Merge branch 'fscache-fixes' into for-next

Documentation/filesystems/caching/backend-api.txt

···
      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

···
 		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
···
 		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

···
 	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

···
  *   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;
···
 		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);
···
 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;
···
 			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);
···
 					    "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);
···
 
 	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");
···
 		 * 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
···
 		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);
···
 		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);
···
 			 * 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;
 
···
 				goto delete_error;
 
 			_debug("redo lookup");
+			fscache_object_retrying_stale(&object->fscache);
 			goto lookup_again;
 		}
 	}
···
 	_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)
···
 	/*  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

···
 
 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;
 	}
···
 	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);
···
 	/* 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

···
 				       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 *);
···
 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 *);
 
 /*
···
 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;
···
 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)
 {

fs/fscache/object.c

···
 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.
  */
 static const struct fscache_state *fscache_abort_initialisation(struct fscache_object *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))
···
 	_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) &&
···
 	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);
···
 	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);
···
 	_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);

fs/fscache/operation.c

···
 atomic_t fscache_op_debug_id;
 EXPORT_SYMBOL(fscache_op_debug_id);
 
+static void fscache_operation_dummy_cancel(struct fscache_operation *op)
+{
+}
+
+/**
+ * fscache_operation_init - Do basic initialisation of an operation
+ * @op: The operation to initialise
+ * @release: The release function to assign
+ *
+ * Do basic initialisation of an operation.  The caller must still set flags,
+ * object and processor if needed.
+ */
+void fscache_operation_init(struct fscache_operation *op,
+			    fscache_operation_processor_t processor,
+			    fscache_operation_cancel_t cancel,
+			    fscache_operation_release_t release)
+{
+	INIT_WORK(&op->work, fscache_op_work_func);
+	atomic_set(&op->usage, 1);
+	op->state = FSCACHE_OP_ST_INITIALISED;
+	op->debug_id = atomic_inc_return(&fscache_op_debug_id);
+	op->processor = processor;
+	op->cancel = cancel ?: fscache_operation_dummy_cancel;
+	op->release = release;
+	INIT_LIST_HEAD(&op->pend_link);
+	fscache_stat(&fscache_n_op_initialised);
+}
+EXPORT_SYMBOL(fscache_operation_init);
+
 /**
  * fscache_enqueue_operation - Enqueue an operation for processing
  * @op: The operation to enqueue
···
 }
 
 /*
- * submit an exclusive operation for an object
- * - other ops are excluded from running simultaneously with this one
- * - this gets any extra refs it needs on an op
- */
-int fscache_submit_exclusive_op(struct fscache_object *object,
-				struct fscache_operation *op)
-{
-	int ret;
-
-	_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
-
-	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
-	ASSERTCMP(atomic_read(&op->usage), >, 0);
-
-	spin_lock(&object->lock);
-	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
-	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
-	ASSERT(list_empty(&op->pend_link));
-
-	op->state = FSCACHE_OP_ST_PENDING;
-	if (fscache_object_is_active(object)) {
-		op->object = object;
-		object->n_ops++;
-		object->n_exclusive++;	/* reads and writes must wait */
-
-		if (object->n_in_progress > 0) {
-			atomic_inc(&op->usage);
-			list_add_tail(&op->pend_link, &object->pending_ops);
-			fscache_stat(&fscache_n_op_pend);
-		} else if (!list_empty(&object->pending_ops)) {
-			atomic_inc(&op->usage);
-			list_add_tail(&op->pend_link, &object->pending_ops);
-			fscache_stat(&fscache_n_op_pend);
-			fscache_start_operations(object);
-		} else {
-			ASSERTCMP(object->n_in_progress, ==, 0);
-			fscache_run_op(object, op);
-		}
-
-		/* need to issue a new write op after this */
-		clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
-		ret = 0;
-	} else if (test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {
-		op->object = object;
-		object->n_ops++;
-		object->n_exclusive++;	/* reads and writes must wait */
-		atomic_inc(&op->usage);
-		list_add_tail(&op->pend_link, &object->pending_ops);
-		fscache_stat(&fscache_n_op_pend);
-		ret = 0;
-	} else {
-		/* If we're in any other state, there must have been an I/O
-		 * error of some nature.
-		 */
-		ASSERT(test_bit(FSCACHE_IOERROR, &object->cache->flags));
-		ret = -EIO;
-	}
-
-	spin_unlock(&object->lock);
-	return ret;
-}
-
-/*
  * report an unexpected submission
  */
 static void fscache_report_unexpected_submission(struct fscache_object *object,
···
 }
 
