summaryrefslogtreecommitdiffstats
path: root/fs/fscache
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /fs/fscache
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/fscache')
-rw-r--r--fs/fscache/Kconfig40
-rw-r--r--fs/fscache/Makefile16
-rw-r--r--fs/fscache/cache.c429
-rw-r--r--fs/fscache/cookie.c1180
-rw-r--r--fs/fscache/internal.h277
-rw-r--r--fs/fscache/io.c327
-rw-r--r--fs/fscache/main.c121
-rw-r--r--fs/fscache/proc.c54
-rw-r--r--fs/fscache/stats.c102
-rw-r--r--fs/fscache/volume.c520
10 files changed, 3066 insertions, 0 deletions
diff --git a/fs/fscache/Kconfig b/fs/fscache/Kconfig
new file mode 100644
index 000000000..b313a978a
--- /dev/null
+++ b/fs/fscache/Kconfig
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config FSCACHE
+ tristate "General filesystem local caching manager"
+ select NETFS_SUPPORT
+ help
+ This option enables a generic filesystem caching manager that can be
+ used by various network and other filesystems to cache data locally.
+ Different sorts of caches can be plugged in, depending on the
+ resources available.
+
+ See Documentation/filesystems/caching/fscache.rst for more information.
+
+config FSCACHE_STATS
+ bool "Gather statistical information on local caching"
+ depends on FSCACHE && PROC_FS
+ select NETFS_STATS
+ help
+ This option causes statistical information to be gathered on local
+ caching and exported through file:
+
+ /proc/fs/fscache/stats
+
+ The gathering of statistics adds a certain amount of overhead to
+ execution as there are a quite a few stats gathered, and on a
+ multi-CPU system these may be on cachelines that keep bouncing
+ between CPUs. On the other hand, the stats are very useful for
+ debugging purposes. Saying 'Y' here is recommended.
+
+ See Documentation/filesystems/caching/fscache.rst for more information.
+
+config FSCACHE_DEBUG
+ bool "Debug FS-Cache"
+ depends on FSCACHE
+ help
+ This permits debugging to be dynamically enabled in the local caching
+ management module. If this is set, the debugging output may be
+ enabled by setting bits in /sys/modules/fscache/parameter/debug.
+
+ See Documentation/filesystems/caching/fscache.rst for more information.
diff --git a/fs/fscache/Makefile b/fs/fscache/Makefile
new file mode 100644
index 000000000..afb090ea1
--- /dev/null
+++ b/fs/fscache/Makefile
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for general filesystem caching code
+#
+
+fscache-y := \
+ cache.o \
+ cookie.o \
+ io.o \
+ main.o \
+ volume.o
+
+fscache-$(CONFIG_PROC_FS) += proc.o
+fscache-$(CONFIG_FSCACHE_STATS) += stats.o
+
+obj-$(CONFIG_FSCACHE) := fscache.o
diff --git a/fs/fscache/cache.c b/fs/fscache/cache.c
new file mode 100644
index 000000000..9397ed39b
--- /dev/null
+++ b/fs/fscache/cache.c
@@ -0,0 +1,429 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* FS-Cache cache handling
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define FSCACHE_DEBUG_LEVEL CACHE
+#include <linux/export.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+static LIST_HEAD(fscache_caches);
+DECLARE_RWSEM(fscache_addremove_sem);
+EXPORT_SYMBOL(fscache_addremove_sem);
+DECLARE_WAIT_QUEUE_HEAD(fscache_clearance_waiters);
+EXPORT_SYMBOL(fscache_clearance_waiters);
+
+static atomic_t fscache_cache_debug_id;
+
+/*
+ * Allocate a cache cookie.
+ */
+static struct fscache_cache *fscache_alloc_cache(const char *name)
+{
+ struct fscache_cache *cache;
+
+ cache = kzalloc(sizeof(*cache), GFP_KERNEL);
+ if (cache) {
+ if (name) {
+ cache->name = kstrdup(name, GFP_KERNEL);
+ if (!cache->name) {
+ kfree(cache);
+ return NULL;
+ }
+ }
+ refcount_set(&cache->ref, 1);
+ INIT_LIST_HEAD(&cache->cache_link);
+ cache->debug_id = atomic_inc_return(&fscache_cache_debug_id);
+ }
+ return cache;
+}
+
+static bool fscache_get_cache_maybe(struct fscache_cache *cache,
+ enum fscache_cache_trace where)
+{
+ bool success;
+ int ref;
+
+ success = __refcount_inc_not_zero(&cache->ref, &ref);
+ if (success)
+ trace_fscache_cache(cache->debug_id, ref + 1, where);
+ return success;
+}
+
+/*
+ * Look up a cache cookie.
+ */
+struct fscache_cache *fscache_lookup_cache(const char *name, bool is_cache)
+{
+ struct fscache_cache *candidate, *cache, *unnamed = NULL;
+
+ /* firstly check for the existence of the cache under read lock */
+ down_read(&fscache_addremove_sem);
+
+ list_for_each_entry(cache, &fscache_caches, cache_link) {
+ if (cache->name && name && strcmp(cache->name, name) == 0 &&
+ fscache_get_cache_maybe(cache, fscache_cache_get_acquire))
+ goto got_cache_r;
+ if (!cache->name && !name &&
+ fscache_get_cache_maybe(cache, fscache_cache_get_acquire))
+ goto got_cache_r;
+ }
+
+ if (!name) {
+ list_for_each_entry(cache, &fscache_caches, cache_link) {
+ if (cache->name &&
+ fscache_get_cache_maybe(cache, fscache_cache_get_acquire))
+ goto got_cache_r;
+ }
+ }
+
+ up_read(&fscache_addremove_sem);
+
+ /* the cache does not exist - create a candidate */
+ candidate = fscache_alloc_cache(name);
+ if (!candidate)
+ return ERR_PTR(-ENOMEM);
+
+ /* write lock, search again and add if still not present */
+ down_write(&fscache_addremove_sem);
+
+ list_for_each_entry(cache, &fscache_caches, cache_link) {
+ if (cache->name && name && strcmp(cache->name, name) == 0 &&
+ fscache_get_cache_maybe(cache, fscache_cache_get_acquire))
+ goto got_cache_w;
+ if (!cache->name) {
+ unnamed = cache;
+ if (!name &&
+ fscache_get_cache_maybe(cache, fscache_cache_get_acquire))
+ goto got_cache_w;
+ }
+ }
+
+ if (unnamed && is_cache &&
+ fscache_get_cache_maybe(unnamed, fscache_cache_get_acquire))
+ goto use_unnamed_cache;
+
+ if (!name) {
+ list_for_each_entry(cache, &fscache_caches, cache_link) {
+ if (cache->name &&
+ fscache_get_cache_maybe(cache, fscache_cache_get_acquire))
+ goto got_cache_w;
+ }
+ }
+
+ list_add_tail(&candidate->cache_link, &fscache_caches);
+ trace_fscache_cache(candidate->debug_id,
+ refcount_read(&candidate->ref),
+ fscache_cache_new_acquire);
+ up_write(&fscache_addremove_sem);
+ return candidate;
+
+got_cache_r:
+ up_read(&fscache_addremove_sem);
+ return cache;
+use_unnamed_cache:
+ cache = unnamed;
+ cache->name = candidate->name;
+ candidate->name = NULL;
+got_cache_w:
+ up_write(&fscache_addremove_sem);
+ kfree(candidate->name);
+ kfree(candidate);
+ return cache;
+}
+
+/**
+ * fscache_acquire_cache - Acquire a cache-level cookie.
+ * @name: The name of the cache.
+ *
+ * Get a cookie to represent an actual cache. If a name is given and there is
+ * a nameless cache record available, this will acquire that and set its name,
+ * directing all the volumes using it to this cache.
+ *
+ * The cache will be switched over to the preparing state if not currently in
+ * use, otherwise -EBUSY will be returned.
+ */
+struct fscache_cache *fscache_acquire_cache(const char *name)
+{
+ struct fscache_cache *cache;
+
+ ASSERT(name);
+ cache = fscache_lookup_cache(name, true);
+ if (IS_ERR(cache))
+ return cache;
+
+ if (!fscache_set_cache_state_maybe(cache,
+ FSCACHE_CACHE_IS_NOT_PRESENT,
+ FSCACHE_CACHE_IS_PREPARING)) {
+ pr_warn("Cache tag %s in use\n", name);
+ fscache_put_cache(cache, fscache_cache_put_cache);
+ return ERR_PTR(-EBUSY);
+ }
+
+ return cache;
+}
+EXPORT_SYMBOL(fscache_acquire_cache);
+
+/**
+ * fscache_put_cache - Release a cache-level cookie.
