From patchwork Tue Aug 14 03:56:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 10565009 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EED7C1390 for ; Tue, 14 Aug 2018 03:58:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E0E412964B for ; Tue, 14 Aug 2018 03:58:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D572F29662; Tue, 14 Aug 2018 03:58:32 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F1C1229653 for ; Tue, 14 Aug 2018 03:58:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731128AbeHNGn1 (ORCPT ); Tue, 14 Aug 2018 02:43:27 -0400 Received: from mx2.suse.de ([195.135.220.15]:45022 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725846AbeHNGn0 (ORCPT ); Tue, 14 Aug 2018 02:43:26 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 38A12AF40; Tue, 14 Aug 2018 03:58:09 +0000 (UTC) From: NeilBrown To: Jeff Layton , Alexander Viro Date: Tue, 14 Aug 2018 13:56:52 +1000 Subject: [PATCH 1/5] fs/locks: rename some lists and pointers. Cc: "J. Bruce Fields" , Martin Wilck , linux-fsdevel@vger.kernel.org, Frank Filz , linux-kernel@vger.kernel.org Message-ID: <153421901196.24426.13628119459456277309.stgit@noble> In-Reply-To: <153421852728.24426.2111161640156686201.stgit@noble> References: <153421852728.24426.2111161640156686201.stgit@noble> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP struct file lock contains an 'fl_next' pointer which is used to point to the lock that this request is blocked waiting for. So rename it to fl_blocker. The fl_blocked list_head in an active lock is the head of a list of blocked requests. In a request it is a node in that list. These are two distinct uses, so replace with two list_heads with different names. fl_blocked is the head of a list of blocked requests fl_block is a node on that list. The two different list_heads are never used at the same time, but that will change in a future patch. Note that a tracepoint is changed to report fl_blocker instead of fl_next. Signed-off-by: NeilBrown --- fs/cifs/file.c | 2 +- fs/locks.c | 40 ++++++++++++++++++++------------------- include/linux/fs.h | 7 +++++-- include/trace/events/filelock.h | 16 ++++++++-------- 4 files changed, 35 insertions(+), 30 deletions(-) diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 8d41ca7bfcf1..066ed2e4ba96 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -1092,7 +1092,7 @@ cifs_posix_lock_set(struct file *file, struct file_lock *flock) rc = posix_lock_file(file, flock, NULL); up_write(&cinode->lock_sem); if (rc == FILE_LOCK_DEFERRED) { - rc = wait_event_interruptible(flock->fl_wait, !flock->fl_next); + rc = wait_event_interruptible(flock->fl_wait, !flock->fl_blocker); if (!rc) goto try_again; posix_unblock_lock(flock); diff --git a/fs/locks.c b/fs/locks.c index db7b6917d9c5..322491e70e41 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -194,7 +194,7 @@ static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); * This lock protects the blocked_hash. Generally, if you're accessing it, you * want to be holding this lock. * - * In addition, it also protects the fl->fl_block list, and the fl->fl_next + * In addition, it also protects the fl->fl_blocked list, and the fl->fl_blocker * pointer for file_lock structures that are acting as lock requests (in * contrast to those that are acting as records of acquired locks). * @@ -203,7 +203,7 @@ static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); * protected by this lock, we can skip acquiring it iff we already hold the * flc_lock. * - * In particular, adding an entry to the fl_block list requires that you hold + * In particular, adding an entry to the fl_blocked list requires that you hold * both the flc_lock and the blocked_lock_lock (acquired in that order). * Deleting an entry from the list however only requires the file_lock_lock. */ @@ -302,6 +302,7 @@ static void locks_init_lock_heads(struct file_lock *fl) { INIT_HLIST_NODE(&fl->fl_link); INIT_LIST_HEAD(&fl->fl_list); + INIT_LIST_HEAD(&fl->fl_blocked); INIT_LIST_HEAD(&fl->fl_block); init_waitqueue_head(&fl->fl_wait); } @@ -341,6 +342,7 @@ void locks_free_lock(struct file_lock *fl) { BUG_ON(waitqueue_active(&fl->fl_wait)); BUG_ON(!list_empty(&fl->fl_list)); + BUG_ON(!list_empty(&fl->fl_blocked)); BUG_ON(!list_empty(&fl->fl_block)); BUG_ON(!hlist_unhashed(&fl->fl_link)); @@ -676,7 +678,7 @@ static void __locks_delete_block(struct file_lock *waiter) { locks_delete_global_blocked(waiter); list_del_init(&waiter->fl_block); - waiter->fl_next = NULL; + waiter->fl_blocker = NULL; } static void locks_delete_block(struct file_lock *waiter) @@ -692,16 +694,16 @@ static void locks_delete_block(struct file_lock *waiter) * it seems like the reasonable thing to do. * * Must be called with both the flc_lock and blocked_lock_lock held. The - * fl_block list itself is protected by the blocked_lock_lock, but by ensuring + * fl_blocked list itself is protected by the blocked_lock_lock, but by ensuring * that the flc_lock is also held on insertions we can avoid taking the - * blocked_lock_lock in some cases when we see that the fl_block list is empty. + * blocked_lock_lock in some cases when we see that the fl_blocked list is empty. */ static void __locks_insert_block(struct file_lock *blocker, struct file_lock *waiter) { BUG_ON(!list_empty(&waiter->fl_block)); - waiter->fl_next = blocker; - list_add_tail(&waiter->fl_block, &blocker->fl_block); + waiter->fl_blocker = blocker; + list_add_tail(&waiter->fl_block, &blocker->fl_blocked); if (IS_POSIX(blocker) && !IS_OFDLCK(blocker)) locks_insert_global_blocked(waiter); } @@ -725,18 +727,18 @@ static void locks_wake_up_blocks(struct file_lock *blocker) /* * Avoid taking global lock if list is empty. This is safe since new * blocked requests are only added to the list under the flc_lock, and - * the flc_lock is always held here. Note that removal from the fl_block + * the flc_lock is always held here. Note that removal from the fl_blocked * list does not require the flc_lock, so we must recheck list_empty() * after acquiring the blocked_lock_lock. */ - if (list_empty(&blocker->fl_block)) + if (list_empty(&blocker->fl_blocked)) return; spin_lock(&blocked_lock_lock); - while (!list_empty(&blocker->fl_block)) { + while (!list_empty(&blocker->fl_blocked)) { struct file_lock *waiter; - waiter = list_first_entry(&blocker->fl_block, + waiter = list_first_entry(&blocker->fl_blocked, struct file_lock, fl_block); __locks_delete_block(waiter); if (waiter->fl_lmops && waiter->fl_lmops->lm_notify) @@ -887,7 +889,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl) 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; + return fl->fl_blocker; } return NULL; } @@ -1245,7 +1247,7 @@ static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl) error = posix_lock_inode(inode, fl, NULL); if (error != FILE_LOCK_DEFERRED) break; - error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); + error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker); if (!error) continue; @@ -1332,7 +1334,7 @@ int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start, error = posix_lock_inode(inode, &fl, NULL); if (error != FILE_LOCK_DEFERRED) break; - error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); + error = wait_event_interruptible(fl.fl_wait, !fl.fl_blocker); if (!error) { /* * If we've been sleeping someone might have @@ -1526,7 +1528,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type) locks_dispose_list(&dispose); error = wait_event_interruptible_timeout(new_fl->fl_wait, - !new_fl->fl_next, break_time); + !new_fl->fl_blocker, break_time); percpu_down_read_preempt_disable(&file_rwsem); spin_lock(&ctx->flc_lock); @@ -1940,7 +1942,7 @@ static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl) error = flock_lock_inode(inode, fl); if (error != FILE_LOCK_DEFERRED) break; - error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); + error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker); if (!error) continue; @@ -2212,7 +2214,7 @@ static int do_lock_file_wait(struct file *filp, unsigned int cmd, error = vfs_lock_file(filp, cmd, fl, NULL); if (error != FILE_LOCK_DEFERRED) break; - error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); + error = wait_event_interruptible(fl->fl_wait, !fl->fl_blocker); if (!error) continue; @@ -2583,7 +2585,7 @@ posix_unblock_lock(struct file_lock *waiter) int status = 0; spin_lock(&blocked_lock_lock); - if (waiter->fl_next) + if (waiter->fl_blocker) __locks_delete_block(waiter); else