 /*
+ * submit an exclusive operation for an object
+ * - other ops are excluded from running simultaneously with this one
+ * - this gets any extra refs it needs on an op
+ */
+int fscache_submit_exclusive_op(struct fscache_object *object,
+				struct fscache_operation *op)
+{
+	const struct fscache_state *ostate;
+	unsigned long flags;
+	int ret;
+
+	_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
+
+	ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
+	ASSERTCMP(atomic_read(&op->usage), >, 0);
+
+	spin_lock(&object->lock);
+	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
+	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
+	ASSERT(list_empty(&op->pend_link));
+
+	ostate = object->state;
+	smp_rmb();
+
+	op->state = FSCACHE_OP_ST_PENDING;
+	flags = READ_ONCE(object->flags);
+	if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
+		fscache_stat(&fscache_n_op_rejected);
+		op->cancel(op);
+		op->state = FSCACHE_OP_ST_CANCELLED;
+		ret = -ENOBUFS;
+	} else if (unlikely(fscache_cache_is_broken(object))) {
+		op->cancel(op);
+		op->state = FSCACHE_OP_ST_CANCELLED;
+		ret = -EIO;
+	} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
+		op->object = object;
+		object->n_ops++;
+		object->n_exclusive++;	/* reads and writes must wait */
+
+		if (object->n_in_progress > 0) {
+			atomic_inc(&op->usage);
+			list_add_tail(&op->pend_link, &object->pending_ops);
+			fscache_stat(&fscache_n_op_pend);
+		} else if (!list_empty(&object->pending_ops)) {
+			atomic_inc(&op->usage);
+			list_add_tail(&op->pend_link, &object->pending_ops);
+			fscache_stat(&fscache_n_op_pend);
+			fscache_start_operations(object);
+		} else {
+			ASSERTCMP(object->n_in_progress, ==, 0);
+			fscache_run_op(object, op);
+		}
+
+		/* need to issue a new write op after this */
+		clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
+		ret = 0;
+	} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
+		op->object = object;
+		object->n_ops++;
+		object->n_exclusive++;	/* reads and writes must wait */
+		atomic_inc(&op->usage);
+		list_add_tail(&op->pend_link, &object->pending_ops);
+		fscache_stat(&fscache_n_op_pend);
+		ret = 0;
+	} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
+		op->cancel(op);
+		op->state = FSCACHE_OP_ST_CANCELLED;
+		ret = -ENOBUFS;
+	} else {
+		fscache_report_unexpected_submission(object, op, ostate);
+		op->cancel(op);
+		op->state = FSCACHE_OP_ST_CANCELLED;
+		ret = -ENOBUFS;
+	}
+
+	spin_unlock(&object->lock);
+	return ret;
+}
+
+/*
  * submit an operation for an object
  * - objects may be submitted only in the following states:
  *   - during object creation (write ops may be submitted)
···
 		      struct fscache_operation *op)
 {
 	const struct fscache_state *ostate;
+	unsigned long flags;
 	int ret;
 
 	_enter("{OBJ%x OP%x},{%u}",
···
 	smp_rmb();
 
 	op->state = FSCACHE_OP_ST_PENDING;
-	if (fscache_object_is_active(object)) {
+	flags = READ_ONCE(object->flags);
+	if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
+		fscache_stat(&fscache_n_op_rejected);
+		op->cancel(op);
+		op->state = FSCACHE_OP_ST_CANCELLED;
+		ret = -ENOBUFS;
+	} else if (unlikely(fscache_cache_is_broken(object))) {
+		op->cancel(op);
+		op->state = FSCACHE_OP_ST_CANCELLED;
+		ret = -EIO;
+	} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
 		op->object = object;
 		object->n_ops++;
 