+ * @cache: The cache cookie to be released
+ * @where: An indication of where the release happened
+ *
+ * Release the caller's reference on a cache-level cookie. The @where
+ * indication should give information about the circumstances in which the call
+ * occurs and will be logged through a tracepoint.
+ */
+void fscache_put_cache(struct fscache_cache *cache,
+ enum fscache_cache_trace where)
+{
+ unsigned int debug_id;
+ bool zero;
+ int ref;
+
+ if (IS_ERR_OR_NULL(cache))
+ return;
+
+ debug_id = cache->debug_id;
+ zero = __refcount_dec_and_test(&cache->ref, &ref);
+ trace_fscache_cache(debug_id, ref - 1, where);
+
+ if (zero) {
+ down_write(&fscache_addremove_sem);
+ list_del_init(&cache->cache_link);
+ up_write(&fscache_addremove_sem);
+ kfree(cache->name);
+ kfree(cache);
+ }
+}
+
+/**
+ * fscache_relinquish_cache - Reset cache state and release cookie
+ * @cache: The cache cookie to be released
+ *
+ * Reset the state of a cache and release the caller's reference on a cache
+ * cookie.
+ */
+void fscache_relinquish_cache(struct fscache_cache *cache)
+{
+ enum fscache_cache_trace where =
+ (cache->state == FSCACHE_CACHE_IS_PREPARING) ?
+ fscache_cache_put_prep_failed :
+ fscache_cache_put_relinquish;
+
+ cache->ops = NULL;
+ cache->cache_priv = NULL;
+ fscache_set_cache_state(cache, FSCACHE_CACHE_IS_NOT_PRESENT);
+ fscache_put_cache(cache, where);
+}
+EXPORT_SYMBOL(fscache_relinquish_cache);
+
+/**
+ * fscache_add_cache - Declare a cache as being open for business
+ * @cache: The cache-level cookie representing the cache
+ * @ops: Table of cache operations to use
+ * @cache_priv: Private data for the cache record
+ *
+ * Add a cache to the system, making it available for netfs's to use.
+ *
+ * See Documentation/filesystems/caching/backend-api.rst for a complete
+ * description.
+ */
+int fscache_add_cache(struct fscache_cache *cache,
+ const struct fscache_cache_ops *ops,
+ void *cache_priv)
+{
+ int n_accesses;
+
+ _enter("{%s,%s}", ops->name, cache->name);
+
+ BUG_ON(fscache_cache_state(cache) != FSCACHE_CACHE_IS_PREPARING);
+
+ /* Get a ref on the cache cookie and keep its n_accesses counter raised
+ * by 1 to prevent wakeups from transitioning it to 0 until we're
+ * withdrawing caching services from it.
+ */
+ n_accesses = atomic_inc_return(&cache->n_accesses);
+ trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),
+ n_accesses, fscache_access_cache_pin);
+
+ down_write(&fscache_addremove_sem);
+
+ cache->ops = ops;
+ cache->cache_priv = cache_priv;
+ fscache_set_cache_state(cache, FSCACHE_CACHE_IS_ACTIVE);
+
+ up_write(&fscache_addremove_sem);
+ pr_notice("Cache \"%s\" added (type %s)\n", cache->name, ops->name);
+ _leave(" = 0 [%s]", cache->name);
+ return 0;
+}
+EXPORT_SYMBOL(fscache_add_cache);
+
+/**
+ * fscache_begin_cache_access - Pin a cache so it can be accessed
+ * @cache: The cache-level 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 it and returns true if successful. This works as follows:
+ *
+ * (1) If the cache tests as not live (state is not FSCACHE_CACHE_IS_ACTIVE),
+ * then we return false to indicate access was not permitted.
+ *
+ * (2) If the cache tests as live, then we increment the n_accesses count and
+ * then recheck the liveness, ending the access if it ceased to be live.
+ *
+ * (3) When we end the access, we decrement n_accesses and wake up the any
+ * waiters if it reaches 0.
+ *
+ * (4) Whilst the cache is caching, n_accesses is kept artificially
+ * incremented to prevent wakeups from happening.
+ *
+ * (5) When the cache is taken offline, the state is changed to prevent new
+ * accesses, n_accesses is decremented and we wait for n_accesses to
+ * become 0.
+ */
+bool fscache_begin_cache_access(struct fscache_cache *cache, enum fscache_access_trace why)
+{
+ int n_accesses;
+
+ if (!fscache_cache_is_live(cache))
+ return false;
+
+ n_accesses = atomic_inc_return(&cache->n_accesses);
+ smp_mb__after_atomic(); /* Reread live flag after n_accesses */
+ trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),
+ n_accesses, why);
+ if (!fscache_cache_is_live(cache)) {
+ fscache_end_cache_access(cache, fscache_access_unlive);
+ return false;
+ }
+ return true;
+}
+
+/**
+ * fscache_end_cache_access - Unpin a cache at the end of an access.
+ * @cache: The cache-level cookie
+ * @why: An indication of the circumstances of the access for tracing
+ *
+ * Unpin a cache after we've accessed it. The @why indicator is merely
+ * provided for tracing purposes.
+ */
+void fscache_end_cache_access(struct fscache_cache *cache, enum fscache_access_trace why)
+{
+ int n_accesses;
+
+ smp_mb__before_atomic();
+ n_accesses = atomic_dec_return(&cache->n_accesses);
+ trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),
+ n_accesses, why);
+ if (n_accesses == 0)
+ wake_up_var(&cache->n_accesses);
+}
+
+/**
+ * fscache_io_error - Note a cache I/O error
+ * @cache: The record describing the cache
+ *
+ * Note that an I/O error occurred in a cache and that it should no longer be
+ * used for anything. This also reports the error into the kernel log.
+ *
+ * See Documentation/filesystems/caching/backend-api.rst for a complete
+ * description.
+ */
+void fscache_io_error(struct fscache_cache *cache)
+{
+ if (fscache_set_cache_state_maybe(cache,
+ FSCACHE_CACHE_IS_ACTIVE,
+ FSCACHE_CACHE_GOT_IOERROR))
+ pr_err("Cache '%s' stopped due to I/O error\n",
+ cache->name);
+}
+EXPORT_SYMBOL(fscache_io_error);
+
+/**
+ * fscache_withdraw_cache - Withdraw a cache from the active service
+ * @cache: The cache cookie
+ *
+ * Begin the process of withdrawing a cache from service. This stops new
+ * cache-level and volume-level accesses from taking place and waits for
+ * currently ongoing cache-level accesses to end.
