X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=blobdiff_plain;f=lustre%2Fldlm%2Fldlm_extent.c;h=ea93e13dca3cfb6b1a72a800f3e1ab06c8d6136c;hp=468eb2b537c4b206349591c07d65eb35cbfa5fa9;hb=7a7e17d4db28fac1ca4bc333d60cbeb8dbc530d6;hpb=b3d298faaa9e2e2f619c6bb607d5e0808e98f9a3 diff --git a/lustre/ldlm/ldlm_extent.c b/lustre/ldlm/ldlm_extent.c index 468eb2b..ea93e13 100644 --- a/lustre/ldlm/ldlm_extent.c +++ b/lustre/ldlm/ldlm_extent.c @@ -1,97 +1,420 @@ /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*- * vim:expandtab:shiftwidth=8:tabstop=8: * - * Copyright (C) 2002 Cluster File Systems, Inc. + * Copyright (c) 2002, 2003 Cluster File Systems, Inc. + * Author: Peter Braam + * Author: Phil Schwan * - * This code is issued under the GNU General Public License. - * See the file COPYING in this distribution + * This file is part of Lustre, http://www.lustre.org. * - * by Cluster File Systems, Inc. - * authors, Peter Braam & - * Phil Schwan + * Lustre is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + * + * Lustre is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with Lustre; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #define DEBUG_SUBSYSTEM S_LDLM +#ifndef __KERNEL__ +# include +#endif #include +#include +#include -/* This function will be called to judge if the granted queue of another child - * (read: another extent) is conflicting and needs its granted queue walked to - * issue callbacks. - * - * This helps to find conflicts between read and write locks on overlapping - * extents. */ -int ldlm_extent_compat(struct ldlm_lock *a, struct ldlm_lock *b) -{ - if (MAX(a->l_extent.start, b->l_extent.start) <= - MIN(a->l_extent.end, b->l_extent.end)) - RETURN(0); - - RETURN(1); -} +#include "ldlm_internal.h" /* The purpose of this function is to return: * - the maximum extent * - containing the requested extent - * - and not overlapping existing extents outside the requested one - * - * An alternative policy is to not shrink the new extent when conflicts exist. - * - * To reconstruct our formulas, take a deep breath. */ -static void policy_internal(struct list_head *queue, struct ldlm_extent *req_ex, - struct ldlm_extent *new_ex, ldlm_mode_t mode) + * - and not overlapping existing conflicting extents outside the requested one + */ +static void +ldlm_extent_internal_policy(struct list_head *queue, struct ldlm_lock *req, + struct ldlm_extent *new_ex) { struct list_head *tmp; + ldlm_mode_t req_mode = req->l_req_mode; + __u64 req_start = req->l_req_extent.start; + __u64 req_end = req->l_req_extent.end; + int conflicting = 0; + ENTRY; + + lockmode_verify(req_mode); list_for_each(tmp, queue) { struct ldlm_lock *lock; + struct ldlm_extent *l_extent; + lock = list_entry(tmp, struct ldlm_lock, l_res_link); + l_extent = &lock->l_policy_data.l_extent; - if (lock->l_extent.end < req_ex->start) - new_ex->start = MIN(lock->l_extent.end, new_ex->start); - else { - if (lock->l_extent.start < req_ex->start && - !lockmode_compat(lock->l_req_mode, mode)) - /* Policy: minimize conflict overlap */ - new_ex->start = req_ex->start; + if (new_ex->start == req_start && new_ex->end == req_end) { + EXIT; + return; } - if (lock->l_extent.start > req_ex->end) - new_ex->end = MAX(lock->l_extent.start, new_ex->end); - else { - if (lock->l_extent.end > req_ex->end && - !lockmode_compat(lock->l_req_mode, mode)) - /* Policy: minimize conflict overlap */ - new_ex->end = req_ex->end; + + /* Don't conflict with ourselves */ + if (req == lock) + continue; + + /* Locks are compatible, overlap doesn't matter */ + /* Until bug 20 is fixed, try to avoid granting overlapping + * locks on one client (they take a long time to cancel) */ + if (lockmode_compat(lock->l_req_mode, req_mode) && + lock->l_export != req->l_export) + continue; + + /* If this is a high-traffic lock, don't grow downwards at all + * or grow upwards too much */ + ++conflicting; + if (conflicting > 4) + new_ex->start = req_start; + + /* If lock doesn't overlap new_ex, skip it. */ + if (l_extent->end < new_ex->start || + l_extent->start > new_ex->end) + continue; + + /* Locks conflicting in requested extents and we can't satisfy + * both locks, so ignore it. Either we will ping-pong this + * extent (we would regardless of what extent we granted) or + * lock is unused and it shouldn't limit our extent growth. */ + if (lock->l_req_extent.end >= req_start && + lock->l_req_extent.start <= req_end) + continue; + + /* We grow extents downwards only as far as they don't overlap + * with already-granted locks, on the assumtion that clients + * will be writing beyond the initial requested end and would + * then need to enqueue a new lock beyond previous request. + * l_req_extent->end strictly < req_start, checked above. */ + if (l_extent->start < req_start && new_ex->start != req_start) { + if (l_extent->end >= req_start) + new_ex->start = req_start; + else + new_ex->start = min(l_extent->end+1, req_start); + } + + /* If we need to cancel this lock anyways because our request + * overlaps the granted lock, we grow up to its requested + * extent start instead of limiting this extent, assuming that + * clients are writing forwards and the lock had over grown + * its extent downwards before we enqueued our request. */ + if (l_extent->end > req_end) { + if (l_extent->start <= req_end) + new_ex->end = max(lock->l_req_extent.start - 1, + req_end); + else + new_ex->end = max(l_extent->start - 1, req_end); } } + +#define LDLM_MAX_GROWN_EXTENT (32 * 1024 * 1024 - 1) + if (conflicting > 32 && (req_mode == LCK_PW || req_mode == LCK_CW)) { + if (req_end < req_start + LDLM_MAX_GROWN_EXTENT) + new_ex->end = min(req_start + LDLM_MAX_GROWN_EXTENT, + new_ex->end); + } + EXIT; +} + +/* In order to determine the largest possible extent we can grant, we need + * to scan all of the queues. */ +static void ldlm_extent_policy(struct ldlm_resource *res, + struct ldlm_lock *lock, int *flags) +{ + struct ldlm_extent new_ex = { .start = 0, .end = ~0}; + + ldlm_extent_internal_policy(&res->lr_granted, lock, &new_ex); + ldlm_extent_internal_policy(&res->lr_waiting, lock, &new_ex); + + if (new_ex.start != lock->l_policy_data.l_extent.start || + new_ex.end != lock->l_policy_data.l_extent.end) { + *flags |= LDLM_FL_LOCK_CHANGED; + lock->l_policy_data.l_extent.start = new_ex.start; + lock->l_policy_data.l_extent.end = new_ex.end; + } } -/* apply the internal policy by walking all the lists */ -int ldlm_extent_policy(struct ldlm_lock *lock, void *req_cookie, - ldlm_mode_t mode, int flags, void *data) +/* Determine if the lock is compatible with all locks on the queue. + * We stop walking the queue if we hit ourselves so we don't take + * conflicting locks enqueued after us into accound, or we'd wait forever. + * + * 0 if the lock is not compatible + * 1 if the lock is compatible + * 2 if this group lock is compatible and requires no further checking + * negative error, such as EWOULDBLOCK for group locks + */ +static int +ldlm_extent_compat_queue(struct list_head *queue, struct ldlm_lock *req, + int send_cbs, int *flags, ldlm_error_t *err) +{ + struct list_head *tmp; + struct ldlm_lock *lock; + ldlm_mode_t req_mode = req->l_req_mode; + __u64 req_start = req->l_req_extent.start; + __u64 req_end = req->l_req_extent.end; + int compat = 1; + int scan = 0; + ENTRY; + + lockmode_verify(req_mode); + + list_for_each(tmp, queue) { + lock = list_entry(tmp, struct ldlm_lock, l_res_link); + + if (req == lock) + RETURN(compat); + + if (scan) { + /* We only get here if we are queuing GROUP lock + and met some incompatible one. The main idea of this + code is to insert GROUP lock past compatible GROUP + lock in the waiting queue or if there is not any, + then in front of first non-GROUP lock */ + if (lock->l_req_mode != LCK_GROUP) { + /* Ok, we hit non-GROUP lock, there should be no + more GROUP locks later on, queue in front of + first non-GROUP lock */ + + ldlm_resource_insert_lock_after(lock, req); + list_del_init(&lock->l_res_link); + ldlm_resource_insert_lock_after(req, lock); + RETURN(0); + } + if (req->l_policy_data.l_extent.gid == + lock->l_policy_data.l_extent.gid) { + /* found it */ + ldlm_resource_insert_lock_after(lock, + req); + RETURN(0); + } + continue; + } + + /* locks are compatible, overlap doesn't matter */ + if (lockmode_compat(lock->l_req_mode, req_mode)) { + /* non-group locks are compatible, overlap doesn't + matter */ + if (req_mode != LCK_GROUP) + continue; + + /* If we are trying to get a GROUP lock and there is + another one of this kind, we need to compare gid */ + if (req->l_policy_data.l_extent.gid == + lock->l_policy_data.l_extent.gid) { + if (lock->l_req_mode == lock->l_granted_mode) + RETURN(2); + + /* If we are in nonblocking mode - return + immediately */ + if (*flags & LDLM_FL_BLOCK_NOWAIT) { + compat = -EWOULDBLOCK; + goto destroylock; + } + /* If this group lock is compatible with another + * group lock on the waiting list, they must be + * together in the list, so they can be granted + * at the same time. Otherwise the later lock + * can get stuck behind another, incompatible, + * lock. */ + ldlm_resource_insert_lock_after(lock, req); + /* Because 'lock' is not granted, we can stop + * processing this queue and return immediately. + * There is no need to check the rest of the + * list. */ + RETURN(0); + } + } + + if (req_mode == LCK_GROUP && + (lock->l_req_mode != lock->l_granted_mode)) { + scan = 1; + compat = 0; + if (lock->l_req_mode != LCK_GROUP) { + /* Ok, we hit non-GROUP lock, there should be no + more GROUP locks later on, queue in front of + first non-GROUP lock */ + + ldlm_resource_insert_lock_after(lock, req); + list_del_init(&lock->l_res_link); + ldlm_resource_insert_lock_after(req, lock); + RETURN(0); + } + if (req->l_policy_data.l_extent.gid == + lock->l_policy_data.l_extent.gid) { + /* found it */ + ldlm_resource_insert_lock_after(lock, req); + RETURN(0); + } + continue; + } + + if (lock->l_req_mode == LCK_GROUP) { + /* If compared lock is GROUP, then requested is PR/PW/=> + * this is not compatible; extent range does not + * matter */ + if (*flags & LDLM_FL_BLOCK_NOWAIT) { + compat = -EWOULDBLOCK; + goto destroylock; + } else { + *flags |= LDLM_FL_NO_TIMEOUT; + } + } else if (lock->l_policy_data.l_extent.end < req_start || + lock->l_policy_data.l_extent.start > req_end) { + /* if a non grouplock doesn't overlap skip it */ + continue; + } + + if (!send_cbs) + RETURN(0); + + compat = 0; + if (lock->l_blocking_ast) + ldlm_add_ast_work_item(lock, req, NULL, 0); + } + + return(compat); +destroylock: + list_del_init(&req->l_res_link); + ldlm_lock_destroy(req); + *err = compat; + RETURN(compat); +} + +/* If first_enq is 0 (ie, called from ldlm_reprocess_queue): + * - blocking ASTs have already been sent + * - the caller has already initialized req->lr_tmp + * - 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 + * - the caller has NOT initialized req->lr_tmp, so we must + * - must call this function with the ns lock held once */ +int ldlm_process_extent_lock(struct ldlm_lock *lock, int *flags, int first_enq, + ldlm_error_t *err) { struct ldlm_resource *res = lock->l_resource; - struct ldlm_extent *req_ex = req_cookie; - struct