status = -ENOENT; @@ -2711,7 +2713,7 @@ static int locks_show(struct seq_file *f, void *v) lock_get_status(f, fl, iter->li_pos, ""); - list_for_each_entry(bfl, &fl->fl_block, fl_block) + list_for_each_entry(bfl, &fl->fl_blocked, fl_block) lock_get_status(f, bfl, iter->li_pos, " ->"); return 0; diff --git a/include/linux/fs.h b/include/linux/fs.h index 805bf22898cf..b168013ef99e 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1002,10 +1002,13 @@ bool opens_in_grace(struct net *); * Obviously, the last two criteria only matter for POSIX locks. */ struct file_lock { - struct file_lock *fl_next; /* singly linked list for this inode */ + struct file_lock *fl_blocker; /* The lock, that is blocking us */ struct list_head fl_list; /* link into file_lock_context */ struct hlist_node fl_link; /* node in global lists */ - struct list_head fl_block; /* circular list of blocked processes */ + struct list_head fl_blocked; /* list of requests with + * ->fl_blocker pointing here */ + struct list_head fl_block; /* node in + * ->fl_blocker->fl_blocked */ fl_owner_t fl_owner; unsigned int fl_flags; unsigned char fl_type; diff --git a/include/trace/events/filelock.h b/include/trace/events/filelock.h index d1faf3597b9d..0e50f985a390 100644 --- a/include/trace/events/filelock.h +++ b/include/trace/events/filelock.h @@ -68,7 +68,7 @@ DECLARE_EVENT_CLASS(filelock_lock, __field(struct file_lock *, fl) __field(unsigned long, i_ino) __field(dev_t, s_dev) - __field(struct file_lock *, fl_next) + __field(struct file_lock *, fl_blocker) __field(fl_owner_t, fl_owner) __field(unsigned int, fl_pid) __field(unsigned int, fl_flags) @@ -82,7 +82,7 @@ DECLARE_EVENT_CLASS(filelock_lock, __entry->fl = fl ? fl : NULL; __entry->s_dev = inode->i_sb->s_dev; __entry->i_ino = inode->i_ino; - __entry->fl_next = fl ? fl->fl_next : NULL; + __entry->fl_blocker = fl ? fl->fl_blocker : NULL; __entry->fl_owner = fl ? fl->fl_owner : NULL; __entry->fl_pid = fl ? fl->fl_pid : 0; __entry->fl_flags = fl ? fl->fl_flags : 0; @@ -92,9 +92,9 @@ DECLARE_EVENT_CLASS(filelock_lock, __entry->ret = ret; ), - TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_next=0x%p fl_owner=0x%p fl_pid=%u fl_flags=%s fl_type=%s fl_start=%lld fl_end=%lld ret=%d", + TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_blocker=0x%p fl_owner=0x%p fl_pid=%u fl_flags=%s fl_type=%s fl_start=%lld fl_end=%lld ret=%d", __entry->fl, MAJOR(__entry->s_dev), MINOR(__entry->s_dev), - __entry->i_ino, __entry->fl_next, __entry->fl_owner, + __entry->i_ino, __entry->fl_blocker, __entry->fl_owner, __entry->fl_pid, show_fl_flags(__entry->fl_flags), show_fl_type(__entry->fl_type), __entry->fl_start, __entry->fl_end, __entry->ret) @@ -122,7 +122,7 @@ DECLARE_EVENT_CLASS(filelock_lease, __field(struct file_lock *, fl) __field(unsigned long, i_ino) __field(dev_t, s_dev) - __field(struct file_lock *, fl_next) + __field(struct file_lock *, fl_blocker) __field(fl_owner_t, fl_owner) __field(unsigned int, fl_flags) __field(unsigned char, fl_type) @@ -134,7 +134,7 @@ DECLARE_EVENT_CLASS(filelock_lease, __entry->fl = fl ? fl : NULL; __entry->s_dev = inode->i_sb->s_dev; __entry->i_ino = inode->i_ino; - __entry->fl_next = fl ? fl->fl_next : NULL; + __entry->fl_blocker = fl ? fl->fl_blocker : NULL; __entry->fl_owner = fl ? fl->fl_owner : NULL; __entry->fl_flags = fl ? fl->fl_flags : 0; __entry->fl_type = fl ? fl->fl_type : 0; @@ -142,9 +142,9 @@ DECLARE_EVENT_CLASS(filelock_lease, __entry->fl_downgrade_time = fl ? fl->fl_downgrade_time : 0; ), - TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_next=0x%p fl_owner=0x%p fl_flags=%s fl_type=%s fl_break_time=%lu fl_downgrade_time=%lu", + TP_printk("fl=0x%p dev=0x%x:0x%x ino=0x%lx fl_blocker=0x%p fl_owner=0x%p fl_flags=%s fl_type=%s fl_break_time=%lu fl_downgrade_time=%lu", __entry->fl, MAJOR(__entry->s_dev), MINOR(__entry->s_dev), - __entry->i_ino, __entry->fl_next, __entry->fl_owner, + __entry->i_ino, __entry->fl_blocker, __entry->fl_owner, show_fl_flags(__entry->fl_flags), show_fl_type(__entry->fl_type), __entry->fl_break_time, __entry->fl_downgrade_time) From patchwork Tue Aug 14 03:56:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 10565007 