+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-or-later
-/* netfs cookie management
- *
- * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells (dhowells@redhat.com)
- *
- * See Documentation/filesystems/caching/netfs-api.rst for more information on
- * the netfs API.
- */
-
-#define FSCACHE_DEBUG_LEVEL COOKIE
-#include <linux/module.h>
-#include <linux/slab.h>
-#include "internal.h"
-
-struct kmem_cache *fscache_cookie_jar;
-
-static void fscache_cookie_lru_timed_out(struct timer_list *timer);
-static void fscache_cookie_lru_worker(struct work_struct *work);
-static void fscache_cookie_worker(struct work_struct *work);
-static void fscache_unhash_cookie(struct fscache_cookie *cookie);
-static void fscache_perform_invalidation(struct fscache_cookie *cookie);
-
-#define fscache_cookie_hash_shift 15
-static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
-static LIST_HEAD(fscache_cookies);
-static DEFINE_RWLOCK(fscache_cookies_lock);
-static LIST_HEAD(fscache_cookie_lru);
-static DEFINE_SPINLOCK(fscache_cookie_lru_lock);
-DEFINE_TIMER(fscache_cookie_lru_timer, fscache_cookie_lru_timed_out);
-static DECLARE_WORK(fscache_cookie_lru_work, fscache_cookie_lru_worker);
-static const char fscache_cookie_states[FSCACHE_COOKIE_STATE__NR] = "-LCAIFUWRD";
-static unsigned int fscache_lru_cookie_timeout = 10 * HZ;
-
-void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
-{
- const u8 *k;
-
- pr_err("%c-cookie c=%08x [fl=%lx na=%u nA=%u s=%c]\n",
- prefix,
- cookie->debug_id,
- cookie->flags,
- atomic_read(&cookie->n_active),
- atomic_read(&cookie->n_accesses),
- fscache_cookie_states[cookie->state]);
- pr_err("%c-cookie V=%08x [%s]\n",
- prefix,
- cookie->volume->debug_id,
- cookie->volume->key);
-
- k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
- cookie->inline_key : cookie->key;
- pr_err("%c-key=[%u] '%*phN'\n", prefix, cookie->key_len, cookie->key_len, k);
-}
-
-static void fscache_free_cookie(struct fscache_cookie *cookie)
-{
- if (WARN_ON_ONCE(!list_empty(&cookie->commit_link))) {
- spin_lock(&fscache_cookie_lru_lock);
- list_del_init(&cookie->commit_link);
- spin_unlock(&fscache_cookie_lru_lock);
- fscache_stat_d(&fscache_n_cookies_lru);
- fscache_stat(&fscache_n_cookies_lru_removed);
- }
-
- if (WARN_ON_ONCE(test_bit(FSCACHE_COOKIE_IS_HASHED, &cookie->flags))) {
- fscache_print_cookie(cookie, 'F');
- return;
- }
-
- write_lock(&fscache_cookies_lock);
- list_del(&cookie->proc_link);
- write_unlock(&fscache_cookies_lock);
- if (cookie->aux_len > sizeof(cookie->inline_aux))
- kfree(cookie->aux);
- if (cookie->key_len > sizeof(cookie->inline_key))
- kfree(cookie->key);
- fscache_stat_d(&fscache_n_cookies);
- kmem_cache_free(fscache_cookie_jar, cookie);
-}
-
-static void __fscache_queue_cookie(struct fscache_cookie *cookie)
-{
- if (!queue_work(fscache_wq, &cookie->work))
- fscache_put_cookie(cookie, fscache_cookie_put_over_queued);
-}
-
-static void fscache_queue_cookie(struct fscache_cookie *cookie,
- enum fscache_cookie_trace where)
-{
- fscache_get_cookie(cookie, where);
- __fscache_queue_cookie(cookie);
-}
-
-/*
- * Initialise the access gate on a cookie by setting a flag to prevent the
- * state machine from being queued when the access counter transitions to 0.
- * We're only interested in this when we withdraw caching services from the
- * cookie.
- */
-static void fscache_init_access_gate(struct fscache_cookie *cookie)
-{
- int n_accesses;
-
- n_accesses = atomic_read(&cookie->n_accesses);
- trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
- n_accesses, fscache_access_cache_pin);
- set_bit(FSCACHE_COOKIE_NO_ACCESS_WAKE, &cookie->flags);
-}
-
-/**
- * fscache_end_cookie_access - Unpin a cache at the end of an access.
- * @cookie: A data file cookie
- * @why: An indication of the circumstances of the access for tracing
- *
- * Unpin a cache cookie after we've accessed it and bring a deferred
- * relinquishment or withdrawal state into effect.
- *
- * The @why indicator is provided for tracing purposes.
- */
-void fscache_end_cookie_access(struct fscache_cookie *cookie,
- enum fscache_access_trace why)
-{
- int n_accesses;
-
- smp_mb__before_atomic();
- n_accesses = atomic_dec_return(&cookie->n_accesses);
- trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
- n_accesses, why);
- if (n_accesses == 0 &&
- !test_bit(FSCACHE_COOKIE_NO_ACCESS_WAKE, &cookie->flags))
- fscache_queue_cookie(cookie, fscache_cookie_get_end_access);
-}
-EXPORT_SYMBOL(fscache_end_cookie_access);
-
-/*
- * Pin the cache behind a cookie so that we can access it.
