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8b8edefa2f
Make fscache object state transition callbacks use workqueue instead of slow-work. New dedicated unbound CPU workqueue fscache_object_wq is created. get/put callbacks are renamed and modified to take @object and called directly from the enqueue wrapper and the work function. While at it, make all open coded instances of get/put to use fscache_get/put_object(). * Unbound workqueue is used. * work_busy() output is printed instead of slow-work flags in object debugging outputs. They mean basically the same thing bit-for-bit. * sysctl fscache.object_max_active added to control concurrency. The default value is nr_cpus clamped between 4 and WQ_UNBOUND_MAX_ACTIVE. * slow_work_sleep_till_thread_needed() is replaced with fscache private implementation fscache_object_sleep_till_congested() which waits on fscache_object_wq congestion. * debugfs support is dropped for now. Tracing API based debug facility is planned to be added. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: David Howells <dhowells@redhat.com>
893 lines
25 KiB
C
893 lines
25 KiB
C
/* FS-Cache object state machine handler
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*
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* See Documentation/filesystems/caching/object.txt for a description of the
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* object state machine and the in-kernel representations.
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*/
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#define FSCACHE_DEBUG_LEVEL COOKIE
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#include <linux/module.h>
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#include "internal.h"
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const char *fscache_object_states[FSCACHE_OBJECT__NSTATES] = {
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[FSCACHE_OBJECT_INIT] = "OBJECT_INIT",
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[FSCACHE_OBJECT_LOOKING_UP] = "OBJECT_LOOKING_UP",
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[FSCACHE_OBJECT_CREATING] = "OBJECT_CREATING",
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[FSCACHE_OBJECT_AVAILABLE] = "OBJECT_AVAILABLE",
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[FSCACHE_OBJECT_ACTIVE] = "OBJECT_ACTIVE",
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[FSCACHE_OBJECT_UPDATING] = "OBJECT_UPDATING",
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[FSCACHE_OBJECT_DYING] = "OBJECT_DYING",
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[FSCACHE_OBJECT_LC_DYING] = "OBJECT_LC_DYING",
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[FSCACHE_OBJECT_ABORT_INIT] = "OBJECT_ABORT_INIT",
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[FSCACHE_OBJECT_RELEASING] = "OBJECT_RELEASING",
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[FSCACHE_OBJECT_RECYCLING] = "OBJECT_RECYCLING",
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[FSCACHE_OBJECT_WITHDRAWING] = "OBJECT_WITHDRAWING",
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[FSCACHE_OBJECT_DEAD] = "OBJECT_DEAD",
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};
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EXPORT_SYMBOL(fscache_object_states);
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const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5] = {
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[FSCACHE_OBJECT_INIT] = "INIT",
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[FSCACHE_OBJECT_LOOKING_UP] = "LOOK",
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[FSCACHE_OBJECT_CREATING] = "CRTN",
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[FSCACHE_OBJECT_AVAILABLE] = "AVBL",
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[FSCACHE_OBJECT_ACTIVE] = "ACTV",
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[FSCACHE_OBJECT_UPDATING] = "UPDT",
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[FSCACHE_OBJECT_DYING] = "DYNG",
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[FSCACHE_OBJECT_LC_DYING] = "LCDY",
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[FSCACHE_OBJECT_ABORT_INIT] = "ABTI",
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[FSCACHE_OBJECT_RELEASING] = "RELS",
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[FSCACHE_OBJECT_RECYCLING] = "RCYC",
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[FSCACHE_OBJECT_WITHDRAWING] = "WTHD",
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[FSCACHE_OBJECT_DEAD] = "DEAD",
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};
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static int fscache_get_object(struct fscache_object *);
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static void fscache_put_object(struct fscache_object *);
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static void fscache_initialise_object(struct fscache_object *);
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static void fscache_lookup_object(struct fscache_object *);
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static void fscache_object_available(struct fscache_object *);
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static void fscache_release_object(struct fscache_object *);
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static void fscache_withdraw_object(struct fscache_object *);
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static void fscache_enqueue_dependents(struct fscache_object *);
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static void fscache_dequeue_object(struct fscache_object *);
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/*
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* we need to notify the parent when an op completes that we had outstanding
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* upon it
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*/
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static inline void fscache_done_parent_op(struct fscache_object *object)
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{
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struct fscache_object *parent = object->parent;
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_enter("OBJ%x {OBJ%x,%x}",
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object->debug_id, parent->debug_id, parent->n_ops);
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spin_lock_nested(&parent->lock, 1);
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parent->n_ops--;
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parent->n_obj_ops--;
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if (parent->n_ops == 0)
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fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
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spin_unlock(&parent->lock);
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}
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/*
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* process events that have been sent to an object's state machine
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* - initiates parent lookup
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* - does object lookup
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* - does object creation
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* - does object recycling and retirement
