 10:09:35 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miao Xie X-Patchwork-Id: 1899241 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id 9719D3FC64 for ; Thu, 20 Dec 2012 10:09:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751775Ab2LTKJL (ORCPT ); Thu, 20 Dec 2012 05:09:11 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:16279 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751423Ab2LTKJI (ORCPT ); Thu, 20 Dec 2012 05:09:08 -0500 X-IronPort-AV: E=Sophos;i="4.84,323,1355068800"; d="scan'208";a="6440903" Received: from unknown (HELO tang.cn.fujitsu.com) ([10.167.250.3]) by song.cn.fujitsu.com with ESMTP; 20 Dec 2012 18:07:13 +0800 Received: from fnstmail02.fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id qBKAA7es013386; Thu, 20 Dec 2012 18:10:08 +0800 Received: from [10.167.225.199] ([10.167.225.199]) by fnstmail02.fnst.cn.fujitsu.com (Lotus Domino Release 8.5.3) with ESMTP id 2012122018080407-533364 ; Thu, 20 Dec 2012 18:08:04 +0800 Message-ID: <50D2E3DF.4010105@cn.fujitsu.com> Date: Thu, 20 Dec 2012 18:09:35 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Linux Fsdevel , Linux Btrfs , Linux Ext4 CC: Christoph Hellwig , Kamal Mostafa , Al Viro Subject: [PATCH RESEND] vfs: re-implement writeback_inodes_sb(_nr)_if_idle() and rename them X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/12/20 18:08:04, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/12/20 18:08:04, Serialize complete at 2012/12/20 18:08:04 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org writeback_inodes_sb(_nr)_if_idle() is re-implemented by replacing down_read() with down_read_trylock() because - If ->s_umount is write locked, then the sb is not idle. That is writeback_inodes_sb(_nr)_if_idle() needn't wait for the lock. - writeback_inodes_sb(_nr)_if_idle() grabs s_umount lock when it want to start writeback, it may bring us deadlock problem when doing umount. In order to fix the problem, ext4 and btrfs implemented their own writeback functions instead of writeback_inodes_sb(_nr)_if_idle(), but it introduced the redundant code, it is better to implement a new writeback_inodes_sb(_nr)_if_idle(). The name of these two functions is cumbersome, so rename them to try_to_writeback_inodes_sb(_nr). This idea came from Christoph Hellwig. Some code is from the patch of Kamal Mostafa. Signed-off-by: Miao Xie Tested-by: David Sterba --- fs/btrfs/extent-tree.c | 20 +++----------------- fs/ext4/inode.c | 8 ++------ fs/fs-writeback.c | 45 ++++++++++++++++++++------------------------- include/linux/writeback.h | 6 +++--- 4 files changed, 28 insertions(+), 51 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index d133edf..994e18e 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3689,20 +3689,6 @@ static int can_overcommit(struct btrfs_root *root, return 0; } -static int writeback_inodes_sb_nr_if_idle_safe(struct super_block *sb, - unsigned long nr_pages, - enum wb_reason reason) -{ - if (!writeback_in_progress(sb->s_bdi) && - down_read_trylock(&sb->s_umount)) { - writeback_inodes_sb_nr(sb, nr_pages, reason); - up_read(&sb->s_umount); - return 1; - } - - return 0; -} - /* * shrink metadata reservation for delalloc */ @@ -3735,9 +3721,9 @@ static void shrink_delalloc(struct btrfs_root *root, u64 to_reclaim, u64 orig, while (delalloc_bytes && loops < 3) { max_reclaim = min(delalloc_bytes, to_reclaim); nr_pages = max_reclaim >> PAGE_CACHE_SHIFT; - writeback_inodes_sb_nr_if_idle_safe(root->fs_info->sb, - nr_pages, - WB_REASON_FS_FREE_SPACE); + try_to_writeback_inodes_sb_nr(root->fs_info->sb, + nr_pages, + WB_REASON_FS_FREE_SPACE); /* * We need to wait for the async pages to actually start before diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index b3c243b..f82d60e 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2465,12 +2465,8 @@ static int ext4_nonda_switch(struct super_block *sb) /* * Start