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Commit 5c61ef1b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'fscache-fixes-20180725' of... 

Merge tag 'fscache-fixes-20180725' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull fscache/cachefiles fixes from David Howells:

 - Allow cancelled operations to be queued so they can be cleaned up.

 - Fix a refcounting bug in the monitoring of reads on backend files
   whereby a race can occur between monitor objects being listed for
   work, the work processing being queued and the work processor running
   and destroying the monitor objects.

 - Fix a ref overput in object attachment, whereby a tentatively
   considered object is put in error handling without first being 'got'.

 - Fix a missing clear of the CACHEFILES_OBJECT_ACTIVE flag whereby an
   assertion occurs when we retry because it seems the object is now
   active.

 - Wait rather BUG'ing on an object collision in the depths of
   cachefiles as the active object should be being cleaned up - also
   depends on the one above.

* tag 'fscache-fixes-20180725' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  cachefiles: Wait rather than BUG'ing on "Unexpected object collision"
  cachefiles: Fix missing clear of the CACHEFILES_OBJECT_ACTIVE flag
  fscache: Fix reference overput in fscache_attach_object() error handling
  cachefiles: Fix refcounting bug in backing-file read monitoring
  fscache: Allow cancelled operations to be enqueued
parents 9981b4fb c2412ac4

fs/cachefiles/bind.c

+2 −1
Original line number Diff line number Diff line
@@ -218,7 +218,8 @@ static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache) 
			   "%s",

			   fsdef->dentry->d_sb->s_id);



	fscache_object_init(&fsdef->fscache, NULL, &cache->cache);

	fscache_object_init(&fsdef->fscache, &fscache_fsdef_index,

			    &cache->cache);



	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);

	if (ret < 0)

fs/cachefiles/namei.c

+1 −2
Original line number Diff line number Diff line
@@ -186,12 +186,12 @@ static int cachefiles_mark_object_active(struct cachefiles_cache *cache, 
	 * need to wait for it to be destroyed */

wait_for_old_object:

	trace_cachefiles_wait_active(object, dentry, xobject);

	clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);



	if (fscache_object_is_live(&xobject->fscache)) {

		pr_err("\n");

		pr_err("Error: Unexpected object collision\n");

		cachefiles_printk_object(object, xobject);

		BUG();

	}

	atomic_inc(&xobject->usage);

	write_unlock(&cache->active_lock);
@@ -248,7 +248,6 @@ static int cachefiles_mark_object_active(struct cachefiles_cache *cache, 
	goto try_again;



requeue:

	clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);

	cache->cache.ops->put_object(&xobject->fscache, cachefiles_obj_put_wait_timeo);

	_leave(" = -ETIMEDOUT");

	return -ETIMEDOUT;

fs/cachefiles/rdwr.c

+12 −5
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ static int cachefiles_read_waiter(wait_queue_entry_t *wait, unsigned mode, 
	struct cachefiles_one_read *monitor =

		container_of(wait, struct cachefiles_one_read, monitor);

	struct cachefiles_object *object;

	struct fscache_retrieval *op = monitor->op;

	struct wait_bit_key *key = _key;

	struct page *page = wait->private;
@@ -51,16 +52,22 @@ static int cachefiles_read_waiter(wait_queue_entry_t *wait, unsigned mode, 
	list_del(&wait->entry);



	/* move onto the action list and queue for FS-Cache thread pool */

	ASSERT(monitor->op);

	ASSERT(op);



	object = container_of(monitor->op->op.object,

			      struct cachefiles_object, fscache);

	/* We need to temporarily bump the usage count as we don't own a ref

	 * here otherwise cachefiles_read_copier() may free the op between the

	 * monitor being enqueued on the op->to_do list and the op getting

	 * enqueued on the work queue.

	 */

	fscache_get_retrieval(op);



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

	spin_lock(&object->work_lock);

	list_add_tail(&monitor->op_link, &monitor->op->to_do);

	list_add_tail(&monitor->op_link, &op->to_do);

	spin_unlock(&object->work_lock);



	fscache_enqueue_retrieval(monitor->op);

	fscache_enqueue_retrieval(op);

	fscache_put_retrieval(op);

	return 0;

}

fs/fscache/cache.c

+1 −1
Original line number Diff line number Diff line
@@ -220,6 +220,7 @@ int fscache_add_cache(struct fscache_cache *cache, 
{

	struct fscache_cache_tag *tag;



	ASSERTCMP(ifsdef->cookie, ==, &fscache_fsdef_index);

	BUG_ON(!cache->ops);

	BUG_ON(!ifsdef);
@@ -248,7 +249,6 @@ int fscache_add_cache(struct fscache_cache *cache, 
	if (!cache->kobj)

		goto error;



	ifsdef->cookie = &fscache_fsdef_index;

	ifsdef->cache = cache;

	cache->fsdef = ifsdef;

fs/fscache/cookie.c

+4 −3
Original line number Diff line number Diff line
@@ -516,6 +516,7 @@ static int fscache_alloc_object(struct fscache_cache *cache, 
		goto error;

	}



	ASSERTCMP(object->cookie, ==, cookie);

	fscache_stat(&fscache_n_object_alloc);



	object->debug_id = atomic_inc_return(&fscache_object_debug_id);
@@ -571,6 +572,8 @@ static int fscache_attach_object(struct fscache_cookie *cookie, 


	_enter("{%s},{OBJ%x}", cookie->def->name, object->debug_id);



	ASSERTCMP(object->cookie, ==, cookie);



	spin_lock(&cookie->lock);



	/* there may be multiple initial creations of this object, but we only
@@ -610,9 +613,7 @@ static int fscache_attach_object(struct fscache_cookie *cookie, 
		spin_unlock(&cache->object_list_lock);

	}



	/* attach to the cookie */

	object->cookie = cookie;

	fscache_cookie_get(cookie, fscache_cookie_get_attach_object);

	/* Attach to the cookie.  The object already has a ref on it. */

	hlist_add_head(&object->cookie_link, &cookie->backing_objects);



	fscache_objlist_add(object);