- */
-static void __fscache_begin_cookie_access(struct fscache_cookie *cookie,
- enum fscache_access_trace why)
-{
- int n_accesses;
-
- n_accesses = atomic_inc_return(&cookie->n_accesses);
- smp_mb__after_atomic(); /* (Future) read state after is-caching.
- * Reread n_accesses after is-caching
- */
- trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
- n_accesses, why);
-}
-
-/**
- * fscache_begin_cookie_access - Pin a cache so data can be accessed
- * @cookie: A data file cookie
- * @why: An indication of the circumstances of the access for tracing
- *
- * Attempt to pin the cache to prevent it from going away whilst we're
- * accessing data and returns true if successful. This works as follows:
- *
- * (1) If the cookie is not being cached (ie. FSCACHE_COOKIE_IS_CACHING is not
- * set), we return false to indicate access was not permitted.
- *
- * (2) If the cookie is being cached, we increment its n_accesses count and
- * then recheck the IS_CACHING flag, ending the access if it got cleared.
- *
- * (3) When we end the access, we decrement the cookie's n_accesses and wake
- * up the any waiters if it reaches 0.
- *
- * (4) Whilst the cookie is actively being cached, its n_accesses is kept
- * artificially incremented to prevent wakeups from happening.
- *
- * (5) When the cache is taken offline or if the cookie is culled, the flag is
- * cleared to prevent new accesses, the cookie's n_accesses is decremented
- * and we wait for it to become 0.
- *
- * The @why indicator are merely provided for tracing purposes.
- */
-bool fscache_begin_cookie_access(struct fscache_cookie *cookie,
- enum fscache_access_trace why)
-{
- if (!test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags))
- return false;
- __fscache_begin_cookie_access(cookie, why);
- if (!test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags) ||
- !fscache_cache_is_live(cookie->volume->cache)) {
- fscache_end_cookie_access(cookie, fscache_access_unlive);
- return false;
- }
- return true;
-}
-
-static inline void wake_up_cookie_state(struct fscache_cookie *cookie)
-{
- /* Use a barrier to ensure that waiters see the state variable
- * change, as spin_unlock doesn't guarantee a barrier.
- *
- * See comments over wake_up_bit() and waitqueue_active().
- */
- smp_mb();
- wake_up_var(&cookie->state);
-}
-
-/*
- * Change the state a cookie is at and wake up anyone waiting for that. Impose
- * an ordering between the stuff stored in the cookie and the state member.
- * Paired with fscache_cookie_state().
- */
-static void __fscache_set_cookie_state(struct fscache_cookie *cookie,
- enum fscache_cookie_state state)
-{
- smp_store_release(&cookie->state, state);
-}
-
-static void fscache_set_cookie_state(struct fscache_cookie *cookie,
- enum fscache_cookie_state state)
-{
- spin_lock(&cookie->lock);
- __fscache_set_cookie_state(cookie, state);
- spin_unlock(&cookie->lock);
- wake_up_cookie_state(cookie);
-}
-
-/**
- * fscache_cookie_lookup_negative - Note negative lookup
- * @cookie: The cookie that was being looked up
- *
- * Note that some part of the metadata path in the cache doesn't exist and so
- * we can release any waiting readers in the certain knowledge that there's
- * nothing for them to actually read.
- *
- * This function uses no locking and must only be called from the state machine.
- */
-void fscache_cookie_lookup_negative(struct fscache_cookie *cookie)
-{
- set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
- fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_CREATING);
-}
-EXPORT_SYMBOL(fscache_cookie_lookup_negative);
-
-/**
- * fscache_resume_after_invalidation - Allow I/O to resume after invalidation
- * @cookie: The cookie that was invalidated
- *
- * Tell fscache that invalidation is sufficiently complete that I/O can be
- * allowed again.
- */
-void fscache_resume_after_invalidation(struct fscache_cookie *cookie)
-{
- fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);
-}
-EXPORT_SYMBOL(fscache_resume_after_invalidation);
-
-/**
- * fscache_caching_failed - Report that a failure stopped caching on a cookie
- * @cookie: The cookie that was affected
- *
- * Tell fscache that caching on a cookie needs to be stopped due to some sort
- * of failure.
- *
- * This function uses no locking and must only be called from the state machine.
- */
-void fscache_caching_failed(struct fscache_cookie *cookie)
-{
- clear_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags);
- fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_FAILED);
- trace_fscache_cookie(cookie->debug_id, refcount_read(&cookie->ref),
- fscache_cookie_failed);
-}
-EXPORT_SYMBOL(fscache_caching_failed);
-
-/*
- * Set the index key in a cookie. The cookie struct has space for a 16-byte
- * key plus length and hash, but if that's not big enough, it's instead a
- * pointer to a buffer containing 3 bytes of hash, 1 byte of length and then
- * the key data.
