From patchwork Sat Jun 1 03:07:26 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 2646581 Return-Path: X-Original-To: patchwork-ceph-devel@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id 92B7E40E1D for ; Sat, 1 Jun 2013 03:08:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757707Ab3FADIN (ORCPT ); Fri, 31 May 2013 23:08:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44485 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754752Ab3FADIL (ORCPT ); Fri, 31 May 2013 23:08:11 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r5137es4006287 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 31 May 2013 23:07:40 -0400 Received: from sikun.lab.eng.rdu2.redhat.com (sikun.lab.eng.rdu2.redhat.com [10.8.0.43]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r5137YWZ001118; Fri, 31 May 2013 23:07:39 -0400 From: Jeff Layton To: viro@zeniv.linux.org.uk, matthew@wil.cx, bfields@fieldses.org Cc: dhowells@redhat.com, sage@inktank.com, smfrench@gmail.com, swhiteho@redhat.com, Trond.Myklebust@netapp.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-afs@lists.infradead.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, piastryyy@gmail.com Subject: [PATCH v1 03/11] locks: comment cleanups and clarifications Date: Fri, 31 May 2013 23:07:26 -0400 Message-Id: <1370056054-25449-4-git-send-email-jlayton@redhat.com> In-Reply-To: <1370056054-25449-1-git-send-email-jlayton@redhat.com> References: <1370056054-25449-1-git-send-email-jlayton@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org Signed-off-by: Jeff Layton --- fs/locks.c | 24 +++++++++++++++++++----- include/linux/fs.h | 6 ++++++ 2 files changed, 25 insertions(+), 5 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index e3140b8..a7d2253 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -150,6 +150,16 @@ static int target_leasetype(struct file_lock *fl) int leases_enable = 1; int lease_break_time = 45; +/* + * The i_flock list is ordered by: + * + * 1) lock type -- FL_LEASEs first, then FL_FLOCK, and finally FL_POSIX + * 2) lock owner + * 3) lock range start + * 4) lock range end + * + * Obviously, the last two criteria only matter for POSIX locks. + */ #define for_each_lock(inode, lockp) \ for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next) @@ -806,6 +816,11 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str } lock_flocks(); + /* + * New lock request. Walk all POSIX locks and look for conflicts. If + * there are any, either return -EAGAIN or put the request on the + * blocker's list of waiters. + */ if (request->fl_type != F_UNLCK) { for_each_lock(inode, before) { fl = *before; @@ -844,7 +859,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str before = &fl->fl_next; } - /* Process locks with this owner. */ + /* Process locks with this owner. */ while ((fl = *before) && posix_same_owner(request, fl)) { /* Detect adjacent or overlapping regions (if same lock type) */ @@ -930,10 +945,9 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str } /* - * The above code only modifies existing locks in case of - * merging or replacing. If new lock(s) need to be inserted - * all modifications are done bellow this, so it's safe yet to - * bail out. + * The above code only modifies existing locks in case of merging or + * replacing. If new lock(s) need to be inserted all modifications are + * done below this, so it's safe yet to bail out. */ error = -ENOLCK; /* "no luck" */ if (right && left == right && !new_fl2) diff --git a/include/linux/fs.h b/include/linux/fs.h index b9d7816..ae377e9 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -926,6 +926,12 @@ int locks_in_grace(struct net *); /* that will die - we need it for nfs_lock_info */ #include +/* + * struct file_lock represents a generic "file lock". It's used to represent + * POSIX byte range locks, BSD (flock) locks, and leases. It's important to + * note that the same struct is used to represent both a request for a lock and + * the lock itself, but the same object is never used for both. + */ struct file_lock { struct file_lock *fl_next; /* singly linked list for this inode */ struct list_head fl_link; /* doubly linked list of all locks */