Commit d0e27b78 authored by David Howells's avatar David Howells
Browse files

CacheFiles: Better showing of debugging information in active object problems 



Show more debugging information if cachefiles_mark_object_active() is asked to
activate an active object.

This may happen, for instance, if the netfs tries to register an object with
the same key multiple times.

The code is changed to (a) get the appropriate object lock to protect the
cookie pointer whilst we dereference it, and (b) get and display the cookie key
if available.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 6511de33

fs/cachefiles/namei.c

+75 −27
Original line number Diff line number Diff line
@@ -27,6 +27,76 @@ static int cachefiles_wait_bit(void *flags) 
	return 0;

}



#define CACHEFILES_KEYBUF_SIZE 512



/*

 * dump debugging info about an object

 */

static noinline

void __cachefiles_printk_object(struct cachefiles_object *object,

				const char *prefix,

				u8 *keybuf)

{

	struct fscache_cookie *cookie;

	unsigned keylen, loop;



	printk(KERN_ERR "%sobject: OBJ%x\n",

	       prefix, object->fscache.debug_id);

	printk(KERN_ERR "%sobjstate=%s fl=%lx swfl=%lx ev=%lx[%lx]\n",

	       prefix, fscache_object_states[object->fscache.state],

	       object->fscache.flags, object->fscache.work.flags,

	       object->fscache.events,

	       object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);

	printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",

	       prefix, object->fscache.n_ops, object->fscache.n_in_progress,

	       object->fscache.n_exclusive);

	printk(KERN_ERR "%sparent=%p\n",

	       prefix, object->fscache.parent);



	spin_lock(&object->fscache.lock);

	cookie = object->fscache.cookie;

	if (cookie) {

		printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",

		       prefix,

		       object->fscache.cookie,

		       object->fscache.cookie->parent,

		       object->fscache.cookie->netfs_data,

		       object->fscache.cookie->flags);

		if (keybuf)

			keylen = cookie->def->get_key(cookie->netfs_data, keybuf,

						      CACHEFILES_KEYBUF_SIZE);

		else

			keylen = 0;

	} else {

		printk(KERN_ERR "%scookie=NULL\n", prefix);

		keylen = 0;

	}

	spin_unlock(&object->fscache.lock);



	if (keylen) {

		printk(KERN_ERR "%skey=[%u] '", prefix, keylen);

		for (loop = 0; loop < keylen; loop++)

			printk("%02x", keybuf[loop]);

		printk("'\n");

	}

}



/*

 * dump debugging info about a pair of objects

 */

static noinline void cachefiles_printk_object(struct cachefiles_object *object,

					      struct cachefiles_object *xobject)

{

	u8 *keybuf;



	keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);

	if (object)

		__cachefiles_printk_object(object, "", keybuf);

	if (xobject)

		__cachefiles_printk_object(xobject, "x", keybuf);

	kfree(keybuf);

}



/*

 * record the fact that an object is now active

 */
@@ -42,8 +112,11 @@ static void cachefiles_mark_object_active(struct cachefiles_cache *cache, 
try_again:

	write_lock(&cache->active_lock);



	if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags))

	if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {

		printk(KERN_ERR "CacheFiles: Error: Object already active\n");

		cachefiles_printk_object(object, NULL);

		BUG();

	}



	dentry = object->dentry;

	_p = &cache->active_nodes.rb_node;
@@ -76,32 +149,7 @@ wait_for_old_object: 
		printk(KERN_ERR "\n");

		printk(KERN_ERR "CacheFiles: Error:"

		       " Unexpected object collision\n");

		printk(KERN_ERR "xobject: OBJ%x\n",

		       xobject->fscache.debug_id);

		printk(KERN_ERR "xobjstate=%s\n",

		       fscache_object_states[xobject->fscache.state]);

		printk(KERN_ERR "xobjflags=%lx\n", xobject->fscache.flags);

		printk(KERN_ERR "xobjevent=%lx [%lx]\n",

		       xobject->fscache.events, xobject->fscache.event_mask);

		printk(KERN_ERR "xops=%u inp=%u exc=%u\n",

		       xobject->fscache.n_ops, xobject->fscache.n_in_progress,

		       xobject->fscache.n_exclusive);

		printk(KERN_ERR "xcookie=%p [pr=%p nd=%p fl=%lx]\n",

		       xobject->fscache.cookie,

		       xobject->fscache.cookie->parent,

		       xobject->fscache.cookie->netfs_data,

		       xobject->fscache.cookie->flags);

		printk(KERN_ERR "xparent=%p\n",

		       xobject->fscache.parent);

		printk(KERN_ERR "object: OBJ%x\n",

		       object->fscache.debug_id);

		printk(KERN_ERR "cookie=%p [pr=%p nd=%p fl=%lx]\n",

		       object->fscache.cookie,

		       object->fscache.cookie->parent,

		       object->fscache.cookie->netfs_data,

		       object->fscache.cookie->flags);

		printk(KERN_ERR "parent=%p\n",

		       object->fscache.parent);

		cachefiles_printk_object(object, xobject);

		BUG();

	}

	atomic_inc(&xobject->usage);

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