X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lustre%2Fldlm%2Fldlm_plain.c;h=38a94b159000a8b94ada7e7f299c2def8ddd749a;hb=a162e24d2d;hp=5240a32e439dde49c996da0daf82d168c09e0a22;hpb=6e3ec5812ebd1b5ecf7cae584f429b013ffe7431;p=fs%2Flustre-release.git diff --git a/lustre/ldlm/ldlm_plain.c b/lustre/ldlm/ldlm_plain.c index 5240a32..38a94b1 100644 --- a/lustre/ldlm/ldlm_plain.c +++ b/lustre/ldlm/ldlm_plain.c @@ -1,6 +1,4 @@ -/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*- - * vim:expandtab:shiftwidth=8:tabstop=8: - * +/* * GPL HEADER START * * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. @@ -17,21 +15,18 @@ * * You should have received a copy of the GNU General Public License * version 2 along with this program; If not, see - * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf - * - * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, - * CA 95054 USA or visit www.sun.com if you need additional information or - * have any questions. + * http://www.gnu.org/licenses/gpl-2.0.html * * GPL HEADER END */ /* - * Copyright 2008 Sun Microsystems, Inc. All rights reserved + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * Use is subject to license terms. + * + * Copyright (c) 2011, 2017, Intel Corporation. */ /* * This file is part of Lustre, http://www.lustre.org/ - * Lustre is a trademark of Sun Microsystems, Inc. * * lustre/ldlm/ldlm_plain.c * @@ -39,122 +34,147 @@ * Author: Phil Schwan */ +/** + * This file contains implementation of PLAIN lock type. + * + * PLAIN locks are the simplest form of LDLM locking, and are used when + * there only needs to be a single lock on a resource. This avoids some + * of the complexity of EXTENT and IBITS lock types, but doesn't allow + * different "parts" of a resource to be locked concurrently. Example + * use cases for PLAIN locks include locking of MGS configuration logs + * and (as of Lustre 2.4) quota records. + */ + #define DEBUG_SUBSYSTEM S_LDLM -#ifdef __KERNEL__ #include #include #include -#else -#include -#endif #include "ldlm_internal.h" +#ifdef HAVE_SERVER_SUPPORT +/** + * Determine if the lock is compatible with all locks on the queue. + * + * If \a work_list is provided, conflicting locks are linked there. + * If \a work_list is not provided, we exit this function on first conflict. + * + * \retval 0 if there are conflicting locks in the \a queue + * \retval 1 if the lock is compatible to all locks in \a queue + */ static inline int -ldlm_plain_compat_queue(cfs_list_t *queue, struct ldlm_lock *req, - cfs_list_t *work_list) +ldlm_plain_compat_queue(struct list_head *queue, struct ldlm_lock *req, + struct list_head *work_list) { - cfs_list_t *tmp; - struct ldlm_lock *lock; - ldlm_mode_t req_mode = req->l_req_mode; - int compat = 1; - ENTRY; - - lockmode_verify(req_mode); - - cfs_list_for_each(tmp, queue) { - lock = cfs_list_entry(tmp, struct ldlm_lock, l_res_link); - - if (req == lock) - RETURN(compat); - - /* last lock in mode group */ - tmp = &cfs_list_entry(lock->l_sl_mode.prev, - struct ldlm_lock, - l_sl_mode)->l_res_link; - - if (lockmode_compat(lock->l_req_mode, req_mode)) - continue; - - if (!work_list) - RETURN(0); - - compat = 0; - - /* add locks of the mode group to @work_list as - * blocking locks for @req */ - if (lock->l_blocking_ast) - ldlm_add_ast_work_item(lock, req, work_list); - - { - cfs_list_t *head; + enum ldlm_mode req_mode = req->l_req_mode; + struct ldlm_lock *lock, *next_lock; + int compat = 1; + + ENTRY; + lockmode_verify(req_mode); + + list_for_each_entry_safe(lock, next_lock, queue, l_res_link) { + + /* + * We stop walking the queue if we hit ourselves so we don't + * take conflicting locks enqueued after us into account, + * or we'd wait forever. + */ + if (req == lock) + RETURN(compat); + + /* Advance loop cursor to last lock of mode group. */ + next_lock = list_entry(list_entry(lock->l_sl_mode.prev, + struct ldlm_lock, + l_sl_mode)->l_res_link.next, + struct ldlm_lock, l_res_link); + + if (lockmode_compat(lock->l_req_mode, req_mode)) + continue; + + if (!work_list) + RETURN(0); + + compat = 0; + + /* + * Add locks of the mode group to \a work_list as + * blocking locks for \a req. + */ + if (lock->l_blocking_ast) + ldlm_add_ast_work_item(lock, req, work_list); + + { + struct list_head *head; + + head = &lock->l_sl_mode; + list_for_each_entry(lock, head, l_sl_mode) + if (lock->l_blocking_ast) + ldlm_add_ast_work_item(lock, req, + work_list); + } + } + + RETURN(compat); +} - head = &lock->l_sl_mode; - cfs_list_for_each_entry(lock, head, l_sl_mode) - if (lock->l_blocking_ast) - ldlm_add_ast_work_item(lock, req, - work_list); - } - } +/** + * Process a granting attempt for plain lock. + * Must be called with ns lock held. + * + * This function looks for any conflicts for \a lock in the granted or + * waiting queues. The lock is granted if no conflicts are found in + * either queue. + */ +int ldlm_process_plain_lock(struct ldlm_lock *lock, __u64 *flags, + enum ldlm_process_intention intention, + enum ldlm_error *err, struct list_head *work_list) +{ + struct ldlm_resource *res = lock->l_resource; + struct list_head *grant_work = intention == LDLM_PROCESS_ENQUEUE ? + NULL : work_list; + int rc; + + ENTRY; + LASSERT(!ldlm_is_granted(lock)); + check_res_locked(res); + *err = ELDLM_OK; + + if (intention == LDLM_PROCESS_RESCAN) { + LASSERT(work_list != NULL); + rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL); + if (!rc) + RETURN(LDLM_ITER_STOP); + rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL); + if (!rc) + RETURN(LDLM_ITER_STOP); + + ldlm_resource_unlink_lock(lock); + ldlm_grant_lock(lock, grant_work); + RETURN(LDLM_ITER_CONTINUE); + } + + rc = ldlm_plain_compat_queue(&res->lr_granted, lock, work_list); + rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, work_list); + + if (rc == 2) { + ldlm_resource_unlink_lock(lock); + ldlm_grant_lock(lock, grant_work); + } + + RETURN(LDLM_ITER_CONTINUE); +} +#endif /* HAVE_SERVER_SUPPORT */ - RETURN(compat); +void ldlm_plain_policy_wire_to_local(const union ldlm_wire_policy_data *wpolicy, + union ldlm_policy_data *lpolicy) +{ + /* No policy for plain locks */ } -/* If first_enq is 0 (ie, called from ldlm_reprocess_queue): - * - blocking ASTs have already been sent - * - must call this function with the resource lock held - * - * If first_enq is 1 (ie, called from ldlm_lock_enqueue): - * - blocking ASTs have not been sent - * - must call this function with the resource lock held */ -int ldlm_process_plain_lock(struct ldlm_lock *lock, int *flags, int first_enq, - ldlm_error_t *err, cfs_list_t *work_list) +void ldlm_plain_policy_local_to_wire(const union ldlm_policy_data *lpolicy, + union ldlm_wire_policy_data *wpolicy) { - struct ldlm_resource *res = lock->l_resource; - CFS_LIST_HEAD(rpc_list); - int rc; - ENTRY; - - check_res_locked(res); - LASSERT(cfs_list_empty(&res->lr_converting)); - - if (!first_enq) { - LASSERT(work_list != NULL); - rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL); - if (!rc) - RETURN(LDLM_ITER_STOP); - rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL); - if (!rc) - RETURN(LDLM_ITER_STOP); - - ldlm_resource_unlink_lock(lock); - ldlm_grant_lock(lock, work_list); - RETURN(LDLM_ITER_CONTINUE); - } - - restart: - rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list); - rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list); - - if (rc != 2) { - /* If either of the compat_queue()s returned 0, then we - * have ASTs to send and must go onto the waiting list. - * - * bug 2322: we used to unlink and re-add here, which was a - * terrible folly -- if we goto restart, we could get - * re-ordered! Causes deadlock, because ASTs aren't sent! */ - if (cfs_list_empty(&lock->l_res_link)) - ldlm_resource_add_lock(res, &res->lr_waiting, lock); - unlock_res(res); - rc = ldlm_run_ast_work(&rpc_list, LDLM_WORK_BL_AST); - lock_res(res); - if (rc == -ERESTART) - GOTO(restart, -ERESTART); - *flags |= LDLM_FL_BLOCK_GRANTED; - } else { - ldlm_resource_unlink_lock(lock); - ldlm_grant_lock(lock, NULL); - } - RETURN(0); + /* No policy for plain locks */ }