From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 01779900089 for ; Mon, 18 Apr 2011 23:10:37 -0400 (EDT) Message-Id: <20110419030532.638670778@intel.com> Date: Tue, 19 Apr 2011 11:00:07 +0800 From: Wu Fengguang Subject: [PATCH 4/6] writeback: introduce writeback_control.inodes_cleaned References: <20110419030003.108796967@intel.com> Content-Disposition: inline; filename=writeback-inodes_written.patch Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Jan Kara , Mel Gorman , Mel Gorman , Wu Fengguang , Dave Chinner , Trond Myklebust , Itaru Kitayama , Minchan Kim , LKML , linux-fsdevel@vger.kernel.org, Linux Memory Management List The flusher works on dirty inodes in batches, and may quit prematurely if the batch of inodes happen to be metadata-only dirtied: in this case wbc->nr_to_write won't be decreased at all, which stands for "no pages written" but also mis-interpreted as "no progress". So introduce writeback_control.inodes_cleaned to count the inodes get cleaned. A non-zero value means there are some progress on writeback, in which case more writeback can be tried. about v1: The initial version was to count successful ->write_inode() calls. However it leads to busy loops for sync() over NFS, because NFS ridiculously returns 0 (success) while at the same time redirties the inode. The NFS case can be trivially fixed, however there may be more hidden bugs in other filesystems.. Acked-by: Mel Gorman Signed-off-by: Wu Fengguang --- fs/fs-writeback.c | 4 ++++ include/linux/writeback.h | 1 + 2 files changed, 5 insertions(+) --- linux-next.orig/fs/fs-writeback.c 2011-04-19 10:18:30.000000000 +0800 +++ linux-next/fs/fs-writeback.c 2011-04-19 10:18:30.000000000 +0800 @@ -473,6 +473,7 @@ writeback_single_inode(struct inode *ino * No need to add it back to the LRU. */ list_del_init(&inode->i_wb_list); + wbc->inodes_cleaned++; } } inode_sync_complete(inode); @@ -736,6 +737,7 @@ static long wb_writeback(struct bdi_writ wbc.more_io = 0; wbc.nr_to_write = write_chunk; wbc.pages_skipped = 0; + wbc.inodes_cleaned = 0; trace_wbc_writeback_start(&wbc, wb->bdi); if (work->sb) @@ -752,6 +754,8 @@ static long wb_writeback(struct bdi_writ */ if (wbc.nr_to_write <= 0) continue; + if (wbc.inodes_cleaned) + continue; /* * Didn't write everything and we don't have more IO, bail */ --- linux-next.orig/include/linux/writeback.h 2011-04-19 10:18:17.000000000 +0800 +++ linux-next/include/linux/writeback.h 2011-04-19 10:18:30.000000000 +0800 @@ -34,6 +34,7 @@ struct writeback_control { long nr_to_write; /* Write this many pages, and decrement this for each page written */ long pages_skipped; /* Pages which were not written */ + long inodes_cleaned; /* # of inodes cleaned */ /* * For a_ops->writepages(): is start or end are non-zero then this is -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org