+ */
+void fscache_withdraw_cache(struct fscache_cache *cache)
+{
+ int n_accesses;
+
+ pr_notice("Withdrawing cache \"%s\" (%u objs)\n",
+ cache->name, atomic_read(&cache->object_count));
+
+ fscache_set_cache_state(cache, FSCACHE_CACHE_IS_WITHDRAWN);
+
+ /* Allow wakeups on dec-to-0 */
+ n_accesses = atomic_dec_return(&cache->n_accesses);
+ trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref),
+ n_accesses, fscache_access_cache_unpin);
+
+ wait_var_event(&cache->n_accesses,
+ atomic_read(&cache->n_accesses) == 0);
+}
+EXPORT_SYMBOL(fscache_withdraw_cache);
+
+#ifdef CONFIG_PROC_FS
+static const char fscache_cache_states[NR__FSCACHE_CACHE_STATE] = "-PAEW";
+
+/*
+ * Generate a list of caches in /proc/fs/fscache/caches
+ */
+static int fscache_caches_seq_show(struct seq_file *m, void *v)
+{
+ struct fscache_cache *cache;
+
+ if (v == &fscache_caches) {
+ seq_puts(m,
+ "CACHE REF VOLS OBJS ACCES S NAME\n"
+ "======== ===== ===== ===== ===== = ===============\n"
+ );
+ return 0;
+ }
+
+ cache = list_entry(v, struct fscache_cache, cache_link);
+ seq_printf(m,
+ "%08x %5d %5d %5d %5d %c %s\n",
+ cache->debug_id,
+ refcount_read(&cache->ref),
+ atomic_read(&cache->n_volumes),
+ atomic_read(&cache->object_count),
+ atomic_read(&cache->n_accesses),
+ fscache_cache_states[cache->state],
+ cache->name ?: "-");
+ return 0;
+}
+
+static void *fscache_caches_seq_start(struct seq_file *m, loff_t *_pos)
+ __acquires(fscache_addremove_sem)
+{
+ down_read(&fscache_addremove_sem);
+ return seq_list_start_head(&fscache_caches, *_pos);
+}
+
+static void *fscache_caches_seq_next(struct seq_file *m, void *v, loff_t *_pos)
+{
+ return seq_list_next(v, &fscache_caches, _pos);
+}
+
+static void fscache_caches_seq_stop(struct seq_file *m, void *v)
+ __releases(fscache_addremove_sem)
+{
+ up_read(&fscache_addremove_sem);
+}
+
+const struct seq_operations fscache_caches_seq_ops = {
+ .start = fscache_caches_seq_start,
+ .next = fscache_caches_seq_next,
+ .stop = fscache_caches_seq_stop,
+ .show = fscache_caches_seq_show,
+};
+#endif /* CONFIG_PROC_FS */
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
new file mode 100644
index 000000000..bce249218
--- /dev/null
+++ b/fs/fscache/cookie.c
@@ -0,0 +1,1180 @@
+// 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
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
new file mode 100644
index 000000000..1336f517e
--- /dev/null
+++ b/fs/fscache/internal.h
@@ -0,0 +1,277 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Internal definitions for FS-Cache
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifdef pr_fmt
+#undef pr_fmt
+#endif
+
+#define pr_fmt(fmt) "FS-Cache: " fmt
+
+#include <linux/slab.h>
+#include <linux/fscache-cache.h>
+#include <trace/events/fscache.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+
+/*
+ * cache.c
+ */
+#ifdef CONFIG_PROC_FS
+extern const struct seq_operations fscache_caches_seq_ops;
+#endif
+bool fscache_begin_cache_access(struct fscache_cache *cache, enum fscache_access_trace why);
+void fscache_end_cache_access(struct fscache_cache *cache, enum fscache_access_trace why);
+struct fscache_cache *fscache_lookup_cache(const char *name, bool is_cache);
+void fscache_put_cache(struct fscache_cache *cache, enum fscache_cache_trace where);
+
+static inline enum fscache_cache_state fscache_cache_state(const struct fscache_cache *cache)
+{
+ return smp_load_acquire(&cache->state);
+}
+
+static inline bool fscache_cache_is_live(const struct fscache_cache *cache)
+{
+ return fscache_cache_state(cache) == FSCACHE_CACHE_IS_ACTIVE;
+}
+
+static inline void fscache_set_cache_state(struct fscache_cache *cache,
+ enum fscache_cache_state new_state)
+{
+ smp_store_release(&cache->state, new_state);
+
+}
+
+static inline bool fscache_set_cache_state_maybe(struct fscache_cache *cache,
+ enum fscache_cache_state old_state,
+ enum fscache_cache_state new_state)
+{
+ return try_cmpxchg_release(&cache->state, &old_state, new_state);
+}
+
+/*
+ * cookie.c
+ */
+extern struct kmem_cache *fscache_cookie_jar;
+#ifdef CONFIG_PROC_FS
+extern const struct seq_operations fscache_cookies_seq_ops;
+#endif
+extern struct timer_list fscache_cookie_lru_timer;
+
+extern void fscache_print_cookie(struct fscache_cookie *cookie, char prefix);
+extern bool fscache_begin_cookie_access(struct fscache_cookie *cookie,
+ enum fscache_access_trace why);
+
+static inline void fscache_see_cookie(struct fscache_cookie *cookie,
+ enum fscache_cookie_trace where)
+{
+ trace_fscache_cookie(cookie->debug_id, refcount_read(&cookie->ref),
+ where);
+}
+
+/*
+ * main.c
+ */
+extern unsigned fscache_debug;
+
+extern unsigned int fscache_hash(unsigned int salt, const void *data, size_t len);
+
+/*
+ * proc.c
+ */
+#ifdef CONFIG_PROC_FS
+extern int __init fscache_proc_init(void);
+extern void fscache_proc_cleanup(void);
+#else
+#define fscache_proc_init() (0)
+#define fscache_proc_cleanup() do {} while (0)
+#endif
+
+/*
+ * stats.c
+ */
+#ifdef CONFIG_FSCACHE_STATS
+extern atomic_t fscache_n_volumes;
+extern atomic_t fscache_n_volumes_collision;
+extern atomic_t fscache_n_volumes_nomem;
+extern atomic_t fscache_n_cookies;
+extern atomic_t fscache_n_cookies_lru;
+extern atomic_t fscache_n_cookies_lru_expired;
+extern atomic_t fscache_n_cookies_lru_removed;
+extern atomic_t fscache_n_cookies_lru_dropped;
+
+extern atomic_t fscache_n_acquires;
+extern atomic_t fscache_n_acquires_ok;
+extern atomic_t fscache_n_acquires_oom;
+
+extern atomic_t fscache_n_invalidates;
+
+extern atomic_t fscache_n_relinquishes;
+extern atomic_t fscache_n_relinquishes_retire;
+extern atomic_t fscache_n_relinquishes_dropped;
+
+extern atomic_t fscache_n_resizes;
+extern atomic_t fscache_n_resizes_null;
+
+static inline void fscache_stat(atomic_t *stat)
+{
+ atomic_inc(stat);
+}
+
+static inline void fscache_stat_d(atomic_t *stat)
+{
+ atomic_dec(stat);
+}
+
+#define __fscache_stat(stat) (stat)
+
+int fscache_stats_show(struct seq_file *m, void *v);
+#else
+
+#define __fscache_stat(stat) (NULL)
+#define fscache_stat(stat) do {} while (0)
+#define fscache_stat_d(stat) do {} while (0)
+#endif
+
+/*
+ * volume.c
+ */
+#ifdef CONFIG_PROC_FS
+extern const struct seq_operations fscache_volumes_seq_ops;
+#endif
+
+struct fscache_volume *fscache_get_volume(struct fscache_volume *volume,
+ enum fscache_volume_trace where);
+void fscache_put_volume(struct fscache_volume *volume,
+ enum fscache_volume_trace where);
+bool fscache_begin_volume_access(struct fscache_volume *volume,
+ struct fscache_cookie *cookie,
+ enum fscache_access_trace why);
+void fscache_create_volume(struct fscache_volume *volume, bool wait);
+
+
+/*****************************************************************************/
+/*
+ * debug tracing
+ */
+#define dbgprintk(FMT, ...) \
+ printk("[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)
+
+#define kenter(FMT, ...) dbgprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
+#define kleave(FMT, ...) dbgprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
+#define kdebug(FMT, ...) dbgprintk(FMT, ##__VA_ARGS__)
+
+#define kjournal(FMT, ...) no_printk(FMT, ##__VA_ARGS__)
+
+#ifdef __KDEBUG
+#define _enter(FMT, ...) kenter(FMT, ##__VA_ARGS__)
+#define _leave(FMT, ...) kleave(FMT, ##__VA_ARGS__)
+#define _debug(FMT, ...) kdebug(FMT, ##__VA_ARGS__)
+
