From patchwork Mon Jun 17 15:13:53 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 2733951 Return-Path: X-Original-To: patchwork-cifs-client@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 0151E9F39E for ; Mon, 17 Jun 2013 15:16:22 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 0403B20372 for ; Mon, 17 Jun 2013 15:16:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 89CD720375 for ; Mon, 17 Jun 2013 15:16:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752376Ab3FQPOi (ORCPT ); Mon, 17 Jun 2013 11:14:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39946 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751784Ab3FQPOh (ORCPT ); Mon, 17 Jun 2013 11:14:37 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r5HFE9Oj014465 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 17 Jun 2013 11:14:09 -0400 Received: from sikun.lab.eng.rdu2.redhat.com (sikun.lab.eng.rdu2.redhat.com [10.8.0.43]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r5HFDuWb009391; Mon, 17 Jun 2013 11:14:08 -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 v3 10/13] locks: add a new "lm_owner_key" lock operation Date: Mon, 17 Jun 2013 11:13:53 -0400 Message-Id: <1371482036-15958-11-git-send-email-jlayton@redhat.com> In-Reply-To: <1371482036-15958-1-git-send-email-jlayton@redhat.com> References: <1371482036-15958-1-git-send-email-jlayton@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Spam-Status: No, score=-8.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently, the hashing that the locking code uses to add these values to the blocked_hash is simply calculated using fl_owner field. That's valid in most cases except for server-side lockd, which validates the owner of a lock based on fl_owner and fl_pid. In the case where you have a small number of NFS clients doing a lot of locking between different processes, you could end up with all the blocked requests sitting in a very small number of hash buckets. Add a new lm_owner_key operation to the lock_manager_operations that will generate an unsigned long to use as the key in the hashtable. That function is only implemented for server-side lockd, and simply XORs the fl_owner and fl_pid. Signed-off-by: Jeff Layton Acked-by: J. Bruce Fields --- Documentation/filesystems/Locking | 16 +++++++++++----- fs/lockd/svclock.c | 12 ++++++++++++ fs/locks.c | 12 ++++++++++-- include/linux/fs.h | 1 + 4 files changed, 34 insertions(+), 7 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 413685f..dfeb01b 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -351,6 +351,7 @@ fl_release_private: maybe no ----------------------- lock_manager_operations --------------------------- prototypes: int (*lm_compare_owner)(struct file_lock *, struct file_lock *); + unsigned long (*lm_owner_key)(struct file_lock *); void (*lm_notify)(struct file_lock *); /* unblock callback */ int (*lm_grant)(struct file_lock *, struct file_lock *, int); void (*lm_break)(struct file_lock *); /* break_lease callback */ @@ -360,16 +361,21 @@ locking rules: inode->i_lock file_lock_lock may block lm_compare_owner: yes[1] maybe no +lm_owner_key yes[1] yes no lm_notify: yes yes no lm_grant: no no no lm_break: yes no no lm_change yes no no -[1]: ->lm_compare_owner is generally called with *an* inode->i_lock held. It -may not be the i_lock of the inode for either file_lock being compared! This is -the case with deadlock detection, since the code has to chase down the owners -of locks that may be entirely unrelated to the one on which the lock is being -acquired. When doing a search for deadlocks, the file_lock_lock is also held. +[1]: ->lm_compare_owner and ->lm_owner_key are generally called with +*an* inode->i_lock held. It may not be the i_lock of the inode +associated with either file_lock argument! This is the case with deadlock +detection, since the code has to chase down the owners of locks that may +be entirely unrelated to the one on which the lock is being acquired. +For deadlock detection however, the file_lock_lock is also held. The +fact that these locks are held ensures that the file_locks do not +disappear out from under you while doing the comparison or generating an +owner key. --------------------------- buffer_head ----------------------------------- prototypes: diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index e703318..ce2cdab 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -744,8 +744,20 @@ static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2) return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid; } +/* + * Since NLM uses two "keys" for tracking locks, we need to hash them down + * to one for the blocked_hash. Here, we're just xor'ing the host address + * with the pid in order to create a key value for picking a hash bucket. + */ +static unsigned long +nlmsvc_owner_key(struct file_lock *fl) +{ + return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid; +} + const struct lock_manager_operations nlmsvc_lock_operations = { .lm_compare_owner = nlmsvc_same_owner, + .lm_owner_key = nlmsvc_owner_key, .lm_notify = nlmsvc_notify_blocked, .lm_grant = nlmsvc_grant_deferred, }; diff --git a/fs/locks.c b/fs/locks.c index d93b291..55f3af7 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -505,10 +505,18 @@ locks_delete_global_locks(struct file_lock *waiter) spin_unlock(&file_lock_lock); } +static unsigned long +posix_owner_key(struct file_lock *fl) +{ + if (fl->fl_lmops && fl->fl_lmops->lm_owner_key) + return fl->fl_lmops->lm_owner_key(fl); + return (unsigned long)fl->fl_owner; +} + static inline void locks_insert_global_blocked(struct file_lock *waiter) { - hash_add(blocked_hash, &waiter->fl_link, (unsigned long)waiter->fl_owner); + hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter)); } static inline void @@ -739,7 +747,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl) { struct file_lock *fl; - hash_for_each_possible(blocked_hash, fl, fl_link, (unsigned long)block_fl->fl_owner) { + hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) { if (posix_same_owner(fl, block_fl)) return fl->fl_next; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 3b340f7..232a345 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -908,6 +908,7 @@ struct file_lock_operations { struct lock_manager_operations { int (*lm_compare_owner)(struct file_lock *, struct file_lock *); + unsigned long (*lm_owner_key)(struct file_lock *); void (*lm_notify)(struct file_lock *); /* unblock callback */ int (*lm_grant)(struct file_lock *, struct file_lock *, int); void (*lm_break)(struct file_lock *);