- */
-static int fscache_set_key(struct fscache_cookie *cookie,
- const void *index_key, size_t index_key_len)
-{
- void *buf;
- size_t buf_size;
-
- buf_size = round_up(index_key_len, sizeof(__le32));
-
- if (index_key_len > sizeof(cookie->inline_key)) {
- buf = kzalloc(buf_size, GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
- cookie->key = buf;
- } else {
- buf = cookie->inline_key;
- }
-
- memcpy(buf, index_key, index_key_len);
- cookie->key_hash = fscache_hash(cookie->volume->key_hash,
- buf, buf_size);
- return 0;
-}
-
-static bool fscache_cookie_same(const struct fscache_cookie *a,
- const struct fscache_cookie *b)
-{
- const void *ka, *kb;
-
- if (a->key_hash != b->key_hash ||
- a->volume != b->volume ||
- a->key_len != b->key_len)
- return false;
-
- if (a->key_len <= sizeof(a->inline_key)) {
- ka = &a->inline_key;
- kb = &b->inline_key;
- } else {
- ka = a->key;
- kb = b->key;
- }
- return memcmp(ka, kb, a->key_len) == 0;
-}
-
-static atomic_t fscache_cookie_debug_id = ATOMIC_INIT(1);
-
-/*
- * Allocate a cookie.
- */
-static struct fscache_cookie *fscache_alloc_cookie(
- struct fscache_volume *volume,
- u8 advice,
- const void *index_key, size_t index_key_len,
- const void *aux_data, size_t aux_data_len,
- loff_t object_size)
-{
- struct fscache_cookie *cookie;
-
- /* allocate and initialise a cookie */
- cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
- if (!cookie)
- return NULL;
- fscache_stat(&fscache_n_cookies);
-
- cookie->volume = volume;
- cookie->advice = advice;
- cookie->key_len = index_key_len;
- cookie->aux_len = aux_data_len;
- cookie->object_size = object_size;
- if (object_size == 0)
- __set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
-
- if (fscache_set_key(cookie, index_key, index_key_len) < 0)
- goto nomem;
-
- if (cookie->aux_len <= sizeof(cookie->inline_aux)) {
- memcpy(cookie->inline_aux, aux_data, cookie->aux_len);
- } else {
- cookie->aux = kmemdup(aux_data, cookie->aux_len, GFP_KERNEL);
- if (!cookie->aux)
- goto nomem;
- }
-
- refcount_set(&cookie->ref, 1);
- cookie->debug_id = atomic_inc_return(&fscache_cookie_debug_id);
- spin_lock_init(&cookie->lock);
- INIT_LIST_HEAD(&cookie->commit_link);
- INIT_WORK(&cookie->work, fscache_cookie_worker);
- __fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
-
- write_lock(&fscache_cookies_lock);
- list_add_tail(&cookie->proc_link, &fscache_cookies);
- write_unlock(&fscache_cookies_lock);
- fscache_see_cookie(cookie, fscache_cookie_new_acquire);
- return cookie;
-
-nomem:
- fscache_free_cookie(cookie);
- return NULL;
-}
-
-static inline bool fscache_cookie_is_dropped(struct fscache_cookie *cookie)
-{
- return READ_ONCE(cookie->state) == FSCACHE_COOKIE_STATE_DROPPED;
-}
-
-static void fscache_wait_on_collision(struct fscache_cookie *candidate,
- struct fscache_cookie *wait_for)
-{
- enum fscache_cookie_state *statep = &wait_for->state;
-
- wait_var_event_timeout(statep, fscache_cookie_is_dropped(wait_for),
- 20 * HZ);
- if (!fscache_cookie_is_dropped(wait_for)) {
- pr_notice("Potential collision c=%08x old: c=%08x",
- candidate->debug_id, wait_for->debug_id);
- wait_var_event(statep, fscache_cookie_is_dropped(wait_for));
- }
-}
-
-/*
- * Attempt to insert the new cookie into the hash. If there's a collision, we
- * wait for the old cookie to complete if it's being relinquished and an error
- * otherwise.
- */
-static bool fscache_hash_cookie(struct fscache_cookie *candidate)
-{
- struct fscache_cookie *cursor, *wait_for = NULL;
- struct hlist_bl_head *h;
- struct hlist_bl_node *p;
- unsigned int bucket;
-
- bucket = candidate->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
- h = &fscache_cookie_hash[bucket];
-
- hlist_bl_lock(h);
- hlist_bl_for_each_entry(cursor, p, h, hash_link) {
- if (fscache_cookie_same(candidate, cursor)) {
- if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cursor->flags))
- goto collision;
- wait_for = fscache_get_cookie(cursor,
- fscache_cookie_get_hash_collision);
- break;
- }
- }
-
- fscache_get_volume(candidate->volume, fscache_volume_get_cookie);
- atomic_inc(&candidate->volume->n_cookies);
- hlist_bl_add_head(&candidate->hash_link, h);
- set_bit(FSCACHE_COOKIE_IS_HASHED, &candidate->flags);
- hlist_bl_unlock(h);
-
- if (wait_for) {
- fscache_wait_on_collision(candidate, wait_for);
- fscache_put_cookie(wait_for, fscache_cookie_put_hash_collision);
- }
- return true;
-
-collision:
- trace_fscache_cookie(cursor->debug_id, refcount_read(&cursor->ref),
- fscache_cookie_collision);
- pr_err("Duplicate cookie detected\n");
- fscache_print_cookie(cursor, 'O');
- fscache_print_cookie(candidate, 'N');
- hlist_bl_unlock(h);
- return false;
-}
-
-/*
- * Request a cookie to represent a data storage object within a volume.