···
 			fscache_run_op(object, op);
 		}
 		ret = 0;
-	} else if (test_bit(FSCACHE_OBJECT_IS_LOOKED_UP, &object->flags)) {
+	} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
 		op->object = object;
 		object->n_ops++;
 		atomic_inc(&op->usage);
 		list_add_tail(&op->pend_link, &object->pending_ops);
 		fscache_stat(&fscache_n_op_pend);
 		ret = 0;
-	} else if (fscache_object_is_dying(object)) {
-		fscache_stat(&fscache_n_op_rejected);
-		op->state = FSCACHE_OP_ST_CANCELLED;
-		ret = -ENOBUFS;
-	} else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
-		fscache_report_unexpected_submission(object, op, ostate);
-		ASSERT(!fscache_object_is_active(object));
+	} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
+		op->cancel(op);
 		op->state = FSCACHE_OP_ST_CANCELLED;
 		ret = -ENOBUFS;
 	} else {
+		fscache_report_unexpected_submission(object, op, ostate);
+		ASSERT(!fscache_object_is_active(object));
+		op->cancel(op);
 		op->state = FSCACHE_OP_ST_CANCELLED;
 		ret = -ENOBUFS;
 	}
···
  * cancel an operation that's pending on an object
  */
 int fscache_cancel_op(struct fscache_operation *op,
-		      void (*do_cancel)(struct fscache_operation *))
+		      bool cancel_in_progress_op)
 {
 	struct fscache_object *object = op->object;
+	bool put = false;
 	int ret;
 
 	_enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
···
 	ret = -EBUSY;
 	if (op->state == FSCACHE_OP_ST_PENDING) {
 		ASSERT(!list_empty(&op->pend_link));
-		fscache_stat(&fscache_n_op_cancelled);
 		list_del_init(&op->pend_link);
-		if (do_cancel)
-			do_cancel(op);
+		put = true;
+
+		fscache_stat(&fscache_n_op_cancelled);
+		op->cancel(op);
 		op->state = FSCACHE_OP_ST_CANCELLED;
 		if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
 			object->n_exclusive--;
 		if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
 			wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
-		fscache_put_operation(op);
+		ret = 0;
+	} else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
+		ASSERTCMP(object->n_in_progress, >, 0);
+		if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
+			object->n_exclusive--;
+		object->n_in_progress--;
+		if (object->n_in_progress == 0)
+			fscache_start_operations(object);
+
+		fscache_stat(&fscache_n_op_cancelled);
+		op->cancel(op);
+		op->state = FSCACHE_OP_ST_CANCELLED;
+		if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
+			object->n_exclusive--;
+		if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
+			wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
 		ret = 0;
 	}
 
+	if (put)
+		fscache_put_operation(op);
 	spin_unlock(&object->lock);
 	_leave(" = %d", ret);
 	return ret;
···
 		list_del_init(&op->pend_link);
 
 		ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
+		op->cancel(op);
 		op->state = FSCACHE_OP_ST_CANCELLED;
 
 		if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
···
 
 	spin_lock(&object->lock);
 
-	op->state = cancelled ?
-		FSCACHE_OP_ST_CANCELLED : FSCACHE_OP_ST_COMPLETE;
+	if (!cancelled) {
+		op->state = FSCACHE_OP_ST_COMPLETE;
+	} else {
+		op->cancel(op);
+		op->state = FSCACHE_OP_ST_CANCELLED;
+	}
 
 	if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
 		object->n_exclusive--;
···
 		return;
 
 	_debug("PUT OP");
-	ASSERTIFCMP(op->state != FSCACHE_OP_ST_COMPLETE,
+	ASSERTIFCMP(op->state != FSCACHE_OP_ST_INITIALISED &&
+		    op->state != FSCACHE_OP_ST_COMPLETE,
 		    op->state, ==, FSCACHE_OP_ST_CANCELLED);
-	op->state = FSCACHE_OP_ST_DEAD;
 
 	fscache_stat(&fscache_n_op_release);
 
