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1133 lines
33 KiB
1133 lines
33 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
|
/* 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 ([email protected]) |
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* |
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* See Documentation/filesystems/caching/object.rst 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 <linux/slab.h> |
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#include <linux/prefetch.h> |
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#include "internal.h" |
|
|
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static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *, int); |
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static const struct fscache_state *fscache_kill_dependents(struct fscache_object *, int); |
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static const struct fscache_state *fscache_drop_object(struct fscache_object *, int); |
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static const struct fscache_state *fscache_initialise_object(struct fscache_object *, int); |
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static const struct fscache_state *fscache_invalidate_object(struct fscache_object *, int); |
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static const struct fscache_state *fscache_jumpstart_dependents(struct fscache_object *, int); |
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static const struct fscache_state *fscache_kill_object(struct fscache_object *, int); |
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static const struct fscache_state *fscache_lookup_failure(struct fscache_object *, int); |
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static const struct fscache_state *fscache_look_up_object(struct fscache_object *, int); |
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static const struct fscache_state *fscache_object_available(struct fscache_object *, int); |
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static const struct fscache_state *fscache_parent_ready(struct fscache_object *, int); |
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static const struct fscache_state *fscache_update_object(struct fscache_object *, int); |
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static const struct fscache_state *fscache_object_dead(struct fscache_object *, int); |
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|
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#define __STATE_NAME(n) fscache_osm_##n |
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#define STATE(n) (&__STATE_NAME(n)) |
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|
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/* |
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* Define a work state. Work states are execution states. No event processing |
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* is performed by them. The function attached to a work state returns a |
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* pointer indicating the next state to which the state machine should |
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* transition. Returning NO_TRANSIT repeats the current state, but goes back |
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* to the scheduler first. |
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*/ |
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#define WORK_STATE(n, sn, f) \ |
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const struct fscache_state __STATE_NAME(n) = { \ |
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.name = #n, \ |
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.short_name = sn, \ |
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.work = f \ |
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} |
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|
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/* |
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* Returns from work states. |
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*/ |
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#define transit_to(state) ({ prefetch(&STATE(state)->work); STATE(state); }) |
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|
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#define NO_TRANSIT ((struct fscache_state *)NULL) |
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|
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/* |
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* Define a wait state. Wait states are event processing states. No execution |
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* is performed by them. Wait states are just tables of "if event X occurs, |
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* clear it and transition to state Y". The dispatcher returns to the |
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* scheduler if none of the events in which the wait state has an interest are |
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* currently pending. |
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*/ |
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#define WAIT_STATE(n, sn, ...) \ |
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const struct fscache_state __STATE_NAME(n) = { \ |
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.name = #n, \ |
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.short_name = sn, \ |
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.work = NULL, \ |
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.transitions = { __VA_ARGS__, { 0, NULL } } \ |
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} |
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|
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#define TRANSIT_TO(state, emask) \ |
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{ .events = (emask), .transit_to = STATE(state) } |
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|
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/* |