- *
- * We never let on to the netfs about errors. We may set a negative cookie
- * pointer, but that's okay
- */
-struct fscache_cookie *__fscache_acquire_cookie(
- struct fscache_volume *volume,
- u8 advice,
- const void *index_key, size_t index_key_len,
- const void *aux_data, size_t aux_data_len,
- loff_t object_size)
-{
- struct fscache_cookie *cookie;
-
- _enter("V=%x", volume->debug_id);
-
- if (!index_key || !index_key_len || index_key_len > 255 || aux_data_len > 255)
- return NULL;
- if (!aux_data || !aux_data_len) {
- aux_data = NULL;
- aux_data_len = 0;
- }
-
- fscache_stat(&fscache_n_acquires);
-
- cookie = fscache_alloc_cookie(volume, advice,
- index_key, index_key_len,
- aux_data, aux_data_len,
- object_size);
- if (!cookie) {
- fscache_stat(&fscache_n_acquires_oom);
- return NULL;
- }
-
- if (!fscache_hash_cookie(cookie)) {
- fscache_see_cookie(cookie, fscache_cookie_discard);
- fscache_free_cookie(cookie);
- return NULL;
- }
-
- trace_fscache_acquire(cookie);
- fscache_stat(&fscache_n_acquires_ok);
- _leave(" = c=%08x", cookie->debug_id);
- return cookie;
-}
-EXPORT_SYMBOL(__fscache_acquire_cookie);
-
-/*
- * Prepare a cache object to be written to.
- */
-static void fscache_prepare_to_write(struct fscache_cookie *cookie)
-{
- cookie->volume->cache->ops->prepare_to_write(cookie);
-}
-
-/*
- * Look up a cookie in the cache.
- */
-static void fscache_perform_lookup(struct fscache_cookie *cookie)
-{
- enum fscache_access_trace trace = fscache_access_lookup_cookie_end_failed;
- bool need_withdraw = false;
-
- _enter("");
-
- if (!cookie->volume->cache_priv) {
- fscache_create_volume(cookie->volume, true);
- if (!cookie->volume->cache_priv) {
- fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
- goto out;
- }
- }
-
- if (!cookie->volume->cache->ops->lookup_cookie(cookie)) {
- if (cookie->state != FSCACHE_COOKIE_STATE_FAILED)
- fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
- need_withdraw = true;
- _leave(" [fail]");
- goto out;
- }
-
- fscache_see_cookie(cookie, fscache_cookie_see_active);
- spin_lock(&cookie->lock);
- if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
- __fscache_set_cookie_state(cookie,
- FSCACHE_COOKIE_STATE_INVALIDATING);
- else
- __fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);
- spin_unlock(&cookie->lock);
- wake_up_cookie_state(cookie);
- trace = fscache_access_lookup_cookie_end;
-
-out:
- fscache_end_cookie_access(cookie, trace);
- if (need_withdraw)
- fscache_withdraw_cookie(cookie);
- fscache_end_volume_access(cookie->volume, cookie, trace);
-}
-
-/*
- * Begin the process of looking up a cookie. We offload the actual process to
- * a worker thread.
- */
-static bool fscache_begin_lookup(struct fscache_cookie *cookie, bool will_modify)
-{
- if (will_modify) {
- set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags);
- set_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
- }
- if (!fscache_begin_volume_access(cookie->volume, cookie,
- fscache_access_lookup_cookie))
- return false;
-
- __fscache_begin_cookie_access(cookie, fscache_access_lookup_cookie);
- __fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_LOOKING_UP);
- set_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags);
- set_bit(FSCACHE_COOKIE_HAS_BEEN_CACHED, &cookie->flags);
- return true;
-}
-
-/*
- * Start using the cookie for I/O. This prevents the backing object from being
- * reaped by VM pressure.
- */
-void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify)
-{
- enum fscache_cookie_state state;
- bool queue = false;
- int n_active;
-
- _enter("c=%08x", cookie->debug_id);
-
- if (WARN(test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
- "Trying to use relinquished cookie\n"))
- return;
-
- spin_lock(&cookie->lock);
-
- n_active = atomic_inc_return(&cookie->n_active);
- trace_fscache_active(cookie->debug_id, refcount_read(&cookie->ref),
- n_active, atomic_read(&cookie->n_accesses),
- will_modify ?