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B9E9E1815 for ; Tue, 14 Aug 2018 03:58:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AD9A22964B for ; Tue, 14 Aug 2018 03:58:32 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A105E29662; Tue, 14 Aug 2018 03:58:32 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 337C329656 for ; Tue, 14 Aug 2018 03:58:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731251AbeHNGnd (ORCPT ); Tue, 14 Aug 2018 02:43:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:45050 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725846AbeHNGnd (ORCPT ); Tue, 14 Aug 2018 02:43:33 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 1D55BAF41; Tue, 14 Aug 2018 03:58:16 +0000 (UTC) From: NeilBrown To: Jeff Layton , Alexander Viro Date: Tue, 14 Aug 2018 13:56:52 +1000 Subject: [PATCH 2/5] fs/locks: split out __locks_wake_up_blocks(). Cc: "J. Bruce Fields" , Martin Wilck , linux-fsdevel@vger.kernel.org, Frank Filz , linux-kernel@vger.kernel.org Message-ID: <153421901201.24426.16491496622832329532.stgit@noble> In-Reply-To: <153421852728.24426.2111161640156686201.stgit@noble> References: <153421852728.24426.2111161640156686201.stgit@noble> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This functionality will be useful in future patches, so split it out from locks_wake_up_blocks(). Signed-off-by: NeilBrown --- fs/locks.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index 322491e70e41..de0b9276f23d 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -681,6 +681,21 @@ static void __locks_delete_block(struct file_lock *waiter) waiter->fl_blocker = NULL; } +static void __locks_wake_up_blocks(struct file_lock *blocker) +{ + while (!list_empty(&blocker->fl_blocked)) { + struct file_lock *waiter; + + waiter = list_first_entry(&blocker->fl_blocked, + struct file_lock, fl_block); + __locks_delete_block(waiter); + if (waiter->fl_lmops && waiter->fl_lmops->lm_notify) + waiter->fl_lmops->lm_notify(waiter); + else + wake_up(&waiter->fl_wait); + } +} + static void locks_delete_block(struct file_lock *waiter) { spin_lock(&blocked_lock_lock); @@ -735,17 +750,7 @@ static void locks_wake_up_blocks(struct file_lock *blocker) return; spin_lock(&blocked_lock_lock); - while (!list_empty(&blocker->fl_blocked)) { - struct file_lock *waiter; - - waiter = list_first_entry(&blocker->fl_blocked, - struct file_lock, fl_block); - __locks_delete_block(waiter); - if (waiter->fl_lmops && waiter->fl_lmops->lm_notify) - waiter->fl_lmops->lm_notify(waiter); - else - wake_up(&waiter->fl_wait); - } + __locks_wake_up_blocks(blocker); spin_unlock(&blocked_lock_lock); } From patchwork Tue Aug 14 03:56:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 10565011 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B96DD1815 for ; Tue, 14 Aug 2018 03:58:33 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A8F4E29656 for ; Tue, 14 Aug 2018 03:58:33 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9AA6B29662; Tue, 14 Aug 2018 03:58:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 563422965D for ; Tue, 14 Aug 2018 03:58:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731399AbeHNGnl (ORCPT ); Tue, 14 Aug 2018 02:43:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:45090 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725846AbeHNGnk (ORCPT ); Tue, 14 Aug 2018 02:43:40 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2CB34AF49; Tue, 14 Aug 2018 03:58:23 +0000 (UTC) From: NeilBrown To: Jeff Layton , Alexander Viro Date: Tue, 14 Aug 2018 13:56:52 +1000 Subject: [PATCH 3/5] fs/locks: allow a lock request to block other requests. Cc: "J. Bruce Fields" , Martin Wilck , linux-fsdevel@vger.kernel.org, Frank Filz , linux-kernel@vger.kernel.org Message-ID: <153421901205.24426.3008401633617707303.stgit@noble> In-Reply-To: <153421852728.24426.2111161640156686201.stgit@noble> References: <153421852728.24426.2111161640156686201.stgit@noble> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently, a lock can block pending requests, but all pending requests are equal. If lots of pending requests are mutually exclusive, this means they will all be woken up and all but one will fail. This can hurt performance. So we will allow pending requests to block