/* -*- 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 EXPORT_SYMTAB
#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)
+#include "ldlm_internal.h"
+
+/* The purpose of this function is to return:
+ * - the maximum extent
+ * - containing the requested extent
+ * - 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)
{
- if (MAX(a->l_extent.start, b->l_extent.start) <=
- MIN(a->l_extent.end, b->l_extent.end))
- RETURN(0);
+ 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;
- RETURN(1);
+ 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;
+ }
+
+ /* 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;
}
-static void policy_internal(struct list_head *queue, struct ldlm_extent *req_ex,
- struct ldlm_extent *new_ex, ldlm_mode_t mode)
+/* 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};
+
+ if (lock->l_req_mode == LCK_GROUP)
+ return;
+
+ 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.
+ *
+ * 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 *flags, struct list_head *work_list,
+ struct list_head **insertp)
{
struct list_head *tmp;
+ struct list_head *save = NULL;
+ struct ldlm_lock *lock = NULL;
+ ldlm_mode_t req_mode = req->l_req_mode;
+ int compat = 1;
+ int found = 0;
+ ENTRY;
+
+ lockmode_verify(req_mode);
+
+ /* Extent locks are only queued once. We can get back here with
+ * insertp != NULL if the blocking ASTs returned -ERESTART. */
+ if (!list_empty(&req->l_res_link))
+ insertp = NULL;
+
+ if (req->l_req_mode != LCK_GROUP) {
+ __u64 req_start = req->l_req_extent.start;
+ __u64 req_end = req->l_req_extent.end;
+
+ list_for_each(tmp, queue) {
+ lock = list_entry(tmp, struct ldlm_lock, l_res_link);
+ if (req == lock)
+ break;
+
+ if (lock->l_req_mode == LCK_GROUP) {
+ if (*flags & LDLM_FL_BLOCK_NOWAIT)
+ RETURN(-EWOULDBLOCK);
+
+ /* No blocking ASTs are sent for group locks. */
+ compat = 0;
+
+ /* there's a blocking group lock in front
+ * of us on the queue. It can be held
+ * indefinitely, so don't timeout. */
+ if (insertp) {
+ *flags |= LDLM_FL_NO_TIMEOUT;
+ /* lock_bitlock(req) is held here. */
+ req->l_flags |= LDLM_FL_NO_TIMEOUT;
+ }
+
+ if (work_list)
+ continue;
+ else
+ break;
+ }
+
+ /* locks are compatible, overlap doesn't matter */
+ if (lockmode_compat(lock->l_req_mode, req_mode))
+ continue;
+
+ if (lock->l_policy_data.l_extent.end < req_start ||
+ lock->l_policy_data.l_extent.start > req_end)
+ continue;
+
+ compat = 0;
+
+ if (!work_list)
+ break;
+
+ if (lock->l_blocking_ast)
+ ldlm_add_ast_work_item(lock, req, work_list);
+ }
+
+ if (insertp)
+ *insertp = queue;
+
+ RETURN(compat);
+ }
list_for_each(tmp, queue) {
- struct ldlm_lock *lock;
lock = list_entry(tmp, struct ldlm_lock, l_res_link);
+ if (req == lock)
+ break;
+
+ if (lock->l_req_mode != LCK_GROUP) {
+ if (lock->l_req_mode != lock->l_granted_mode) {
+ /* we must be traversing the waitq. */
+
+ /* If a group lock was already found then
+ * req can be queued before any extent locks
+ * that come after the found group lock. */
+ if (found)
+ break;
+
+ if (!insertp) {
+ /* We've hit a conflicting extent lock
+ * on the waitq before hitting the req
+ * group lock. See comments below. */
+ compat = 0;
+ break;
+ }
+
+ /* Group locks are not normally blocked by
+ * waiting PR|PW locks. */
+
+ /* If NO_TIMEOUT was sent back to the client
+ * we can queue the group lock in front of
+ * this extent lock. */
+ if (lock->l_flags & LDLM_FL_NO_TIMEOUT) {
+ if (save == NULL)
+ save = tmp;
+ continue;
+ }
+
+ /* If we did NOT send NO_TIMEOUT back to the
+ * client for this extent lock then the client
+ * could possibly timeout if we queue this
+ * group lock before it, so don't. This is the
+ * only way to get a conflicting extent lock
+ * in front of a group lock on the waitq. */
+ }
+
+ compat = 0;
+ if (!work_list) {
+ LASSERT(save == NULL);
+ break;
+ }
+
+ /* If we previously skipped over some extent locks
+ * because we thought we were going to queue the
+ * group lock in front of them then we need to go back
+ * and send blocking ASTs for the locks we skipped. */
+ if (save != NULL) {
+ struct ldlm_lock *lck2;
+
+ for (; save != tmp; save = save->next) {
+ lck2 = list_entry(save,
+ struct ldlm_lock,
+ l_res_link);
+
+ /* If there was a group lock after save
+ * then we would have exited this loop
+ * above. */
+ LASSERT(lck2->l_req_mode!=LCK_GROUP);
+
+ if (lck2->l_blocking_ast) {
+ ldlm_add_ast_work_item(lck2,req,
+ work_list);
+ }
+ }
+ save = NULL;
+ }
+
+ if (lock->l_blocking_ast)
+ ldlm_add_ast_work_item(lock, req, work_list);