ldlm_extent new_ex; - new_ex.start = 0; - new_ex.end = ~0; + struct list_head rpc_list = LIST_HEAD_INIT(rpc_list); + int rc, rc2; + ENTRY; - if (!res) - LBUG(); + LASSERT(list_empty(&res->lr_converting)); + *err = ELDLM_OK; + + if (!first_enq) { + /* Careful observers will note that we don't handle -EWOULDBLOCK + * here, but it's ok for a non-obvious reason -- compat_queue + * can only return -EWOULDBLOCK if (flags & BLOCK_NOWAIT). + * flags should always be zero here, and if that ever stops + * being true, we want to find out. */ + LASSERT(*flags == 0); + LASSERT(res->lr_tmp != NULL); + rc = ldlm_extent_compat_queue(&res->lr_granted, lock, 0, flags, + err); + if (rc == 1) { + rc = ldlm_extent_compat_queue(&res->lr_waiting, lock, 0, + flags, err); + } + if (rc == 0) + RETURN(LDLM_ITER_STOP); + + ldlm_resource_unlink_lock(lock); + + ldlm_extent_policy(res, lock, flags); + ldlm_grant_lock(lock, NULL, 0, 1); + RETURN(LDLM_ITER_CONTINUE); + } + + restart: + LASSERT(res->lr_tmp == NULL); + res->lr_tmp = &rpc_list; + rc = ldlm_extent_compat_queue(&res->lr_granted, lock, 1, flags, err); + if (rc < 0) + GOTO(out, rc); /* lock was destroyed */ + if (rc == 2) { + res->lr_tmp = NULL; + goto grant; + } + + rc2 = ldlm_extent_compat_queue(&res->lr_waiting, lock, 1, flags, err); + if (rc2 < 0) + GOTO(out, rc = rc2); /* lock was destroyed */ + res->lr_tmp = NULL; + + if (rc + rc2 == 2) { + grant: + ldlm_extent_policy(res, lock, flags); + ldlm_resource_unlink_lock(lock); + ldlm_grant_lock(lock, NULL, 0, 0); + } else { + /* If either of the compat_queue()s returned failure, 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 (list_empty(&lock->l_res_link)) + ldlm_resource_add_lock(res, &res->lr_waiting, lock); + l_unlock(&res->lr_namespace->ns_lock); + rc = ldlm_run_ast_work(res->lr_namespace, &rpc_list); + l_lock(&res->lr_namespace->ns_lock); + if (rc == -ERESTART) + GOTO(restart, -ERESTART); + *flags |= LDLM_FL_BLOCK_GRANTED; + } + rc = 0; +out: + res->lr_tmp = NULL; + RETURN(rc); +} + +/* When a lock is cancelled by a client, the KMS may undergo change if this + * is the "highest lock". This function returns the new KMS value. + * + * NB: A lock on [x,y] protects a KMS of up to y + 1 bytes! */ +__u64 ldlm_extent_shift_kms(struct ldlm_lock *lock, __u64 old_kms) +{ + struct ldlm_resource *res = lock->l_resource; + struct list_head *tmp; + struct ldlm_lock *lck; + __u64 kms = 0; + ENTRY; l_lock(&res->lr_namespace->ns_lock); - policy_internal(&res->lr_granted, req_ex, &new_ex, mode); - policy_internal(&res->lr_converting, req_ex, &new_ex, mode); - policy_internal(&res->lr_waiting, req_ex, &new_ex, mode); - l_unlock(&res->lr_namespace->ns_lock); - memcpy(&lock->l_extent, &new_ex, sizeof(new_ex)); + /* don't let another thread in ldlm_extent_shift_kms race in just after + * we finish and take our lock into account in its calculation of the + * kms */ + lock->l_flags |= LDLM_FL_KMS_IGNORE; + + list_for_each(tmp, &res->lr_granted) { + lck = list_entry(tmp, struct ldlm_lock, l_res_link); - LDLM_DEBUG(lock, "new extent "LPU64" -> "LPU64, new_ex.start, - new_ex.end); + if (lck->l_flags & LDLM_FL_KMS_IGNORE) + continue; - if (new_ex.end != req_ex->end || new_ex.start != req_ex->start) - return ELDLM_LOCK_CHANGED; - else - return 0; + if (lck->l_policy_data.l_extent.end >= old_kms) + GOTO(out, kms = old_kms); + + /* This extent _has_ to be smaller than old_kms (checked above) + * so kms can only ever be smaller or the same as old_kms. */ + if (lck->l_policy_data.l_extent.end + 1 > kms) + kms = lck->l_policy_data.l_extent.end + 1; + } + LASSERTF(kms <= old_kms, "kms "LPU64" old_kms "LPU64"\n", kms, old_kms); + + GOTO(out, kms); + out: + l_unlock(&res->lr_namespace->ns_lock); + return kms; }