--- /dev/null
+// 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);
+
+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);
+}
+
+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_var_event_timeout(&candidate->flags,
+ fscache_is_acquire_pending(candidate), 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_var_event(&candidate->flags, fscache_is_acquire_pending(candidate));
+ }
+}
+
+/*
+ * 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 (test_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &candidate->flags))
+ 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;
+ char *key;
+
+ cache = fscache_lookup_cache(cache_name, false);
+ if (IS_ERR(cache))
+ return NULL;
+
+ volume = kzalloc(sizeof(*volume), GFP_KERNEL);
+ if (!volume)
+ goto err_cache;
+
+ volume->cache = cache;
+ INIT_LIST_HEAD(&volume->proc_link);
+ INIT_WORK(&volume->work, NULL /* PLACEHOLDER */);
+ 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.
+ */
+ klen = strlen(volume_key);
+ 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;
+}
+
+/*
+ * 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);
+ }
+
+ // PLACEHOLDER: Create the volume if we have a cache available
+ 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_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &cursor->flags);
+ wake_up_bit(&cursor->flags, FSCACHE_VOLUME_ACQUIRE_PENDING);
+ 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) {
+ // PLACEHOLDER: Detach any attached cache
+ }
+
+ 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);
+
+ fscache_put_volume(volume, fscache_volume_put_relinquish);
+}
+EXPORT_SYMBOL(__fscache_relinquish_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 */
#if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
#define __fscache_available (1)
#define fscache_available() (1)
+#define fscache_volume_valid(volume) (volume)
#define fscache_cookie_valid(cookie) (cookie)
#define fscache_cookie_enabled(cookie) (cookie)
#else
#define __fscache_available (0)
#define fscache_available() (0)
+#define fscache_volume_valid(volume) (0)
#define fscache_cookie_valid(cookie) (0)
#define fscache_cookie_enabled(cookie) (0)
#endif
+/*
+ * Volume representation cookie.
+ */
+struct fscache_volume {
+ refcount_t ref;
+ atomic_t n_cookies; /* Number of data cookies in volume */
+ atomic_t n_accesses; /* Number of cache accesses in progress */
+ unsigned int debug_id;
+ unsigned int key_hash; /* Hash of key string */
+ char *key; /* Volume ID, eg. "afs@example.com@1234" */
+ struct list_head proc_link; /* Link in /proc/fs/fscache/volumes */
+ struct hlist_bl_node hash_link; /* Link in hash table */
+ struct work_struct work;
+ struct fscache_cache *cache; /* The cache in which this resides */
+ void *cache_priv; /* Cache private data */
+ spinlock_t lock;
+ unsigned long flags;
+#define FSCACHE_VOLUME_RELINQUISHED 0 /* Volume is being cleaned up */
+#define FSCACHE_VOLUME_INVALIDATE 1 /* Volume was invalidated */
+#define FSCACHE_VOLUME_COLLIDED_WITH 2 /* Volume was collided with */
+#define FSCACHE_VOLUME_ACQUIRE_PENDING 3 /* Volume is waiting to complete acquisition */
+#define FSCACHE_VOLUME_CREATING 4 /* Volume is being created on disk */
+};
+
+/*
+ * slow-path functions for when there is actually caching available, and the
+ * netfs does actually have a valid token
+ * - these are not to be called directly
+ * - these are undefined symbols when FS-Cache is not configured and the
+ * optimiser takes care of not using them
+ */
+extern struct fscache_volume *__fscache_acquire_volume(const char *, const char *,
+ const void *, size_t);
+extern void __fscache_relinquish_volume(struct fscache_volume *, const void *, bool);
+
+/**
+ * fscache_acquire_volume - Register a volume as desiring caching services
+ * @volume_key: An identification string for the volume
+ * @cache_name: The name of the cache to use (or NULL for the default)
+ * @coherency_data: Piece of arbitrary coherency data to check (or NULL)
+ * @coherency_len: The size of the coherency data
+ *
+ * Register a volume as desiring caching services if they're available. The
+ * caller must provide an identifier for the volume and may also indicate which
+ * cache it should be in. If a preexisting volume entry is found in the cache,
+ * the coherency data must match otherwise the entry will be invalidated.
+ *
+ * Returns a cookie pointer on success, -ENOMEM if out of memory or -EBUSY if a
+ * cache volume of that name is already acquired. Note that "NULL" is a valid
+ * cookie pointer and can be returned if caching is refused.