+ continue;
+ }
+
+ /* If it was safe to insert a group lock at save,
+ * i.e. save != NULL, then this group lock already
+ * on the queue would have been inserted before save. */
+ LASSERT(save == NULL);
+
+ /* Note: no blocking ASTs are sent for group locks. */
+
+ if (lock->l_policy_data.l_extent.gid ==
+ req->l_policy_data.l_extent.gid) {
+ /* group locks with this gid already on the waitq. */
+ found = 2;
+
+ if (lock->l_req_mode == lock->l_granted_mode) {
+ /* if a group lock with this gid has already
+ * been granted then grant this one. */
+ compat = 2;
+ break;
+ }
+ } else {
+ if (found == 2)
+ break;
+
+ /* group locks already exist on the queue. */
+ found = 1;
+
+ if (*flags & LDLM_FL_BLOCK_NOWAIT)
+ RETURN(-EWOULDBLOCK);
+
+ compat = 0;
+
+ /* there's a blocking group lock in front
+ * of us on the queue. It can be held
+ * indefinitely, so don't timeout. */
+ *flags |= LDLM_FL_NO_TIMEOUT;
- 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;
+ /* the only reason to continue traversing the
+ * list at this point is to find the proper
+ * place to insert the lock in the waitq. */
+ if (!insertp)
+ break;
}
- 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 (insertp != NULL) {
+ if (save != NULL)
+ *insertp = save;
+ else
+ *insertp = tmp;
+ }
+
+ 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 list_head *work_list)
+{
+ struct ldlm_resource *res = lock->l_resource;
+ struct list_head rpc_list = LIST_HEAD_INIT(rpc_list);
+ struct list_head *insertp = NULL;
+ int rc, rc2;
+ ENTRY;
+
+ LASSERT(list_empty(&res->lr_converting));
+ *err = ELDLM_OK;
+
+ if (!first_enq) {
+ /* -EWOULDBLOCK can't occur here since (flags & BLOCK_NOWAIT)
+ * lock requests would either be granted or fail on their
+ * first_enq. flags should always be zero here, and if that
+ * ever changes we want to find out. */
+ LASSERT(*flags == 0);
+ rc = ldlm_extent_compat_queue(&res->lr_granted, lock,
+ flags, NULL, NULL);
+ if (rc == 1) {
+ rc = ldlm_extent_compat_queue(&res->lr_waiting, lock,
+ flags, NULL, NULL);
}
+ if (rc == 0)
+ RETURN(LDLM_ITER_STOP);
+
+ ldlm_resource_unlink_lock(lock);
+ ldlm_extent_policy(res, lock, flags);
+ lock_bitlock(lock);
+ lock->l_flags &= ~LDLM_FL_NO_TIMEOUT;
+ unlock_bitlock(lock);
+ ldlm_grant_lock(lock, work_list);
+ RETURN(LDLM_ITER_CONTINUE);
+ }
+
+ restart:
+ rc = ldlm_extent_compat_queue(&res->lr_granted, lock, flags, &rpc_list,
+ NULL);
+ if (rc < 0)
+ GOTO(destroylock, rc);
+ if (rc == 2)
+ goto grant;
+
+ /* Traverse the waiting list in case there are other conflicting
+ * lock requests ahead of us in the queue and send blocking ASTs */
+ rc2 = ldlm_extent_compat_queue(&res->lr_waiting, lock, flags, &rpc_list,
+ &insertp);
+ if (rc2 < 0)
+ GOTO(destroylock, rc);
+ if (rc + rc2 == 2) {
+ grant:
+ ldlm_extent_policy(res, lock, flags);
+ ldlm_resource_unlink_lock(lock);
+ lock->l_flags &= ~LDLM_FL_NO_TIMEOUT;
+ ldlm_grant_lock(lock, NULL);
+ } 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, insertp, lock);
+ unlock_res(res);
+ rc = ldlm_run_bl_ast_work(&rpc_list);
+ lock_res(res);
+ if (rc == -ERESTART)
+ GOTO(restart, -ERESTART);
+ *flags |= LDLM_FL_BLOCK_GRANTED;
}
+
+ RETURN(0);
+
+ destroylock:
+ list_del_init(&lock->l_res_link);
+ unlock_res(res);
+ ldlm_lock_destroy(lock);
+ lock_res(res);
+ *err = rc;
+ RETURN(rc);
}
-/* 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.
+/* 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.
+ * Caller must hold ns_lock already.
*
- * To reconstruct our formulas, take a deep breath. */
-int ldlm_extent_policy(struct ldlm_resource *res, struct ldlm_extent *req_ex,
- struct ldlm_extent *new_ex, ldlm_mode_t mode, void *data)
+ * 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)
{
- new_ex->start = 0;
- new_ex->end = ~0;
+ struct ldlm_resource *res = lock->l_resource;
+ struct list_head *tmp;
+ struct ldlm_lock *lck;
+ __u64 kms = 0;
+ ENTRY;
+
+ /* 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;
- if (!res)
- LBUG();
+ list_for_each(tmp, &res->lr_granted) {
+ lck = list_entry(tmp, struct ldlm_lock, l_res_link);
- 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);
+ if (lck->l_flags & LDLM_FL_KMS_IGNORE)
+ continue;
+
+ if (lck->l_policy_data.l_extent.end >= old_kms)
+ RETURN(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);
- if (new_ex->end != req_ex->end || new_ex->start != req_ex->start)
- return ELDLM_LOCK_CHANGED;
- return 0;
+ RETURN(kms);
}
git://git.whamcloud.com / fs / lustre-release.git / blobdiff