Merge branch 'fscache-fixes' into for-next

Documentation/filesystems/caching/backend-api.txt

@@ -676,6 +676,29 @@ FS-Cache provides some utilities that a cache backend may make use of:
      as possible.
 
 
+ (*) Indicate that a stale object was found and discarded:
+
+	void fscache_object_retrying_stale(struct fscache_object *object);
+
+     This is called to indicate that the lookup procedure found an object in
+     the cache that the netfs decided was stale.  The object has been
+     discarded from the cache and the lookup will be performed again.
+
+
+ (*) Indicate that the caching backend killed an object:
+
+	void fscache_object_mark_killed(struct fscache_object *object,
+					enum fscache_why_object_killed why);
+
+     This is called to indicate that the cache backend preemptively killed an
+     object.  The why parameter should be set to indicate the reason:
+
+	FSCACHE_OBJECT_IS_STALE - the object was stale and needs discarding.
+	FSCACHE_OBJECT_NO_SPACE - there was insufficient cache space
+	FSCACHE_OBJECT_WAS_RETIRED - the object was retired when relinquished.
+	FSCACHE_OBJECT_WAS_CULLED - the object was culled to make space.
+
+
  (*) Get and release references on a retrieval record:
 
 	void fscache_get_retrieval(struct fscache_retrieval *op);

Documentation/filesystems/caching/fscache.txt

@@ -284,8 +284,9 @@ proc files.
 		enq=N	Number of times async ops queued for processing
 		can=N	Number of async ops cancelled
 		rej=N	Number of async ops rejected due to object lookup/create failure
+		ini=N	Number of async ops initialised
 		dfr=N	Number of async ops queued for deferred release
-		rel=N	Number of async ops released
+		rel=N	Number of async ops released (should equal ini=N when idle)
 		gc=N	Number of deferred-release async ops garbage collected
 	CacheOp	alo=N	Number of in-progress alloc_object() cache ops
 		luo=N	Number of in-progress lookup_object() cache ops
@@ -303,6 +304,10 @@ proc files.
 		wrp=N	Number of in-progress write_page() cache ops
 		ucp=N	Number of in-progress uncache_page() cache ops
 		dsp=N	Number of in-progress dissociate_pages() cache ops
+	CacheEv	nsp=N	Number of object lookups/creations rejected due to lack of space
+		stl=N	Number of stale objects deleted
+		rtr=N	Number of objects retired when relinquished
+		cul=N	Number of objects culled
 
 
  (*) /proc/fs/fscache/histogram

fs/cachefiles/internal.h

@@ -43,7 +43,6 @@ struct cachefiles_object {
 	loff_t				i_size;		/* object size */
 	unsigned long			flags;
 #define CACHEFILES_OBJECT_ACTIVE	0		/* T if marked active */
-#define CACHEFILES_OBJECT_BURIED	1		/* T if preemptively buried */
 	atomic_t			usage;		/* object usage count */
 	uint8_t				type;		/* object type */
 	uint8_t				new;		/* T if object new */

fs/cachefiles/namei.c

@@ -97,7 +97,8 @@ static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
  */
 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
-					  struct dentry *dentry)
+					  struct dentry *dentry,
+					  enum fscache_why_object_killed why)
 {
 	struct cachefiles_object *object;
 	struct rb_node *p;
@@ -132,8 +133,9 @@ static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 		pr_err("\n");
 		pr_err("Error: Can't preemptively bury live object\n");
 		cachefiles_printk_object(object, NULL);
-	} else if (test_and_set_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
-		pr_err("Error: Object already preemptively buried\n");
+	} else {
+		if (why != FSCACHE_OBJECT_IS_STALE)
+			fscache_object_mark_killed(&object->fscache, why);
 	}
 
 	write_unlock(&cache->active_lock);
@@ -265,7 +267,8 @@ static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 				  struct dentry *dir,
 				  struct dentry *rep,
-				  bool preemptive)
+				  bool preemptive,
+				  enum fscache_why_object_killed why)
 {
 	struct dentry *grave, *trap;
 	struct path path, path_to_graveyard;
@@ -289,7 +292,7 @@ static int cachefiles_bury_object(struct cachefiles_cache *cache,
 			ret = vfs_unlink(d_inode(dir), rep, NULL);
 
 			if (preemptive)
-				cachefiles_mark_object_buried(cache, rep);
+				cachefiles_mark_object_buried(cache, rep, why);
 		}
 
 		mutex_unlock(&d_inode(dir)->i_mutex);
@@ -394,7 +397,7 @@ static int cachefiles_bury_object(struct cachefiles_cache *cache,
 					    "Rename failed with error %d", ret);
 
 		if (preemptive)
-			cachefiles_mark_object_buried(cache, rep);
+			cachefiles_mark_object_buried(cache, rep, why);
 	}
 
 	unlock_rename(cache->graveyard, dir);
@@ -422,7 +425,7 @@ int cachefiles_delete_object(struct cachefiles_cache *cache,
 
 	mutex_lock_nested(&d_inode(dir)->i_mutex, I_MUTEX_PARENT);
 
