FS-Cache: Add cache management
Implement the entry points by which a cache backend may initialise, add, declare an error upon and withdraw a cache. Further, an object is created in sysfs under which each cache added will get an object created: /sys/fs/fscache/<cachetag>/ All of this is described in Documentation/filesystems/caching/backend-api.txt added by a previous patch. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Tested-by: Daire Byrne <Daire.Byrne@framestore.com>
This commit is contained in:
David Howells
parent
0e04d4cefc
commit
4c515dd47a
@ -16,6 +16,8 @@
|
||||
|
||||
LIST_HEAD(fscache_cache_list);
|
||||
DECLARE_RWSEM(fscache_addremove_sem);
|
||||
DECLARE_WAIT_QUEUE_HEAD(fscache_cache_cleared_wq);
|
||||
EXPORT_SYMBOL(fscache_cache_cleared_wq);
|
||||
|
||||
static LIST_HEAD(fscache_cache_tag_list);
|
||||
|
||||
@ -164,3 +166,250 @@ no_preference:
|
||||
_leave(" = %p [first]", cache);
|
||||
return cache;
|
||||
}
|
||||
|
||||
/**
|
||||
* fscache_init_cache - Initialise a cache record
|
||||
* @cache: The cache record to be initialised
|
||||
* @ops: The cache operations to be installed in that record
|
||||
* @idfmt: Format string to define identifier
|
||||
* @...: sprintf-style arguments
|
||||
*
|
||||
* Initialise a record of a cache and fill in the name.
|
||||
*
|
||||
* See Documentation/filesystems/caching/backend-api.txt for a complete
|
||||
* description.
|
||||
*/
|
||||
void fscache_init_cache(struct fscache_cache *cache,
|
||||
const struct fscache_cache_ops *ops,
|
||||
const char *idfmt,
|
||||
...)
|
||||
{
|
||||
va_list va;
|
||||
|
||||
memset(cache, 0, sizeof(*cache));
|
||||
|
||||
cache->ops = ops;
|
||||
|
||||
va_start(va, idfmt);
|
||||
vsnprintf(cache->identifier, sizeof(cache->identifier), idfmt, va);
|
||||
va_end(va);
|
||||
|
||||
INIT_WORK(&cache->op_gc, NULL);
|
||||
INIT_LIST_HEAD(&cache->link);
|
||||
INIT_LIST_HEAD(&cache->object_list);
|
||||
INIT_LIST_HEAD(&cache->op_gc_list);
|
||||
spin_lock_init(&cache->object_list_lock);
|
||||
spin_lock_init(&cache->op_gc_list_lock);
|
||||
}
|
||||
EXPORT_SYMBOL(fscache_init_cache);
|
||||
|
||||
/**
|
||||
* fscache_add_cache - Declare a cache as being open for business
|
||||
* @cache: The record describing the cache
|
||||
* @ifsdef: The record of the cache object describing the top-level index
|
||||
* @tagname: The tag describing this cache
|
||||
*
|
||||
* Add a cache to the system, making it available for netfs's to use.
|
||||
*
|
||||
* See Documentation/filesystems/caching/backend-api.txt for a complete
|
||||
* description.