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* The object state machine. |
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*/ |
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static WORK_STATE(INIT_OBJECT, "INIT", fscache_initialise_object); |
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static WORK_STATE(PARENT_READY, "PRDY", fscache_parent_ready); |
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static WORK_STATE(ABORT_INIT, "ABRT", fscache_abort_initialisation); |
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static WORK_STATE(LOOK_UP_OBJECT, "LOOK", fscache_look_up_object); |
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static WORK_STATE(CREATE_OBJECT, "CRTO", fscache_look_up_object); |
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static WORK_STATE(OBJECT_AVAILABLE, "AVBL", fscache_object_available); |
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static WORK_STATE(JUMPSTART_DEPS, "JUMP", fscache_jumpstart_dependents); |
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|
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static WORK_STATE(INVALIDATE_OBJECT, "INVL", fscache_invalidate_object); |
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static WORK_STATE(UPDATE_OBJECT, "UPDT", fscache_update_object); |
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|
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static WORK_STATE(LOOKUP_FAILURE, "LCFL", fscache_lookup_failure); |
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static WORK_STATE(KILL_OBJECT, "KILL", fscache_kill_object); |
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static WORK_STATE(KILL_DEPENDENTS, "KDEP", fscache_kill_dependents); |
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static WORK_STATE(DROP_OBJECT, "DROP", fscache_drop_object); |
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static WORK_STATE(OBJECT_DEAD, "DEAD", fscache_object_dead); |
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|
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static WAIT_STATE(WAIT_FOR_INIT, "?INI", |
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TRANSIT_TO(INIT_OBJECT, 1 << FSCACHE_OBJECT_EV_NEW_CHILD)); |
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|
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static WAIT_STATE(WAIT_FOR_PARENT, "?PRN", |
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TRANSIT_TO(PARENT_READY, 1 << FSCACHE_OBJECT_EV_PARENT_READY)); |
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|
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static WAIT_STATE(WAIT_FOR_CMD, "?CMD", |
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TRANSIT_TO(INVALIDATE_OBJECT, 1 << FSCACHE_OBJECT_EV_INVALIDATE), |
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TRANSIT_TO(UPDATE_OBJECT, 1 << FSCACHE_OBJECT_EV_UPDATE), |
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TRANSIT_TO(JUMPSTART_DEPS, 1 << FSCACHE_OBJECT_EV_NEW_CHILD)); |
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|
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static WAIT_STATE(WAIT_FOR_CLEARANCE, "?CLR", |
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TRANSIT_TO(KILL_OBJECT, 1 << FSCACHE_OBJECT_EV_CLEARED)); |
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|
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/* |
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* Out-of-band event transition tables. These are for handling unexpected |
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* events, such as an I/O error. If an OOB event occurs, the state machine |
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* clears and disables the event and forces a transition to the nominated work |
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* state (acurrently executing work states will complete first). |
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* |
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* In such a situation, object->state remembers the state the machine should |
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* have been in/gone to and returning NO_TRANSIT returns to that. |
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*/ |
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static const struct fscache_transition fscache_osm_init_oob[] = { |
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TRANSIT_TO(ABORT_INIT, |
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(1 << FSCACHE_OBJECT_EV_ERROR) | |
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(1 << FSCACHE_OBJECT_EV_KILL)), |
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{ 0, NULL } |
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}; |
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|
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static const struct fscache_transition fscache_osm_lookup_oob[] = { |
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TRANSIT_TO(LOOKUP_FAILURE, |
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(1 << FSCACHE_OBJECT_EV_ERROR) | |
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(1 << FSCACHE_OBJECT_EV_KILL)), |
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{ 0, NULL } |
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}; |
|
|
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static const struct fscache_transition fscache_osm_run_oob[] = { |
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TRANSIT_TO(KILL_OBJECT, |
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(1 << FSCACHE_OBJECT_EV_ERROR) | |
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(1 << FSCACHE_OBJECT_EV_KILL)), |
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{ 0, NULL } |
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}; |
|
|
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static int fscache_get_object(struct fscache_object *, |
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enum fscache_obj_ref_trace); |
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static void fscache_put_object(struct fscache_object *, |
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enum fscache_obj_ref_trace); |
