/* -*- 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 <braam@clusterfs.com>
+ * Author: Phil Schwan <phil@clusterfs.com>
*
- * 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 <braam@clusterfs.com> &
- * Phil Schwan <phil@clusterfs.com>
+ * 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 <liblustre.h>
+#endif
#include <linux/lustre_dlm.h>
+#include <linux/obd_support.h>
+#include <linux/lustre_lib.h>
-/* 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;
+ 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 (new_ex->start == req_start && new_ex->end == req_end) {
+ EXIT;
+ return;
+ }
- 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;
+ /* Don't conflict with ourselves */
+ if (req == lock)
+ continue;
+
+ /* If lock doesn't overlap new_ex, skip it. */
+ if (l_extent->end < new_ex->start ||
+ l_extent->start > new_ex->end)
+ continue;
+
+ /* Locks are compatible, overlap doesn't matter */
+ if (lockmode_compat(lock->l_req_mode, req_mode))
+ 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 the previous request.
+ * We don't grow downwards if there are lots of lockers. */
+ if (l_extent->start < req_start) {
+ if (atomic_read(&req->l_resource->lr_refcount) > 20)
+ new_ex->start = req_start;
+ else
+ new_ex->start = min(l_extent->end+1, req_start);
}
- 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;
+
+ /* 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);
}
}
+ 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;
+ }
+}
+
+/* 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. */
+static int
+ldlm_extent_compat_queue(struct list_head *queue, struct ldlm_lock *req,
+ int send_cbs)
+{
+ 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;
+ 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);
+
+ /* locks are compatible, overlap doesn't matter */
+ if (lockmode_compat(lock->l_req_mode, req_mode))
+ continue;
+
+ /* if lock doesn't overlap skip it */
+ if (lock->l_policy_data.l_extent.end < req_start ||
+ lock->l_policy_data.l_extent.start > req_end)
+ continue;
+
+ if (!send_cbs)
+ RETURN(0);
+
+ compat = 0;
+ if (lock->l_blocking_ast)
+ ldlm_add_ast_work_item(lock, req, NULL, 0);
+ }
+
+ RETURN(compat);
}
-/* apply the internal policy by walking all the lists */
-int ldlm_extent_policy(struct ldlm_namespace *ns, struct ldlm_lock *lock,
- void *req_cookie,
- ldlm_mode_t mode, int flags, void *data)
+/* 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;
+ ENTRY;
- if (!res)
- LBUG();
+ LASSERT(list_empty(&res->lr_converting));
- l_lock(&ns->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(&ns->ns_lock);
+ if (!first_enq) {
+ LASSERT(res->lr_tmp != NULL);
+ rc = ldlm_extent_compat_queue(&res->lr_granted, lock, 0);
+ if (!rc)
+ RETURN(LDLM_ITER_STOP);
+ rc = ldlm_extent_compat_queue(&res->lr_waiting, lock, 0);
+ if (!rc)
+ RETURN(LDLM_ITER_STOP);
- memcpy(&lock->l_extent, &new_ex, sizeof(new_ex));
+ ldlm_resource_unlink_lock(lock);
- LDLM_DEBUG(lock, "new extent "LPU64" -> "LPU64, new_ex.start,
- new_ex.end);
+ 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);
+ rc += ldlm_extent_compat_queue(&res->lr_waiting, lock, 1);
+ res->lr_tmp = NULL;
+
+ 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 (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;
+ } else {
+ ldlm_extent_policy(res, lock, flags);
+ ldlm_resource_unlink_lock(lock);
+ ldlm_grant_lock(lock, NULL, 0, 0);
+ }
+ RETURN(0);
+}
+
+/* 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);
+ list_for_each(tmp, &res->lr_granted) {
+ lck = list_entry(tmp, struct ldlm_lock, l_res_link);
+
+ if (lock == lck)
+ continue;
+ if (lck->l_policy_data.l_extent.end >= old_kms)
+ GOTO(out, kms = old_kms);
+ kms = lck->l_policy_data.l_extent.end + 1;
+ }
- if (new_ex.end != req_ex->end || new_ex.start != req_ex->start)
- return ELDLM_LOCK_CHANGED;
- else
- return 0;
+ GOTO(out, kms);
+ out:
+ l_unlock(&res->lr_namespace->ns_lock);
+ return kms;
}
git://git.whamcloud.com / fs / lustre-release.git / blobdiff