| /* FS-Cache object state machine handler |
| * |
| * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| * |
| * See Documentation/filesystems/caching/object.txt for a description of the |
| * object state machine and the in-kernel representations. |
| */ |
| |
| #define FSCACHE_DEBUG_LEVEL COOKIE |
| #include <linux/module.h> |
| #include <linux/slab.h> |
| #include "internal.h" |
| |
| const char *fscache_object_states[FSCACHE_OBJECT__NSTATES] = { |
| [FSCACHE_OBJECT_INIT] = "OBJECT_INIT", |
| [FSCACHE_OBJECT_LOOKING_UP] = "OBJECT_LOOKING_UP", |
| [FSCACHE_OBJECT_CREATING] = "OBJECT_CREATING", |
| [FSCACHE_OBJECT_AVAILABLE] = "OBJECT_AVAILABLE", |
| [FSCACHE_OBJECT_ACTIVE] = "OBJECT_ACTIVE", |
| [FSCACHE_OBJECT_INVALIDATING] = "OBJECT_INVALIDATING", |
| [FSCACHE_OBJECT_UPDATING] = "OBJECT_UPDATING", |
| [FSCACHE_OBJECT_DYING] = "OBJECT_DYING", |
| [FSCACHE_OBJECT_LC_DYING] = "OBJECT_LC_DYING", |
| [FSCACHE_OBJECT_ABORT_INIT] = "OBJECT_ABORT_INIT", |
| [FSCACHE_OBJECT_RELEASING] = "OBJECT_RELEASING", |
| [FSCACHE_OBJECT_RECYCLING] = "OBJECT_RECYCLING", |
| [FSCACHE_OBJECT_WITHDRAWING] = "OBJECT_WITHDRAWING", |
| [FSCACHE_OBJECT_DEAD] = "OBJECT_DEAD", |
| }; |
| EXPORT_SYMBOL(fscache_object_states); |
| |
| const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5] = { |
| [FSCACHE_OBJECT_INIT] = "INIT", |
| [FSCACHE_OBJECT_LOOKING_UP] = "LOOK", |
| [FSCACHE_OBJECT_CREATING] = "CRTN", |
| [FSCACHE_OBJECT_AVAILABLE] = "AVBL", |
| [FSCACHE_OBJECT_ACTIVE] = "ACTV", |
| [FSCACHE_OBJECT_INVALIDATING] = "INVL", |
| [FSCACHE_OBJECT_UPDATING] = "UPDT", |
| [FSCACHE_OBJECT_DYING] = "DYNG", |
| [FSCACHE_OBJECT_LC_DYING] = "LCDY", |
| [FSCACHE_OBJECT_ABORT_INIT] = "ABTI", |
| [FSCACHE_OBJECT_RELEASING] = "RELS", |
| [FSCACHE_OBJECT_RECYCLING] = "RCYC", |
| [FSCACHE_OBJECT_WITHDRAWING] = "WTHD", |
| [FSCACHE_OBJECT_DEAD] = "DEAD", |
| }; |
| |
| static int fscache_get_object(struct fscache_object *); |
| static void fscache_put_object(struct fscache_object *); |
| static void fscache_initialise_object(struct fscache_object *); |
| static void fscache_lookup_object(struct fscache_object *); |
| static void fscache_object_available(struct fscache_object *); |
| static void fscache_invalidate_object(struct fscache_object *); |
| static void fscache_release_object(struct fscache_object *); |
| static void fscache_withdraw_object(struct fscache_object *); |
| static void fscache_enqueue_dependents(struct fscache_object *); |
| static void fscache_dequeue_object(struct fscache_object *); |
| |
| /* |
| * we need to notify the parent when an op completes that we had outstanding |
| * upon it |
| */ |
| static inline void fscache_done_parent_op(struct fscache_object *object) |
| { |
| struct fscache_object *parent = object->parent; |
| |
| _enter("OBJ%x {OBJ%x,%x}", |
| object->debug_id, parent->debug_id, parent->n_ops); |
| |
| spin_lock_nested(&parent->lock, 1); |
| parent->n_ops--; |
| parent->n_obj_ops--; |
| if (parent->n_ops == 0) |
| fscache_raise_event(parent, FSCACHE_OBJECT_EV_CLEARED); |
| spin_unlock(&parent->lock); |
| } |
| |
| /* |
| * Notify netfs of invalidation completion. |
| */ |
| static inline void fscache_invalidation_complete(struct fscache_cookie *cookie) |
| { |
| if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) |
| wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING); |
| } |
| |
| /* |
| * process events that have been sent to an object's state machine |
| * - initiates parent lookup |
| * - does object lookup |
| * - does object creation |
| * - does object recycling and retirement |
| * - does object withdrawal |
| */ |
| static void fscache_object_state_machine(struct fscache_object *object) |
| { |
| enum fscache_object_state new_state; |
| struct fscache_cookie *cookie; |
| int event; |
| |
| ASSERT(object != NULL); |
| |
| _enter("{OBJ%x,%s,%lx}", |
| object->debug_id, fscache_object_states[object->state], |
| object->events); |
| |
| switch (object->state) { |
| /* wait for the parent object to become ready */ |
| case FSCACHE_OBJECT_INIT: |
| object->event_mask = |
| FSCACHE_OBJECT_EVENTS_MASK & |
| ~(1 << FSCACHE_OBJECT_EV_CLEARED); |
| fscache_initialise_object(object); |
| goto done; |
| |
| /* look up the object metadata on disk */ |
| case FSCACHE_OBJECT_LOOKING_UP: |
| fscache_lookup_object(object); |
| goto lookup_transit; |
| |
| /* create the object metadata on disk */ |
| case FSCACHE_OBJECT_CREATING: |
| fscache_lookup_object(object); |
| goto lookup_transit; |
| |
| /* handle an object becoming available; start pending |
| * operations and queue dependent operations for processing */ |
| case FSCACHE_OBJECT_AVAILABLE: |
| fscache_object_available(object); |
| goto active_transit; |
| |
| /* normal running state */ |
| case FSCACHE_OBJECT_ACTIVE: |
| goto active_transit; |
| |
| /* Invalidate an object on disk */ |
| case FSCACHE_OBJECT_INVALIDATING: |
| clear_bit(FSCACHE_OBJECT_EV_INVALIDATE, &object->events); |
| fscache_stat(&fscache_n_invalidates_run); |
| fscache_stat(&fscache_n_cop_invalidate_object); |
| fscache_invalidate_object(object); |
| fscache_stat_d(&fscache_n_cop_invalidate_object); |
| fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE); |
| goto active_transit; |
| |
| /* update the object metadata on disk */ |
| case FSCACHE_OBJECT_UPDATING: |
| clear_bit(FSCACHE_OBJECT_EV_UPDATE, &object->events); |
| 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); |
| goto active_transit; |
| |
| /* handle an object dying during lookup or creation */ |
| case FSCACHE_OBJECT_LC_DYING: |
| object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE); |
| fscache_stat(&fscache_n_cop_lookup_complete); |
| object->cache->ops->lookup_complete(object); |
| fscache_stat_d(&fscache_n_cop_lookup_complete); |
| |
| spin_lock(&object->lock); |
| object->state = FSCACHE_OBJECT_DYING; |
| cookie = object->cookie; |
| if (cookie) { |
| if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, |
| &cookie->flags)) |
| wake_up_bit(&cookie->flags, |
| FSCACHE_COOKIE_LOOKING_UP); |
| if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, |
| &cookie->flags)) |
| wake_up_bit(&cookie->flags, |
| FSCACHE_COOKIE_CREATING); |
| } |
| spin_unlock(&object->lock); |
| |
| fscache_done_parent_op(object); |
| |
| /* wait for completion of all active operations on this object |
| * and the death of all child objects of this object */ |
| case FSCACHE_OBJECT_DYING: |
| dying: |
| clear_bit(FSCACHE_OBJECT_EV_CLEARED, &object->events); |
| spin_lock(&object->lock); |
| _debug("dying OBJ%x {%d,%d}", |
| object->debug_id, object->n_ops, object->n_children); |