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* - does object withdrawal
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*/
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static void fscache_object_state_machine(struct fscache_object *object)
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{
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enum fscache_object_state new_state;
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struct fscache_cookie *cookie;
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ASSERT(object != NULL);
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_enter("{OBJ%x,%s,%lx}",
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object->debug_id, fscache_object_states[object->state],
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object->events);
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switch (object->state) {
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/* wait for the parent object to become ready */
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case FSCACHE_OBJECT_INIT:
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object->event_mask =
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ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
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fscache_initialise_object(object);
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goto done;
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/* look up the object metadata on disk */
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case FSCACHE_OBJECT_LOOKING_UP:
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fscache_lookup_object(object);
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goto lookup_transit;
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/* create the object metadata on disk */
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case FSCACHE_OBJECT_CREATING:
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fscache_lookup_object(object);
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goto lookup_transit;
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/* handle an object becoming available; start pending
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* operations and queue dependent operations for processing */
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case FSCACHE_OBJECT_AVAILABLE:
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fscache_object_available(object);
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goto active_transit;
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/* normal running state */
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case FSCACHE_OBJECT_ACTIVE:
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goto active_transit;
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/* update the object metadata on disk */
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case FSCACHE_OBJECT_UPDATING:
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clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events);
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fscache_stat(&fscache_n_updates_run);
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fscache_stat(&fscache_n_cop_update_object);
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object->cache->ops->update_object(object);
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fscache_stat_d(&fscache_n_cop_update_object);
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goto active_transit;
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/* handle an object dying during lookup or creation */
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case FSCACHE_OBJECT_LC_DYING:
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object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
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fscache_stat(&fscache_n_cop_lookup_complete);
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object->cache->ops->lookup_complete(object);
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fscache_stat_d(&fscache_n_cop_lookup_complete);
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spin_lock(&object->lock);
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object->state = FSCACHE_OBJECT_DYING;
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cookie = object->cookie;
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if (cookie) {
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if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP,
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&cookie->flags))
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wake_up_bit(&cookie->flags,
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FSCACHE_COOKIE_LOOKING_UP);
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if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
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&cookie->flags))
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wake_up_bit(&cookie->flags,
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FSCACHE_COOKIE_CREATING);
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}
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spin_unlock(&object->lock);
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fscache_done_parent_op(object);
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/* wait for completion of all active operations on this object
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* and the death of all child objects of this object */
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case FSCACHE_OBJECT_DYING:
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dying:
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clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events);
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spin_lock(&object->lock);
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_debug("dying OBJ%x {%d,%d}",
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object->debug_id, object->n_ops, object->n_children);
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if (object->n_ops == 0 && object->n_children == 0) {
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object->event_mask &=
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~(1 << FSCACHE_OBJECT_EV_CLEARED);
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object->event_mask |=
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(1 << FSCACHE_OBJECT_EV_WITHDRAW) |
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(1 << FSCACHE_OBJECT_EV_RETIRE) |
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(1 << FSCACHE_OBJECT_EV_RELEASE) |
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(1 << FSCACHE_OBJECT_EV_ERROR);
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} else {
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object->event_mask &=
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~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
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(1 << FSCACHE_OBJECT_EV_RETIRE) |
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(1 << FSCACHE_OBJECT_EV_RELEASE) |
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(1 << FSCACHE_OBJECT_EV_ERROR));
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object->event_mask |=
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1 << FSCACHE_OBJECT_EV_CLEARED;
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}