···
 		op->release(op);
 		op->release = NULL;
 	}
+	op->state = FSCACHE_OP_ST_DEAD;
 
 	object = op->object;
+	if (likely(object)) {
+		if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
+			atomic_dec(&object->n_reads);
+		if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
+			fscache_unuse_cookie(object);
 
-	if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
-		atomic_dec(&object->n_reads);
-	if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
-		fscache_unuse_cookie(object);
+		/* now... we may get called with the object spinlock held, so we
+		 * complete the cleanup here only if we can immediately acquire the
+		 * lock, and defer it otherwise */
+		if (!spin_trylock(&object->lock)) {
+			_debug("defer put");
+			fscache_stat(&fscache_n_op_deferred_release);
 
-	/* now... we may get called with the object spinlock held, so we
-	 * complete the cleanup here only if we can immediately acquire the
-	 * lock, and defer it otherwise */
-	if (!spin_trylock(&object->lock)) {
-		_debug("defer put");
-		fscache_stat(&fscache_n_op_deferred_release);
+			cache = object->cache;
+			spin_lock(&cache->op_gc_list_lock);
+			list_add_tail(&op->pend_link, &cache->op_gc_list);
+			spin_unlock(&cache->op_gc_list_lock);
+			schedule_work(&cache->op_gc);
+			_leave(" [defer]");
+			return;
+		}
 
-		cache = object->cache;
-		spin_lock(&cache->op_gc_list_lock);
-		list_add_tail(&op->pend_link, &cache->op_gc_list);
-		spin_unlock(&cache->op_gc_list_lock);
-		schedule_work(&cache->op_gc);
-		_leave(" [defer]");
-		return;
+		ASSERTCMP(object->n_ops, >, 0);
+		object->n_ops--;
+		if (object->n_ops == 0)
+			fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
+
+		spin_unlock(&object->lock);
 	}
-
-	ASSERTCMP(object->n_ops, >, 0);
-	object->n_ops--;
-	if (object->n_ops == 0)
-		fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
-
-	spin_unlock(&object->lock);
 
 	kfree(op);
 	_leave(" [done]");

fs/fscache/page.c

···
 		return -ENOMEM;
 	}
 
-	fscache_operation_init(op, fscache_attr_changed_op, NULL);
+	fscache_operation_init(op, fscache_attr_changed_op, NULL, NULL);
 	op->flags = FSCACHE_OP_ASYNC |
 		(1 << FSCACHE_OP_EXCLUSIVE) |
 		(1 << FSCACHE_OP_UNUSE_COOKIE);
···
 	wake_cookie = __fscache_unuse_cookie(cookie);
 nobufs:
 	spin_unlock(&cookie->lock);
-	kfree(op);
+	fscache_put_operation(op);
 	if (wake_cookie)
 		__fscache_wake_unused_cookie(cookie);
 	fscache_stat(&fscache_n_attr_changed_nobufs);
···
 	return -ENOBUFS;
 }
 EXPORT_SYMBOL(__fscache_attr_changed);
+
+/*
+ * Handle cancellation of a pending retrieval op
+ */
+static void fscache_do_cancel_retrieval(struct fscache_operation *_op)
+{
+	struct fscache_retrieval *op =
+		container_of(_op, struct fscache_retrieval, op);
+
+	atomic_set(&op->n_pages, 0);
+}
 
 /*
  * release a retrieval op reference
···
 
 	_enter("{OP%x}", op->op.debug_id);
 
-	ASSERTCMP(atomic_read(&op->n_pages), ==, 0);
+	ASSERTIFCMP(op->op.state != FSCACHE_OP_ST_INITIALISED,
+		    atomic_read(&op->n_pages), ==, 0);
 
 	fscache_hist(fscache_retrieval_histogram, op->start_time);
 	if (op->context)
-		fscache_put_context(op->op.object->cookie, op->context);
+		fscache_put_context(op->cookie, op->context);
 
