From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Kennedy Subject: [PATCH] fs-writeback : check sync bit earlier in inode_wait_for_writeback Date: Fri, 16 Apr 2010 16:33:39 +0100 Message-ID: <1271432019.2075.31.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: lkml , linux-fsdevel , Wu Fengguang To: Alexander Viro , Jens Axboe Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org When wb_writeback() hasn't written anything it will re-acquire the inode lock before calling inode_wait_for_writeback. This change tests the sync bit first so that is doesn't need to drop & re-acquire the lock if the inode became available while wb_writeback() was waiting to get the lock. Signed-off-by: Richard Kennedy ---- patch against 2.6.34-rc4 compiled & tested on 86_64 regards Richard diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 4b37f7c..b1e398e 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -398,11 +398,11 @@ static void inode_wait_for_writeback(struct inode *inode) wait_queue_head_t *wqh; wqh = bit_waitqueue(&inode->i_state, __I_SYNC); - do { + while (inode->i_state & I_SYNC) { spin_unlock(&inode_lock); __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); spin_lock(&inode_lock); - } while (inode->i_state & I_SYNC); + } } /*