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static bool fscache_enqueue_dependents(struct fscache_object *, int); |
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static void fscache_dequeue_object(struct fscache_object *); |
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static void fscache_update_aux_data(struct fscache_object *); |
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|
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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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|
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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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|
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spin_lock_nested(&parent->lock, 1); |
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parent->n_obj_ops--; |
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parent->n_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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/* |
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* Object state machine dispatcher. |
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*/ |
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static void fscache_object_sm_dispatcher(struct fscache_object *object) |
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{ |
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const struct fscache_transition *t; |
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const struct fscache_state *state, *new_state; |
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unsigned long events, event_mask; |
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bool oob; |
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int event = -1; |
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|
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ASSERT(object != NULL); |
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|
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_enter("{OBJ%x,%s,%lx}", |
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object->debug_id, object->state->name, object->events); |
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|
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event_mask = object->event_mask; |
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restart: |
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object->event_mask = 0; /* Mask normal event handling */ |
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state = object->state; |
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restart_masked: |
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events = object->events; |
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|
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/* Handle any out-of-band events (typically an error) */ |
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if (events & object->oob_event_mask) { |
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_debug("{OBJ%x} oob %lx", |
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object->debug_id, events & object->oob_event_mask); |
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oob = true; |
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for (t = object->oob_table; t->events; t++) { |
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if (events & t->events) { |
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state = t->transit_to; |
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ASSERT(state->work != NULL); |
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event = fls(events & t->events) - 1; |
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__clear_bit(event, &object->oob_event_mask); |
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clear_bit(event, &object->events); |
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goto execute_work_state; |
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} |
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} |
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} |
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oob = false; |
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|
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/* Wait states are just transition tables */ |
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if (!state->work) { |
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if (events & event_mask) { |
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for (t = state->transitions; t->events; t++) { |
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if (events & t->events) { |
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new_state = t->transit_to; |
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event = fls(events & t->events) - 1; |
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trace_fscache_osm(object, state, |
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true, false, event); |
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clear_bit(event, &object->events); |
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_debug("{OBJ%x} ev %d: %s -> %s", |
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object->debug_id, event, |
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state->name, new_state->name); |
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object->state = state = new_state; |
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goto execute_work_state; |
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} |
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} |
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|
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/* The event mask didn't include all the tabled bits */ |
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BUG(); |
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} |
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/* Randomly woke up */ |
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goto unmask_events; |
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} |
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|