+#elif defined(CONFIG_FSCACHE_DEBUG)
+#define _enter(FMT, ...) \
+do { \
+ if (__do_kdebug(ENTER)) \
+ kenter(FMT, ##__VA_ARGS__); \
+} while (0)
+
+#define _leave(FMT, ...) \
+do { \
+ if (__do_kdebug(LEAVE)) \
+ kleave(FMT, ##__VA_ARGS__); \
+} while (0)
+
+#define _debug(FMT, ...) \
+do { \
+ if (__do_kdebug(DEBUG)) \
+ kdebug(FMT, ##__VA_ARGS__); \
+} while (0)
+
+#else
+#define _enter(FMT, ...) no_printk("==> %s("FMT")", __func__, ##__VA_ARGS__)
+#define _leave(FMT, ...) no_printk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
+#define _debug(FMT, ...) no_printk(FMT, ##__VA_ARGS__)
+#endif
+
+/*
+ * determine whether a particular optional debugging point should be logged
+ * - we need to go through three steps to persuade cpp to correctly join the
+ * shorthand in FSCACHE_DEBUG_LEVEL with its prefix
+ */
+#define ____do_kdebug(LEVEL, POINT) \
+ unlikely((fscache_debug & \
+ (FSCACHE_POINT_##POINT << (FSCACHE_DEBUG_ ## LEVEL * 3))))
+#define ___do_kdebug(LEVEL, POINT) \
+ ____do_kdebug(LEVEL, POINT)
+#define __do_kdebug(POINT) \
+ ___do_kdebug(FSCACHE_DEBUG_LEVEL, POINT)
+
+#define FSCACHE_DEBUG_CACHE 0
+#define FSCACHE_DEBUG_COOKIE 1
+#define FSCACHE_DEBUG_OBJECT 2
+#define FSCACHE_DEBUG_OPERATION 3
+
+#define FSCACHE_POINT_ENTER 1
+#define FSCACHE_POINT_LEAVE 2
+#define FSCACHE_POINT_DEBUG 4
+
+#ifndef FSCACHE_DEBUG_LEVEL
+#define FSCACHE_DEBUG_LEVEL CACHE
+#endif
+
+/*
+ * assertions
+ */
+#if 1 /* defined(__KDEBUGALL) */
+
+#define ASSERT(X) \
+do { \
+ if (unlikely(!(X))) { \
+ pr_err("\n"); \
+ pr_err("Assertion failed\n"); \
+ BUG(); \
+ } \
+} while (0)
+
+#define ASSERTCMP(X, OP, Y) \
+do { \
+ if (unlikely(!((X) OP (Y)))) { \
+ pr_err("\n"); \
+ pr_err("Assertion failed\n"); \
+ pr_err("%lx " #OP " %lx is false\n", \
+ (unsigned long)(X), (unsigned long)(Y)); \
+ BUG(); \
+ } \
+} while (0)
+
+#define ASSERTIF(C, X) \
+do { \
+ if (unlikely((C) && !(X))) { \
+ pr_err("\n"); \
+ pr_err("Assertion failed\n"); \
+ BUG(); \
+ } \
+} while (0)
+
+#define ASSERTIFCMP(C, X, OP, Y) \
+do { \
+ if (unlikely((C) && !((X) OP (Y)))) { \
+ pr_err("\n"); \
+ pr_err("Assertion failed\n"); \
+ pr_err("%lx " #OP " %lx is false\n", \
+ (unsigned long)(X), (unsigned long)(Y)); \
+ BUG(); \
+ } \
+} while (0)
+
+#else
+
+#define ASSERT(X) do {} while (0)
+#define ASSERTCMP(X, OP, Y) do {} while (0)
+#define ASSERTIF(C, X) do {} while (0)
+#define ASSERTIFCMP(C, X, OP, Y) do {} while (0)
+
+#endif /* assert or not */
diff --git a/fs/fscache/io.c b/fs/fscache/io.c
new file mode 100644
index 000000000..0d2b8dec8
--- /dev/null
+++ b/fs/fscache/io.c
@@ -0,0 +1,327 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Cache data I/O routines
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#define FSCACHE_DEBUG_LEVEL OPERATION
+#include <linux/fscache-cache.h>
+#include <linux/uio.h>
+#include <linux/bvec.h>
+#include <linux/slab.h>
+#include <linux/uio.h>
+#include "internal.h"
+
+/**
+ * fscache_wait_for_operation - Wait for an object become accessible
+ * @cres: The cache resources for the operation being performed
+ * @want_state: The minimum state the object must be at
+ *
+ * See if the target cache object is at the specified minimum state of
+ * accessibility yet, and if not, wait for it.
+ */
+bool fscache_wait_for_operation(struct netfs_cache_resources *cres,
+ enum fscache_want_state want_state)
+{
+ struct fscache_cookie *cookie = fscache_cres_cookie(cres);
+ enum fscache_cookie_state state;
+
+again:
+ if (!fscache_cache_is_live(cookie->volume->cache)) {
+ _leave(" [broken]");
+ return false;
+ }
+
+ state = fscache_cookie_state(cookie);
+ _enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
+
+ switch (state) {
+ case FSCACHE_COOKIE_STATE_CREATING:
+ case FSCACHE_COOKIE_STATE_INVALIDATING:
+ if (want_state == FSCACHE_WANT_PARAMS)
+ goto ready; /* There can be no content */
+ fallthrough;
+ case FSCACHE_COOKIE_STATE_LOOKING_UP:
+ case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
+ wait_var_event(&cookie->state,
+ fscache_cookie_state(cookie) != state);
+ goto again;
+
+ case FSCACHE_COOKIE_STATE_ACTIVE:
+ goto ready;
+ case FSCACHE_COOKIE_STATE_DROPPED:
+ case FSCACHE_COOKIE_STATE_RELINQUISHING:
+ default:
+ _leave(" [not live]");
+ return false;
+ }
+
+ready:
+ if (!cres->cache_priv2)
+ return cookie->volume->cache->ops->begin_operation(cres, want_state);
+ return true;
+}
+EXPORT_SYMBOL(fscache_wait_for_operation);
+
+/*
+ * Begin an I/O operation on the cache, waiting till we reach the right state.
+ *
+ * Attaches the resources required to the operation resources record.
+ */
+static int fscache_begin_operation(struct netfs_cache_resources *cres,
+ struct fscache_cookie *cookie,
+ enum fscache_want_state want_state,
+ enum fscache_access_trace why)
+{
+ enum fscache_cookie_state state;
+ long timeo;
+ bool once_only = false;
+
+ cres->ops = NULL;
+ cres->cache_priv = cookie;
+ cres->cache_priv2 = NULL;
+ cres->debug_id = cookie->debug_id;
+ cres->inval_counter = cookie->inval_counter;
+
+ if (!fscache_begin_cookie_access(cookie, why))
+ return -ENOBUFS;
+
+again:
+ spin_lock(&cookie->lock);
+
+ state = fscache_cookie_state(cookie);
+ _enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
+
+ switch (state) {
+ case FSCACHE_COOKIE_STATE_LOOKING_UP:
+ case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
+ case FSCACHE_COOKIE_STATE_INVALIDATING:
+ goto wait_for_file_wrangling;
+ case FSCACHE_COOKIE_STATE_CREATING:
+ if (want_state == FSCACHE_WANT_PARAMS)
+ goto ready; /* There can be no content */
+ goto wait_for_file_wrangling;
+ case FSCACHE_COOKIE_STATE_ACTIVE:
+ goto ready;
+ case FSCACHE_COOKIE_STATE_DROPPED:
+ case FSCACHE_COOKIE_STATE_RELINQUISHING:
+ WARN(1, "Can't use cookie in state %u\n", cookie->state);
+ goto not_live;
+ default:
+ goto not_live;
+ }
+
+ready:
+ spin_unlock(&cookie->lock);
+ if (!cookie->volume->cache->ops->begin_operation(cres, want_state))
+ goto failed;
+ return 0;
+
+wait_for_file_wrangling:
+ spin_unlock(&cookie->lock);
+ trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
+ atomic_read(&cookie->n_accesses),
+ fscache_access_io_wait);
+ timeo = wait_var_event_timeout(&cookie->state,
+ fscache_cookie_state(cookie) != state, 20 * HZ);
+ if (timeo <= 1 && !once_only) {
+ pr_warn("%s: cookie state change wait timed out: cookie->state=%u state=%u",
+ __func__, fscache_cookie_state(cookie), state);
+ fscache_print_cookie(cookie, 'O');
+ once_only = true;
+ }
+ goto again;
+
+not_live:
+ spin_unlock(&cookie->lock);
+failed:
+ cres->cache_priv = NULL;
+ cres->ops = NULL;
+ fscache_end_cookie_access(cookie, fscache_access_io_not_live);
+ _leave(" = -ENOBUFS");
+ return -ENOBUFS;
+}
+
+int __fscache_begin_read_operation(struct netfs_cache_resources *cres,
+ struct fscache_cookie *cookie)
+{
+ return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
+ fscache_access_io_read);
+}
+EXPORT_SYMBOL(__fscache_begin_read_operation);
+
+int __fscache_begin_write_operation(struct netfs_cache_resources *cres,
+ struct fscache_cookie *cookie)
+{
+ return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
+ fscache_access_io_write);
+}
+EXPORT_SYMBOL(__fscache_begin_write_operation);
+
+/**
+ * fscache_dirty_folio - Mark folio dirty and pin a cache object for writeback
+ * @mapping: The mapping the folio belongs to.
