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The cache's policy may have been established using the "default" alias, which is currently the "mq" policy but the default policy may change in the future. It is useful to know exactly which policy is being used. Add a 'real' member to the dm_cache_policy_type structure and have the "default" dm_cache_policy_type point to the real "mq" dm_cache_policy_type. Update dm_cache_policy_get_name() to check if real is set, if so report the name of the real policy (not the alias). Requested-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
174 lines
3.6 KiB
C
174 lines
3.6 KiB
C
/*
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* Copyright (C) 2012 Red Hat. All rights reserved.
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*
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* This file is released under the GPL.
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*/
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#include "dm-cache-policy-internal.h"
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#include "dm.h"
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#include <linux/module.h>
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#include <linux/slab.h>
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/*----------------------------------------------------------------*/
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#define DM_MSG_PREFIX "cache-policy"
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static DEFINE_SPINLOCK(register_lock);
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static LIST_HEAD(register_list);
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static struct dm_cache_policy_type *__find_policy(const char *name)
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{
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struct dm_cache_policy_type *t;
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list_for_each_entry(t, ®ister_list, list)
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if (!strcmp(t->name, name))
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return t;
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return NULL;
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}
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static struct dm_cache_policy_type *__get_policy_once(const char *name)
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{
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struct dm_cache_policy_type *t = __find_policy(name);
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if (t && !try_module_get(t->owner)) {
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DMWARN("couldn't get module %s", name);
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t = ERR_PTR(-EINVAL);
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}
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return t;
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}
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static struct dm_cache_policy_type *get_policy_once(const char *name)
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{
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struct dm_cache_policy_type *t;
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spin_lock(®ister_lock);
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t = __get_policy_once(name);
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spin_unlock(®ister_lock);
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return t;
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}
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static struct dm_cache_policy_type *get_policy(const char *name)
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{
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struct dm_cache_policy_type *t;
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t = get_policy_once(name);
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if (IS_ERR(t))
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return NULL;
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if (t)
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return t;
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request_module("dm-cache-%s", name);
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t = get_policy_once(name);
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if (IS_ERR(t))
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return NULL;
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return t;
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}
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static void put_policy(struct dm_cache_policy_type *t)
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{
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module_put(t->owner);
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}
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int dm_cache_policy_register(struct dm_cache_policy_type *type)
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{
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int r;
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/* One size fits all for now */
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if (type->hint_size != 0 && type->hint_size != 4) {
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DMWARN("hint size must be 0 or 4 but %llu supplied.", (unsigned long long) type->hint_size);
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return -EINVAL;
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}
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spin_lock(®ister_lock);
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if (__find_policy(type->name)) {
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DMWARN("attempt to register policy under duplicate name %s", type->name);
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r = -EINVAL;
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} else {
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list_add(&type->list, ®ister_list);
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r = 0;
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}
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spin_unlock(®ister_lock);
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return r;
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}
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EXPORT_SYMBOL_GPL(dm_cache_policy_register);
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void dm_cache_policy_unregister(struct dm_cache_policy_type *type)
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{
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spin_lock(®ister_lock);
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list_del_init(&type->list);
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spin_unlock(®ister_lock);
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}
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EXPORT_SYMBOL_GPL(dm_cache_policy_unregister);
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struct dm_cache_policy *dm_cache_policy_create(const char *name,
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dm_cblock_t cache_size,
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sector_t origin_size,
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sector_t cache_block_size)
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{
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struct dm_cache_policy *p = NULL;
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struct dm_cache_policy_type *type;
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type = get_policy(name);
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if (!type) {
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DMWARN("unknown policy type");
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return ERR_PTR(-EINVAL);
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}
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p = type->create(cache_size, origin_size, cache_block_size);
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if (!p) {
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put_policy(type);
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return ERR_PTR(-ENOMEM);
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}
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p->private = type;
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return p;
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}
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EXPORT_SYMBOL_GPL(dm_cache_policy_create);
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void dm_cache_policy_destroy(struct dm_cache_policy *p)
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{
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struct dm_cache_policy_type *t = p->private;
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p->destroy(p);
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put_policy(t);
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}
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EXPORT_SYMBOL_GPL(dm_cache_policy_destroy);
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const char *dm_cache_policy_get_name(struct dm_cache_policy *p)
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{
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struct dm_cache_policy_type *t = p->private;
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/* if t->real is set then an alias was used (e.g. "default") */
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if (t->real)
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return t->real->name;
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return t->name;
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}
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EXPORT_SYMBOL_GPL(dm_cache_policy_get_name);
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const unsigned *dm_cache_policy_get_version(struct dm_cache_policy *p)
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{
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struct dm_cache_policy_type *t = p->private;
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return t->version;
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}
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EXPORT_SYMBOL_GPL(dm_cache_policy_get_version);
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size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p)
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{
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struct dm_cache_policy_type *t = p->private;
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return t->hint_size;
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}
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EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size);
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/*----------------------------------------------------------------*/
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