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execute_work_state: |
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_debug("{OBJ%x} exec %s", object->debug_id, state->name); |
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|
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trace_fscache_osm(object, state, false, oob, event); |
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new_state = state->work(object, event); |
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event = -1; |
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if (new_state == NO_TRANSIT) { |
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_debug("{OBJ%x} %s notrans", object->debug_id, state->name); |
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if (unlikely(state == STATE(OBJECT_DEAD))) { |
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_leave(" [dead]"); |
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return; |
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} |
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fscache_enqueue_object(object); |
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event_mask = object->oob_event_mask; |
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goto unmask_events; |
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} |
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_debug("{OBJ%x} %s -> %s", |
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object->debug_id, state->name, new_state->name); |
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object->state = state = new_state; |
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|
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if (state->work) { |
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if (unlikely(state == STATE(OBJECT_DEAD))) { |
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_leave(" [dead]"); |
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return; |
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} |
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goto restart_masked; |
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} |
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|
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/* Transited to wait state */ |
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event_mask = object->oob_event_mask; |
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for (t = state->transitions; t->events; t++) |
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event_mask |= t->events; |
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|
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unmask_events: |
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object->event_mask = event_mask; |
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smp_mb(); |
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events = object->events; |
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if (events & event_mask) |
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goto restart; |
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_leave(" [msk %lx]", event_mask); |
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} |
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|
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/* |
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* execute an object |
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*/ |
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static 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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|
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_enter("{OBJ%x}", object->debug_id); |
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|
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start = jiffies; |
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fscache_object_sm_dispatcher(object); |
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fscache_hist(fscache_objs_histogram, start); |
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fscache_put_object(object, fscache_obj_put_work); |
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} |
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|
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/** |
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* fscache_object_init - Initialise a cache object description |
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* @object: Object description |
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* @cookie: Cookie object will be attached to |
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* @cache: Cache in which backing object will be found |
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* |
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* Initialise a cache object description to its basic values. |
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* |
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* See Documentation/filesystems/caching/backend-api.rst for a complete |
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* description. |
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*/ |
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void fscache_object_init(struct fscache_object *object, |
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struct fscache_cookie *cookie, |
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struct fscache_cache *cache) |
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{ |
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const struct fscache_transition *t; |
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|
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atomic_inc(&cache->object_count); |
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|
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object->state = STATE(WAIT_FOR_INIT); |
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object->oob_table = fscache_osm_init_oob; |
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object->flags = 1 << FSCACHE_OBJECT_IS_LIVE; |
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spin_lock_init(&object->lock); |