+ * @folio: The folio being dirtied.
+ * @cookie: The cookie referring to the cache object
+ *
+ * Set the dirty flag on a folio and pin an in-use cache object in memory
+ * so that writeback can later write to it. This is intended
+ * to be called from the filesystem's ->dirty_folio() method.
+ *
+ * Return: true if the dirty flag was set on the folio, false otherwise.
+ */
+bool fscache_dirty_folio(struct address_space *mapping, struct folio *folio,
+ struct fscache_cookie *cookie)
+{
+ struct inode *inode = mapping->host;
+ bool need_use = false;
+
+ _enter("");
+
+ if (!filemap_dirty_folio(mapping, folio))
+ return false;
+ if (!fscache_cookie_valid(cookie))
+ return true;
+
+ if (!(inode->i_state & I_PINNING_FSCACHE_WB)) {
+ spin_lock(&inode->i_lock);
+ if (!(inode->i_state & I_PINNING_FSCACHE_WB)) {
+ inode->i_state |= I_PINNING_FSCACHE_WB;
+ need_use = true;
+ }
+ spin_unlock(&inode->i_lock);
+
+ if (need_use)
+ fscache_use_cookie(cookie, true);
+ }
+ return true;
+}
+EXPORT_SYMBOL(fscache_dirty_folio);
+
+struct fscache_write_request {
+ struct netfs_cache_resources cache_resources;
+ struct address_space *mapping;
+ loff_t start;
+ size_t len;
+ bool set_bits;
+ netfs_io_terminated_t term_func;
+ void *term_func_priv;
+};
+
+void __fscache_clear_page_bits(struct address_space *mapping,
+ loff_t start, size_t len)
+{
+ pgoff_t first = start / PAGE_SIZE;
+ pgoff_t last = (start + len - 1) / PAGE_SIZE;
+ struct page *page;
+
+ if (len) {
+ XA_STATE(xas, &mapping->i_pages, first);
+
+ rcu_read_lock();
+ xas_for_each(&xas, page, last) {
+ end_page_fscache(page);
+ }
+ rcu_read_unlock();
+ }
+}
+EXPORT_SYMBOL(__fscache_clear_page_bits);
+
+/*
+ * Deal with the completion of writing the data to the cache.
+ */
+static void fscache_wreq_done(void *priv, ssize_t transferred_or_error,
+ bool was_async)
+{
+ struct fscache_write_request *wreq = priv;
+
+ fscache_clear_page_bits(wreq->mapping, wreq->start, wreq->len,
+ wreq->set_bits);
+
+ if (wreq->term_func)
+ wreq->term_func(wreq->term_func_priv, transferred_or_error,
+ was_async);
+ fscache_end_operation(&wreq->cache_resources);
+ kfree(wreq);
+}
+
+void __fscache_write_to_cache(struct fscache_cookie *cookie,
+ struct address_space *mapping,
+ loff_t start, size_t len, loff_t i_size,
+ netfs_io_terminated_t term_func,
+ void *term_func_priv,
+ bool cond)
+{
+ struct fscache_write_request *wreq;
+ struct netfs_cache_resources *cres;
+ struct iov_iter iter;
+ int ret = -ENOBUFS;
+
+ if (len == 0)
+ goto abandon;
+
+ _enter("%llx,%zx", start, len);
+
+ wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS);
+ if (!wreq)
+ goto abandon;
+ wreq->mapping = mapping;
+ wreq->start = start;
+ wreq->len = len;
+ wreq->set_bits = cond;
+ wreq->term_func = term_func;
+ wreq->term_func_priv = term_func_priv;
+
+ cres = &wreq->cache_resources;
+ if (fscache_begin_operation(cres, cookie, FSCACHE_WANT_WRITE,
+ fscache_access_io_write) < 0)
+ goto abandon_free;
+
+ ret = cres->ops->prepare_write(cres, &start, &len, i_size, false);
+ if (ret < 0)
+ goto abandon_end;
+
+ /* TODO: Consider clearing page bits now for space the write isn't
+ * covering. This is more complicated than it appears when THPs are
+ * taken into account.
+ */
+
+ iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
+ fscache_write(cres, start, &iter, fscache_wreq_done, wreq);
+ return;
+
+abandon_end:
+ return fscache_wreq_done(wreq, ret, false);
+abandon_free:
+ kfree(wreq);
+abandon:
+ fscache_clear_page_bits(mapping, start, len, cond);
+ if (term_func)
+ term_func(term_func_priv, ret, false);
+}
+EXPORT_SYMBOL(__fscache_write_to_cache);
+
+/*
+ * Change the size of a backing object.
+ */
+void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
+{
+ struct netfs_cache_resources cres;
+
+ trace_fscache_resize(cookie, new_size);
+ if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE,
+ fscache_access_io_resize) == 0) {
+ fscache_stat(&fscache_n_resizes);
+ set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
+
+ /* We cannot defer a resize as we need to do it inside the
+ * netfs's inode lock so that we're serialised with respect to
+ * writes.
+ */
+ cookie->volume->cache->ops->resize_cookie(&cres, new_size);
+ fscache_end_operation(&cres);
+ } else {
+ fscache_stat(&fscache_n_resizes_null);
+ }
+}
+EXPORT_SYMBOL(__fscache_resize_cookie);
diff --git a/fs/fscache/main.c b/fs/fscache/main.c
new file mode 100644
index 000000000..dad85fd84
--- /dev/null
+++ b/fs/fscache/main.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* General filesystem local caching manager
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define FSCACHE_DEBUG_LEVEL CACHE
+#include <linux/module.h>
+#include <linux/init.h>
+#define CREATE_TRACE_POINTS
+#include "internal.h"
+
+MODULE_DESCRIPTION("FS Cache Manager");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");
+
+unsigned fscache_debug;
+module_param_named(debug, fscache_debug, uint,
+ S_IWUSR | S_IRUGO);
+MODULE_PARM_DESC(fscache_debug,
+ "FS-Cache debugging mask");
+
+EXPORT_TRACEPOINT_SYMBOL(fscache_access_cache);
+EXPORT_TRACEPOINT_SYMBOL(fscache_access_volume);
+EXPORT_TRACEPOINT_SYMBOL(fscache_access);
+
+struct workqueue_struct *fscache_wq;
+EXPORT_SYMBOL(fscache_wq);
+
+/*
+ * Mixing scores (in bits) for (7,20):
+ * Input delta: 1-bit 2-bit
+ * 1 round: 330.3 9201.6
+ * 2 rounds: 1246.4 25475.4
+ * 3 rounds: 1907.1 31295.1
+ * 4 rounds: 2042.3 31718.6
+ * Perfect: 2048 31744
+ * (32*64) (32*31/2 * 64)
+ */
+#define HASH_MIX(x, y, a) \
+ ( x ^= (a), \
+ y ^= x, x = rol32(x, 7),\
+ x += y, y = rol32(y,20),\
+ y *= 9 )
+
+static inline unsigned int fold_hash(unsigned long x, unsigned long y)
+{
+ /* Use arch-optimized multiply if one exists */
+ return __hash_32(y ^ __hash_32(x));
+}
+
+/*
+ * Generate a hash. This is derived from full_name_hash(), but we want to be
+ * sure it is arch independent and that it doesn't change as bits of the
+ * computed hash value might appear on disk. The caller must guarantee that
+ * the source data is a multiple of four bytes in size.
