From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: [PATCH] ext4: move_extent improve bh vanishing success factor Date: Wed, 5 Nov 2014 11:53:49 -0500 Message-ID: <20141105165349.GE27083@thunk.org> References: <1413620984-7736-1-git-send-email-dmonakhov@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Dmitry Monakhov Return-path: Received: from imap.thunk.org ([74.207.234.97]:40452 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753303AbaKEQx5 (ORCPT ); Wed, 5 Nov 2014 11:53:57 -0500 Content-Disposition: inline In-Reply-To: <1413620984-7736-1-git-send-email-dmonakhov@openvz.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sat, Oct 18, 2014 at 12:29:44PM +0400, Dmitry Monakhov wrote: > Xiaoguang Wang has reported sporadic EBUSY failures of ext4/302 > Unfortunetly there is nothing we can do if some other task holds > BH's refenrence. So we must return EBUSY in this case. From other > point we can decrease false positive report raito. One of such > cases is filesystem under ENOSPC conditions. We should try to kick > the journal regardless to number of free blocks. > > Signed-off-by: Dmitry Monakhov Thanks, applied but I did modify the patch slightly because we weren't actually properly handling the ENOSPC case (we were checking for the wrong error code). - Ted commit 88c6b61ff1cfb4013a3523227d91ad11b2892388 Author: Dmitry Monakhov Date: Wed Nov 5 11:52:38 2014 -0500 ext4: move_extent improve bh vanishing success factor Xiaoguang Wang has reported sporadic EBUSY failures of ext4/302 Unfortunetly there is nothing we can do if some other task holds BH's refenrence. So we must return EBUSY in this case. But we can try kicking the journal to see if the other task releases the bh reference after the commit is complete. Also decrease false positives by properly checking for ENOSPC and retrying the allocation after kicking the journal --- which is done by ext4_should_retry_alloc(). [ Modified by tytso to properly check for ENOSPC. ] Signed-off-by: Dmitry Monakhov Signed-off-by: Theodore Ts'o diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c index 9f2311b..503ea15 100644 --- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -273,6 +273,7 @@ move_extent_per_page(struct file *o_filp, struct inode *donor_inode, int replaced_count = 0; int from = data_offset_in_page << orig_inode->i_blkbits; int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits; + struct super_block *sb = orig_inode->i_sb; /* * It needs twice the amount of ordinary journal buffers because @@ -405,10 +406,13 @@ unlock_pages: page_cache_release(pagep[1]); stop_journal: ext4_journal_stop(handle); + if (*err == -ENOSPC && + ext4_should_retry_alloc(sb, &retries)) + goto again; /* Buffer was busy because probably is pinned to journal transaction, * force transaction commit may help to free it. */ - if (*err == -EBUSY && ext4_should_retry_alloc(orig_inode->i_sb, - &retries)) + if (*err == -EBUSY && retries++ < 4 && EXT4_SB(sb)->s_journal && + jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal)) goto again; return replaced_count;