| if (object->n_ops == 0 && object->n_children == 0) { |
| object->event_mask &= |
| ~(1 << FSCACHE_OBJECT_EV_CLEARED); |
| object->event_mask |= |
| (1 << FSCACHE_OBJECT_EV_WITHDRAW) | |
| (1 << FSCACHE_OBJECT_EV_RETIRE) | |
| (1 << FSCACHE_OBJECT_EV_RELEASE) | |
| (1 << FSCACHE_OBJECT_EV_ERROR); |
| } else { |
| object->event_mask &= |
| ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | |
| (1 << FSCACHE_OBJECT_EV_RETIRE) | |
| (1 << FSCACHE_OBJECT_EV_RELEASE) | |
| (1 << FSCACHE_OBJECT_EV_ERROR)); |
| object->event_mask |= |
| 1 << FSCACHE_OBJECT_EV_CLEARED; |
| } |
| spin_unlock(&object->lock); |
| fscache_enqueue_dependents(object); |
| fscache_start_operations(object); |
| goto terminal_transit; |
| |
| /* handle an abort during initialisation */ |
| case FSCACHE_OBJECT_ABORT_INIT: |
| _debug("handle abort init %lx", object->events); |
| object->event_mask &= ~(1 << FSCACHE_OBJECT_EV_UPDATE); |
| |
| spin_lock(&object->lock); |
| fscache_dequeue_object(object); |
| |
| object->state = FSCACHE_OBJECT_DYING; |
| if (test_and_clear_bit(FSCACHE_COOKIE_CREATING, |
| &object->cookie->flags)) |
| wake_up_bit(&object->cookie->flags, |
| FSCACHE_COOKIE_CREATING); |
| spin_unlock(&object->lock); |
| goto dying; |
| |
| /* handle the netfs releasing an object and possibly marking it |
| * obsolete too */ |
| case FSCACHE_OBJECT_RELEASING: |
| case FSCACHE_OBJECT_RECYCLING: |
| object->event_mask &= |
| ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | |
| (1 << FSCACHE_OBJECT_EV_RETIRE) | |
| (1 << FSCACHE_OBJECT_EV_RELEASE) | |
| (1 << FSCACHE_OBJECT_EV_ERROR)); |
| fscache_release_object(object); |
| spin_lock(&object->lock); |
| object->state = FSCACHE_OBJECT_DEAD; |
| spin_unlock(&object->lock); |
| fscache_stat(&fscache_n_object_dead); |
| goto terminal_transit; |
| |
| /* handle the parent cache of this object being withdrawn from |
| * active service */ |
| case FSCACHE_OBJECT_WITHDRAWING: |
| object->event_mask &= |
| ~((1 << FSCACHE_OBJECT_EV_WITHDRAW) | |
| (1 << FSCACHE_OBJECT_EV_RETIRE) | |
| (1 << FSCACHE_OBJECT_EV_RELEASE) | |
| (1 << FSCACHE_OBJECT_EV_ERROR)); |
| fscache_withdraw_object(object); |
| spin_lock(&object->lock); |
| object->state = FSCACHE_OBJECT_DEAD; |
| spin_unlock(&object->lock); |
| fscache_stat(&fscache_n_object_dead); |
| goto terminal_transit; |
| |
| /* complain about the object being woken up once it is |
| * deceased */ |
| case FSCACHE_OBJECT_DEAD: |
| printk(KERN_ERR "FS-Cache:" |
| " Unexpected event in dead state %lx\n", |
| object->events & object->event_mask); |
| BUG(); |
| |
| default: |
| printk(KERN_ERR "FS-Cache: Unknown object state %u\n", |
| object->state); |
| BUG(); |
| } |
| |
| /* determine the transition from a lookup state */ |
| lookup_transit: |
| event = fls(object->events & object->event_mask) - 1; |
| switch (event) { |
| case FSCACHE_OBJECT_EV_WITHDRAW: |
| case FSCACHE_OBJECT_EV_RETIRE: |
| case FSCACHE_OBJECT_EV_RELEASE: |
| case FSCACHE_OBJECT_EV_ERROR: |
| new_state = FSCACHE_OBJECT_LC_DYING; |
| goto change_state; |
| case FSCACHE_OBJECT_EV_REQUEUE: |
| goto done; |
| case -1: |
| goto done; /* sleep until event */ |
| default: |
| goto unsupported_event; |
| } |
| |
| /* determine the transition from an active state */ |
| active_transit: |
| event = fls(object->events & object->event_mask) - 1; |