+ */
+unsigned int fscache_hash(unsigned int salt, const void *data, size_t len)
+{
+ const __le32 *p = data;
+ unsigned int a, x = 0, y = salt, n = len / sizeof(__le32);
+
+ for (; n; n--) {
+ a = le32_to_cpu(*p++);
+ HASH_MIX(x, y, a);
+ }
+ return fold_hash(x, y);
+}
+
+/*
+ * initialise the fs caching module
+ */
+static int __init fscache_init(void)
+{
+ int ret = -ENOMEM;
+
+ fscache_wq = alloc_workqueue("fscache", WQ_UNBOUND | WQ_FREEZABLE, 0);
+ if (!fscache_wq)
+ goto error_wq;
+
+ ret = fscache_proc_init();
+ if (ret < 0)
+ goto error_proc;
+
+ fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
+ sizeof(struct fscache_cookie),
+ 0, 0, NULL);
+ if (!fscache_cookie_jar) {
+ pr_notice("Failed to allocate a cookie jar\n");
+ ret = -ENOMEM;
+ goto error_cookie_jar;
+ }
+
+ pr_notice("Loaded\n");
+ return 0;
+
+error_cookie_jar:
+ fscache_proc_cleanup();
+error_proc:
+ destroy_workqueue(fscache_wq);
+error_wq:
+ return ret;
+}
+
+fs_initcall(fscache_init);
+
+/*
+ * clean up on module removal
+ */
+static void __exit fscache_exit(void)
+{
+ _enter("");
+
+ kmem_cache_destroy(fscache_cookie_jar);
+ fscache_proc_cleanup();
+ destroy_workqueue(fscache_wq);
+ pr_notice("Unloaded\n");
+}
+
+module_exit(fscache_exit);
diff --git a/fs/fscache/proc.c b/fs/fscache/proc.c
new file mode 100644
index 000000000..dc3b0e9c8
--- /dev/null
+++ b/fs/fscache/proc.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* FS-Cache statistics viewing interface
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define FSCACHE_DEBUG_LEVEL CACHE
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include "internal.h"
+
+/*
+ * initialise the /proc/fs/fscache/ directory
+ */
+int __init fscache_proc_init(void)
+{
+ if (!proc_mkdir("fs/fscache", NULL))
+ goto error_dir;
+
+ if (!proc_create_seq("fs/fscache/caches", S_IFREG | 0444, NULL,
+ &fscache_caches_seq_ops))
+ goto error;
+
+ if (!proc_create_seq("fs/fscache/volumes", S_IFREG | 0444, NULL,
+ &fscache_volumes_seq_ops))
+ goto error;
+
+ if (!proc_create_seq("fs/fscache/cookies", S_IFREG | 0444, NULL,
+ &fscache_cookies_seq_ops))
+ goto error;
+
+#ifdef CONFIG_FSCACHE_STATS
+ if (!proc_create_single("fs/fscache/stats", S_IFREG | 0444, NULL,
+ fscache_stats_show))
+ goto error;
+#endif
+
+ return 0;
+
+error:
+ remove_proc_entry("fs/fscache", NULL);
+error_dir:
+ return -ENOMEM;
+}
+
+/*
+ * clean up the /proc/fs/fscache/ directory
+ */
+void fscache_proc_cleanup(void)
+{
+ remove_proc_subtree("fs/fscache", NULL);
+}
diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
new file mode 100644
index 000000000..fc94e5e79
--- /dev/null
+++ b/fs/fscache/stats.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* FS-Cache statistics
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define FSCACHE_DEBUG_LEVEL CACHE
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include "internal.h"
+
+/*
+ * operation counters
+ */
+atomic_t fscache_n_volumes;
+atomic_t fscache_n_volumes_collision;
+atomic_t fscache_n_volumes_nomem;
+atomic_t fscache_n_cookies;
+atomic_t fscache_n_cookies_lru;
+atomic_t fscache_n_cookies_lru_expired;
+atomic_t fscache_n_cookies_lru_removed;
+atomic_t fscache_n_cookies_lru_dropped;
+
+atomic_t fscache_n_acquires;
+atomic_t fscache_n_acquires_ok;
+atomic_t fscache_n_acquires_oom;
+
+atomic_t fscache_n_invalidates;
+
+atomic_t fscache_n_updates;
+EXPORT_SYMBOL(fscache_n_updates);
+
+atomic_t fscache_n_relinquishes;
+atomic_t fscache_n_relinquishes_retire;
+atomic_t fscache_n_relinquishes_dropped;
+
+atomic_t fscache_n_resizes;
+atomic_t fscache_n_resizes_null;
+
+atomic_t fscache_n_read;
+EXPORT_SYMBOL(fscache_n_read);
+atomic_t fscache_n_write;
+EXPORT_SYMBOL(fscache_n_write);
+atomic_t fscache_n_no_write_space;
+EXPORT_SYMBOL(fscache_n_no_write_space);
+atomic_t fscache_n_no_create_space;
+EXPORT_SYMBOL(fscache_n_no_create_space);
+atomic_t fscache_n_culled;
+EXPORT_SYMBOL(fscache_n_culled);
+
+/*
+ * display the general statistics
+ */
+int fscache_stats_show(struct seq_file *m, void *v)
+{
+ seq_puts(m, "FS-Cache statistics\n");
+ seq_printf(m, "Cookies: n=%d v=%d vcol=%u voom=%u\n",
+ atomic_read(&fscache_n_cookies),
+ atomic_read(&fscache_n_volumes),
+ atomic_read(&fscache_n_volumes_collision),
+ atomic_read(&fscache_n_volumes_nomem)
+ );
+
+ seq_printf(m, "Acquire: n=%u ok=%u oom=%u\n",
+ atomic_read(&fscache_n_acquires),
+ atomic_read(&fscache_n_acquires_ok),
+ atomic_read(&fscache_n_acquires_oom));
+
+ seq_printf(m, "LRU : n=%u exp=%u rmv=%u drp=%u at=%ld\n",
+ atomic_read(&fscache_n_cookies_lru),
+ atomic_read(&fscache_n_cookies_lru_expired),
+ atomic_read(&fscache_n_cookies_lru_removed),
+ atomic_read(&fscache_n_cookies_lru_dropped),
+ timer_pending(&fscache_cookie_lru_timer) ?
+ fscache_cookie_lru_timer.expires - jiffies : 0);
+
+ seq_printf(m, "Invals : n=%u\n",
+ atomic_read(&fscache_n_invalidates));
+
+ seq_printf(m, "Updates: n=%u rsz=%u rsn=%u\n",
+ atomic_read(&fscache_n_updates),
+ atomic_read(&fscache_n_resizes),
+ atomic_read(&fscache_n_resizes_null));
+
+ seq_printf(m, "Relinqs: n=%u rtr=%u drop=%u\n",
+ atomic_read(&fscache_n_relinquishes),
+ atomic_read(&fscache_n_relinquishes_retire),
+ atomic_read(&fscache_n_relinquishes_dropped));
+
+ seq_printf(m, "NoSpace: nwr=%u ncr=%u cull=%u\n",
+ atomic_read(&fscache_n_no_write_space),
+ atomic_read(&fscache_n_no_create_space),
+ atomic_read(&fscache_n_culled));
+
+ seq_printf(m, "IO : rd=%u wr=%u\n",
+ atomic_read(&fscache_n_read),
+ atomic_read(&fscache_n_write));
+
+ netfs_stats_show(m);
+ return 0;
+}
diff --git a/fs/fscache/volume.c b/fs/fscache/volume.c
new file mode 100644
index 000000000..cdf991bdd
--- /dev/null
+++ b/fs/fscache/volume.c
@@ -0,0 +1,520 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Volume-level cache cookie handling.
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define FSCACHE_DEBUG_LEVEL COOKIE
+#include <linux/export.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+#define fscache_volume_hash_shift 10
+static struct hlist_bl_head fscache_volume_hash[1 << fscache_volume_hash_shift];
+static atomic_t fscache_volume_debug_id;
+static LIST_HEAD(fscache_volumes);
+
+static void fscache_create_volume_work(struct work_struct *work);
+
+struct fscache_volume *fscache_get_volume(struct fscache_volume *volume,
+ enum fscache_volume_trace where)
+{
+ int ref;
+
+ __refcount_inc(&volume->ref, &ref);
+ trace_fscache_volume(volume->debug_id, ref + 1, where);
+ return volume;
+}
+
+static void fscache_see_volume(struct fscache_volume *volume,
+ enum fscache_volume_trace where)
+{
+ int ref = refcount_read(&volume->ref);
+
+ trace_fscache_volume(volume->debug_id, ref, where);
+}
+
+/*
+ * Pin the cache behind a volume so that we can access it.
+ */
+static void __fscache_begin_volume_access(struct fscache_volume *volume,
+ struct fscache_cookie *cookie,
+ enum fscache_access_trace why)
+{
+ int n_accesses;
+
+ n_accesses = atomic_inc_return(&volume->n_accesses);
+ smp_mb__after_atomic();
+ trace_fscache_access_volume(volume->debug_id, cookie ? cookie->debug_id : 0,
+ refcount_read(&volume->ref),
+ n_accesses, why);
+}
+
+/**
+ * fscache_begin_volume_access - Pin a cache so a volume can be accessed
+ * @volume: The volume cookie
+ * @cookie: A datafile cookie for a tracing reference (or NULL)
+ * @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 a volume and returns true if successful. This works as follows:
+ *
+ * (1) If the cache tests as not live (state is not FSCACHE_CACHE_IS_ACTIVE),
+ * then we return false to indicate access was not permitted.
