From patchwork Tue Sep 12 21:53:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Aring X-Patchwork-Id: 13382219 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BC544BA2F for ; Tue, 12 Sep 2023 21:53:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694555632; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=bm5ioigpX2H28oED9HeU/1D9TJk7vRwYC7hWBAcGBxQ=; b=dKbN0fMYfEEi4+aL3F7NZhOBVBOTXfO+Y8nUaf88Fovo0YlOx0G+fW6Q8FSKxaDkzStOnp s1ho0aPrK2Y8k1WD8K1bKsl9NtMmkQqDpOOiHeeiBBeOTmB/hQYPCCipTTwzRyND8cGkVv wWVphVLwjbf8uOdTAlsPihr9BGkeG1M= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-323-nnXGloXVPLiYsP6t52r-AQ-1; Tue, 12 Sep 2023 17:53:48 -0400 X-MC-Unique: nnXGloXVPLiYsP6t52r-AQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1A4AA181A6E0; Tue, 12 Sep 2023 21:53:48 +0000 (UTC) Received: from fs-i40c-03.fs.lab.eng.bos.redhat.com (fs-i40c-03.fs.lab.eng.bos.redhat.com [10.16.224.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id C061B40C2009; Tue, 12 Sep 2023 21:53:47 +0000 (UTC) From: Alexander Aring To: linux-nfs@vger.kernel.org Cc: gfs2@lists.linux.dev, ocfs2-devel@lists.linux.dev, linux-fsdevel@vger.kernel.org, teigland@redhat.com, rpeterso@redhat.com, agruenba@redhat.com, trond.myklebust@hammerspace.com, anna@kernel.org, chuck.lever@oracle.com, jlayton@kernel.org, aahringo@redhat.com Subject: [PATCHv2 nfsd/master 3/7] lockd: fix race in async lock request handling Date: Tue, 12 Sep 2023 17:53:20 -0400 Message-Id: <20230912215324.3310111-4-aahringo@redhat.com> In-Reply-To: <20230912215324.3310111-1-aahringo@redhat.com> References: <20230912215324.3310111-1-aahringo@redhat.com> Precedence: bulk X-Mailing-List: ocfs2-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 This patch fixes a race in async lock request handling between adding the relevant struct nlm_block to nlm_blocked list after the request was sent by vfs_lock_file() and nlmsvc_grant_deferred() does a lookup of the nlm_block in the nlm_blocked list. It could be that the async request is completed before the nlm_block was added to the list. This would end in a -ENOENT and a kernel log message of "lockd: grant for unknown block". To solve this issue we add the nlm_block before the vfs_lock_file() call to be sure it has been added when a possible nlmsvc_grant_deferred() is called. If the vfs_lock_file() results in an case when it wouldn't be added to nlm_blocked list, the nlm_block struct will be removed from this list again. Reviewed-by: Jeff Layton Signed-off-by: Alexander Aring --- fs/lockd/svclock.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index c313622a9578..993999297e31 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -555,6 +555,9 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, ret = nlm_lck_blocked; goto out; } + + /* Append to list of blocked */ + nlmsvc_insert_block_locked(block, NLM_NEVER); spin_unlock(&nlm_blocked_lock); if (!wait) @@ -566,9 +569,12 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, dprintk("lockd: vfs_lock_file returned %d\n", error); switch (error) { case 0: + nlmsvc_remove_block(block); ret = nlm_granted; goto out; case -EAGAIN: + if (!wait) + nlmsvc_remove_block(block); ret = async_block ? nlm_lck_blocked : nlm_lck_denied; goto out; case FILE_LOCK_DEFERRED: @@ -579,17 +585,16 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, ret = nlmsvc_defer_lock_rqst(rqstp, block); goto out; case -EDEADLK: + nlmsvc_remove_block(block); ret = nlm_deadlock; goto out; default: /* includes ENOLCK */ + nlmsvc_remove_block(block); ret = nlm_lck_denied_nolocks; goto out; } ret = nlm_lck_blocked; - - /* Append to list of blocked */ - nlmsvc_insert_block(block, NLM_NEVER); out: mutex_unlock(&file->f_mutex); nlmsvc_release_block(block);