From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750920AbdAPDU3 (ORCPT ); Sun, 15 Jan 2017 22:20:29 -0500 Received: from smtp2.provo.novell.com ([137.65.250.81]:59511 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750742AbdAPDUZ (ORCPT ); Sun, 15 Jan 2017 22:20:25 -0500 Subject: Re: [PATCH 2/2] ocfs2: fix deadlocks when taking inode lock at vfs entry points To: Junxiao Bi , ocfs2-devel@oss.oracle.com References: <1483630262-22227-1-git-send-email-zren@suse.com> <1483630262-22227-3-git-send-email-zren@suse.com> <31cc0413-6aa2-2493-fce6-f8f8ab9aaa16@suse.com> <6b3f4c7c-9276-321b-4e75-33c87a855757@oracle.com> <1d56b79c-1c2b-b988-7861-6b80df1d0a20@suse.com> Cc: akpm@linux-foundation.org, mfasheh@versity.com, jlbec@evilplan.org, ghe@suse.com, jiangqi903@gmail.com, linux-kernel@vger.kernel.org From: Eric Ren Message-ID: <7db68770-0e1f-65f6-5b7a-c9ad47c43d3a@suse.com> Date: Mon, 16 Jan 2017 11:17:41 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/16/2017 11:13 AM, Junxiao Bi wrote: > On 01/16/2017 11:06 AM, Eric Ren wrote: >> Hi Junxiao, >> >> On 01/16/2017 10:46 AM, Junxiao Bi wrote: >>>>> If had_lock==true, it is a bug? I think we should BUG_ON for it, that >>>>> can help us catch bug at the first time. >>>> Good idea! But I'm not sure if "ocfs2_setattr" is always the first one >>>> who takes the cluster lock. >>>> It's harder for me to name all the possible paths;-/ >>> The BUG_ON() can help catch the path where ocfs2_setattr is not the >>> first one. >> Yes, I understand. But, the problem is that the vfs entries calling >> order is out of our control. >> I don't want to place an assertion where I'm not 100% sure it's >> absolutely right;-) > If it is not the first one, is it another recursive locking bug? In this > case, if you don't like BUG_ON(), you can dump the call trace and print > some warning message. Yes! I like this idea, will add it in next version, thanks! Eric > > Thanks, > Junxiao. >> Thanks, >> Eric >> >>> Thanks, >>> Junxiao. >>> >>>>>> + if (had_lock) >>>>>> + arg_flags = OCFS2_META_LOCK_GETBH; >>>>>> + status = ocfs2_inode_lock_full(inode, &bh, 1, arg_flags); >>>>>> if (status < 0) { >>>>>> if (status != -ENOENT) >>>>>> mlog_errno(status); >>>>>> goto bail_unlock_rw; >>>>>> } >>>>>> - inode_locked = 1; >>>>>> + if (!had_lock) { >>>>>> + ocfs2_add_holder(lockres, &oh); >>>>>> + inode_locked = 1; >>>>>> + } >>>>>> if (size_change) { >>>>>> status = inode_newsize_ok(inode, attr->ia_size); >>>>>> @@ -1260,7 +1270,8 @@ int ocfs2_setattr(struct dentry *dentry, struct >>>>>> iattr *attr) >>>>>> bail_commit: >>>>>> ocfs2_commit_trans(osb, handle); >>>>>> bail_unlock: >>>>>> - if (status) { >>>>>> + if (status && inode_locked) { >>>>>> + ocfs2_remove_holder(lockres, &oh); >>>>>> ocfs2_inode_unlock(inode, 1); >>>>>> inode_locked = 0; >>>>>> } >>>>>> @@ -1278,8 +1289,10 @@ int ocfs2_setattr(struct dentry *dentry, >>>>>> struct iattr *attr) >>>>>> if (status < 0) >>>>>> mlog_errno(status); >>>>>> } >>>>>> - if (inode_locked) >>>>>> + if (inode_locked) { >>>>>> + ocfs2_remove_holder(lockres, &oh); >>>>>> ocfs2_inode_unlock(inode, 1); >>>>>> + } >>>>>> brelse(bh); >>>>>> return status; >>>>>> @@ -1321,20 +1334,31 @@ int ocfs2_getattr(struct vfsmount *mnt, >>>>>> int ocfs2_permission(struct inode *inode, int mask) >>>>>> { >>>>>> int ret; >>>>>> + int has_locked; >>>>>> + struct ocfs2_holder oh; >>>>>> + struct ocfs2_lock_res *lockres; >>>>>> if (mask & MAY_NOT_BLOCK) >>>>>> return -ECHILD; >>>>>> - ret = ocfs2_inode_lock(inode, NULL, 0); >>>>>> - if (ret) { >>>>>> - if (ret != -ENOENT) >>>>>> - mlog_errno(ret); >>>>>> - goto out; >>>>>> + lockres = &OCFS2_I(inode)->ip_inode_lockres; >>>>>> + has_locked = (ocfs2_is_locked_by_me(lockres) != NULL); >>>>> The same thing as ocfs2_setattr. >>>> OK. I will think over your suggestions! >>>> >>>> Thanks, >>>> Eric >>>> >>>>> Thanks, >>>>> Junxiao. >>>>>> + if (!has_locked) { >>>>>> + ret = ocfs2_inode_lock(inode, NULL, 0); >>>>>> + if (ret) { >>>>>> + if (ret != -ENOENT) >>>>>> + mlog_errno(ret); >>>>>> + goto out; >>>>>> + } >>>>>> + ocfs2_add_holder(lockres, &oh); >>>>>> } >>>>>> ret = generic_permission(inode, mask); >>>>>> - ocfs2_inode_unlock(inode, 0); >>>>>> + if (!has_locked) { >>>>>> + ocfs2_remove_holder(lockres, &oh); >>>>>> + ocfs2_inode_unlock(inode, 0); >>>>>> + } >>>>>> out: >>>>>> return ret; >>>>>> } >>>>>> >