- fscache_active_use_modify : fscache_active_use);
-
-again:
- state = fscache_cookie_state(cookie);
- switch (state) {
- case FSCACHE_COOKIE_STATE_QUIESCENT:
- queue = fscache_begin_lookup(cookie, will_modify);
- break;
-
- case FSCACHE_COOKIE_STATE_LOOKING_UP:
- case FSCACHE_COOKIE_STATE_CREATING:
- if (will_modify)
- set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags);
- break;
- case FSCACHE_COOKIE_STATE_ACTIVE:
- case FSCACHE_COOKIE_STATE_INVALIDATING:
- if (will_modify &&
- !test_and_set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags)) {
- set_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
- queue = true;
- }
- /*
- * We could race with cookie_lru which may set LRU_DISCARD bit
- * but has yet to run the cookie state machine. If this happens
- * and another thread tries to use the cookie, clear LRU_DISCARD
- * so we don't end up withdrawing the cookie while in use.
- */
- if (test_and_clear_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags))
- fscache_see_cookie(cookie, fscache_cookie_see_lru_discard_clear);
- break;
-
- case FSCACHE_COOKIE_STATE_FAILED:
- case FSCACHE_COOKIE_STATE_WITHDRAWING:
- break;
-
- case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
- spin_unlock(&cookie->lock);
- wait_var_event(&cookie->state,
- fscache_cookie_state(cookie) !=
- FSCACHE_COOKIE_STATE_LRU_DISCARDING);
- spin_lock(&cookie->lock);
- goto again;
-
- case FSCACHE_COOKIE_STATE_DROPPED:
- case FSCACHE_COOKIE_STATE_RELINQUISHING:
- WARN(1, "Can't use cookie in state %u\n", state);
- break;
- }
-
- spin_unlock(&cookie->lock);
- if (queue)
- fscache_queue_cookie(cookie, fscache_cookie_get_use_work);
- _leave("");
-}
-EXPORT_SYMBOL(__fscache_use_cookie);
-
-static void fscache_unuse_cookie_locked(struct fscache_cookie *cookie)
-{
- clear_bit(FSCACHE_COOKIE_DISABLED, &cookie->flags);
- if (!test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags))
- return;
-
- cookie->unused_at = jiffies;
- spin_lock(&fscache_cookie_lru_lock);
- if (list_empty(&cookie->commit_link)) {
- fscache_get_cookie(cookie, fscache_cookie_get_lru);
- fscache_stat(&fscache_n_cookies_lru);
- }
- list_move_tail(&cookie->commit_link, &fscache_cookie_lru);
-
- spin_unlock(&fscache_cookie_lru_lock);
- timer_reduce(&fscache_cookie_lru_timer,
- jiffies + fscache_lru_cookie_timeout);
-}
-
-/*
- * Stop using the cookie for I/O.
- */
-void __fscache_unuse_cookie(struct fscache_cookie *cookie,
- const void *aux_data, const loff_t *object_size)
-{
- unsigned int debug_id = cookie->debug_id;
- unsigned int r = refcount_read(&cookie->ref);
- unsigned int a = atomic_read(&cookie->n_accesses);
- unsigned int c;
-
- if (aux_data || object_size)
- __fscache_update_cookie(cookie, aux_data, object_size);
-
- /* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
- c = atomic_fetch_add_unless(&cookie->n_active, -1, 1);
- if (c != 1) {
- trace_fscache_active(debug_id, r, c - 1, a, fscache_active_unuse);
- return;
- }
-
- spin_lock(&cookie->lock);
- r = refcount_read(&cookie->ref);
- a = atomic_read(&cookie->n_accesses);
- c = atomic_dec_return(&cookie->n_active);
- trace_fscache_active(debug_id, r, c, a, fscache_active_unuse);
- if (c == 0)
- fscache_unuse_cookie_locked(cookie);
- spin_unlock(&cookie->lock);
-}
-EXPORT_SYMBOL(__fscache_unuse_cookie);
-
-/*
- * Perform work upon the cookie, such as committing its cache state,
- * relinquishing it or withdrawing the backing cache. We're protected from the
- * cache going away under us as object withdrawal must come through this
- * non-reentrant work item.
- */
-static void fscache_cookie_state_machine(struct fscache_cookie *cookie)
-{
- enum fscache_cookie_state state;
- bool wake = false;
-
- _enter("c=%x", cookie->debug_id);
-
-again:
- spin_lock(&cookie->lock);
-again_locked:
- state = cookie->state;
- switch (state) {
- case FSCACHE_COOKIE_STATE_QUIESCENT:
- /* The QUIESCENT state is jumped to the LOOKING_UP state by
- * fscache_use_cookie().