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spin_unlock(&object->lock);
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fscache_enqueue_dependents(object);
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fscache_start_operations(object);
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goto terminal_transit;
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/* handle an abort during initialisation */
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case FSCACHE_OBJECT_ABORT_INIT:
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_debug("handle abort init %lx", object->events);
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object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE);
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spin_lock(&object->lock);
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fscache_dequeue_object(object);
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object->state = FSCACHE_OBJECT_DYING;
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if (test_and_clear_bit(FSCACHE_COOKIE_CREATING,
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&object->cookie->flags))
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wake_up_bit(&object->cookie->flags,
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FSCACHE_COOKIE_CREATING);
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spin_unlock(&object->lock);
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goto dying;
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/* handle the netfs releasing an object and possibly marking it
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* obsolete too */
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case FSCACHE_OBJECT_RELEASING:
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case FSCACHE_OBJECT_RECYCLING:
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object->event_mask &=
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~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
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(1 << FSCACHE_OBJECT_EV_RETIRE) |
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(1 << FSCACHE_OBJECT_EV_RELEASE) |
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(1 << FSCACHE_OBJECT_EV_ERROR));
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fscache_release_object(object);
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spin_lock(&object->lock);
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object->state = FSCACHE_OBJECT_DEAD;
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spin_unlock(&object->lock);
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fscache_stat(&fscache_n_object_dead);
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goto terminal_transit;
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/* handle the parent cache of this object being withdrawn from
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* active service */
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case FSCACHE_OBJECT_WITHDRAWING:
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object->event_mask &=
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~((1 << FSCACHE_OBJECT_EV_WITHDRAW) |
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(1 << FSCACHE_OBJECT_EV_RETIRE) |
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(1 << FSCACHE_OBJECT_EV_RELEASE) |
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(1 << FSCACHE_OBJECT_EV_ERROR));
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fscache_withdraw_object(object);
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spin_lock(&object->lock);
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object->state = FSCACHE_OBJECT_DEAD;
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spin_unlock(&object->lock);
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fscache_stat(&fscache_n_object_dead);
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goto terminal_transit;
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/* complain about the object being woken up once it is
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* deceased */
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case FSCACHE_OBJECT_DEAD:
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printk(KERN_ERR "FS-Cache:"
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" Unexpected event in dead state %lx\n",
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object->events & object->event_mask);
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BUG();
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default:
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printk(KERN_ERR "FS-Cache: Unknown object state %u\n",
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object->state);
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BUG();
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}
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/* determine the transition from a lookup state */
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lookup_transit:
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switch (fls(object->events & object->event_mask) - 1) {
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case FSCACHE_OBJECT_EV_WITHDRAW:
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case FSCACHE_OBJECT_EV_RETIRE:
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case FSCACHE_OBJECT_EV_RELEASE:
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case FSCACHE_OBJECT_EV_ERROR:
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new_state = FSCACHE_OBJECT_LC_DYING;
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goto change_state;
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case FSCACHE_OBJECT_EV_REQUEUE:
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goto done;
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case -1:
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goto done; /* sleep until event */
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default:
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goto unsupported_event;
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}
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/* determine the transition from an active state */
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active_transit:
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switch (fls(object->events & object->event_mask) - 1) {
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case FSCACHE_OBJECT_EV_WITHDRAW:
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case FSCACHE_OBJECT_EV_RETIRE:
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case FSCACHE_OBJECT_EV_RELEASE:
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case FSCACHE_OBJECT_EV_ERROR:
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new_state = FSCACHE_OBJECT_DYING;
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goto change_state;
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case FSCACHE_OBJECT_EV_UPDATE:
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new_state = FSCACHE_OBJECT_UPDATING;
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goto change_state;
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case -1:
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new_state = FSCACHE_OBJECT_ACTIVE;
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goto change_state; /* sleep until event */
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default:
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goto unsupported_event;
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}
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/* determine the transition from a terminal state */
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terminal_transit:
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switch (fls(object->events & object->event_mask) - 1) {
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case FSCACHE_OBJECT_EV_WITHDRAW:
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new_state = FSCACHE_OBJECT_WITHDRAWING;
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goto change_state;
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case FSCACHE_OBJECT_EV_RETIRE:
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new_state = FSCACHE_OBJECT_RECYCLING;
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goto change_state;
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case FSCACHE_OBJECT_EV_RELEASE:
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new_state = FSCACHE_OBJECT_RELEASING;
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goto change_state;
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case FSCACHE_OBJECT_EV_ERROR:
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new_state = FSCACHE_OBJECT_WITHDRAWING;
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goto change_state;
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case FSCACHE_OBJECT_EV_CLEARED:
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new_state = FSCACHE_OBJECT_DYING;
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goto change_state;
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case -1:
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goto done; /* sleep until event */
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default:
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goto unsupported_event;
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}
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change_state:
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spin_lock(&object->lock);
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object->state = new_state;
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spin_unlock(&object->lock);
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done:
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_leave(" [->%s]", fscache_object_states[object->state]);
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return;
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unsupported_event:
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printk(KERN_ERR "FS-Cache:"
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" Unsupported event %lx [mask %lx] in state %s\n",
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object->events, object->event_mask,
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fscache_object_states[object->state]);
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BUG();
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}
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/*
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* execute an object
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*/
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void fscache_object_work_func(struct work_struct *work)
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{
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struct fscache_object *object =
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container_of(work, struct fscache_object, work);
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unsigned long start;
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_enter("{OBJ%x}", object->debug_id);
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start = jiffies;
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fscache_object_state_machine(object);
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fscache_hist(fscache_objs_histogram, start);
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if (object->events & object->event_mask)
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fscache_enqueue_object(object);
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clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
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fscache_put_object(object);
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}
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EXPORT_SYMBOL(fscache_object_work_func);
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/*
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* initialise an object
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* - check the specified object's parent to see if we can make use of it
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* immediately to do a creation
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* - we may need to start the process of creating a parent and we need to wait
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* for the parent's lookup and creation to complete if it's not there yet
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* - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
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* leaf-most cookies of the object and all its children
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*/
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static void fscache_initialise_object(struct fscache_object *object)
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{
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struct fscache_object *parent;
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_enter("");
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ASSERT(object->cookie != NULL);
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ASSERT(object->cookie->parent != NULL);
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if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) |
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(1 << FSCACHE_OBJECT_EV_RELEASE) |
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(1 << FSCACHE_OBJECT_EV_RETIRE) |
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(1 << FSCACHE_OBJECT_EV_WITHDRAW))) {
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_debug("abort init %lx", object->events);
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spin_lock(&object->lock);
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object->state = FSCACHE_OBJECT_ABORT_INIT;
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spin_unlock(&object->lock);
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return;
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}
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spin_lock(&object->cookie->lock);
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spin_lock_nested(&object->cookie->parent->lock, 1);
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parent = object->parent;
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if (!parent) {
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_debug("no parent");
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set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
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} else {
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spin_lock(&object->lock);
