--- /dev/null
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Use is subject to license terms.
+ *
+ * Copyright (c) 2011, 2012, Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ *
+ * Implementation of cl_lock for LOVSUB layer.
+ *
+ * Author: Nikita Danilov <nikita.danilov@sun.com>
+ */
+
+#define DEBUG_SUBSYSTEM S_LOV
+
+#include "lov_cl_internal.h"
+
+/** \addtogroup lov
+ * @{
+ */
+
+/*****************************************************************************
+ *
+ * Lovsub lock operations.
+ *
+ */
+
+static void lovsub_lock_fini(const struct lu_env *env,
+ struct cl_lock_slice *slice)
+{
+ struct lovsub_lock *lsl;
+
+ lsl = cl2lovsub_lock(slice);
+ LASSERT(list_empty(&lsl->lss_parents));
+ OBD_SLAB_FREE_PTR(lsl, lovsub_lock_kmem);
+}
+
+static void lovsub_parent_lock(const struct lu_env *env, struct lov_lock *lov)
+{
+ struct cl_lock *parent;
+
+ parent = lov->lls_cl.cls_lock;
+ cl_lock_get(parent);
+ lu_ref_add(&parent->cll_reference, "lovsub-parent", current);
+ cl_lock_mutex_get(env, parent);
+}
+
+static void lovsub_parent_unlock(const struct lu_env *env, struct lov_lock *lov)
+{
+ struct cl_lock *parent;
+
+ parent = lov->lls_cl.cls_lock;
+ cl_lock_mutex_put(env, lov->lls_cl.cls_lock);
+ lu_ref_del(&parent->cll_reference, "lovsub-parent", current);
+ cl_lock_put(env, parent);
+}
+
+/**
+ * Implements cl_lock_operations::clo_state() method for lovsub layer, which
+ * method is called whenever sub-lock state changes. Propagates state change
+ * to the top-locks.
+ */
+static void lovsub_lock_state(const struct lu_env *env,
+ const struct cl_lock_slice *slice,
+ enum cl_lock_state state)
+{
+ struct lovsub_lock *sub = cl2lovsub_lock(slice);
+ struct lov_lock_link *scan;
+
+ LASSERT(cl_lock_is_mutexed(slice->cls_lock));
+
+ list_for_each_entry(scan, &sub->lss_parents, lll_list) {
+ struct lov_lock *lov = scan->lll_super;
+ struct cl_lock *parent = lov->lls_cl.cls_lock;
+
+ if (sub->lss_active != parent) {
+ lovsub_parent_lock(env, lov);
+ cl_lock_signal(env, parent);
+ lovsub_parent_unlock(env, lov);
+ }
+ }
+}
+
+/**
+ * Implementation of cl_lock_operation::clo_weigh() estimating lock weight by
+ * asking parent lock.
+ */
+static unsigned long lovsub_lock_weigh(const struct lu_env *env,
+ const struct cl_lock_slice *slice)
+{
+ struct lovsub_lock *lock = cl2lovsub_lock(slice);
+ struct lov_lock *lov;
+ unsigned long dumbbell;
+
+ LASSERT(cl_lock_is_mutexed(slice->cls_lock));
+
+ if (!list_empty(&lock->lss_parents)) {
+ /*
+ * It is not clear whether all parents have to be asked and
+ * their estimations summed, or it is enough to ask one. For
+ * the current usages, one is always enough.
+ */
+ lov = container_of(lock->lss_parents.next,
+ struct lov_lock_link, lll_list)->lll_super;
+
+ lovsub_parent_lock(env, lov);
+ dumbbell = cl_lock_weigh(env, lov->lls_cl.cls_lock);
+ lovsub_parent_unlock(env, lov);
+ } else
+ dumbbell = 0;
+
+ return dumbbell;
+}
+
+/**
+ * Maps start/end offsets within a stripe, to offsets within a file.