- */
-
- if (atomic_read(&cookie->n_accesses) == 0 &&
- test_bit(FSCACHE_COOKIE_DO_RELINQUISH, &cookie->flags)) {
- __fscache_set_cookie_state(cookie,
- FSCACHE_COOKIE_STATE_RELINQUISHING);
- wake = true;
- goto again_locked;
- }
- break;
-
- case FSCACHE_COOKIE_STATE_LOOKING_UP:
- spin_unlock(&cookie->lock);
- fscache_init_access_gate(cookie);
- fscache_perform_lookup(cookie);
- goto again;
-
- case FSCACHE_COOKIE_STATE_INVALIDATING:
- spin_unlock(&cookie->lock);
- fscache_perform_invalidation(cookie);
- goto again;
-
- case FSCACHE_COOKIE_STATE_ACTIVE:
- if (test_and_clear_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags)) {
- spin_unlock(&cookie->lock);
- fscache_prepare_to_write(cookie);
- spin_lock(&cookie->lock);
- }
- if (test_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags)) {
- __fscache_set_cookie_state(cookie,
- FSCACHE_COOKIE_STATE_LRU_DISCARDING);
- wake = true;
- goto again_locked;
- }
- fallthrough;
-
- case FSCACHE_COOKIE_STATE_FAILED:
- if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
- fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
-
- if (atomic_read(&cookie->n_accesses) != 0)
- break;
- if (test_bit(FSCACHE_COOKIE_DO_RELINQUISH, &cookie->flags)) {
- __fscache_set_cookie_state(cookie,
- FSCACHE_COOKIE_STATE_RELINQUISHING);
- wake = true;
- goto again_locked;
- }
- if (test_bit(FSCACHE_COOKIE_DO_WITHDRAW, &cookie->flags)) {
- __fscache_set_cookie_state(cookie,
- FSCACHE_COOKIE_STATE_WITHDRAWING);
- wake = true;
- goto again_locked;
- }
- break;
-
- case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
- case FSCACHE_COOKIE_STATE_RELINQUISHING:
- case FSCACHE_COOKIE_STATE_WITHDRAWING:
- if (cookie->cache_priv) {
- spin_unlock(&cookie->lock);
- cookie->volume->cache->ops->withdraw_cookie(cookie);
- spin_lock(&cookie->lock);
- }
-
- if (test_and_clear_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
- fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
-
- switch (state) {
- case FSCACHE_COOKIE_STATE_RELINQUISHING:
- fscache_see_cookie(cookie, fscache_cookie_see_relinquish);
- fscache_unhash_cookie(cookie);
- __fscache_set_cookie_state(cookie,
- FSCACHE_COOKIE_STATE_DROPPED);
- wake = true;
- goto out;
- case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
- fscache_see_cookie(cookie, fscache_cookie_see_lru_discard);
- break;
- case FSCACHE_COOKIE_STATE_WITHDRAWING:
- fscache_see_cookie(cookie, fscache_cookie_see_withdraw);
- break;
- default:
- BUG();
- }
-
- clear_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
- clear_bit(FSCACHE_COOKIE_DO_WITHDRAW, &cookie->flags);
- clear_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags);
- clear_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
- set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
- __fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_QUIESCENT);
- wake = true;
- goto again_locked;
-
- case FSCACHE_COOKIE_STATE_DROPPED:
- break;
-
- default:
- WARN_ONCE(1, "Cookie %x in unexpected state %u\n",
- cookie->debug_id, state);
- break;
- }
-
-out:
- spin_unlock(&cookie->lock);
- if (wake)
- wake_up_cookie_state(cookie);
- _leave("");
-}
-
-static void fscache_cookie_worker(struct work_struct *work)
-{
- struct fscache_cookie *cookie = container_of(work, struct fscache_cookie, work);
-
- fscache_see_cookie(cookie, fscache_cookie_see_work);
- fscache_cookie_state_machine(cookie);
- fscache_put_cookie(cookie, fscache_cookie_put_work);
-}
-
-/*
- * Wait for the object to become inactive. The cookie's work item will be
- * scheduled when someone transitions n_accesses to 0 - but if someone's
- * already done that, schedule it anyway.
- */
-static void __fscache_withdraw_cookie(struct fscache_cookie *cookie)
-{
- int n_accesses;
- bool unpinned;
-
- unpinned = test_and_clear_bit(FSCACHE_COOKIE_NO_ACCESS_WAKE, &cookie->flags);
-
- /* Need to read the access count after unpinning */
- n_accesses = atomic_read(&cookie->n_accesses);
- if (unpinned)
- trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
- n_accesses, fscache_access_cache_unpin);
- if (n_accesses == 0)
- fscache_queue_cookie(cookie, fscache_cookie_get_end_access);
-}
-
-static void fscache_cookie_lru_do_one(struct fscache_cookie *cookie)
-{
- fscache_see_cookie(cookie, fscache_cookie_see_lru_do_one);
-
- spin_lock(&cookie->lock);
- if (cookie->state != FSCACHE_COOKIE_STATE_ACTIVE ||
- time_before(jiffies, cookie->unused_at + fscache_lru_cookie_timeout) ||
- atomic_read(&cookie->n_active) > 0) {
- spin_unlock(&cookie->lock);
- fscache_stat(&fscache_n_cookies_lru_removed);
- } else {
- set_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags);
- spin_unlock(&cookie->lock);
- fscache_stat(&fscache_n_cookies_lru_expired);
- _debug("lru c=%x", cookie->debug_id);
- __fscache_withdraw_cookie(cookie);
- }
-
- fscache_put_cookie(cookie, fscache_cookie_put_lru);
-}
-
-static void fscache_cookie_lru_worker(struct work_struct *work)
-{
- struct fscache_cookie *cookie;
- unsigned long unused_at;
-
- spin_lock(&fscache_cookie_lru_lock);
-
- while (!list_empty(&fscache_cookie_lru)) {
- cookie = list_first_entry(&fscache_cookie_lru,
- struct fscache_cookie, commit_link);
- unused_at = cookie->unused_at + fscache_lru_cookie_timeout;
- if (time_before(jiffies, unused_at)) {
- timer_reduce(&fscache_cookie_lru_timer, unused_at);
- break;
- }
-
- list_del_init(&cookie->commit_link);
- fscache_stat_d(&fscache_n_cookies_lru);
- spin_unlock(&fscache_cookie_lru_lock);
- fscache_cookie_lru_do_one(cookie);
- spin_lock(&fscache_cookie_lru_lock);
- }
-
- spin_unlock(&fscache_cookie_lru_lock);
-}
-
-static void fscache_cookie_lru_timed_out(struct timer_list *timer)
-{
- queue_work(fscache_wq, &fscache_cookie_lru_work);
-}
-
-static void fscache_cookie_drop_from_lru(struct fscache_cookie *cookie)
-{
- bool need_put = false;
-
- if (!list_empty(&cookie->commit_link)) {
- spin_lock(&fscache_cookie_lru_lock);
- if (!list_empty(&cookie->commit_link)) {
- list_del_init(&cookie->commit_link);
- fscache_stat_d(&fscache_n_cookies_lru);
- fscache_stat(&fscache_n_cookies_lru_dropped);
- need_put = true;
- }
- spin_unlock(&fscache_cookie_lru_lock);
- if (need_put)
- fscache_put_cookie(cookie, fscache_cookie_put_lru);
- }
-}
-
-/*
- * Remove a cookie from the hash table.