-	if (test_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
+	if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
 		/* object allocation for the same key preemptively deleted this
 		 * object's file so that it could create its own file */
 		_debug("object preemptively buried");
@@ -433,7 +436,8 @@ int cachefiles_delete_object(struct cachefiles_cache *cache,
 		 * may have been renamed */
 		if (dir == object->dentry->d_parent) {
 			ret = cachefiles_bury_object(cache, dir,
-						     object->dentry, false);
+						     object->dentry, false,
+						     FSCACHE_OBJECT_WAS_RETIRED);
 		} else {
 			/* it got moved, presumably by cachefilesd culling it,
 			 * so it's no longer in the key path and we can ignore
@@ -522,7 +526,7 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 		if (d_is_negative(next)) {
 			ret = cachefiles_has_space(cache, 1, 0);
 			if (ret < 0)
-				goto create_error;
+				goto no_space_error;
 
 			path.dentry = dir;
 			ret = security_path_mkdir(&path, next, 0);
@@ -551,7 +555,7 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 		if (d_is_negative(next)) {
 			ret = cachefiles_has_space(cache, 1, 0);
 			if (ret < 0)
-				goto create_error;
+				goto no_space_error;
 
 			path.dentry = dir;
 			ret = security_path_mknod(&path, next, S_IFREG, 0);
@@ -602,14 +606,16 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 			 * mutex) */
 			object->dentry = NULL;
 
-			ret = cachefiles_bury_object(cache, dir, next, true);
+			ret = cachefiles_bury_object(cache, dir, next, true,
+						     FSCACHE_OBJECT_IS_STALE);
 			dput(next);
 			next = NULL;
 
 			if (ret < 0)
 				goto delete_error;
 
 			_debug("redo lookup");
+			fscache_object_retrying_stale(&object->fscache);
 			goto lookup_again;
 		}
 	}
@@ -662,6 +668,8 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 	_leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
 	return 0;
 
+no_space_error:
+	fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
 create_error:
 	_debug("create error %d", ret);
 	if (ret == -EIO)
@@ -927,7 +935,8 @@ int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 	/*  actually remove the victim (drops the dir mutex) */
 	_debug("bury");
 
-	ret = cachefiles_bury_object(cache, dir, victim, false);
+	ret = cachefiles_bury_object(cache, dir, victim, false,
+				     FSCACHE_OBJECT_WAS_CULLED);
 	if (ret < 0)
 		goto error;
 

fs/fscache/cookie.c

@@ -327,7 +327,8 @@ static int fscache_alloc_object(struct fscache_cache *cache,
 
 object_already_extant:
 	ret = -ENOBUFS;
-	if (fscache_object_is_dead(object)) {
+	if (fscache_object_is_dying(object) ||
+	    fscache_cache_is_broken(object)) {
 		spin_unlock(&cookie->lock);
 		goto error;
 	}
@@ -671,7 +672,7 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
 	if (!op)
 		return -ENOMEM;
 
-	fscache_operation_init(op, NULL, NULL);
+	fscache_operation_init(op, NULL, NULL, NULL);
 	op->flags = FSCACHE_OP_MYTHREAD |
 		(1 << FSCACHE_OP_WAITING) |
 		(1 << FSCACHE_OP_UNUSE_COOKIE);
@@ -695,8 +696,7 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
 	/* the work queue now carries its own ref on the object */
 	spin_unlock(&cookie->lock);
 
-	ret = fscache_wait_for_operation_activation(object, op,
-						    NULL, NULL, NULL);
+	ret = fscache_wait_for_operation_activation(object, op, NULL, NULL);
 	if (ret == 0) {
 		/* ask the cache to honour the operation */
 		ret = object->cache->ops->check_consistency(op);

fs/fscache/internal.h

@@ -124,8 +124,7 @@ extern int fscache_submit_exclusive_op(struct fscache_object *,
 				       struct fscache_operation *);
 extern int fscache_submit_op(struct fscache_object *,
 			     struct fscache_operation *);
-extern int fscache_cancel_op(struct fscache_operation *,
-			     void (*)(struct fscache_operation *));
+extern int fscache_cancel_op(struct fscache_operation *, bool);
 extern void fscache_cancel_all_ops(struct fscache_object *);
 extern void fscache_abort_object(struct fscache_object *);
 extern void fscache_start_operations(struct fscache_object *);
@@ -138,8 +137,7 @@ extern int fscache_wait_for_deferred_lookup(struct fscache_cookie *);
 extern int fscache_wait_for_operation_activation(struct fscache_object *,
 						 struct fscache_operation *,
 						 atomic_t *,
-						 atomic_t *,
-						 void (*)(struct fscache_operation *));
+						 atomic_t *);
 extern void fscache_invalidate_writes(struct fscache_cookie *);
 