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spin_lock_nested(&parent->lock, 1);
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_debug("parent %s", fscache_object_states[parent->state]);
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if (parent->state >= FSCACHE_OBJECT_DYING) {
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_debug("bad parent");
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set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
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} else if (parent->state < FSCACHE_OBJECT_AVAILABLE) {
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_debug("wait");
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/* we may get woken up in this state by child objects
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* binding on to us, so we need to make sure we don't
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* add ourself to the list multiple times */
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if (list_empty(&object->dep_link)) {
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fscache_stat(&fscache_n_cop_grab_object);
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object->cache->ops->grab_object(object);
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fscache_stat_d(&fscache_n_cop_grab_object);
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list_add(&object->dep_link,
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&parent->dependents);
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/* fscache_acquire_non_index_cookie() uses this
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* to wake the chain up */
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if (parent->state == FSCACHE_OBJECT_INIT)
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fscache_enqueue_object(parent);
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}
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} else {
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_debug("go");
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parent->n_ops++;
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parent->n_obj_ops++;
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object->lookup_jif = jiffies;
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object->state = FSCACHE_OBJECT_LOOKING_UP;
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set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
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}
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spin_unlock(&parent->lock);
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spin_unlock(&object->lock);
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}
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spin_unlock(&object->cookie->parent->lock);
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spin_unlock(&object->cookie->lock);
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_leave("");
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}
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/*
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* look an object up in the cache from which it was allocated
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* - we hold an "access lock" on the parent object, so the parent object cannot
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* be withdrawn by either party till we've finished
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* - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the
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* leaf-most cookies of the object and all its children
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*/
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static void fscache_lookup_object(struct fscache_object *object)
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{
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struct fscache_cookie *cookie = object->cookie;
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struct fscache_object *parent;
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int ret;
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_enter("");
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parent = object->parent;
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ASSERT(parent != NULL);
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ASSERTCMP(parent->n_ops, >, 0);
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|
ASSERTCMP(parent->n_obj_ops, >, 0);
|
|
|
|
/* make sure the parent is still available */
|
|
ASSERTCMP(parent->state, >=, FSCACHE_OBJECT_AVAILABLE);
|
|
|
|
if (parent->state >= FSCACHE_OBJECT_DYING ||
|
|
test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
|
|
_debug("unavailable");
|
|
set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events);
|
|
_leave("");
|
|
return;
|
|
}
|
|
|
|
_debug("LOOKUP \"%s/%s\" in \"%s\"",
|
|
parent->cookie->def->name, cookie->def->name,
|
|
object->cache->tag->name);
|
|
|
|
fscache_stat(&fscache_n_object_lookups);
|
|
fscache_stat(&fscache_n_cop_lookup_object);
|
|
ret = object->cache->ops->lookup_object(object);
|
|
fscache_stat_d(&fscache_n_cop_lookup_object);
|
|
|
|
if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events))
|
|
set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
|
|
|
|
if (ret == -ETIMEDOUT) {
|
|
/* probably stuck behind another object, so move this one to
|
|
* the back of the queue */
|
|
fscache_stat(&fscache_n_object_lookups_timed_out);
|
|
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
|
|
}
|
|
|
|
_leave("");
|
|
}
|
|
|
|
/**
|
|
* fscache_object_lookup_negative - Note negative cookie lookup
|
|
* @object: Object pointing to cookie to mark
|
|
*
|
|
* Note negative lookup, permitting those waiting to read data from an already
|
|
* existing backing object to continue as there's no data for them to read.
|
|
*/
|
|
void fscache_object_lookup_negative(struct fscache_object *object)
|
|
{
|
|
struct fscache_cookie *cookie = object->cookie;
|
|
|
|
_enter("{OBJ%x,%s}",
|
|
object->debug_id, fscache_object_states[object->state]);
|
|
|
|
spin_lock(&object->lock);
|
|
if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
|
|
fscache_stat(&fscache_n_object_lookups_negative);
|
|
|
|
/* transit here to allow write requests to begin stacking up
|
|
* and read requests to begin returning ENODATA */
|
|
object->state = FSCACHE_OBJECT_CREATING;
|
|
spin_unlock(&object->lock);
|
|
|
|
set_bit(FSCACHE_COOKIE_PENDING_FILL, &cookie->flags);
|
|
set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
|
|
|
|
_debug("wake up lookup %p", &cookie->flags);
|
|
smp_mb__before_clear_bit();
|
|
clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
|
|
smp_mb__after_clear_bit();
|
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
|
|
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
|
|
} else {
|
|
ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
|
|
spin_unlock(&object->lock);
|
|
}
|
|
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(fscache_object_lookup_negative);
|
|
|
|
/**
|
|
* fscache_obtained_object - Note successful object lookup or creation
|
|
* @object: Object pointing to cookie to mark
|
|
*
|
|
* Note successful lookup and/or creation, permitting those waiting to write
|
|
* data to a backing object to continue.
|
|
*
|
|
* Note that after calling this, an object's cookie may be relinquished by the
|
|
* netfs, and so must be accessed with object lock held.