+ */
+static void lovsub_lock_descr_map(const struct cl_lock_descr *in,
+ struct lov_object *lov,
+ int stripe, struct cl_lock_descr *out)
+{
+ pgoff_t size; /* stripe size in pages */
+ pgoff_t skip; /* how many pages in every stripe are occupied by
+ * "other" stripes */
+ pgoff_t start;
+ pgoff_t end;
+
+ start = in->cld_start;
+ end = in->cld_end;
+
+ if (lov->lo_lsm->lsm_stripe_count > 1) {
+ size = cl_index(lov2cl(lov), lov->lo_lsm->lsm_stripe_size);
+ skip = (lov->lo_lsm->lsm_stripe_count - 1) * size;
+
+ /* XXX overflow check here? */
+ start += start/size * skip + stripe * size;
+
+ if (end != CL_PAGE_EOF) {
+ end += end/size * skip + stripe * size;
+ /*
+ * And check for overflow...
+ */
+ if (end < in->cld_end)
+ end = CL_PAGE_EOF;
+ }
+ }
+ out->cld_start = start;
+ out->cld_end = end;
+}
+
+/**
+ * Adjusts parent lock extent when a sub-lock is attached to a parent. This is
+ * called in two ways:
+ *
+ * - as part of receive call-back, when server returns granted extent to
+ * the client, and
+ *
+ * - when top-lock finds existing sub-lock in the cache.
+ *
+ * Note, that lock mode is not propagated to the parent: i.e., if CLM_READ
+ * top-lock matches CLM_WRITE sub-lock, top-lock is still CLM_READ.
+ */
+int lov_sublock_modify(const struct lu_env *env, struct lov_lock *lov,
+ struct lovsub_lock *sublock,
+ const struct cl_lock_descr *d, int idx)
+{
+ struct cl_lock *parent;
+ struct lovsub_object *subobj;
+ struct cl_lock_descr *pd;
+ struct cl_lock_descr *parent_descr;
+ int result;
+
+ parent = lov->lls_cl.cls_lock;
+ parent_descr = &parent->cll_descr;
+ LASSERT(cl_lock_mode_match(d->cld_mode, parent_descr->cld_mode));
+
+ subobj = cl2lovsub(sublock->lss_cl.cls_obj);
+ pd = &lov_env_info(env)->lti_ldescr;
+
+ pd->cld_obj = parent_descr->cld_obj;
+ pd->cld_mode = parent_descr->cld_mode;
+ pd->cld_gid = parent_descr->cld_gid;
+ lovsub_lock_descr_map(d, subobj->lso_super, subobj->lso_index, pd);
+ lov->lls_sub[idx].sub_got = *d;
+ /*
+ * Notify top-lock about modification, if lock description changes
+ * materially.
+ */
+ if (!cl_lock_ext_match(parent_descr, pd))
+ result = cl_lock_modify(env, parent, pd);
+ else
+ result = 0;
+ return result;
+}
+
+static int lovsub_lock_modify(const struct lu_env *env,
+ const struct cl_lock_slice *s,
+ const struct cl_lock_descr *d)
+{
+ struct lovsub_lock *lock = cl2lovsub_lock(s);
+ struct lov_lock_link *scan;
+ struct lov_lock *lov;
+ int result = 0;
+
+ LASSERT(cl_lock_mode_match(d->cld_mode,
+ s->cls_lock->cll_descr.cld_mode));
+ list_for_each_entry(scan, &lock->lss_parents, lll_list) {
+ int rc;
+
+ lov = scan->lll_super;
+ lovsub_parent_lock(env, lov);
+ rc = lov_sublock_modify(env, lov, lock, d, scan->lll_idx);
+ lovsub_parent_unlock(env, lov);
+ result = result ?: rc;
+ }
+ return result;
+}
+
+static int lovsub_lock_closure(const struct lu_env *env,
+ const struct cl_lock_slice *slice,
+ struct cl_lock_closure *closure)
+{
+ struct lovsub_lock *sub;
+ struct cl_lock *parent;
+ struct lov_lock_link *scan;
+ int result;
+
+ LASSERT(cl_lock_is_mutexed(slice->cls_lock));
+
+ sub = cl2lovsub_lock(slice);
+ result = 0;
+
+ list_for_each_entry(scan, &sub->lss_parents, lll_list) {
+ parent = scan->lll_super->lls_cl.cls_lock;
+ result = cl_lock_closure_build(env, parent, closure);
+ if (result != 0)
+ break;
+ }
+ return result;
+}
+
+/**
+ * A helper function for lovsub_lock_delete() that deals with a given parent
+ * top-lock.