other requests. Only the first request will be woken, and it will wake the others. This patch doesn't implement this fully, but prepares the way. - It acknowledges that a request might be blocking other requests, and when the request is converted to a lock, those blocked requests are moved across. - When a request is requeued or discarded, all blocked requests are woken. - When deadlock-detection looks for the lock which blocks a given request, we follow the chain of ->fl_blocker all the way to the top. Signed-off-by: NeilBrown --- fs/locks.c | 43 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 8 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index de0b9276f23d..9439eebd4eb9 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -408,9 +408,19 @@ void locks_copy_lock(struct file_lock *new, struct file_lock *fl) fl->fl_ops->fl_copy_lock(new, fl); } } - EXPORT_SYMBOL(locks_copy_lock); +static void locks_move_blocks(struct file_lock *new, struct file_lock *fl) +{ + struct file_lock *f; + + spin_lock(&blocked_lock_lock); + list_splice_init(&fl->fl_blocked, &new->fl_blocked); + list_for_each_entry(f, &fl->fl_blocked, fl_block) + f->fl_blocker = new; + spin_unlock(&blocked_lock_lock); +} + static inline int flock_translate_cmd(int cmd) { if (cmd & LOCK_MAND) return cmd & (LOCK_MAND | LOCK_RW); @@ -683,11 +693,15 @@ static void __locks_delete_block(struct file_lock *waiter) static void __locks_wake_up_blocks(struct file_lock *blocker) { + /* Wake up all requests in blocker->fl_blocked, including + * requests blocked by those requests. + */ while (!list_empty(&blocker->fl_blocked)) { struct file_lock *waiter; waiter = list_first_entry(&blocker->fl_blocked, struct file_lock, fl_block); + list_splice_init(&waiter->fl_blocked, &blocker->fl_blocked); __locks_delete_block(waiter); if (waiter->fl_lmops && waiter->fl_lmops->lm_notify) waiter->fl_lmops->lm_notify(waiter); @@ -699,6 +713,7 @@ static void __locks_wake_up_blocks(struct file_lock *blocker) static void locks_delete_block(struct file_lock *waiter) { spin_lock(&blocked_lock_lock); + __locks_wake_up_blocks(waiter); __locks_delete_block(waiter); spin_unlock(&blocked_lock_lock); } @@ -714,13 +729,19 @@ static void locks_delete_block(struct file_lock *waiter) * blocked_lock_lock in some cases when we see that the fl_blocked list is empty. */ static void __locks_insert_block(struct file_lock *blocker, - struct file_lock *waiter) + struct file_lock *waiter) { BUG_ON(!list_empty(&waiter->fl_block)); waiter->fl_blocker = blocker; list_add_tail(&waiter->fl_block, &blocker->fl_blocked); if (IS_POSIX(blocker) && !IS_OFDLCK(blocker)) locks_insert_global_blocked(waiter); + + /* The requests in waiter->fl_blocked are known to conflict with + * waiter, but might not conflict with blocker, or the requests + * and lock which block it. So they all need to be woken. + */ + __locks_wake_up_blocks(waiter); } /* Must be called with flc_lock held. */ @@ -893,8 +914,11 @@ 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, posix_owner_key(block_fl)) { - if (posix_same_owner(fl, block_fl)) - return fl->fl_blocker; + if (posix_same_owner(fl, block_fl)) { + while (fl->fl_blocker) + fl = fl->fl_blocker; + return fl; + } } return NULL; } @@ -987,6 +1011,7 @@ static int flock_lock_inode(struct inode *inode, struct file_lock *request) if (request->fl_flags & FL_ACCESS) goto out; locks_copy_lock(new_fl, request); + locks_move_blocks(new_fl, request); locks_insert_lock_ctx(new_fl, &ctx->flc_flock); new_fl = NULL; error = 0; @@ -1179,6 +1204,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request, goto out; } locks_copy_lock(new_fl, request); + locks_move_blocks(new_fl, request); locks_insert_lock_ctx(new_fl, &fl->fl_list); fl = new_fl; new_fl = NULL; @@ -2587,13 +2613,14 @@ void locks_remove_file(struct file *filp) int posix_unblock_lock(struct file_lock *waiter) { - int status = 0; + int status = -ENOENT; spin_lock(&blocked_lock_lock); - if (waiter->fl_blocker) + if (waiter->fl_blocker) { + __locks_wake_up_blocks(waiter); __locks_delete_block(waiter); - else - status = -ENOENT; + status = 0; + } spin_unlock(&blocked_lock_lock); return status; } From patchwork Tue Aug 14 03:56:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 