|
|
*/
|
|
void fscache_obtained_object(struct fscache_object *object)
|
|
{
|
|
struct fscache_cookie *cookie = object->cookie;
|
|
|
|
_enter("{OBJ%x,%s}",
|
|
object->debug_id, fscache_object_states[object->state]);
|
|
|
|
/* if we were still looking up, then we must have a positive lookup
|
|
* result, in which case there may be data available */
|
|
spin_lock(&object->lock);
|
|
if (object->state == FSCACHE_OBJECT_LOOKING_UP) {
|
|
fscache_stat(&fscache_n_object_lookups_positive);
|
|
|
|
clear_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
|
|
|
|
object->state = FSCACHE_OBJECT_AVAILABLE;
|
|
spin_unlock(&object->lock);
|
|
|
|
smp_mb__before_clear_bit();
|
|
clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
|
|
smp_mb__after_clear_bit();
|
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);
|
|
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
|
|
} else {
|
|
ASSERTCMP(object->state, ==, FSCACHE_OBJECT_CREATING);
|
|
fscache_stat(&fscache_n_object_created);
|
|
|
|
object->state = FSCACHE_OBJECT_AVAILABLE;
|
|
spin_unlock(&object->lock);
|
|
set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
|
|
smp_wmb();
|
|
}
|
|
|
|
if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, &cookie->flags))
|
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_CREATING);
|
|
|
|
_leave("");
|
|
}
|
|
EXPORT_SYMBOL(fscache_obtained_object);
|
|
|
|
/*
|
|
* handle an object that has just become available
|
|
*/
|
|
static void fscache_object_available(struct fscache_object *object)
|
|
{
|
|
_enter("{OBJ%x}", object->debug_id);
|
|
|
|
spin_lock(&object->lock);
|
|
|
|
if (object->cookie &&
|
|
test_and_clear_bit(FSCACHE_COOKIE_CREATING, &object->cookie->flags))
|
|
wake_up_bit(&object->cookie->flags, FSCACHE_COOKIE_CREATING);
|
|
|
|
fscache_done_parent_op(object);
|
|
if (object->n_in_progress == 0) {
|
|
if (object->n_ops > 0) {
|
|
ASSERTCMP(object->n_ops, >=, object->n_obj_ops);
|
|
ASSERTIF(object->n_ops > object->n_obj_ops,
|
|
!list_empty(&object->pending_ops));
|
|
fscache_start_operations(object);
|
|
} else {
|
|
ASSERT(list_empty(&object->pending_ops));
|
|
}
|
|
}
|
|
spin_unlock(&object->lock);
|
|
|
|
fscache_stat(&fscache_n_cop_lookup_complete);
|
|
object->cache->ops->lookup_complete(object);
|
|
fscache_stat_d(&fscache_n_cop_lookup_complete);
|
|
fscache_enqueue_dependents(object);
|
|
|
|
fscache_hist(fscache_obj_instantiate_histogram, object->lookup_jif);
|
|
fscache_stat(&fscache_n_object_avail);
|
|
|
|
_leave("");
|
|
}
|
|
|
|
/*
|
|
* drop an object's attachments
|
|
*/
|
|
static void fscache_drop_object(struct fscache_object *object)
|
|
{
|
|
struct fscache_object *parent = object->parent;
|
|
struct fscache_cache *cache = object->cache;
|
|
|
|
_enter("{OBJ%x,%d}", object->debug_id, object->n_children);
|
|
|
|
ASSERTCMP(object->cookie, ==, NULL);
|
|
ASSERT(hlist_unhashed(&object->cookie_link));
|
|
|
|
spin_lock(&cache->object_list_lock);
|
|
list_del_init(&object->cache_link);
|
|
spin_unlock(&cache->object_list_lock);
|
|
|
|
fscache_stat(&fscache_n_cop_drop_object);
|
|
cache->ops->drop_object(object);
|
|
fscache_stat_d(&fscache_n_cop_drop_object);
|
|
|
|
if (parent) {
|
|
_debug("release parent OBJ%x {%d}",
|
|
parent->debug_id, parent->n_children);
|
|
|
|
spin_lock(&parent->lock);
|
|
parent->n_children--;
|
|
if (parent->n_children == 0)
|
|
fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED);
|
|
spin_unlock(&parent->lock);
|
|
object->parent = NULL;
|
|
}
|
|
|
|
/* this just shifts the object release to the work processor */
|
|
fscache_put_object(object);
|
|