+ */
+static int lovsub_lock_delete_one(const struct lu_env *env,
+ struct cl_lock *child, struct lov_lock *lov)
+{
+ struct cl_lock *parent;
+ int result;
+
+ parent = lov->lls_cl.cls_lock;
+ if (parent->cll_error)
+ return 0;
+
+ result = 0;
+ switch (parent->cll_state) {
+ case CLS_ENQUEUED:
+ /* See LU-1355 for the case that a glimpse lock is
+ * interrupted by signal */
+ LASSERT(parent->cll_flags & CLF_CANCELLED);
+ break;
+ case CLS_QUEUING:
+ case CLS_FREEING:
+ cl_lock_signal(env, parent);
+ break;
+ case CLS_INTRANSIT:
+ /*
+ * Here lies a problem: a sub-lock is canceled while top-lock
+ * is being unlocked. Top-lock cannot be moved into CLS_NEW
+ * state, because unlocking has to succeed eventually by
+ * placing lock into CLS_CACHED (or failing it), see
+ * cl_unuse_try(). Nor can top-lock be left in CLS_CACHED
+ * state, because lov maintains an invariant that all
+ * sub-locks exist in CLS_CACHED (this allows cached top-lock
+ * to be reused immediately). Nor can we wait for top-lock
+ * state to change, because this can be synchronous to the
+ * current thread.
+ *
+ * We know for sure that lov_lock_unuse() will be called at
+ * least one more time to finish un-using, so leave a mark on
+ * the top-lock, that will be seen by the next call to
+ * lov_lock_unuse().
+ */
+ if (cl_lock_is_intransit(parent))
+ lov->lls_cancel_race = 1;
+ break;
+ case CLS_CACHED:
+ /*
+ * if a sub-lock is canceled move its top-lock into CLS_NEW
+ * state to preserve an invariant that a top-lock in
+ * CLS_CACHED is immediately ready for re-use (i.e., has all
+ * sub-locks), and so that next attempt to re-use the top-lock
+ * enqueues missing sub-lock.
+ */
+ cl_lock_state_set(env, parent, CLS_NEW);
+ /* fall through */
+ case CLS_NEW:
+ /*
+ * if last sub-lock is canceled, destroy the top-lock (which
+ * is now `empty') proactively.
+ */
+ if (lov->lls_nr_filled == 0) {
+ /* ... but unfortunately, this cannot be done easily,
+ * as cancellation of a top-lock might acquire mutices
+ * of its other sub-locks, violating lock ordering,
+ * see cl_lock_{cancel,delete}() preconditions.
+ *
+ * To work around this, the mutex of this sub-lock is
+ * released, top-lock is destroyed, and sub-lock mutex
+ * acquired again. The list of parents has to be
+ * re-scanned from the beginning after this.
+ *
+ * Only do this if no mutices other than on @child and
+ * @parent are held by the current thread.
+ *
+ * TODO: The lock modal here is too complex, because
+ * the lock may be canceled and deleted by voluntarily:
+ * cl_lock_request
+ * -> osc_lock_enqueue_wait
+ * -> osc_lock_cancel_wait
+ * -> cl_lock_delete
+ * -> lovsub_lock_delete
+ * -> cl_lock_cancel/delete
+ * -> ...