10565013 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D007B1390 for ; Tue, 14 Aug 2018 03:58:33 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C2D6F2964B for ; Tue, 14 Aug 2018 03:58:33 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A94C929679; Tue, 14 Aug 2018 03:58:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4FF9C2964B for ; Tue, 14 Aug 2018 03:58:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731493AbeHNGnr (ORCPT ); Tue, 14 Aug 2018 02:43:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:45156 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725846AbeHNGnr (ORCPT ); Tue, 14 Aug 2018 02:43:47 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id F2C26AF53; Tue, 14 Aug 2018 03:58:29 +0000 (UTC) From: NeilBrown To: Jeff Layton , Alexander Viro Date: Tue, 14 Aug 2018 13:56:52 +1000 Subject: [PATCH 4/5] fs/locks: change all *_conflict() functions to return bool. Cc: "J. Bruce Fields" , Martin Wilck , linux-fsdevel@vger.kernel.org, Frank Filz , linux-kernel@vger.kernel.org Message-ID: <153421901208.24426.12703365395600257400.stgit@noble> In-Reply-To: <153421852728.24426.2111161640156686201.stgit@noble> References: <153421852728.24426.2111161640156686201.stgit@noble> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP posix_locks_conflict() and flock_locks_conflict() both return int. leases_conflict() returns bool. This inconsistency will cause problems for the next patch if not fixed. So change posix_locks_conflict() and flock_locks_conflict() to return bool. Also change the locks_conflict() helper. And convert some return (foo); to return foo; Signed-off-by: NeilBrown --- fs/locks.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index 9439eebd4eb9..c7a372cebff1 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -803,47 +803,50 @@ locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose) /* Determine if lock sys_fl blocks lock caller_fl. Common functionality * checks for shared/exclusive status of overlapping locks. */ -static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) +static bool locks_conflict(struct file_lock *caller_fl, + struct file_lock *sys_fl) { if (sys_fl->fl_type == F_WRLCK) - return 1; + return true; if (caller_fl->fl_type == F_WRLCK) - return 1; - return 0; + return true; + return false; } /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific * checking before calling the locks_conflict(). */ -static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) +static bool posix_locks_conflict(struct file_lock *caller_fl, + struct file_lock *sys_fl) { /* POSIX locks owned by the same process do not conflict with * each other. */ if (posix_same_owner(caller_fl, sys_fl)) - return (0); + return false; /* Check whether they overlap */ if (!locks_overlap(caller_fl, sys_fl)) - return 0; + return false; - return (locks_conflict(caller_fl, sys_fl)); + return locks_conflict(caller_fl, sys_fl); } /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific * checking before calling the locks_conflict(). */ -static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) +static bool flock_locks_conflict(struct file_lock *caller_fl, + struct file_lock *sys_fl) { /* FLOCK locks referring to the same filp do not conflict with * each other. */ if (caller_fl->fl_file == sys_fl->fl_file) - return (0); + return false; if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) - return 0; + return false; - return (locks_conflict(caller_fl, sys_fl)); + return locks_conflict(caller_fl, sys_fl); } void From patchwork Tue Aug 14 03:56:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 10565015 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E1A481390 for ; Tue, 14 Aug 2018 03:58:44 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D3C292964B for ; Tue, 14 Aug 2018 03:58:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C7CD429656; Tue, 14 Aug 2018 03:58:44 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 641972964B for ; Tue, 14 Aug 2018 03:58:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731608AbeHNGnz (ORCPT ); Tue, 14 Aug 2018 02:43:55 -0400 Received: from mx2.suse.de ([195.135.220.15]:45210 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725846AbeHNGny (ORCPT ); Tue, 14 Aug 2018 02:43:54 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id CAC31AF4E; Tue, 14 Aug 2018 03:58:36 +0000 (UTC) From: NeilBrown To: Jeff Layton , Alexander Viro Date: Tue, 14 Aug 2018 13:56:52 +1000 Subject: [PATCH 5/5] fs/locks: create a tree of dependent requests. Cc: "J. Bruce Fields" , Martin Wilck , linux-fsdevel@vger.kernel.org, Frank Filz , linux-kernel@vger.kernel.org Message-ID: <153421901212.24426.17984275454924451738.stgit@noble> In-Reply-To: <153421852728.24426.2111161640156686201.stgit@noble> References: <153421852728.24426.2111161640156686201.stgit@noble> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When we find an existing lock which conflicts with a request, and the request wants to wait, we currently add the request to a list. When the lock is removed, the whole list is woken. This can cause the thundering-herd problem. To reduce the problem, we make use of the (new) fact that a pending request can itself have a list of blocked requests. When we find a conflict, we look through the existing blocked requests. If any one of them blocks the new request, the new request is attached below that request, otherwise it is added to the list of blocked requests, which are now known to be mutually non-conflicting. This way, when the lock is released, only a set of non-conflicting locks will be woken, the rest can stay asleep. If the lock request cannot be granted and the request needs to be requeued, all the other requests it blocks will then be woken Reported-and-tested-by: Martin Wilck Signed-off-by: NeilBrown --- fs/locks.c | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-) diff --git a/fs/locks.c b/fs/locks.c index c7a372cebff1..af250afceff4 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -727,11 +727,25 @@ static void locks_delete_block(struct file_lock *waiter) * fl_blocked list itself is protected by the blocked_lock_lock, but by ensuring * that the flc_lock is also held on insertions we can avoid taking the * blocked_lock_lock in some cases when we see that the fl_blocked list is empty. + * + * Rather than just adding to the list, we check for conflicts with any existing + * waiters, and add beneath any waiter that blocks the new waiter. + * Thus wakeups don't happen until needed. */ static void __locks_insert_block(struct file_lock *blocker, - struct file_lock *waiter) + struct file_lock *waiter, + bool conflict(struct file_lock *, + struct file_lock *)) { + struct file_lock *fl; BUG_ON(!list_empty(&waiter->fl_block)); + +new_blocker: + list_for_each_entry(fl, &blocker->fl_blocked, fl_block) + if (conflict(fl, waiter)) { + blocker = fl; + goto new_blocker; + } waiter->fl_blocker = blocker; list_add_tail(&waiter->fl_block, &blocker->fl_blocked); if (IS_POSIX(blocker) && !IS_OFDLCK(blocker)) @@ -746,10 +760,12 @@ static void __locks_insert_block(struct file_lock *blocker, /* Must be called with flc_lock held. */ static void locks_insert_block(struct file_lock *blocker, - struct file_lock *waiter) + struct file_lock *waiter, + bool conflict(struct file_lock *, + struct file_lock *)) { spin_lock(&blocked_lock_lock); - __locks_insert_block(blocker, waiter); + __locks_insert_block(blocker, waiter, conflict); spin_unlock(&blocked_lock_lock); } @@ -1008,7 +1024,7 @@ static int flock_lock_inode(struct inode *inode, struct file_lock *request) if (!(request->fl_flags & FL_SLEEP)) goto out; error = FILE_LOCK_DEFERRED; - locks_insert_block(fl, request); + locks_insert_block(fl, request, flock_locks_conflict); goto out; } if (request->fl_flags & FL_ACCESS) @@ -1082,7 +1098,8 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request, spin_lock(&blocked_lock_lock); if (likely(!posix_locks_deadlock(request, fl))) { error = FILE_LOCK_DEFERRED; - __locks_insert_block(fl, request); + __locks_insert_block(fl, request, + posix_locks_conflict); } spin_unlock(&blocked_lock_lock); goto out; @@ -1555,7 +1572,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type) break_time -= jiffies; if (break_time == 0) break_time++; - locks_insert_block(fl, new_fl); + locks_insert_block(fl, new_fl, leases_conflict); trace_break_lease_block(inode, new_fl); spin_unlock(&ctx->flc_lock); percpu_up_read_preempt_enable(&file_rwsem);