|
|
_leave("");
|
|
}
|
|
|
|
/*
|
|
* release or recycle an object that the netfs has discarded
|
|
*/
|
|
static void fscache_release_object(struct fscache_object *object)
|
|
{
|
|
_enter("");
|
|
|
|
fscache_drop_object(object);
|
|
}
|
|
|
|
/*
|
|
* withdraw an object from active service
|
|
*/
|
|
static void fscache_withdraw_object(struct fscache_object *object)
|
|
{
|
|
struct fscache_cookie *cookie;
|
|
bool detached;
|
|
|
|
_enter("");
|
|
|
|
spin_lock(&object->lock);
|
|
cookie = object->cookie;
|
|
if (cookie) {
|
|
/* need to get the cookie lock before the object lock, starting
|
|
* from the object pointer */
|
|
atomic_inc(&cookie->usage);
|
|
spin_unlock(&object->lock);
|
|
|
|
detached = false;
|
|
spin_lock(&cookie->lock);
|
|
spin_lock(&object->lock);
|
|
|
|
if (object->cookie == cookie) {
|
|
hlist_del_init(&object->cookie_link);
|
|
object->cookie = NULL;
|
|
detached = true;
|
|
}
|
|
spin_unlock(&cookie->lock);
|
|
fscache_cookie_put(cookie);
|
|
if (detached)
|
|
fscache_cookie_put(cookie);
|
|
}
|
|
|
|
spin_unlock(&object->lock);
|
|
|
|
fscache_drop_object(object);
|
|
}
|
|
|
|
/*
|
|
* withdraw an object from active service at the behest of the cache
|
|
* - need break the links to a cached object cookie
|
|
* - called under two situations:
|
|
* (1) recycler decides to reclaim an in-use object
|
|
* (2) a cache is unmounted
|
|
* - have to take care as the cookie can be being relinquished by the netfs
|
|
* simultaneously
|
|
* - the object is pinned by the caller holding a refcount on it
|
|
*/
|
|
void fscache_withdrawing_object(struct fscache_cache *cache,
|
|
struct fscache_object *object)
|
|
{
|
|
bool enqueue = false;
|
|
|
|
_enter(",OBJ%x", object->debug_id);
|
|
|
|
spin_lock(&object->lock);
|
|
if (object->state < FSCACHE_OBJECT_WITHDRAWING) {
|
|
object->state = FSCACHE_OBJECT_WITHDRAWING;
|
|
enqueue = true;
|
|
}
|
|
spin_unlock(&object->lock);
|
|
|
|
if (enqueue)
|
|
fscache_enqueue_object(object);
|
|
|
|
_leave("");
|
|
}
|
|
|
|
/*
|
|
* get a ref on an object
|
|
*/
|
|
static int fscache_get_object(struct fscache_object *object)
|
|
{
|
|
int ret;
|
|
|
|
fscache_stat(&fscache_n_cop_grab_object);
|
|
ret = object->cache->ops->grab_object(object) ? 0 : -EAGAIN;
|
|
fscache_stat_d(&fscache_n_cop_grab_object);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* discard a ref on a work item
|
|
*/
|
|
static void fscache_put_object(struct fscache_object *object)
|
|
{
|
|
fscache_stat(&fscache_n_cop_put_object);
|
|
object->cache->ops->put_object(object);
|
|
fscache_stat_d(&fscache_n_cop_put_object);
|
|
}
|
|
|
|
/*
|
|
* enqueue an object for metadata-type processing
|
|
*/
|
|
void fscache_enqueue_object(struct fscache_object *object)
|
|
{
|
|
_enter("{OBJ%x}", object->debug_id);
|
|
|
|
if (fscache_get_object(object) >= 0) {
|
|
wait_queue_head_t *cong_wq =
|
|
&get_cpu_var(fscache_object_cong_wait);
|
|
|
|
if (queue_work(fscache_object_wq, &object->work)) {
|
|
if (fscache_object_congested())
|
|
wake_up(cong_wq);
|
|
} else
|
|
fscache_put_object(object);
|
|
|
|
put_cpu_var(fscache_object_cong_wait);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* fscache_object_sleep_till_congested - Sleep until object wq is congested
|
|
* @timoutp: Scheduler sleep timeout
|
|
*
|
|
* Allow an object handler to sleep until the object workqueue is congested.
|
|
*
|
|
* The caller must set up a wake up event before calling this and must have set
|
|
* the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own
|
|
* condition before calling this function as no test is made here.