 	_leave("");
 }
···
 		return NULL;
 	}
 
-	fscache_operation_init(&op->op, NULL, fscache_release_retrieval_op);
+	fscache_operation_init(&op->op, NULL,
+			       fscache_do_cancel_retrieval,
+			       fscache_release_retrieval_op);
 	op->op.flags	= FSCACHE_OP_MYTHREAD |
 		(1UL << FSCACHE_OP_WAITING) |
 		(1UL << FSCACHE_OP_UNUSE_COOKIE);
+	op->cookie	= cookie;
 	op->mapping	= mapping;
 	op->end_io_func	= end_io_func;
 	op->context	= context;
 	op->start_time	= jiffies;
 	INIT_LIST_HEAD(&op->to_do);
+
+	/* Pin the netfs read context in case we need to do the actual netfs
+	 * read because we've encountered a cache read failure.
+	 */
+	if (context)
+		fscache_get_context(op->cookie, context);
 	return op;
 }
 
···
 }
 
 /*
- * Handle cancellation of a pending retrieval op
- */
-static void fscache_do_cancel_retrieval(struct fscache_operation *_op)
-{
-	struct fscache_retrieval *op =
-		container_of(_op, struct fscache_retrieval, op);
-
-	atomic_set(&op->n_pages, 0);
-}
-
-/*
  * wait for an object to become active (or dead)
  */
 int fscache_wait_for_operation_activation(struct fscache_object *object,
 					  struct fscache_operation *op,
 					  atomic_t *stat_op_waits,
-					  atomic_t *stat_object_dead,
-					  void (*do_cancel)(struct fscache_operation *))
+					  atomic_t *stat_object_dead)
 {
 	int ret;
 
···
 		fscache_stat(stat_op_waits);
 	if (wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
 			TASK_INTERRUPTIBLE) != 0) {
-		ret = fscache_cancel_op(op, do_cancel);
+		ret = fscache_cancel_op(op, false);
 		if (ret == 0)
 			return -ERESTARTSYS;
 
···
 		_leave(" = -ENOBUFS [cancelled]");
 		return -ENOBUFS;
 	}
-	if (unlikely(fscache_object_is_dead(object))) {
-		pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->state);
-		fscache_cancel_op(op, do_cancel);
+	if (unlikely(fscache_object_is_dying(object) ||
+		     fscache_cache_is_broken(object))) {
+		enum fscache_operation_state state = op->state;
+		fscache_cancel_op(op, true);
 		if (stat_object_dead)
 			fscache_stat(stat_object_dead);
+		_leave(" = -ENOBUFS [obj dead %d]", state);
 		return -ENOBUFS;
 	}
 	return 0;
···
 
 	fscache_stat(&fscache_n_retrieval_ops);
 
-	/* pin the netfs read context in case we need to do the actual netfs
-	 * read because we've encountered a cache read failure */
-	fscache_get_context(object->cookie, op->context);
-
 	/* we wait for the operation to become active, and then process it
 	 * *here*, in this thread, and not in the thread pool */
 	ret = fscache_wait_for_operation_activation(
 		object, &op->op,
 		__fscache_stat(&fscache_n_retrieval_op_waits),
-		__fscache_stat(&fscache_n_retrievals_object_dead),
-		fscache_do_cancel_retrieval);
+		__fscache_stat(&fscache_n_retrievals_object_dead));
 	if (ret < 0)
 		goto error;
 
···
 	spin_unlock(&cookie->lock);
 	if (wake_cookie)
 		__fscache_wake_unused_cookie(cookie);
-	kfree(op);
+	fscache_put_retrieval(op);
 nobufs:
 	fscache_stat(&fscache_n_retrievals_nobufs);
 	_leave(" = -ENOBUFS");
···
 
 	fscache_stat(&fscache_n_retrieval_ops);
 
-	/* pin the netfs read context in case we need to do the actual netfs
-	 * read because we've encountered a cache read failure */
-	fscache_get_context(object->cookie, op->context);
-
 	/* we wait for the operation to become active, and then process it
 	 * *here*, in this thread, and not in the thread pool */
 	ret = fscache_wait_for_operation_activation(
 		object, &op->op,
 		__fscache_stat(&fscache_n_retrieval_op_waits),
-		__fscache_stat(&fscache_n_retrievals_object_dead),
-		fscache_do_cancel_retrieval);
+		__fscache_stat(&fscache_n_retrievals_object_dead));
 	if (ret < 0)
 		goto error;
 
