linux-kernel - Re: [PATCH v3 2/2] ceph: wait the first reply of inflight async unlink

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <acf2457a-a984-d490-2833-be7cfd25c729@redhat.com>
Date:   Wed, 18 May 2022 09:03:00 +0800
From:   Xiubo Li <xiubli@...hat.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     jlayton@...nel.org, viro@...iv.linux.org.uk, idryomov@...il.com,
        vshankar@...hat.com, ceph-devel@...r.kernel.org,
        dchinner@...hat.com, hch@....de, arnd@...db.de, mcgrof@...nel.org,
        akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v3 2/2] ceph: wait the first reply of inflight async
 unlink


On 5/17/22 10:36 PM, Matthew Wilcox wrote:
> On Tue, May 17, 2022 at 08:55:49PM +0800, Xiubo Li wrote:
>> +int ceph_wait_on_conflict_unlink(struct dentry *dentry)
>> +{
>> +	struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb);
>> +	struct dentry *pdentry = dentry->d_parent;
>> +	struct dentry *udentry, *found = NULL;
>> +	struct ceph_dentry_info *di;
>> +	struct qstr dname;
>> +	u32 hash = dentry->d_name.hash;
>> +	int err;
>> +
>> +	dname.name = dentry->d_name.name;
>> +	dname.len = dentry->d_name.len;
>> +
>> +	rcu_read_lock();
>> +	hash_for_each_possible_rcu(fsc->async_unlink_conflict, di,
>> +				   hnode, hash) {
>> +		udentry = di->dentry;
>> +
>> +		spin_lock(&udentry->d_lock);
>> +		if (udentry->d_name.hash != hash)
>> +			goto next;
>> +		if (unlikely(udentry->d_parent != pdentry))
>> +			goto next;
>> +		if (!hash_hashed(&di->hnode))
>> +			goto next;
>> +
>> +		if (!test_bit(CEPH_DENTRY_ASYNC_UNLINK_BIT, &di->flags))
>> +			pr_warn("%s dentry %p:%pd async unlink bit is not set\n",
>> +				__func__, dentry, dentry);
>> +
>> +		if (d_compare(pdentry, udentry, &dname))
>> +			goto next;
>> +
>> +		spin_unlock(&udentry->d_lock);
>> +		found = dget(udentry);
>> +		break;
>> +next:
>> +		spin_unlock(&udentry->d_lock);
>> +	}
>> +	rcu_read_unlock();
>> +
>> +	if (likely(!found))
>> +		return 0;
>> +
>> +	dout("%s dentry %p:%pd conflict with old %p:%pd\n", __func__,
>> +	     dentry, dentry, found, found);
>> +
>> +	err = wait_on_bit(&di->flags, CEPH_DENTRY_ASYNC_UNLINK_BIT,
>> +			  TASK_INTERRUPTIBLE);
> Do you really want to use TASK_INTERRUPTIBLE here?  If the window is
> resized and you get a SIGWINCH, or a timer goes off and you get a
> SIGALRM, you want to return -EINTR?  I would suggest that TASK_KILLABLE
> is probably the semantics that you want.
>
Sounds reasonable.  I will switch to use the TASK_KILLABLE.

@Jeff

I just copied this code from ceph_wait_on_async_create(). BTW, do we 
have any other consideration that we must use the TASK_INTERRUPTIBLE there ?

Thanks.

-- Xiubo