X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lustre%2Fldlm%2Fldlm_plain.c;h=dd3df5a6b62bb4156b641eefc76160c276eb829f;hb=59a59cc9d33f94fb857129b255ad42f393d7242e;hp=8cbb2e812ecb645c255987feee63351bccc6dfef;hpb=e3a7c58aebafce40323db54bf6056029e5af4a70;p=fs%2Flustre-release.git diff --git a/lustre/ldlm/ldlm_plain.c b/lustre/ldlm/ldlm_plain.c index 8cbb2e8..dd3df5a 100644 --- a/lustre/ldlm/ldlm_plain.c +++ b/lustre/ldlm/ldlm_plain.c @@ -27,7 +27,7 @@ * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * Use is subject to license terms. * - * Copyright (c) 2011, Whamcloud, Inc. + * Copyright (c) 2011, 2013, Intel Corporation. */ /* * This file is part of Lustre, http://www.lustre.org/ @@ -39,43 +39,59 @@ * 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)) + ldlm_mode_t req_mode = req->l_req_mode; + struct ldlm_lock *lock; + struct list_head *tmp; + int compat = 1; + ENTRY; + + lockmode_verify(req_mode); + + list_for_each_entry(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. */ + tmp = &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) @@ -83,16 +99,16 @@ ldlm_plain_compat_queue(cfs_list_t *queue, struct ldlm_lock *req, compat = 0; - /* add locks of the mode group to @work_list as - * blocking locks for @req */ + /* 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); { - cfs_list_t *head; + struct list_head *head; head = &lock->l_sl_mode; - cfs_list_for_each_entry(lock, head, 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); @@ -102,23 +118,34 @@ ldlm_plain_compat_queue(cfs_list_t *queue, struct ldlm_lock *req, RETURN(compat); } -/* If first_enq is 0 (ie, called from ldlm_reprocess_queue): +/** + * 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. + * + * If \a 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) + * If \a first_enq is 1 (ie, called from ldlm_lock_enqueue): + * - blocking ASTs have not been sent yet, so list of conflicting locks + * would be collected and ASTs sent. + */ +int ldlm_process_plain_lock(struct ldlm_lock *lock, __u64 *flags, + int first_enq, ldlm_error_t *err, + struct list_head *work_list) { - struct ldlm_resource *res = lock->l_resource; - CFS_LIST_HEAD(rpc_list); - int rc; - ENTRY; + struct ldlm_resource *res = lock->l_resource; + struct list_head rpc_list; + int rc; + ENTRY; - check_res_locked(res); - LASSERT(cfs_list_empty(&res->lr_converting)); + LASSERT(lock->l_granted_mode != lock->l_req_mode); + check_res_locked(res); + LASSERT(list_empty(&res->lr_converting)); + INIT_LIST_HEAD(&rpc_list); if (!first_enq) { LASSERT(work_list != NULL); @@ -145,14 +172,14 @@ int ldlm_process_plain_lock(struct ldlm_lock *lock, int *flags, int first_enq, * 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)) + if (list_empty(&lock->l_res_link)) ldlm_resource_add_lock(res, &res->lr_waiting, lock); unlock_res(res); rc = ldlm_run_ast_work(ldlm_res_to_ns(res), &rpc_list, LDLM_WORK_BL_AST); lock_res(res); - if (rc == -ERESTART) - GOTO(restart, -ERESTART); + if (rc == -ERESTART) + GOTO(restart, rc); *flags |= LDLM_FL_BLOCK_GRANTED; } else { ldlm_resource_unlink_lock(lock);