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INIT_LIST_HEAD(&object->cache_link); |
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INIT_HLIST_NODE(&object->cookie_link); |
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INIT_WORK(&object->work, fscache_object_work_func); |
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INIT_LIST_HEAD(&object->dependents); |
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INIT_LIST_HEAD(&object->dep_link); |
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INIT_LIST_HEAD(&object->pending_ops); |
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object->n_children = 0; |
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object->n_ops = object->n_in_progress = object->n_exclusive = 0; |
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object->events = 0; |
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object->store_limit = 0; |
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object->store_limit_l = 0; |
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object->cache = cache; |
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object->cookie = cookie; |
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fscache_cookie_get(cookie, fscache_cookie_get_attach_object); |
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object->parent = NULL; |
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#ifdef CONFIG_FSCACHE_OBJECT_LIST |
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RB_CLEAR_NODE(&object->objlist_link); |
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#endif |
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|
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object->oob_event_mask = 0; |
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for (t = object->oob_table; t->events; t++) |
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object->oob_event_mask |= t->events; |
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object->event_mask = object->oob_event_mask; |
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for (t = object->state->transitions; t->events; t++) |
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object->event_mask |= t->events; |
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} |
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EXPORT_SYMBOL(fscache_object_init); |
|
|
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/* |
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* Mark the object as no longer being live, making sure that we synchronise |
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* against op submission. |
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*/ |
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static inline void fscache_mark_object_dead(struct fscache_object *object) |
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{ |
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spin_lock(&object->lock); |
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clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags); |
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spin_unlock(&object->lock); |
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} |
|
|
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/* |
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* Abort object initialisation before we start it. |
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*/ |
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static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *object, |
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int event) |
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{ |
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_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
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object->oob_event_mask = 0; |
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fscache_dequeue_object(object); |
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return transit_to(KILL_OBJECT); |
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} |
|
|
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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 |
|
* - 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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*/ |
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static const struct fscache_state *fscache_initialise_object(struct fscache_object *object, |
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int event) |
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{ |
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struct fscache_object *parent; |
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bool success; |
|
|
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_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
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ASSERT(list_empty(&object->dep_link)); |
|
|
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parent = object->parent; |
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if (!parent) { |
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_leave(" [no parent]"); |
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return transit_to(DROP_OBJECT); |
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} |
|
|
|
_debug("parent: %s of:%lx", parent->state->name, parent->flags); |
|
|
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if (fscache_object_is_dying(parent)) { |
|
_leave(" [bad parent]"); |
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return transit_to(DROP_OBJECT); |
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} |
|
|
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if (fscache_object_is_available(parent)) { |
|
_leave(" [ready]"); |
|
return transit_to(PARENT_READY); |
|
} |
|
|
|
_debug("wait"); |
|
|
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spin_lock(&parent->lock); |
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fscache_stat(&fscache_n_cop_grab_object); |
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success = false; |