|
|
*
|
|
* %true is returned if the object wq is congested, %false otherwise.
|
|
*/
|
|
bool fscache_object_sleep_till_congested(signed long *timeoutp)
|
|
{
|
|
wait_queue_head_t *cong_wq = &__get_cpu_var(fscache_object_cong_wait);
|
|
DEFINE_WAIT(wait);
|
|
|
|
if (fscache_object_congested())
|
|
return true;
|
|
|
|
add_wait_queue_exclusive(cong_wq, &wait);
|
|
if (!fscache_object_congested())
|
|
*timeoutp = schedule_timeout(*timeoutp);
|
|
finish_wait(cong_wq, &wait);
|
|
|
|
return fscache_object_congested();
|
|
}
|
|
EXPORT_SYMBOL_GPL(fscache_object_sleep_till_congested);
|
|
|
|
/*
|
|
* enqueue the dependents of an object for metadata-type processing
|
|
* - the caller must hold the object's lock
|
|
* - this may cause an already locked object to wind up being processed again
|
|
*/
|
|
static void fscache_enqueue_dependents(struct fscache_object *object)
|
|
{
|
|
struct fscache_object *dep;
|
|
|
|
_enter("{OBJ%x}", object->debug_id);
|
|
|
|
if (list_empty(&object->dependents))
|
|
return;
|
|
|
|
spin_lock(&object->lock);
|
|
|
|
while (!list_empty(&object->dependents)) {
|
|
dep = list_entry(object->dependents.next,
|
|
struct fscache_object, dep_link);
|
|
list_del_init(&dep->dep_link);
|
|
|
|
|
|
/* sort onto appropriate lists */
|
|
fscache_enqueue_object(dep);
|
|
fscache_put_object(dep);
|
|
|
|
if (!list_empty(&object->dependents))
|
|
cond_resched_lock(&object->lock);
|
|
}
|
|
|
|
spin_unlock(&object->lock);
|
|
}
|
|
|
|
/*
|
|
* remove an object from whatever queue it's waiting on
|
|
* - the caller must hold object->lock
|
|
*/
|
|
void fscache_dequeue_object(struct fscache_object *object)
|
|
{
|
|
_enter("{OBJ%x}", object->debug_id);
|
|
|
|
if (!list_empty(&object->dep_link)) {
|
|
spin_lock(&object->parent->lock);
|
|
list_del_init(&object->dep_link);
|
|
spin_unlock(&object->parent->lock);
|
|
}
|
|
|
|
_leave("");
|
|
}
|
|
|
|
/**
|
|
* fscache_check_aux - Ask the netfs whether an object on disk is still valid
|
|
* @object: The object to ask about
|
|
* @data: The auxiliary data for the object
|
|
* @datalen: The size of the auxiliary data
|
|
*
|
|
* This function consults the netfs about the coherency state of an object
|
|
*/
|
|
enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
|
|
const void *data, uint16_t datalen)
|
|
{
|
|
enum fscache_checkaux result;
|
|
|
|
if (!object->cookie->def->check_aux) {
|
|
fscache_stat(&fscache_n_checkaux_none);
|
|
return FSCACHE_CHECKAUX_OKAY;
|
|
}
|
|
|
|
result = object->cookie->def->check_aux(object->cookie->netfs_data,
|
|
data, datalen);
|
|
switch (result) {
|
|
/* entry okay as is */
|
|
case FSCACHE_CHECKAUX_OKAY:
|
|
fscache_stat(&fscache_n_checkaux_okay);
|
|
break;
|
|
|
|
/* entry requires update */
|
|
case FSCACHE_CHECKAUX_NEEDS_UPDATE:
|
|
fscache_stat(&fscache_n_checkaux_update);
|
|
break;
|
|
|
|
/* entry requires deletion */
|
|
case FSCACHE_CHECKAUX_OBSOLETE:
|
|
fscache_stat(&fscache_n_checkaux_obsolete);
|
|
break;
|
|
|
|
default:
|
|
BUG();
|
|
}
|
|
|
|
return result;
|
|
}
|
|
EXPORT_SYMBOL(fscache_check_aux);
|