// SPDX-License-Identifier: GPL-2.0-or-later
/* netfs cookie management
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells ([email protected])
*
* 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)) {
if (atomic_read(&cookie->n_accesses) != 0)
/* still being accessed: postpone it */
break;
__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
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