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if (fscache_object_is_live(parent) && |
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object->cache->ops->grab_object(object, fscache_obj_get_add_to_deps)) { |
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list_add(&object->dep_link, &parent->dependents); |
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success = true; |
|
} |
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fscache_stat_d(&fscache_n_cop_grab_object); |
|
spin_unlock(&parent->lock); |
|
if (!success) { |
|
_leave(" [grab failed]"); |
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return transit_to(DROP_OBJECT); |
|
} |
|
|
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/* fscache_acquire_non_index_cookie() uses this |
|
* to wake the chain up */ |
|
fscache_raise_event(parent, FSCACHE_OBJECT_EV_NEW_CHILD); |
|
_leave(" [wait]"); |
|
return transit_to(WAIT_FOR_PARENT); |
|
} |
|
|
|
/* |
|
* Once the parent object is ready, we should kick off our lookup op. |
|
*/ |
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static const struct fscache_state *fscache_parent_ready(struct fscache_object *object, |
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int event) |
|
{ |
|
struct fscache_object *parent = object->parent; |
|
|
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_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
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ASSERT(parent != NULL); |
|
|
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spin_lock(&parent->lock); |
|
parent->n_ops++; |
|
parent->n_obj_ops++; |
|
object->lookup_jif = jiffies; |
|
spin_unlock(&parent->lock); |
|
|
|
_leave(""); |
|
return transit_to(LOOK_UP_OBJECT); |
|
} |
|
|
|
/* |
|
* look an object up in the cache from which it was allocated |
|
* - we hold an "access lock" on the parent object, so the parent object cannot |
|
* be withdrawn by either party till we've finished |
|
*/ |
|
static const struct fscache_state *fscache_look_up_object(struct fscache_object *object, |
|
int event) |
|
{ |
|
struct fscache_cookie *cookie = object->cookie; |
|
struct fscache_object *parent = object->parent; |
|
int ret; |
|
|
|
_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
|
object->oob_table = fscache_osm_lookup_oob; |
|
|
|
ASSERT(parent != NULL); |
|
ASSERTCMP(parent->n_ops, >, 0); |
|
ASSERTCMP(parent->n_obj_ops, >, 0); |
|
|
|
/* make sure the parent is still available */ |
|
ASSERT(fscache_object_is_available(parent)); |
|
|
|
if (fscache_object_is_dying(parent) || |
|
test_bit(FSCACHE_IOERROR, &object->cache->flags) || |
|
!fscache_use_cookie(object)) { |
|
_leave(" [unavailable]"); |
|
return transit_to(LOOKUP_FAILURE); |
|
} |
|
|
|
_debug("LOOKUP \"%s\" in \"%s\"", |
|
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); |
|
|
|
fscache_unuse_cookie(object); |
|
|
|
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); |
|
_leave(" [timeout]"); |
|
return NO_TRANSIT; |
|
} |
|
|
|
if (ret < 0) { |
|
_leave(" [error]"); |
|
return transit_to(LOOKUP_FAILURE); |
|
} |
|
|
|
_leave(" [ok]"); |
|
return transit_to(OBJECT_AVAILABLE); |
|
} |
|
|
|
/** |
|
* 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, object->state->name); |
|
|
|
if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) { |
|
fscache_stat(&fscache_n_object_lookups_negative); |
|
|
|
/* Allow write requests to begin stacking up and read requests to begin |
|
* returning ENODATA. |
|
*/ |
|
set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); |
|
clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); |
|
|
|
_debug("wake up lookup %p", &cookie->flags); |
|
clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); |
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); |
|
} |
|
_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, object->state->name); |
|
|
|
/* if we were still looking up, then we must have a positive lookup |
|
* result, in which case there may be data available */ |
|
if (!test_and_set_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) { |
|
fscache_stat(&fscache_n_object_lookups_positive); |
|
|
|
/* We do (presumably) have data */ |
|
clear_bit_unlock(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); |
|
clear_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); |
|
|
|
/* Allow write requests to begin stacking up and read requests |
|
* to begin shovelling data. |
|
*/ |
|
clear_bit_unlock(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags); |
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); |
|
} else { |
|
fscache_stat(&fscache_n_object_created); |
|
} |
|
|
|
set_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags); |
|
_leave(""); |
|
} |
|
EXPORT_SYMBOL(fscache_obtained_object); |
|
|
|
/* |
|
* handle an object that has just become available |
|
*/ |
|
static const struct fscache_state *fscache_object_available(struct fscache_object *object, |
|
int event) |
|
{ |
|
_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
|
object->oob_table = fscache_osm_run_oob; |
|
|
|
spin_lock(&object->lock); |
|
|
|
fscache_done_parent_op(object); |
|
if (object->n_in_progress == 0) { |
|
if (object->n_ops > 0) { |
|
ASSERTCMP(object->n_ops, >=, object->n_obj_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_hist(fscache_obj_instantiate_histogram, object->lookup_jif); |
|
fscache_stat(&fscache_n_object_avail); |
|
|
|
_leave(""); |
|
return transit_to(JUMPSTART_DEPS); |
|
} |
|
|
|
/* |
|
* Wake up this object's dependent objects now that we've become available. |
|
*/ |
|
static const struct fscache_state *fscache_jumpstart_dependents(struct fscache_object *object, |
|
int event) |
|
{ |
|
_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
|
if (!fscache_enqueue_dependents(object, FSCACHE_OBJECT_EV_PARENT_READY)) |
|
return NO_TRANSIT; /* Not finished; requeue */ |
|
return transit_to(WAIT_FOR_CMD); |
|
} |
|
|
|
/* |
|
* Handle lookup or creation failute. |
|
*/ |
|
static const struct fscache_state *fscache_lookup_failure(struct fscache_object *object, |
|
int event) |
|
{ |
|
struct fscache_cookie *cookie; |
|
|
|
_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
|