|
||||
*/
|
||||
int fscache_add_cache(struct fscache_cache *cache,
|
||||
struct fscache_object *ifsdef,
|
||||
const char *tagname)
|
||||
{
|
||||
struct fscache_cache_tag *tag;
|
||||
|
||||
BUG_ON(!cache->ops);
|
||||
BUG_ON(!ifsdef);
|
||||
|
||||
cache->flags = 0;
|
||||
ifsdef->event_mask = ULONG_MAX & ~(1 << FSCACHE_OBJECT_EV_CLEARED);
|
||||
ifsdef->state = FSCACHE_OBJECT_ACTIVE;
|
||||
|
||||
if (!tagname)
|
||||
tagname = cache->identifier;
|
||||
|
||||
BUG_ON(!tagname[0]);
|
||||
|
||||
_enter("{%s.%s},,%s", cache->ops->name, cache->identifier, tagname);
|
||||
|
||||
/* we use the cache tag to uniquely identify caches */
|
||||
tag = __fscache_lookup_cache_tag(tagname);
|
||||
if (IS_ERR(tag))
|
||||
goto nomem;
|
||||
|
||||
if (test_and_set_bit(FSCACHE_TAG_RESERVED, &tag->flags))
|
||||
goto tag_in_use;
|
||||
|
||||
cache->kobj = kobject_create_and_add(tagname, fscache_root);
|
||||
if (!cache->kobj)
|
||||
goto error;
|
||||
|
||||
ifsdef->cookie = &fscache_fsdef_index;
|
||||
ifsdef->cache = cache;
|
||||
cache->fsdef = ifsdef;
|
||||
|
||||
down_write(&fscache_addremove_sem);
|
||||
|
||||
tag->cache = cache;
|
||||
cache->tag = tag;
|
||||
|
||||
/* add the cache to the list */
|
||||
list_add(&cache->link, &fscache_cache_list);
|
||||
|
||||
/* add the cache's netfs definition index object to the cache's
|
||||
* list */
|
||||
spin_lock(&cache->object_list_lock);
|
||||
list_add_tail(&ifsdef->cache_link, &cache->object_list);
|
||||
spin_unlock(&cache->object_list_lock);
|
||||
|
||||
/* add the cache's netfs definition index object to the top level index
|
||||
* cookie as a known backing object */
|
||||
spin_lock(&fscache_fsdef_index.lock);
|
||||
|
||||
hlist_add_head(&ifsdef->cookie_link,
|
||||
&fscache_fsdef_index.backing_objects);
|
||||
|
||||
atomic_inc(&fscache_fsdef_index.usage);
|
||||
|
||||
/* done */
|
||||
spin_unlock(&fscache_fsdef_index.lock);
|
||||
up_write(&fscache_addremove_sem);
|
||||
|
||||
printk(KERN_NOTICE "FS-Cache: Cache \"%s\" added (type %s)\n",
|
||||
cache->tag->name, cache->ops->name);
|
||||
kobject_uevent(cache->kobj, KOBJ_ADD);
|
||||
|
||||
_leave(" = 0 [%s]", cache->identifier);
|
||||
return 0;
|
||||
|
||||
tag_in_use:
|
||||
printk(KERN_ERR "FS-Cache: Cache tag '%s' already in use\n", tagname);
|
||||
__fscache_release_cache_tag(tag);
|
||||
_leave(" = -EXIST");
|
||||
return -EEXIST;
|
||||
|
||||
error:
|
||||
__fscache_release_cache_tag(tag);
|
||||
_leave(" = -EINVAL");
|
||||
return -EINVAL;
|
||||
|
||||
nomem:
|
||||
_leave(" = -ENOMEM");
|
||||
return -ENOMEM;
|
||||
}
|
||||
EXPORT_SYMBOL(fscache_add_cache);
|
||||
|
||||
/**
|
||||
* 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.txt for a complete
|
||||
* description.
|
||||
*/
|
||||
void fscache_io_error(struct fscache_cache *cache)
|
||||
{
|
||||
set_bit(FSCACHE_IOERROR, &cache->flags);
|
||||
|
||||
printk(KERN_ERR "FS-Cache: Cache %s stopped due to I/O error\n",
|
||||
cache->ops->name);
|
||||
}
|
||||
EXPORT_SYMBOL(fscache_io_error);
|
||||
|
||||
/*
|
||||
* request withdrawal of all the objects in a cache
|
||||
* - all the objects being withdrawn are moved onto the supplied list
|
||||
*/
|
||||
static void fscache_withdraw_all_objects(struct fscache_cache *cache,
|
||||
struct list_head *dying_objects)
|
||||
{
|
||||
struct fscache_object *object;
|
||||
|
||||
spin_lock(&cache->object_list_lock);
|
||||
|
||||
while (!list_empty(&cache->object_list)) {
|
||||
object = list_entry(cache->object_list.next,
|
||||
struct fscache_object, cache_link);
|
||||
list_move_tail(&object->cache_link, dying_objects);
|
||||
|
||||
_debug("withdraw %p", object->cookie);
|
||||
|
||||
spin_lock(&object->lock);
|
||||
spin_unlock(&cache->object_list_lock);
|
||||
fscache_raise_event(object, FSCACHE_OBJECT_EV_WITHDRAW);
|
||||
spin_unlock(&object->lock);
|
||||
|
||||
cond_resched();
|
||||
spin_lock(&cache->object_list_lock);
|
||||
}
|
||||
|
||||
spin_unlock(&cache->object_list_lock);
|
||||
}
|
||||
|
||||
/**
|
||||
* fscache_withdraw_cache - Withdraw a cache from the active service
|
||||
* @cache: The record describing the cache
|
||||
*
|
||||
* Withdraw a cache from service, unbinding all its cache objects from the
|
||||
* netfs cookies they're currently representing.