+ *
+ * (2) If the cache tests as live, then we increment the volume's n_accesses
+ * count and then recheck the cache liveness, ending the access if it
+ * ceased to be live.
+ *
+ * (3) When we end the access, we decrement the volume's n_accesses and wake
+ * up the any waiters if it reaches 0.
+ *
+ * (4) Whilst the cache is caching, the volume's n_accesses is kept
+ * artificially incremented to prevent wakeups from happening.
+ *
+ * (5) When the cache is taken offline, the state is changed to prevent new
+ * accesses, the volume's n_accesses is decremented and we wait for it to
+ * become 0.
+ *
+ * The datafile @cookie and the @why indicator are merely provided for tracing
+ * purposes.
+ */
+bool fscache_begin_volume_access(struct fscache_volume *volume,
+ struct fscache_cookie *cookie,
+ enum fscache_access_trace why)
+{
+ if (!fscache_cache_is_live(volume->cache))
+ return false;
+ __fscache_begin_volume_access(volume, cookie, why);
+ if (!fscache_cache_is_live(volume->cache)) {
+ fscache_end_volume_access(volume, cookie, fscache_access_unlive);
+ return false;
+ }
+ return true;
+}
+
+/**
+ * fscache_end_volume_access - Unpin a cache at the end of an access.
+ * @volume: The volume cookie
+ * @cookie: A datafile cookie for a tracing reference (or NULL)
+ * @why: An indication of the circumstances of the access for tracing
+ *
+ * Unpin a cache volume after we've accessed it. The datafile @cookie and the
+ * @why indicator are merely provided for tracing purposes.
+ */
+void fscache_end_volume_access(struct fscache_volume *volume,
+ struct fscache_cookie *cookie,
+ enum fscache_access_trace why)
+{
+ int n_accesses;
+
+ smp_mb__before_atomic();
+ n_accesses = atomic_dec_return(&volume->n_accesses);
+ trace_fscache_access_volume(volume->debug_id, cookie ? cookie->debug_id : 0,
+ refcount_read(&volume->ref),
+ n_accesses, why);
+ if (n_accesses == 0)
+ wake_up_var(&volume->n_accesses);
+}
+EXPORT_SYMBOL(fscache_end_volume_access);
+
+static bool fscache_volume_same(const struct fscache_volume *a,
+ const struct fscache_volume *b)
+{
+ size_t klen;
+
+ if (a->key_hash != b->key_hash ||
+ a->cache != b->cache ||
+ a->key[0] != b->key[0])
+ return false;
+
+ klen = round_up(a->key[0] + 1, sizeof(__le32));
+ return memcmp(a->key, b->key, klen) == 0;
+}
+
+static bool fscache_is_acquire_pending(struct fscache_volume *volume)
+{
+ return test_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &volume->flags);
+}
+
+static void fscache_wait_on_volume_collision(struct fscache_volume *candidate,
+ unsigned int collidee_debug_id)
+{
+ wait_on_bit_timeout(&candidate->flags, FSCACHE_VOLUME_ACQUIRE_PENDING,
+ TASK_UNINTERRUPTIBLE, 20 * HZ);
+ if (fscache_is_acquire_pending(candidate)) {
+ pr_notice("Potential volume collision new=%08x old=%08x",
+ candidate->debug_id, collidee_debug_id);
+ fscache_stat(&fscache_n_volumes_collision);
+ wait_on_bit(&candidate->flags, FSCACHE_VOLUME_ACQUIRE_PENDING,
+ TASK_UNINTERRUPTIBLE);
+ }
+}
+
+/*
+ * Attempt to insert the new volume into the hash. If there's a collision, we
+ * wait for the old volume to complete if it's being relinquished and an error
+ * otherwise.
+ */
+static bool fscache_hash_volume(struct fscache_volume *candidate)
+{
+ struct fscache_volume *cursor;
+ struct hlist_bl_head *h;
+ struct hlist_bl_node *p;
+ unsigned int bucket, collidee_debug_id = 0;
+
+ bucket = candidate->key_hash & (ARRAY_SIZE(fscache_volume_hash) - 1);
+ h = &fscache_volume_hash[bucket];
+
+ hlist_bl_lock(h);
+ hlist_bl_for_each_entry(cursor, p, h, hash_link) {
+ if (fscache_volume_same(candidate, cursor)) {
+ if (!test_bit(FSCACHE_VOLUME_RELINQUISHED, &cursor->flags))
+ goto collision;
+ fscache_see_volume(cursor, fscache_volume_get_hash_collision);
+ set_bit(FSCACHE_VOLUME_COLLIDED_WITH, &cursor->flags);
+ set_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &candidate->flags);
+ collidee_debug_id = cursor->debug_id;
+ break;
+ }
+ }
+
+ hlist_bl_add_head(&candidate->hash_link, h);
+ hlist_bl_unlock(h);
+
+ if (fscache_is_acquire_pending(candidate))
+ fscache_wait_on_volume_collision(candidate, collidee_debug_id);
+ return true;
+
+collision:
+ fscache_see_volume(cursor, fscache_volume_collision);
+ hlist_bl_unlock(h);
+ return false;
+}
+
+/*
+ * Allocate and initialise a volume representation cookie.
+ */
+static struct fscache_volume *fscache_alloc_volume(const char *volume_key,
+ const char *cache_name,
+ const void *coherency_data,
+ size_t coherency_len)
+{
+ struct fscache_volume *volume;
+ struct fscache_cache *cache;
+ size_t klen, hlen;
+ u8 *key;
+
+ klen = strlen(volume_key);
+ if (klen > NAME_MAX)
+ return NULL;
+
+ if (!coherency_data)
+ coherency_len = 0;
+
+ cache = fscache_lookup_cache(cache_name, false);
+ if (IS_ERR(cache))
+ return NULL;
+
+ volume = kzalloc(struct_size(volume, coherency, coherency_len),
+ GFP_KERNEL);
+ if (!volume)
+ goto err_cache;
+
+ volume->cache = cache;
+ volume->coherency_len = coherency_len;
+ if (coherency_data)
+ memcpy(volume->coherency, coherency_data, coherency_len);
+ INIT_LIST_HEAD(&volume->proc_link);
+ INIT_WORK(&volume->work, fscache_create_volume_work);
+ refcount_set(&volume->ref, 1);
+ spin_lock_init(&volume->lock);
+
+ /* Stick the length on the front of the key and pad it out to make
+ * hashing easier.
+ */
+ hlen = round_up(1 + klen + 1, sizeof(__le32));
+ key = kzalloc(hlen, GFP_KERNEL);
+ if (!key)
+ goto err_vol;
+ key[0] = klen;
+ memcpy(key + 1, volume_key, klen);
+
+ volume->key = key;
+ volume->key_hash = fscache_hash(0, key, hlen);
+
+ volume->debug_id = atomic_inc_return(&fscache_volume_debug_id);
+ down_write(&fscache_addremove_sem);
+ atomic_inc(&cache->n_volumes);
+ list_add_tail(&volume->proc_link, &fscache_volumes);
+ fscache_see_volume(volume, fscache_volume_new_acquire);
+ fscache_stat(&fscache_n_volumes);
+ up_write(&fscache_addremove_sem);
+ _leave(" = v=%x", volume->debug_id);
+ return volume;
+
+err_vol:
+ kfree(volume);
+err_cache:
+ fscache_put_cache(cache, fscache_cache_put_alloc_volume);
+ fscache_stat(&fscache_n_volumes_nomem);
+ return NULL;
+}
+
+/*
+ * Create a volume's representation on disk. Have a volume ref and a cache
+ * access we have to release.
+ */
+static void fscache_create_volume_work(struct work_struct *work)
+{
+ const struct fscache_cache_ops *ops;
+ struct fscache_volume *volume =
+ container_of(work, struct fscache_volume, work);
+
+ fscache_see_volume(volume, fscache_volume_see_create_work);
+
+ ops = volume->cache->ops;
+ if (ops->acquire_volume)
+ ops->acquire_volume(volume);
+ fscache_end_cache_access(volume->cache,
+ fscache_access_acquire_volume_end);
+
+ clear_and_wake_up_bit(FSCACHE_VOLUME_CREATING, &volume->flags);
+ fscache_put_volume(volume, fscache_volume_put_create_work);
+}
+
+/*
+ * Dispatch a worker thread to create a volume's representation on disk.