+ */
+static inline
+struct fscache_volume *fscache_acquire_volume(const char *volume_key,
+ const char *cache_name,
+ const void *coherency_data,
+ size_t coherency_len)
+{
+ if (!fscache_available())
+ return NULL;
+ return __fscache_acquire_volume(volume_key, cache_name,
+ coherency_data, coherency_len);
+}
+
+/**
+ * fscache_relinquish_volume - Cease caching a volume
+ * @volume: The volume cookie
+ * @coherency_data: Piece of arbitrary coherency data to set (or NULL)
+ * @invalidate: True if the volume should be invalidated
+ *
+ * Indicate that a filesystem no longer desires caching services for a volume.
+ * The caller must have relinquished all file cookies prior to calling this.
+ * The stored coherency data is updated.
+ */
+static inline
+void fscache_relinquish_volume(struct fscache_volume *volume,
+ const void *coherency_data,
+ bool invalidate)
+{
+ if (fscache_volume_valid(volume))
+ __fscache_relinquish_volume(volume, coherency_data, invalidate);
+}
+
#endif /* _LINUX_FSCACHE_H */
fscache_cache_collision,
fscache_cache_get_acquire,
fscache_cache_new_acquire,
+ fscache_cache_put_alloc_volume,
fscache_cache_put_cache,
fscache_cache_put_prep_failed,
fscache_cache_put_relinquish,
+ fscache_cache_put_volume,
+};
+
+enum fscache_volume_trace {
+ fscache_volume_collision,
+ fscache_volume_get_cookie,
+ fscache_volume_get_create_work,
+ fscache_volume_get_hash_collision,
+ fscache_volume_free,
+ fscache_volume_new_acquire,
+ fscache_volume_put_cookie,
+ fscache_volume_put_create_work,
+ fscache_volume_put_hash_collision,
+ fscache_volume_put_relinquish,
+ fscache_volume_see_create_work,
+ fscache_volume_see_hash_wake,
};
#endif
EM(fscache_cache_collision, "*COLLIDE*") \
EM(fscache_cache_get_acquire, "GET acq ") \
EM(fscache_cache_new_acquire, "NEW acq ") \
+ EM(fscache_cache_put_alloc_volume, "PUT alvol") \
EM(fscache_cache_put_cache, "PUT cache") \
EM(fscache_cache_put_prep_failed, "PUT pfail") \
- E_(fscache_cache_put_relinquish, "PUT relnq")
+ EM(fscache_cache_put_relinquish, "PUT relnq") \
+ E_(fscache_cache_put_volume, "PUT vol ")
+
+#define fscache_volume_traces \
+ EM(fscache_volume_collision, "*COLLIDE*") \
+ EM(fscache_volume_get_cookie, "GET cook ") \
+ EM(fscache_volume_get_create_work, "GET creat") \
+ EM(fscache_volume_get_hash_collision, "GET hcoll") \
+ EM(fscache_volume_free, "FREE ") \
+ EM(fscache_volume_new_acquire, "NEW acq ") \
+ EM(fscache_volume_put_cookie, "PUT cook ") \
+ EM(fscache_volume_put_create_work, "PUT creat") \
+ EM(fscache_volume_put_hash_collision, "PUT hcoll") \
+ EM(fscache_volume_put_relinquish, "PUT relnq") \
+ EM(fscache_volume_see_create_work, "SEE creat") \
+ E_(fscache_volume_see_hash_wake, "SEE hwake")
/*
* Export enum symbols via userspace.
#define E_(a, b) TRACE_DEFINE_ENUM(a);
fscache_cache_traces;
+fscache_volume_traces;
/*
* Now redefine the EM() and E_() macros to map the enums to the strings that
__entry->usage)
);
+TRACE_EVENT(fscache_volume,
+ TP_PROTO(unsigned int volume_debug_id,
+ int usage,
+ enum fscache_volume_trace where),
+
+ TP_ARGS(volume_debug_id, usage, where),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, volume )
+ __field(int, usage )
+ __field(enum fscache_volume_trace, where )
+ ),
+
+ TP_fast_assign(
+ __entry->volume = volume_debug_id;
+ __entry->usage = usage;
+ __entry->where = where;
+ ),
+
+ TP_printk("V=%08x %s u=%d",
+ __entry->volume,
+ __print_symbolic(__entry->where, fscache_volume_traces),
+ __entry->usage)
+ );
+
#endif /* _TRACE_FSCACHE_H */
/* This part must be outside protection */
projects / linux-2.6-microblaze.git / commitdiff