| switch (event) { |
| case FSCACHE_OBJECT_EV_WITHDRAW: |
| case FSCACHE_OBJECT_EV_RETIRE: |
| case FSCACHE_OBJECT_EV_RELEASE: |
| case FSCACHE_OBJECT_EV_ERROR: |
| new_state = FSCACHE_OBJECT_DYING; |
| goto change_state; |
| case FSCACHE_OBJECT_EV_INVALIDATE: |
| new_state = FSCACHE_OBJECT_INVALIDATING; |
| goto change_state; |
| case FSCACHE_OBJECT_EV_UPDATE: |
| new_state = FSCACHE_OBJECT_UPDATING; |
| goto change_state; |
| case -1: |
| new_state = FSCACHE_OBJECT_ACTIVE; |
| goto change_state; /* sleep until event */ |
| default: |
| goto unsupported_event; |
| } |
| |
| /* determine the transition from a terminal state */ |
| terminal_transit: |
| event = fls(object->events & object->event_mask) - 1; |
| switch (event) { |
| case FSCACHE_OBJECT_EV_WITHDRAW: |
| new_state = FSCACHE_OBJECT_WITHDRAWING; |
| goto change_state; |
| case FSCACHE_OBJECT_EV_RETIRE: |
| new_state = FSCACHE_OBJECT_RECYCLING; |
| goto change_state; |
| case FSCACHE_OBJECT_EV_RELEASE: |
| new_state = FSCACHE_OBJECT_RELEASING; |
| goto change_state; |
| case FSCACHE_OBJECT_EV_ERROR: |
| new_state = FSCACHE_OBJECT_WITHDRAWING; |
| goto change_state; |
| case FSCACHE_OBJECT_EV_CLEARED: |
| new_state = FSCACHE_OBJECT_DYING; |
| goto change_state; |
| case -1: |
| goto done; /* sleep until event */ |
| default: |
| goto unsupported_event; |
| } |
| |
| change_state: |
| spin_lock(&object->lock); |
| object->state = new_state; |
| spin_unlock(&object->lock); |
| |
| done: |
| _leave(" [->%s]", fscache_object_states[object->state]); |
| return; |
| |
| unsupported_event: |
| printk(KERN_ERR "FS-Cache:" |
| " Unsupported event %d [%lx/%lx] in state %s\n", |
| event, object->events, object->event_mask, |
| fscache_object_states[object->state]); |
| BUG(); |
| } |
| |
| /* |
| * execute an object |
| */ |
| void fscache_object_work_func(struct work_struct *work) |
| { |
| struct fscache_object *object = |
| container_of(work, struct fscache_object, work); |
| unsigned long start; |
| |
| _enter("{OBJ%x}", object->debug_id); |
| |
| start = jiffies; |
| fscache_object_state_machine(object); |
| fscache_hist(fscache_objs_histogram, start); |
| if (object->events & object->event_mask) |
| fscache_enqueue_object(object); |
| clear_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); |
| fscache_put_object(object); |
| } |
| EXPORT_SYMBOL(fscache_object_work_func); |
| |
| /* |
| * initialise an object |
| * - check the specified object's parent to see if we can make use of it |
| * immediately to do a creation |
| * - we may need to start the process of creating a parent and we need to wait |
| * for the parent's lookup and creation to complete if it's not there yet |
| * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the |
| * leaf-most cookies of the object and all its children |
| */ |
| static void fscache_initialise_object(struct fscache_object *object) |
| { |
| struct fscache_object *parent; |
| |
| _enter(""); |
| ASSERT(object->cookie != NULL); |
| ASSERT(object->cookie->parent != NULL); |
| |
| if (object->events & ((1 << FSCACHE_OBJECT_EV_ERROR) | |
| (1 << FSCACHE_OBJECT_EV_RELEASE) | |
| (1 << FSCACHE_OBJECT_EV_RETIRE) | |
| (1 << FSCACHE_OBJECT_EV_WITHDRAW))) { |
| _debug("abort init %lx", object->events); |
| spin_lock(&object->lock); |