+ *
+ * The better choice is to spawn a kernel thread for
+ * this purpose. -jay
+ */
+ if (cl_lock_nr_mutexed(env) == 2) {
+ cl_lock_mutex_put(env, child);
+ cl_lock_cancel(env, parent);
+ cl_lock_delete(env, parent);
+ result = 1;
+ }
+ }
+ break;
+ case CLS_HELD:
+ CL_LOCK_DEBUG(D_ERROR, env, parent, "Delete CLS_HELD lock\n");
+ default:
+ CERROR("Impossible state: %d\n", parent->cll_state);
+ LBUG();
+ break;
+ }
+
+ return result;
+}
+
+/**
+ * An implementation of cl_lock_operations::clo_delete() method. This is
+ * invoked in "bottom-to-top" delete, when lock destruction starts from the
+ * sub-lock (e.g, as a result of ldlm lock LRU policy).
+ */
+static void lovsub_lock_delete(const struct lu_env *env,
+ const struct cl_lock_slice *slice)
+{
+ struct cl_lock *child = slice->cls_lock;
+ struct lovsub_lock *sub = cl2lovsub_lock(slice);
+ int restart;
+
+ LASSERT(cl_lock_is_mutexed(child));
+
+ /*
+ * Destruction of a sub-lock might take multiple iterations, because
+ * when the last sub-lock of a given top-lock is deleted, top-lock is
+ * canceled proactively, and this requires to release sub-lock
+ * mutex. Once sub-lock mutex has been released, list of its parents
+ * has to be re-scanned from the beginning.
+ */
+ do {
+ struct lov_lock *lov;
+ struct lov_lock_link *scan;
+ struct lov_lock_link *temp;
+ struct lov_lock_sub *subdata;
+
+ restart = 0;
+ list_for_each_entry_safe(scan, temp,
+ &sub->lss_parents, lll_list) {
+ lov = scan->lll_super;
+ subdata = &lov->lls_sub[scan->lll_idx];
+ lovsub_parent_lock(env, lov);
+ subdata->sub_got = subdata->sub_descr;
+ lov_lock_unlink(env, scan, sub);
+ restart = lovsub_lock_delete_one(env, child, lov);
+ lovsub_parent_unlock(env, lov);
+
+ if (restart) {
+ cl_lock_mutex_get(env, child);
+ break;
+ }
+ }
+ } while (restart);
+}
+
+static int lovsub_lock_print(const struct lu_env *env, void *cookie,
+ lu_printer_t p, const struct cl_lock_slice *slice)
+{
+ struct lovsub_lock *sub = cl2lovsub_lock(slice);
+ struct lov_lock *lov;
+ struct lov_lock_link *scan;
+
+ list_for_each_entry(scan, &sub->lss_parents, lll_list) {
+ lov = scan->lll_super;
+ (*p)(env, cookie, "[%d %p ", scan->lll_idx, lov);
+ if (lov != NULL)
+ cl_lock_descr_print(env, cookie, p,
+ &lov->lls_cl.cls_lock->cll_descr);
+ (*p)(env, cookie, "] ");
+ }
+ return 0;
+}
+
+static const struct cl_lock_operations lovsub_lock_ops = {
+ .clo_fini = lovsub_lock_fini,
+ .clo_state = lovsub_lock_state,
+ .clo_delete = lovsub_lock_delete,
+ .clo_modify = lovsub_lock_modify,
+ .clo_closure = lovsub_lock_closure,
+ .clo_weigh = lovsub_lock_weigh,
+ .clo_print = lovsub_lock_print
+};
+
+int lovsub_lock_init(const struct lu_env *env, struct cl_object *obj,
+ struct cl_lock *lock, const struct cl_io *io)
+{
+ struct lovsub_lock *lsk;
+ int result;
+
+ OBD_SLAB_ALLOC_PTR_GFP(lsk, lovsub_lock_kmem, GFP_NOFS);
+ if (lsk != NULL) {
+ INIT_LIST_HEAD(&lsk->lss_parents);
+ cl_lock_slice_add(lock, &lsk->lss_cl, obj, &lovsub_lock_ops);
+ result = 0;
+ } else
+ result = -ENOMEM;
+ return result;
+}
+
+/** @} lov */
Code Review / kvmfornfv.git / blobdiff