 /*
@@ -164,6 +162,7 @@ extern atomic_t fscache_n_op_pend;
 extern atomic_t fscache_n_op_run;
 extern atomic_t fscache_n_op_enqueue;
 extern atomic_t fscache_n_op_deferred_release;
+extern atomic_t fscache_n_op_initialised;
 extern atomic_t fscache_n_op_release;
 extern atomic_t fscache_n_op_gc;
 extern atomic_t fscache_n_op_cancelled;
@@ -271,6 +270,11 @@ extern atomic_t fscache_n_cop_write_page;
 extern atomic_t fscache_n_cop_uncache_page;
 extern atomic_t fscache_n_cop_dissociate_pages;
 
+extern atomic_t fscache_n_cache_no_space_reject;
+extern atomic_t fscache_n_cache_stale_objects;
+extern atomic_t fscache_n_cache_retired_objects;
+extern atomic_t fscache_n_cache_culled_objects;
+
 static inline void fscache_stat(atomic_t *stat)
 {
 	atomic_inc(stat);

fs/fscache/object.c

@@ -327,6 +327,17 @@ void fscache_object_init(struct fscache_object *object,
 }
 EXPORT_SYMBOL(fscache_object_init);
 
+/*
+ * Mark the object as no longer being live, making sure that we synchronise
+ * against op submission.
+ */
+static inline void fscache_mark_object_dead(struct fscache_object *object)
+{
+	spin_lock(&object->lock);
+	clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
+	spin_unlock(&object->lock);
+}
+
 /*
  * Abort object initialisation before we start it.
  */
@@ -610,6 +621,8 @@ static const struct fscache_state *fscache_lookup_failure(struct fscache_object
 	object->cache->ops->lookup_complete(object);
 	fscache_stat_d(&fscache_n_cop_lookup_complete);
 
+	set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags);
+
 	cookie = object->cookie;
 	set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
 	if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags))
@@ -629,7 +642,7 @@ static const struct fscache_state *fscache_kill_object(struct fscache_object *ob
 	_enter("{OBJ%x,%d,%d},%d",
 	       object->debug_id, object->n_ops, object->n_children, event);
 
-	clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
+	fscache_mark_object_dead(object);
 	object->oob_event_mask = 0;
 
 	if (list_empty(&object->dependents) &&
@@ -948,7 +961,8 @@ static const struct fscache_state *_fscache_invalidate_object(struct fscache_obj
 	if (!op)
 		goto nomem;
 
-	fscache_operation_init(op, object->cache->ops->invalidate_object, NULL);
+	fscache_operation_init(op, object->cache->ops->invalidate_object,
+			       NULL, NULL);
 	op->flags = FSCACHE_OP_ASYNC |
 		(1 << FSCACHE_OP_EXCLUSIVE) |
 		(1 << FSCACHE_OP_UNUSE_COOKIE);
@@ -974,13 +988,13 @@ static const struct fscache_state *_fscache_invalidate_object(struct fscache_obj
 	return transit_to(UPDATE_OBJECT);
 
 nomem:
-	clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
+	fscache_mark_object_dead(object);
 	fscache_unuse_cookie(object);
 	_leave(" [ENOMEM]");
 	return transit_to(KILL_OBJECT);
 
 submit_op_failed:
-	clear_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
+	fscache_mark_object_dead(object);
 	spin_unlock(&cookie->lock);
 	fscache_unuse_cookie(object);
 	kfree(op);
@@ -1016,3 +1030,50 @@ static const struct fscache_state *fscache_update_object(struct fscache_object *
 	_leave("");
 	return transit_to(WAIT_FOR_CMD);
 }
+
+/**
+ * fscache_object_retrying_stale - Note retrying stale object
+ * @object: The object that will be retried
+ *
+ * Note that an object lookup found an on-disk object that was adjudged to be
+ * stale and has been deleted.  The lookup will be retried.
+ */
+void fscache_object_retrying_stale(struct fscache_object *object)
+{
+	fscache_stat(&fscache_n_cache_no_space_reject);
+}
+EXPORT_SYMBOL(fscache_object_retrying_stale);
+
+/**
+ * fscache_object_mark_killed - Note that an object was killed
+ * @object: The object that was culled
+ * @why: The reason the object was killed.
+ *
+ * Note that an object was killed.  Returns true if the object was
+ * already marked killed, false if it wasn't.
+ */
+void fscache_object_mark_killed(struct fscache_object *object,
+				enum fscache_why_object_killed why)
+{
+	if (test_and_set_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->flags)) {
+		pr_err("Error: Object already killed by cache [%s]\n",
+		       object->cache->identifier);
+		return;
+	}
+
+	switch (why) {
+	case FSCACHE_OBJECT_NO_SPACE:
+		fscache_stat(&fscache_n_cache_no_space_reject);
+		break;
+	case FSCACHE_OBJECT_IS_STALE:
+		fscache_stat(&fscache_n_cache_stale_objects);
+		break;
+	case FSCACHE_OBJECT_WAS_RETIRED:
+		fscache_stat(&fscache_n_cache_retired_objects);
+		break;
+	case FSCACHE_OBJECT_WAS_CULLED:
+		fscache_stat(&fscache_n_cache_culled_objects);
+		break;
+	}
+}
+EXPORT_SYMBOL(fscache_object_mark_killed);