X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lustre%2Fldlm%2Fldlm_inodebits.c;h=e306115c9279ad80a2f55af4103df1abe4fe91b1;hb=aa41babe16b57f0719656eeb5b189254c4072898;hp=1cc1d05da6609e45838256400c99c2f67daea75b;hpb=e3a7c58aebafce40323db54bf6056029e5af4a70;p=fs%2Flustre-release.git diff --git a/lustre/ldlm/ldlm_inodebits.c b/lustre/ldlm/ldlm_inodebits.c index 1cc1d05..e306115 100644 --- a/lustre/ldlm/ldlm_inodebits.c +++ b/lustre/ldlm/ldlm_inodebits.c @@ -27,7 +27,7 @@ * Copyright (c) 2004, 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/ @@ -39,6 +39,18 @@ * Author: Phil Schwan */ +/** + * This file contains implementation of IBITS lock type + * + * IBITS lock type contains a bit mask determining various properties of an + * object. The meanings of specific bits are specific to the caller and are + * opaque to LDLM code. + * + * Locks with intersecting bitmasks and conflicting lock modes (e.g. LCK_PW) + * are considered conflicting. See the lock mode compatibility matrix + * in lustre_dlm.h. + */ + #define DEBUG_SUBSYSTEM S_LDLM #ifndef __KERNEL__ # include @@ -51,7 +63,21 @@ #include "ldlm_internal.h" #ifdef HAVE_SERVER_SUPPORT -/* Determine if the lock is compatible with all locks on the queue. */ +/** + * 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 + * + * IBITS locks in granted queue are organized in bunches of + * same-mode/same-bits locks called "skip lists". The First lock in the + * bunch contains a pointer to the end of the bunch. This allows us to + * skip an entire bunch when iterating the list in search for conflicting + * locks if first lock of the bunch is not conflicting with us. + */ static int ldlm_inodebits_compat_queue(cfs_list_t *queue, struct ldlm_lock *req, cfs_list_t *work_list) @@ -72,6 +98,9 @@ ldlm_inodebits_compat_queue(cfs_list_t *queue, struct ldlm_lock *req, lock = cfs_list_entry(tmp, struct ldlm_lock, 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); @@ -91,27 +120,27 @@ ldlm_inodebits_compat_queue(cfs_list_t *queue, struct ldlm_lock *req, for (;;) { cfs_list_t *head; - /* last lock in policy group */ - tmp = &cfs_list_entry(lock->l_sl_policy.prev, - struct ldlm_lock, - l_sl_policy)->l_res_link; - - /* locks with bits overlapped are conflicting locks */ - if (lock->l_policy_data.l_inodebits.bits & req_bits) { - /* COS lock from the same client is - not conflicting */ - if (lock->l_req_mode == LCK_COS && - lock->l_client_cookie == req->l_client_cookie) - goto not_conflicting; - /* conflicting policy */ - if (!work_list) - RETURN(0); - - compat = 0; - - /* add locks of the policy group to - * @work_list as blocking locks for - * @req */ + /* Advance loop cursor to last lock in policy group. */ + tmp = &cfs_list_entry(lock->l_sl_policy.prev, + struct ldlm_lock, + l_sl_policy)->l_res_link; + + /* Locks with overlapping bits conflict. */ + if (lock->l_policy_data.l_inodebits.bits & req_bits) { + /* COS lock mode has a special compatibility + * requirement: it is only compatible with + * locks from the same client. */ + if (lock->l_req_mode == LCK_COS && + lock->l_client_cookie == req->l_client_cookie) + goto not_conflicting; + /* Found a conflicting policy group. */ + if (!work_list) + RETURN(0); + + compat = 0; + + /* Add locks of the policy group to @work_list + * as blocking locks for @req */ if (lock->l_blocking_ast) ldlm_add_ast_work_item(lock, req, work_list); @@ -128,20 +157,28 @@ ldlm_inodebits_compat_queue(cfs_list_t *queue, struct ldlm_lock *req, tmp = tmp->next; lock = cfs_list_entry(tmp, struct ldlm_lock, l_res_link); - } /* loop over policy groups within one mode group */ - } /* loop over mode groups within @queue */ + } /* Loop over policy groups within one mode group. */ + } /* Loop over mode groups within @queue. */ - RETURN(compat); + RETURN(compat); } -/* If first_enq is 0 (ie, called from ldlm_reprocess_queue): - * - blocking ASTs have already been sent - * - must call this function with the ns 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 ns lock held once */ -int ldlm_process_inodebits_lock(struct ldlm_lock *lock, int *flags, +/** + * Process a granting attempt for IBITS 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 + * + * 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_inodebits_lock(struct ldlm_lock *lock, __u64 *flags, int first_enq, ldlm_error_t *err, cfs_list_t *work_list) { @@ -153,8 +190,12 @@ int ldlm_process_inodebits_lock(struct ldlm_lock *lock, int *flags, LASSERT(cfs_list_empty(&res->lr_converting)); check_res_locked(res); - if (!first_enq) { - LASSERT(work_list != NULL); + /* (*flags & LDLM_FL_BLOCK_NOWAIT) is for layout lock right now. */ + if (!first_enq || (*flags & LDLM_FL_BLOCK_NOWAIT)) { + *err = ELDLM_LOCK_ABORTED; + if (*flags & LDLM_FL_BLOCK_NOWAIT) + *err = ELDLM_LOCK_WOULDBLOCK; + rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, NULL); if (!rc) RETURN(LDLM_ITER_STOP); @@ -164,6 +205,8 @@ int ldlm_process_inodebits_lock(struct ldlm_lock *lock, int *flags, ldlm_resource_unlink_lock(lock); ldlm_grant_lock(lock, work_list); + + *err = ELDLM_OK; RETURN(LDLM_ITER_CONTINUE); }