object->oob_event_mask = 0; |
|
|
|
fscache_stat(&fscache_n_cop_lookup_complete); |
|
object->cache->ops->lookup_complete(object); |
|
fscache_stat_d(&fscache_n_cop_lookup_complete); |
|
|
|
set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags); |
|
|
|
cookie = object->cookie; |
|
set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags); |
|
if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) |
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); |
|
|
|
fscache_done_parent_op(object); |
|
return transit_to(KILL_OBJECT); |
|
} |
|
|
|
/* |
|
* Wait for completion of all active operations on this object and the death of |
|
* all child objects of this object. |
|
*/ |
|
static const struct fscache_state *fscache_kill_object(struct fscache_object *object, |
|
int event) |
|
{ |
|
_enter("{OBJ%x,%d,%d},%d", |
|
object->debug_id, object->n_ops, object->n_children, event); |
|
|
|
fscache_mark_object_dead(object); |
|
object->oob_event_mask = 0; |
|
|
|
if (test_bit(FSCACHE_OBJECT_RETIRED, &object->flags)) { |
|
/* Reject any new read/write ops and abort any that are pending. */ |
|
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); |
|
fscache_cancel_all_ops(object); |
|
} |
|
|
|
if (list_empty(&object->dependents) && |
|
object->n_ops == 0 && |
|
object->n_children == 0) |
|
return transit_to(DROP_OBJECT); |
|
|
|
if (object->n_in_progress == 0) { |
|
spin_lock(&object->lock); |
|
if (object->n_ops > 0 && object->n_in_progress == 0) |
|
fscache_start_operations(object); |
|
spin_unlock(&object->lock); |
|
} |
|
|
|
if (!list_empty(&object->dependents)) |
|
return transit_to(KILL_DEPENDENTS); |
|
|
|
return transit_to(WAIT_FOR_CLEARANCE); |
|
} |
|
|
|
/* |
|
* Kill dependent objects. |
|
*/ |
|
static const struct fscache_state *fscache_kill_dependents(struct fscache_object *object, |
|
int event) |
|
{ |
|
_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
|
if (!fscache_enqueue_dependents(object, FSCACHE_OBJECT_EV_KILL)) |
|
return NO_TRANSIT; /* Not finished */ |
|
return transit_to(WAIT_FOR_CLEARANCE); |
|
} |
|
|
|
/* |
|
* Drop an object's attachments |
|
*/ |
|
static const struct fscache_state *fscache_drop_object(struct fscache_object *object, |
|
int event) |
|
{ |
|
struct fscache_object *parent = object->parent; |
|
struct fscache_cookie *cookie = object->cookie; |
|
struct fscache_cache *cache = object->cache; |
|
bool awaken = false; |
|
|
|
_enter("{OBJ%x,%d},%d", object->debug_id, object->n_children, event); |
|
|
|
ASSERT(cookie != NULL); |
|
ASSERT(!hlist_unhashed(&object->cookie_link)); |
|
|
|
if (test_bit(FSCACHE_COOKIE_AUX_UPDATED, &cookie->flags)) { |
|
_debug("final update"); |
|
fscache_update_aux_data(object); |
|
} |
|
|
|
/* Make sure the cookie no longer points here and that the netfs isn't |
|
* waiting for us. |
|
*/ |
|
spin_lock(&cookie->lock); |
|
hlist_del_init(&object->cookie_link); |
|
if (hlist_empty(&cookie->backing_objects) && |
|
test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) |
|
awaken = true; |
|
spin_unlock(&cookie->lock); |
|
|
|
if (awaken) |
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING); |
|
if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags)) |
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP); |
|
|
|
|
|
/* Prevent a race with our last child, which has to signal EV_CLEARED |
|
* before dropping our spinlock. |
|
*/ |
|
spin_lock(&object->lock); |
|
spin_unlock(&object->lock); |
|
|
|
/* Discard from the cache's collection of objects */ |
|
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); |
|
|
|
/* The parent object wants to know when all it dependents have gone */ |
|
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, fscache_obj_put_drop_obj); |
|
fscache_stat(&fscache_n_object_dead); |
|
|
|
_leave(""); |
|
return transit_to(OBJECT_DEAD); |
|
} |
|
|
|
/* |
|
* get a ref on an object |
|
*/ |
|
static int fscache_get_object(struct fscache_object *object, |
|
enum fscache_obj_ref_trace why) |
|
{ |
|
int ret; |
|
|
|
fscache_stat(&fscache_n_cop_grab_object); |
|
ret = object->cache->ops->grab_object(object, why) ? 0 : -EAGAIN; |
|
fscache_stat_d(&fscache_n_cop_grab_object); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Discard a ref on an object |
|
*/ |
|
static void fscache_put_object(struct fscache_object *object, |
|
enum fscache_obj_ref_trace why) |
|
{ |
|
fscache_stat(&fscache_n_cop_put_object); |
|
object->cache->ops->put_object(object, why); |
|
fscache_stat_d(&fscache_n_cop_put_object); |
|
} |
|
|
|
/** |
|
* fscache_object_destroy - Note that a cache object is about to be destroyed |
|
* @object: The object to be destroyed |
|
* |
|
* Note the imminent destruction and deallocation of a cache object record. |
|
*/ |
|
void fscache_object_destroy(struct fscache_object *object) |
|
{ |
|
fscache_objlist_remove(object); |
|
|
|
/* We can get rid of the cookie now */ |
|
fscache_cookie_put(object->cookie, fscache_cookie_put_object); |
|
object->cookie = NULL; |
|
} |
|
EXPORT_SYMBOL(fscache_object_destroy); |
|
|
|
/* |
|
* 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, fscache_obj_get_queue) >= 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, fscache_obj_put_queue); |
|
|
|
put_cpu_var(fscache_object_cong_wait); |
|
} |
|
} |
|
|
|
/** |
|
* fscache_object_sleep_till_congested - Sleep until object wq is congested |
|
* @timeoutp: 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 = this_cpu_ptr(&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. |
|
* |
|
* If we don't manage to finish the list before the scheduler wants to run |
|
* again then return false immediately. We return true if the list was |
|
* cleared. |
|
*/ |
|
static bool fscache_enqueue_dependents(struct fscache_object *object, int event) |
|
{ |
|
struct fscache_object *dep; |
|
bool ret = true; |
|
|
|
_enter("{OBJ%x}", object->debug_id); |
|
|
|
if (list_empty(&object->dependents)) |
|
return true; |
|
|
|
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); |
|
|
|
fscache_raise_event(dep, event); |
|
fscache_put_object(dep, fscache_obj_put_enq_dep); |
|
|
|
if (!list_empty(&object->dependents) && need_resched()) { |
|
ret = false; |
|
break; |
|
} |