pushing delalloc when 1/2 of free blocks are dirty. */ - if (dirty_blocks && (free_blocks < 2 * dirty_blocks) && - !writeback_in_progress(sb->s_bdi) && - down_read_trylock(&sb->s_umount)) { - writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE); - up_read(&sb->s_umount); - } + if (dirty_blocks && (free_blocks < 2 * dirty_blocks)) + try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE); if (2 * free_blocks < 3 * dirty_blocks || free_blocks < (dirty_blocks + EXT4_FREECLUSTERS_WATERMARK)) { diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 3e3422f..9a04ef2 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1314,7 +1314,6 @@ void writeback_inodes_sb_nr(struct super_block *sb, bdi_queue_work(sb->s_bdi, &work); wait_for_completion(&done); } -EXPORT_SYMBOL(writeback_inodes_sb_nr); /** * writeback_inodes_sb - writeback dirty inodes from given super_block @@ -1332,47 +1331,43 @@ void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) EXPORT_SYMBOL(writeback_inodes_sb); /** - * writeback_inodes_sb_if_idle - start writeback if none underway + * try_to_writeback_inodes_sb_nr - try to start writeback if none underway * @sb: the superblock - * @reason: reason why some writeback work was initiated + * @nr: the number of pages to write + * @reason: the reason of writeback * - * Invoke writeback_inodes_sb if no writeback is currently underway. + * Invoke writeback_inodes_sb_nr if no writeback is currently underway. * Returns 1 if writeback was started, 0 if not. */ -int writeback_inodes_sb_if_idle(struct super_block *sb, enum wb_reason reason) +int try_to_writeback_inodes_sb_nr(struct super_block *sb, + unsigned long nr, + enum wb_reason reason) { - if (!writeback_in_progress(sb->s_bdi)) { - down_read(&sb->s_umount); - writeback_inodes_sb(sb, reason); - up_read(&sb->s_umount); + if (writeback_in_progress(sb->s_bdi)) return 1; - } else + + if (!down_read_trylock(&sb->s_umount)) return 0; + + writeback_inodes_sb_nr(sb, nr, reason); + up_read(&sb->s_umount); + return 1; } -EXPORT_SYMBOL(writeback_inodes_sb_if_idle); +EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr); /** - * writeback_inodes_sb_nr_if_idle - start writeback if none underway + * try_to_writeback_inodes_sb - try to start writeback if none underway * @sb: the superblock - * @nr: the number of pages to write * @reason: reason why some writeback work was initiated * - * Invoke writeback_inodes_sb if no writeback is currently underway. + * Implement by try_to_writeback_inodes_sb_nr() * Returns 1 if writeback was started, 0 if not. */ -int writeback_inodes_sb_nr_if_idle(struct super_block *sb, - unsigned long nr, - enum wb_reason reason) +int try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) { - if (!writeback_in_progress(sb->s_bdi)) { - down_read(&sb->s_umount); - writeback_inodes_sb_nr(sb, nr, reason); - up_read(&sb->s_umount); - return 1; - } else - return 0; + return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); } -EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle); +EXPORT_SYMBOL(try_to_writeback_inodes_sb); /** * sync_inodes_sb - sync sb inode pages diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 50c3e8f..ecdd0e0 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -87,9 +87,9 @@ int inode_wait(void *); void writeback_inodes_sb(struct super_block *, enum wb_reason reason); void writeback_inodes_sb_nr(struct super_block *, unsigned long nr, enum wb_reason reason); -int writeback_inodes_sb_if_idle(struct super_block *, enum wb_reason reason); -int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr, - enum wb_reason reason); +int try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason); +int try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr, + enum wb_reason reason); void sync_inodes_sb(struct super_block *); long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, enum wb_reason reason);