Commit 5002d7be authored by David Howells's avatar David Howells
Browse files

CacheFiles: Implement interface to check cache consistency 



Implement the FS-Cache interface to check the consistency of a cache object in
CacheFiles.

Original-author: Hongyi Jia <jiayisuse@gmail.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Hongyi Jia <jiayisuse@gmail.com>
cc: Milosz Tanski <milosz@adfin.com>
parent da9803bc

fs/cachefiles/interface.c

+26 −0
Original line number Diff line number Diff line
@@ -377,6 +377,31 @@ static void cachefiles_sync_cache(struct fscache_cache *_cache) 
				    ret);

}



/*

 * check if the backing cache is updated to FS-Cache

 * - called by FS-Cache when evaluates if need to invalidate the cache

 */

static bool cachefiles_check_consistency(struct fscache_operation *op)

{

	struct cachefiles_object *object;

	struct cachefiles_cache *cache;

	const struct cred *saved_cred;

	int ret;



	_enter("{OBJ%x}", op->object->debug_id);



	object = container_of(op->object, struct cachefiles_object, fscache);

	cache = container_of(object->fscache.cache,

			     struct cachefiles_cache, cache);



	cachefiles_begin_secure(cache, &saved_cred);

	ret = cachefiles_check_auxdata(object);

	cachefiles_end_secure(cache, saved_cred);



	_leave(" = %d", ret);

	return ret;

}



/*

 * notification the attributes on an object have changed

 * - called with reads/writes excluded by FS-Cache
@@ -522,4 +547,5 @@ const struct fscache_cache_ops cachefiles_cache_ops = { 
	.write_page		= cachefiles_write_page,

	.uncache_page		= cachefiles_uncache_page,

	.dissociate_pages	= cachefiles_dissociate_pages,

	.check_consistency	= cachefiles_check_consistency,

};

fs/cachefiles/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -235,6 +235,7 @@ extern int cachefiles_set_object_xattr(struct cachefiles_object *object, 
				       struct cachefiles_xattr *auxdata);

extern int cachefiles_update_object_xattr(struct cachefiles_object *object,

					  struct cachefiles_xattr *auxdata);

extern int cachefiles_check_auxdata(struct cachefiles_object *object);

extern int cachefiles_check_object_xattr(struct cachefiles_object *object,

					 struct cachefiles_xattr *auxdata);

extern int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,

fs/cachefiles/xattr.c

+36 −0
Original line number Diff line number Diff line
@@ -156,6 +156,42 @@ int cachefiles_update_object_xattr(struct cachefiles_object *object, 
	return ret;

}



/*

 * check the consistency between the backing cache and the FS-Cache cookie

 */

int cachefiles_check_auxdata(struct cachefiles_object *object)

{

	struct cachefiles_xattr *auxbuf;

	struct dentry *dentry = object->dentry;

	unsigned int dlen;

	int ret;



	ASSERT(dentry);

	ASSERT(dentry->d_inode);

	ASSERT(object->fscache.cookie->def->check_aux);



	auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);

	if (!auxbuf)

		return -ENOMEM;



	auxbuf->len = vfs_getxattr(dentry, cachefiles_xattr_cache,

				   &auxbuf->type, 512 + 1);

	if (auxbuf->len < 1)

		return -ESTALE;



	if (auxbuf->type != object->fscache.cookie->def->type)

		return -ESTALE;



	dlen = auxbuf->len - 1;

	ret = fscache_check_aux(&object->fscache, &auxbuf->data, dlen);



	kfree(auxbuf);

	if (ret != FSCACHE_CHECKAUX_OKAY)

		return -ESTALE;



	return 0;

}



/*

 * check the state xattr on a cache file

 * - return -ESTALE if the object should be deleted