|
||||
*
|
||||
* See Documentation/filesystems/caching/backend-api.txt for a complete
|
||||
* description.
|
||||
*/
|
||||
void fscache_withdraw_cache(struct fscache_cache *cache)
|
||||
{
|
||||
LIST_HEAD(dying_objects);
|
||||
|
||||
_enter("");
|
||||
|
||||
printk(KERN_NOTICE "FS-Cache: Withdrawing cache \"%s\"\n",
|
||||
cache->tag->name);
|
||||
|
||||
/* make the cache unavailable for cookie acquisition */
|
||||
if (test_and_set_bit(FSCACHE_CACHE_WITHDRAWN, &cache->flags))
|
||||
BUG();
|
||||
|
||||
down_write(&fscache_addremove_sem);
|
||||
list_del_init(&cache->link);
|
||||
cache->tag->cache = NULL;
|
||||
up_write(&fscache_addremove_sem);
|
||||
|
||||
/* make sure all pages pinned by operations on behalf of the netfs are
|
||||
* written to disk */
|
||||
cache->ops->sync_cache(cache);
|
||||
|
||||
/* dissociate all the netfs pages backed by this cache from the block
|
||||
* mappings in the cache */
|
||||
cache->ops->dissociate_pages(cache);
|
||||
|
||||
/* we now have to destroy all the active objects pertaining to this
|
||||
* cache - which we do by passing them off to thread pool to be
|
||||
* disposed of */
|
||||
_debug("destroy");
|
||||
|
||||
fscache_withdraw_all_objects(cache, &dying_objects);
|
||||
|
||||
/* wait for all extant objects to finish their outstanding operations
|
||||
* and go away */
|
||||
_debug("wait for finish");
|
||||
wait_event(fscache_cache_cleared_wq,
|
||||
atomic_read(&cache->object_count) == 0);
|
||||
_debug("wait for clearance");
|
||||
wait_event(fscache_cache_cleared_wq,
|
||||
list_empty(&cache->object_list));
|
||||
_debug("cleared");
|
||||
ASSERT(list_empty(&dying_objects));
|
||||
|
||||
kobject_put(cache->kobj);
|
||||
|
||||
clear_bit(FSCACHE_TAG_RESERVED, &cache->tag->flags);
|
||||
fscache_release_cache_tag(cache->tag);
|
||||
cache->tag = NULL;
|
||||
|
||||
_leave("");
|
||||
}
|
||||
EXPORT_SYMBOL(fscache_withdraw_cache);
|
||||
|
||||
@ -56,9 +56,15 @@ static int __init fscache_init(void)
|
||||
if (ret < 0)
|
||||
goto error_proc;
|
||||
|
||||
fscache_root = kobject_create_and_add("fscache", kernel_kobj);
|
||||
if (!fscache_root)
|
||||
goto error_kobj;
|
||||
|
||||
printk(KERN_NOTICE "FS-Cache: Loaded\n");
|
||||
return 0;
|
||||
|
||||
error_kobj:
|
||||
fscache_proc_cleanup();
|
||||
error_proc:
|
||||
slow_work_unregister_user();
|
||||
error_slow_work:
|
||||
@ -74,6 +80,7 @@ static void __exit fscache_exit(void)
|
||||
{
|
||||
_enter("");
|
||||
|
||||
kobject_put(fscache_root);
|
||||
fscache_proc_cleanup();
|
||||
slow_work_unregister_user();
|
||||
printk(KERN_NOTICE "FS-Cache: Unloaded\n");
|
||||
|
||||
Loading…
Reference in New Issue
Block a user