|
} |
|
|
|
spin_unlock(&object->lock); |
|
return ret; |
|
} |
|
|
|
/* |
|
* remove an object from whatever queue it's waiting on |
|
*/ |
|
static 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. |
|
* The caller must be holding a ref on cookie->n_active (held by |
|
* fscache_look_up_object() on behalf of the cache backend during object lookup |
|
* and creation). |
|
*/ |
|
enum fscache_checkaux fscache_check_aux(struct fscache_object *object, |
|
const void *data, uint16_t datalen, |
|
loff_t object_size) |
|
{ |
|
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, object_size); |
|
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); |
|
|
|
/* |
|
* Asynchronously invalidate an object. |
|
*/ |
|
static const struct fscache_state *_fscache_invalidate_object(struct fscache_object *object, |
|
int event) |
|
{ |
|
struct fscache_operation *op; |
|
struct fscache_cookie *cookie = object->cookie; |
|
|
|
_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
|
/* We're going to need the cookie. If the cookie is not available then |
|
* retire the object instead. |
|
*/ |
|
if (!fscache_use_cookie(object)) { |
|
ASSERT(radix_tree_empty(&object->cookie->stores)); |
|
set_bit(FSCACHE_OBJECT_RETIRED, &object->flags); |
|
_leave(" [no cookie]"); |
|
return transit_to(KILL_OBJECT); |
|
} |
|
|
|
/* Reject any new read/write ops and abort any that are pending. */ |
|
fscache_invalidate_writes(cookie); |
|
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags); |
|
fscache_cancel_all_ops(object); |
|
|
|
/* Now we have to wait for in-progress reads and writes */ |
|
op = kzalloc(sizeof(*op), GFP_KERNEL); |
|
if (!op) |
|
goto nomem; |
|
|
|
fscache_operation_init(cookie, op, object->cache->ops->invalidate_object, |
|
NULL, NULL); |
|
op->flags = FSCACHE_OP_ASYNC | |
|
(1 << FSCACHE_OP_EXCLUSIVE) | |
|
(1 << FSCACHE_OP_UNUSE_COOKIE); |
|
trace_fscache_page_op(cookie, NULL, op, fscache_page_op_invalidate); |
|
|
|
spin_lock(&cookie->lock); |
|
if (fscache_submit_exclusive_op(object, op) < 0) |
|
goto submit_op_failed; |
|
spin_unlock(&cookie->lock); |
|
fscache_put_operation(op); |
|
|
|
/* Once we've completed the invalidation, we know there will be no data |
|
* stored in the cache and thus we can reinstate the data-check-skip |
|
* optimisation. |
|
*/ |
|
set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags); |
|
|
|
/* We can allow read and write requests to come in once again. They'll |
|
* queue up behind our exclusive invalidation operation. |
|
*/ |
|
if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) |
|
wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING); |
|
_leave(" [ok]"); |
|
return transit_to(UPDATE_OBJECT); |
|
|
|
nomem: |
|
fscache_mark_object_dead(object); |
|
fscache_unuse_cookie(object); |
|
_leave(" [ENOMEM]"); |
|
return transit_to(KILL_OBJECT); |
|
|
|
submit_op_failed: |
|
fscache_mark_object_dead(object); |
|
spin_unlock(&cookie->lock); |
|
fscache_unuse_cookie(object); |
|
kfree(op); |
|
_leave(" [EIO]"); |
|
return transit_to(KILL_OBJECT); |
|
} |
|
|
|
static const struct fscache_state *fscache_invalidate_object(struct fscache_object *object, |
|
int event) |
|
{ |
|
const struct fscache_state *s; |
|
|
|
fscache_stat(&fscache_n_invalidates_run); |
|
fscache_stat(&fscache_n_cop_invalidate_object); |
|
s = _fscache_invalidate_object(object, event); |
|
fscache_stat_d(&fscache_n_cop_invalidate_object); |
|
return s; |
|
} |
|
|
|
/* |
|
* Update auxiliary data. |
|
*/ |
|
static void fscache_update_aux_data(struct fscache_object *object) |
|
{ |
|
fscache_stat(&fscache_n_updates_run); |
|
fscache_stat(&fscache_n_cop_update_object); |
|
object->cache->ops->update_object(object); |
|
fscache_stat_d(&fscache_n_cop_update_object); |
|
} |
|
|
|
/* |
|
* Asynchronously update an object. |
|
*/ |
|
static const struct fscache_state *fscache_update_object(struct fscache_object *object, |
|
int event) |
|
{ |
|
_enter("{OBJ%x},%d", object->debug_id, event); |
|
|
|
fscache_update_aux_data(object); |
|
|
|
_leave(""); |
|
return transit_to(WAIT_FOR_CMD); |
|
} |
|
|
|
/** |
|
* fscache_object_retrying_stale - Note retrying stale object |
|
* @object: The object that will be retried |
|
* |
|
* Note that an object lookup found an on-disk object that was adjudged to be |
|
* stale and has been deleted. The lookup will be retried. |
|
*/ |
|
void fscache_object_retrying_stale(struct fscache_object *object) |
|
{ |
|
fscache_stat(&fscache_n_cache_no_space_reject); |
|
} |
|
EXPORT_SYMBOL(fscache_object_retrying_stale); |
|
|
|
/** |
|
* fscache_object_mark_killed - Note that an object was killed |
|
* @object: The object that was culled |
|
* @why: The reason the object was killed. |
|
* |
|
* Note that an object was killed. Returns true if the object was |
|
* already marked killed, false if it wasn't. |
|
*/ |
|
void fscache_object_mark_killed(struct fscache_object *object, |
|
enum fscache_why_object_killed why) |
|
{ |
|
if (test_and_set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags)) { |
|
pr_err("Error: Object already killed by cache [%s]\n", |
|
object->cache->identifier); |
|
return; |
|
} |
|
|
|
switch (why) { |
|
case FSCACHE_OBJECT_NO_SPACE: |
|
fscache_stat(&fscache_n_cache_no_space_reject); |
|
break; |
|
case FSCACHE_OBJECT_IS_STALE: |
|
fscache_stat(&fscache_n_cache_stale_objects); |
|
break; |
|
case FSCACHE_OBJECT_WAS_RETIRED: |
|
fscache_stat(&fscache_n_cache_retired_objects); |
|
break; |
|
case FSCACHE_OBJECT_WAS_CULLED: |
|
fscache_stat(&fscache_n_cache_culled_objects); |
|
break; |
|
} |
|
} |
|
EXPORT_SYMBOL(fscache_object_mark_killed); |
|
|
|
/* |
|
* The object is dead. We can get here if an object gets queued by an event |
|
* that would lead to its death (such as EV_KILL) when the dispatcher is |
|
* already running (and so can be requeued) but hasn't yet cleared the event |
|
* mask. |
|
*/ |
|
static const struct fscache_state *fscache_object_dead(struct fscache_object *object, |
|
int event) |
|
{ |
|
if (!test_and_set_bit(FSCACHE_OBJECT_RUN_AFTER_DEAD, |
|
&object->flags)) |
|
return NO_TRANSIT; |
|
|
|
WARN(true, "FS-Cache object redispatched after death"); |
|
return NO_TRANSIT; |
|
}
|
|
|