| object->state = FSCACHE_OBJECT_ABORT_INIT; |
| spin_unlock(&object->lock); |
| return; |
| } |
| |
| spin_lock(&object->cookie->lock); |
| spin_lock_nested(&object->cookie->parent->lock, 1); |
| |
| parent = object->parent; |
| if (!parent) { |
| _debug("no parent"); |
| set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); |
| } else { |
| spin_lock(&object->lock); |
| spin_lock_nested(&parent->lock, 1); |
| _debug("parent %s", fscache_object_states[parent->state]); |
| |
| if (parent->state >= FSCACHE_OBJECT_DYING) { |
| _debug("bad parent"); |
| set_bit(FSCACHE_OBJECT_EV_WITHDRAW, &object->events); |
| } else if (parent->state < FSCACHE_OBJECT_AVAILABLE) { |
| _debug("wait"); |
| |
| /* we may get woken up in this state by child objects |
| * binding on to us, so we need to make sure we don't |
| * add ourself to the list multiple times */ |
| if (list_empty(&object->dep_link)) { |
| fscache_stat(&fscache_n_cop_grab_object); |
| object->cache->ops->grab_object(object); |
| fscache_stat_d(&fscache_n_cop_grab_object); |
| list_add(&object->dep_link, |
| &parent->dependents); |
| |
| /* fscache_acquire_non_index_cookie() uses this |
| * to wake the chain up */ |
| if (parent->state == FSCACHE_OBJECT_INIT) |
| fscache_enqueue_object(parent); |
| } |
| } else { |
| _debug("go"); |
| parent->n_ops++; |
| parent->n_obj_ops++; |
| object->lookup_jif = jiffies; |
| object->state = FSCACHE_OBJECT_LOOKING_UP; |
| set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events); |
| } |
| |
| spin_unlock(&parent->lock); |
| spin_unlock(&object->lock); |
| } |
| |
| spin_unlock(&object->cookie->parent->lock); |
| spin_unlock(&object->cookie->lock); |
| _leave(""); |
| } |
| |
| /* |
| * 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 |
| * - an object's cookie is pinned until we clear FSCACHE_COOKIE_CREATING on the |
| * leaf-most cookies of the object and all its children |
| */ |
| static void fscache_lookup_object(struct fscache_object *object) |
| { |
| struct fscache_cookie *cookie = object->cookie; |
| struct fscache_object *parent; |
| int ret; |
| |
| _enter(""); |
| |
| parent = object->parent; |
| ASSERT(parent != NULL); |
| ASSERTCMP(parent->n_ops, >, 0); |
| 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); |
| 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; |
| fscache_invalidation_complete(cookie); |
| 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); |
| |
| /* |
| * Asynchronously invalidate an object. |
| */ |
| static void fscache_invalidate_object(struct fscache_object *object) |
| { |
| struct fscache_operation *op; |
| struct fscache_cookie *cookie = object->cookie; |
| |
| _enter("{OBJ%x}", object->debug_id); |
| |
| /* 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) { |
| fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR); |
| _leave(" [ENOMEM]"); |
| return; |
| } |
| |
| fscache_operation_init(op, object->cache->ops->invalidate_object, NULL); |
| op->flags = FSCACHE_OP_ASYNC | (1 << FSCACHE_OP_EXCLUSIVE); |
| |
| 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. |
| */ |
| fscache_invalidation_complete(cookie); |
| _leave(""); |
| return; |
| |
| submit_op_failed: |
| spin_unlock(&cookie->lock); |
| kfree(op); |
| fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR); |
| _leave(" [EIO]"); |
| } |