+ */
+void fscache_create_volume(struct fscache_volume *volume, bool wait)
+{
+ if (test_and_set_bit(FSCACHE_VOLUME_CREATING, &volume->flags))
+ goto maybe_wait;
+ if (volume->cache_priv)
+ goto no_wait; /* We raced */
+ if (!fscache_begin_cache_access(volume->cache,
+ fscache_access_acquire_volume))
+ goto no_wait;
+
+ fscache_get_volume(volume, fscache_volume_get_create_work);
+ if (!schedule_work(&volume->work))
+ fscache_put_volume(volume, fscache_volume_put_create_work);
+
+maybe_wait:
+ if (wait) {
+ fscache_see_volume(volume, fscache_volume_wait_create_work);
+ wait_on_bit(&volume->flags, FSCACHE_VOLUME_CREATING,
+ TASK_UNINTERRUPTIBLE);
+ }
+ return;
+no_wait:
+ clear_bit_unlock(FSCACHE_VOLUME_CREATING, &volume->flags);
+ wake_up_bit(&volume->flags, FSCACHE_VOLUME_CREATING);
+}
+
+/*
+ * Acquire a volume representation cookie and link it to a (proposed) cache.
+ */
+struct fscache_volume *__fscache_acquire_volume(const char *volume_key,
+ const char *cache_name,
+ const void *coherency_data,
+ size_t coherency_len)
+{
+ struct fscache_volume *volume;
+
+ volume = fscache_alloc_volume(volume_key, cache_name,
+ coherency_data, coherency_len);
+ if (!volume)
+ return ERR_PTR(-ENOMEM);
+
+ if (!fscache_hash_volume(volume)) {
+ fscache_put_volume(volume, fscache_volume_put_hash_collision);
+ return ERR_PTR(-EBUSY);
+ }
+
+ fscache_create_volume(volume, false);
+ return volume;
+}
+EXPORT_SYMBOL(__fscache_acquire_volume);
+
+static void fscache_wake_pending_volume(struct fscache_volume *volume,
+ struct hlist_bl_head *h)
+{
+ struct fscache_volume *cursor;
+ struct hlist_bl_node *p;
+
+ hlist_bl_for_each_entry(cursor, p, h, hash_link) {
+ if (fscache_volume_same(cursor, volume)) {
+ fscache_see_volume(cursor, fscache_volume_see_hash_wake);
+ clear_and_wake_up_bit(FSCACHE_VOLUME_ACQUIRE_PENDING,
+ &cursor->flags);
+ return;
+ }
+ }
+}
+
+/*
+ * Remove a volume cookie from the hash table.
+ */
+static void fscache_unhash_volume(struct fscache_volume *volume)
+{
+ struct hlist_bl_head *h;
+ unsigned int bucket;
+
+ bucket = volume->key_hash & (ARRAY_SIZE(fscache_volume_hash) - 1);
+ h = &fscache_volume_hash[bucket];
+
+ hlist_bl_lock(h);
+ hlist_bl_del(&volume->hash_link);
+ if (test_bit(FSCACHE_VOLUME_COLLIDED_WITH, &volume->flags))
+ fscache_wake_pending_volume(volume, h);
+ hlist_bl_unlock(h);
+}
+
+/*
+ * Drop a cache's volume attachments.
+ */
+static void fscache_free_volume(struct fscache_volume *volume)
+{
+ struct fscache_cache *cache = volume->cache;
+
+ if (volume->cache_priv) {
+ __fscache_begin_volume_access(volume, NULL,
+ fscache_access_relinquish_volume);
+ if (volume->cache_priv)
+ cache->ops->free_volume(volume);
+ fscache_end_volume_access(volume, NULL,
+ fscache_access_relinquish_volume_end);
+ }
+
+ down_write(&fscache_addremove_sem);
+ list_del_init(&volume->proc_link);
+ atomic_dec(&volume->cache->n_volumes);
+ up_write(&fscache_addremove_sem);
+
+ if (!hlist_bl_unhashed(&volume->hash_link))
+ fscache_unhash_volume(volume);
+
+ trace_fscache_volume(volume->debug_id, 0, fscache_volume_free);
+ kfree(volume->key);
+ kfree(volume);
+ fscache_stat_d(&fscache_n_volumes);
+ fscache_put_cache(cache, fscache_cache_put_volume);
+}
+
+/*
+ * Drop a reference to a volume cookie.
+ */
+void fscache_put_volume(struct fscache_volume *volume,
+ enum fscache_volume_trace where)
+{
+ if (volume) {
+ unsigned int debug_id = volume->debug_id;
+ bool zero;
+ int ref;
+
+ zero = __refcount_dec_and_test(&volume->ref, &ref);
+ trace_fscache_volume(debug_id, ref - 1, where);
+ if (zero)
+ fscache_free_volume(volume);
+ }
+}
+
+/*
+ * Relinquish a volume representation cookie.
+ */
+void __fscache_relinquish_volume(struct fscache_volume *volume,
+ const void *coherency_data,
+ bool invalidate)
+{
+ if (WARN_ON(test_and_set_bit(FSCACHE_VOLUME_RELINQUISHED, &volume->flags)))
+ return;
+
+ if (invalidate) {
+ set_bit(FSCACHE_VOLUME_INVALIDATE, &volume->flags);
+ } else if (coherency_data) {
+ memcpy(volume->coherency, coherency_data, volume->coherency_len);
+ }
+
+ fscache_put_volume(volume, fscache_volume_put_relinquish);
+}
+EXPORT_SYMBOL(__fscache_relinquish_volume);
+
+/**
+ * fscache_withdraw_volume - Withdraw a volume from being cached
+ * @volume: Volume cookie
+ *
+ * Withdraw a cache volume from service, waiting for all accesses to complete
+ * before returning.
+ */
+void fscache_withdraw_volume(struct fscache_volume *volume)
+{
+ int n_accesses;
+
+ _debug("withdraw V=%x", volume->debug_id);
+
+ /* Allow wakeups on dec-to-0 */
+ n_accesses = atomic_dec_return(&volume->n_accesses);
+ trace_fscache_access_volume(volume->debug_id, 0,
+ refcount_read(&volume->ref),
+ n_accesses, fscache_access_cache_unpin);
+
+ wait_var_event(&volume->n_accesses,
+ atomic_read(&volume->n_accesses) == 0);
+}
+EXPORT_SYMBOL(fscache_withdraw_volume);
+
+#ifdef CONFIG_PROC_FS
+/*
+ * Generate a list of volumes in /proc/fs/fscache/volumes
+ */
+static int fscache_volumes_seq_show(struct seq_file *m, void *v)
+{
+ struct fscache_volume *volume;
+
+ if (v == &fscache_volumes) {
+ seq_puts(m,
+ "VOLUME REF nCOOK ACC FL CACHE KEY\n"
+ "======== ===== ===== === == =============== ================\n");
+ return 0;
+ }
+
+ volume = list_entry(v, struct fscache_volume, proc_link);
+ seq_printf(m,
+ "%08x %5d %5d %3d %02lx %-15.15s %s\n",
+ volume->debug_id,
+ refcount_read(&volume->ref),
+ atomic_read(&volume->n_cookies),
+ atomic_read(&volume->n_accesses),
+ volume->flags,
+ volume->cache->name ?: "-",
+ volume->key + 1);
+ return 0;
+}
+
+static void *fscache_volumes_seq_start(struct seq_file *m, loff_t *_pos)
+ __acquires(&fscache_addremove_sem)
+{
+ down_read(&fscache_addremove_sem);
+ return seq_list_start_head(&fscache_volumes, *_pos);
+}
+
+static void *fscache_volumes_seq_next(struct seq_file *m, void *v, loff_t *_pos)
+{
+ return seq_list_next(v, &fscache_volumes, _pos);
+}
+
+static void fscache_volumes_seq_stop(struct seq_file *m, void *v)
+ __releases(&fscache_addremove_sem)
+{
+ up_read(&fscache_addremove_sem);
+}
+
+const struct seq_operations fscache_volumes_seq_ops = {
+ .start = fscache_volumes_seq_start,
+ .next = fscache_volumes_seq_next,
+ .stop = fscache_volumes_seq_stop,
+ .show = fscache_volumes_seq_show,
+};
+#endif /* CONFIG_PROC_FS */