- */
-static void fscache_unhash_cookie(struct fscache_cookie *cookie)
-{
- struct hlist_bl_head *h;
- unsigned int bucket;
-
- bucket = cookie->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
- h = &fscache_cookie_hash[bucket];
-
- hlist_bl_lock(h);
- hlist_bl_del(&cookie->hash_link);
- clear_bit(FSCACHE_COOKIE_IS_HASHED, &cookie->flags);
- hlist_bl_unlock(h);
- fscache_stat(&fscache_n_relinquishes_dropped);
-}
-
-static void fscache_drop_withdraw_cookie(struct fscache_cookie *cookie)
-{
- fscache_cookie_drop_from_lru(cookie);
- __fscache_withdraw_cookie(cookie);
-}
-
-/**
- * fscache_withdraw_cookie - Mark a cookie for withdrawal
- * @cookie: The cookie to be withdrawn.
- *
- * Allow the cache backend to withdraw the backing for a cookie for its own
- * reasons, even if that cookie is in active use.
- */
-void fscache_withdraw_cookie(struct fscache_cookie *cookie)
-{
- set_bit(FSCACHE_COOKIE_DO_WITHDRAW, &cookie->flags);
- fscache_drop_withdraw_cookie(cookie);
-}
-EXPORT_SYMBOL(fscache_withdraw_cookie);
-
-/*
- * Allow the netfs to release a cookie back to the cache.
- * - the object will be marked as recyclable on disk if retire is true
- */
-void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
-{
- fscache_stat(&fscache_n_relinquishes);
- if (retire)
- fscache_stat(&fscache_n_relinquishes_retire);
-
- _enter("c=%08x{%d},%d",
- cookie->debug_id, atomic_read(&cookie->n_active), retire);
-
- if (WARN(test_and_set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
- "Cookie c=%x already relinquished\n", cookie->debug_id))
- return;
-
- if (retire)
- set_bit(FSCACHE_COOKIE_RETIRED, &cookie->flags);
- trace_fscache_relinquish(cookie, retire);
-
- ASSERTCMP(atomic_read(&cookie->n_active), ==, 0);
- ASSERTCMP(atomic_read(&cookie->volume->n_cookies), >, 0);
- atomic_dec(&cookie->volume->n_cookies);
-
- if (test_bit(FSCACHE_COOKIE_HAS_BEEN_CACHED, &cookie->flags)) {
- set_bit(FSCACHE_COOKIE_DO_RELINQUISH, &cookie->flags);
- fscache_drop_withdraw_cookie(cookie);
- } else {
- fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_DROPPED);
- fscache_unhash_cookie(cookie);
- }
- fscache_put_cookie(cookie, fscache_cookie_put_relinquish);
-}
-EXPORT_SYMBOL(__fscache_relinquish_cookie);
-
-/*
- * Drop a reference to a cookie.
- */
-void fscache_put_cookie(struct fscache_cookie *cookie,
- enum fscache_cookie_trace where)
-{
- struct fscache_volume *volume = cookie->volume;
- unsigned int cookie_debug_id = cookie->debug_id;
- bool zero;
- int ref;
-
- zero = __refcount_dec_and_test(&cookie->ref, &ref);
- trace_fscache_cookie(cookie_debug_id, ref - 1, where);
- if (zero) {
- fscache_free_cookie(cookie);
- fscache_put_volume(volume, fscache_volume_put_cookie);
- }
-}
-EXPORT_SYMBOL(fscache_put_cookie);
-
-/*
- * Get a reference to a cookie.
