Commit fe2140e2 authored by David Howells's avatar David Howells
Browse files

cachefiles: Implement volume support 



Implement support for creating the directory layout for a volume on disk
and setting up and withdrawing volume caching.

Each volume has a directory named for the volume key under the root of the
cache (prefixed with an 'I' to indicate to cachefilesd that it's an index)
and then creates a bunch of hash bucket subdirectories under that (named as
'@' plus a hex number) in which cookie files will be created.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819635314.215744.13081522301564537723.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906936397.143852.17788457778396467161.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967143860.1823006.7185205806080225038.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021545212.640689.5064821392307582927.stgit@warthog.procyon.org.uk/ # v4
parent d1065b0a

fs/cachefiles/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -9,7 +9,8 @@ cachefiles-y := \ 
	interface.o \

	main.o \

	namei.o \

	security.o

	security.o \

	volume.o



cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o

fs/cachefiles/cache.c

+27 −1
Original line number Diff line number Diff line
@@ -262,6 +262,32 @@ int cachefiles_has_space(struct cachefiles_cache *cache, 
	return ret;

}



/*

 * Withdraw volumes.

 */

static void cachefiles_withdraw_volumes(struct cachefiles_cache *cache)

{

	_enter("");



	for (;;) {

		struct cachefiles_volume *volume = NULL;



		spin_lock(&cache->object_list_lock);

		if (!list_empty(&cache->volumes)) {

			volume = list_first_entry(&cache->volumes,

						  struct cachefiles_volume, cache_link);

			list_del_init(&volume->cache_link);

		}

		spin_unlock(&cache->object_list_lock);

		if (!volume)

			break;



		cachefiles_withdraw_volume(volume);

	}



	_leave("");

}



/*

 * Sync a cache to backing disk.

 */
@@ -303,7 +329,7 @@ void cachefiles_withdraw_cache(struct cachefiles_cache *cache) 
	// PLACEHOLDER: Withdraw objects

	fscache_wait_for_objects(fscache);



	// PLACEHOLDER: Withdraw volume

	cachefiles_withdraw_volumes(cache);

	cachefiles_sync_cache(cache);

	cache->cache = NULL;

	fscache_relinquish_cache(fscache);

fs/cachefiles/daemon.c

+2 −0
Original line number Diff line number Diff line
@@ -105,6 +105,8 @@ static int cachefiles_daemon_open(struct inode *inode, struct file *file) 


	mutex_init(&cache->daemon_mutex);

	init_waitqueue_head(&cache->daemon_pollwq);

	INIT_LIST_HEAD(&cache->volumes);

	spin_lock_init(&cache->object_list_lock);



	/* set default caching limits

	 * - limit at 1% free space and/or free files

fs/cachefiles/interface.c

+2 −0
Original line number Diff line number Diff line
@@ -15,4 +15,6 @@ 


const struct fscache_cache_ops cachefiles_cache_ops = {

	.name			= "cachefiles",

	.acquire_volume		= cachefiles_acquire_volume,

	.free_volume		= cachefiles_free_volume,

};

fs/cachefiles/internal.h

+20 −0
Original line number Diff line number Diff line
@@ -19,6 +19,17 @@ 
struct cachefiles_cache;

struct cachefiles_object;



/*

 * Cached volume representation.

 */

struct cachefiles_volume {

	struct cachefiles_cache		*cache;

	struct list_head		cache_link;	/* Link in cache->volumes */

	struct fscache_volume		*vcookie;	/* The netfs's representation */

	struct dentry			*dentry;	/* The volume dentry */

	struct dentry			*fanout[256];	/* Fanout subdirs */

};



/*

 * Data file records.

 */
@@ -35,6 +46,8 @@ struct cachefiles_cache { 
	struct dentry			*store;		/* Directory into which live objects go */

	struct dentry			*graveyard;	/* directory into which dead objects go */

	struct file			*cachefilesd;	/* manager daemon handle */

	struct list_head		volumes;	/* List of volume objects */

	spinlock_t			object_list_lock; /* Lock for volumes and object_list */

	const struct cred		*cache_cred;	/* security override for accessing cache */

	struct mutex			daemon_mutex;	/* command serialisation mutex */

	wait_queue_head_t		daemon_pollwq;	/* poll waitqueue for daemon */
@@ -163,6 +176,13 @@ static inline void cachefiles_end_secure(struct cachefiles_cache *cache, 
	revert_creds(saved_cred);

}



/*

 * volume.c

 */

void cachefiles_acquire_volume(struct fscache_volume *volume);

void cachefiles_free_volume(struct fscache_volume *volume);

void cachefiles_withdraw_volume(struct cachefiles_volume *volume);



/*

 * Error handling

 */