- */
-struct fscache_cookie *fscache_get_cookie(struct fscache_cookie *cookie,
- enum fscache_cookie_trace where)
-{
- int ref;
-
- __refcount_inc(&cookie->ref, &ref);
- trace_fscache_cookie(cookie->debug_id, ref + 1, where);
- return cookie;
-}
-EXPORT_SYMBOL(fscache_get_cookie);
-
-/*
- * Ask the cache to effect invalidation of a cookie.
- */
-static void fscache_perform_invalidation(struct fscache_cookie *cookie)
-{
- if (!cookie->volume->cache->ops->invalidate_cookie(cookie))
- fscache_caching_failed(cookie);
- fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
-}
-
-/*
- * Invalidate an object.
- */
-void __fscache_invalidate(struct fscache_cookie *cookie,
- const void *aux_data, loff_t new_size,
- unsigned int flags)
-{
- bool is_caching;
-
- _enter("c=%x", cookie->debug_id);
-
- fscache_stat(&fscache_n_invalidates);
-
- if (WARN(test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
- "Trying to invalidate relinquished cookie\n"))
- return;
-
- if ((flags & FSCACHE_INVAL_DIO_WRITE) &&
- test_and_set_bit(FSCACHE_COOKIE_DISABLED, &cookie->flags))
- return;
-
- spin_lock(&cookie->lock);
- set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
- fscache_update_aux(cookie, aux_data, &new_size);
- cookie->inval_counter++;
- trace_fscache_invalidate(cookie, new_size);
-
- switch (cookie->state) {
- case FSCACHE_COOKIE_STATE_INVALIDATING: /* is_still_valid will catch it */
- default:
- spin_unlock(&cookie->lock);
- _leave(" [no %u]", cookie->state);
- return;
-
- case FSCACHE_COOKIE_STATE_LOOKING_UP:
- if (!test_and_set_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags))
- __fscache_begin_cookie_access(cookie, fscache_access_invalidate_cookie);
- fallthrough;
- case FSCACHE_COOKIE_STATE_CREATING:
- spin_unlock(&cookie->lock);
- _leave(" [look %x]", cookie->inval_counter);
- return;
-
- case FSCACHE_COOKIE_STATE_ACTIVE:
- is_caching = fscache_begin_cookie_access(
- cookie, fscache_access_invalidate_cookie);
- if (is_caching)
- __fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_INVALIDATING);
- spin_unlock(&cookie->lock);
- wake_up_cookie_state(cookie);
-
- if (is_caching)
- fscache_queue_cookie(cookie, fscache_cookie_get_inval_work);
- _leave(" [inv]");
- return;
- }
-}
-EXPORT_SYMBOL(__fscache_invalidate);
-
-#ifdef CONFIG_PROC_FS
-/*
- * Generate a list of extant cookies in /proc/fs/fscache/cookies
- */
-static int fscache_cookies_seq_show(struct seq_file *m, void *v)
-{
- struct fscache_cookie *cookie;
- unsigned int keylen = 0, auxlen = 0;
- u8 *p;
-
- if (v == &fscache_cookies) {
- seq_puts(m,
- "COOKIE VOLUME REF ACT ACC S FL DEF \n"
- "======== ======== === === === = == ================\n"
- );
- return 0;
- }
-
- cookie = list_entry(v, struct fscache_cookie, proc_link);
-
- seq_printf(m,
- "%08x %08x %3d %3d %3d %c %02lx",
- cookie->debug_id,
- cookie->volume->debug_id,
- refcount_read(&cookie->ref),
- atomic_read(&cookie->n_active),
- atomic_read(&cookie->n_accesses),
- fscache_cookie_states[cookie->state],
- cookie->flags);
-
- keylen = cookie->key_len;
- auxlen = cookie->aux_len;
-
- if (keylen > 0 || auxlen > 0) {
- seq_puts(m, " ");
- p = keylen <= sizeof(cookie->inline_key) ?
- cookie->inline_key : cookie->key;
- for (; keylen > 0; keylen--)
- seq_printf(m, "%02x", *p++);
- if (auxlen > 0) {
- seq_puts(m, ", ");
- p = auxlen <= sizeof(cookie->inline_aux) ?
- cookie->inline_aux : cookie->aux;
- for (; auxlen > 0; auxlen--)
- seq_printf(m, "%02x", *p++);
- }
- }
-
- seq_puts(m, "\n");
- return 0;
-}
-
-static void *fscache_cookies_seq_start(struct seq_file *m, loff_t *_pos)
- __acquires(fscache_cookies_lock)
-{
- read_lock(&fscache_cookies_lock);
- return seq_list_start_head(&fscache_cookies, *_pos);
-}
-
-static void *fscache_cookies_seq_next(struct seq_file *m, void *v, loff_t *_pos)
-{
- return seq_list_next(v, &fscache_cookies, _pos);
-}
-
-static void fscache_cookies_seq_stop(struct seq_file *m, void *v)
- __releases(rcu)
-{
- read_unlock(&fscache_cookies_lock);
-}
-
-
-const struct seq_operations fscache_cookies_seq_ops = {
- .start = fscache_cookies_seq_start,
- .next = fscache_cookies_seq_next,
- .stop = fscache_cookies_seq_stop,
- .show = fscache_cookies_seq_show,
-};
-#endif
projects / linux-2.6-microblaze.git / blobdiff