···
 	wake_cookie = __fscache_unuse_cookie(cookie);
 nobufs_unlock:
 	spin_unlock(&cookie->lock);
-	kfree(op);
+	fscache_put_retrieval(op);
 	if (wake_cookie)
 		__fscache_wake_unused_cookie(cookie);
 nobufs:
···
 	ret = fscache_wait_for_operation_activation(
 		object, &op->op,
 		__fscache_stat(&fscache_n_alloc_op_waits),
-		__fscache_stat(&fscache_n_allocs_object_dead),
-		fscache_do_cancel_retrieval);
+		__fscache_stat(&fscache_n_allocs_object_dead));
 	if (ret < 0)
 		goto error;
 
···
 	wake_cookie = __fscache_unuse_cookie(cookie);
 nobufs_unlock:
 	spin_unlock(&cookie->lock);
-	kfree(op);
+	fscache_put_retrieval(op);
 	if (wake_cookie)
 		__fscache_wake_unused_cookie(cookie);
 nobufs:
···
 	if (!op)
 		goto nomem;
 
-	fscache_operation_init(&op->op, fscache_write_op,
+	fscache_operation_init(&op->op, fscache_write_op, NULL,
 			       fscache_release_write_op);
 	op->op.flags = FSCACHE_OP_ASYNC |
 		(1 << FSCACHE_OP_WAITING) |
···
 	spin_unlock(&object->lock);
 	spin_unlock(&cookie->lock);
 	radix_tree_preload_end();
-	kfree(op);
+	fscache_put_operation(&op->op);
 	fscache_stat(&fscache_n_stores_ok);
 	_leave(" = 0");
 	return 0;
···
 nobufs:
 	spin_unlock(&cookie->lock);
 	radix_tree_preload_end();
-	kfree(op);
+	fscache_put_operation(&op->op);
 	if (wake_cookie)
 		__fscache_wake_unused_cookie(cookie);
 	fscache_stat(&fscache_n_stores_nobufs);
···
 	return -ENOBUFS;
 
 nomem_free:
-	kfree(op);
+	fscache_put_operation(&op->op);
 nomem:
 	fscache_stat(&fscache_n_stores_oom);
 	_leave(" = -ENOMEM");

fs/fscache/stats.c

···
 atomic_t fscache_n_op_enqueue;
 atomic_t fscache_n_op_requeue;
 atomic_t fscache_n_op_deferred_release;
+atomic_t fscache_n_op_initialised;
 atomic_t fscache_n_op_release;
 atomic_t fscache_n_op_gc;
 atomic_t fscache_n_op_cancelled;
···
 atomic_t fscache_n_cop_write_page;
 atomic_t fscache_n_cop_uncache_page;
 atomic_t fscache_n_cop_dissociate_pages;
+
+atomic_t fscache_n_cache_no_space_reject;
+atomic_t fscache_n_cache_stale_objects;
+atomic_t fscache_n_cache_retired_objects;
+atomic_t fscache_n_cache_culled_objects;
 
 /*
  * display the general statistics
···
 		   atomic_read(&fscache_n_op_enqueue),
 		   atomic_read(&fscache_n_op_cancelled),
 		   atomic_read(&fscache_n_op_rejected));
-	seq_printf(m, "Ops    : dfr=%u rel=%u gc=%u\n",
+	seq_printf(m, "Ops    : ini=%u dfr=%u rel=%u gc=%u\n",
+		   atomic_read(&fscache_n_op_initialised),
 		   atomic_read(&fscache_n_op_deferred_release),
 		   atomic_read(&fscache_n_op_release),
 		   atomic_read(&fscache_n_op_gc));
···
 		   atomic_read(&fscache_n_cop_write_page),
 		   atomic_read(&fscache_n_cop_uncache_page),
 		   atomic_read(&fscache_n_cop_dissociate_pages));
+	seq_printf(m, "CacheEv: nsp=%d stl=%d rtr=%d cul=%d\n",
+		   atomic_read(&fscache_n_cache_no_space_reject),
+		   atomic_read(&fscache_n_cache_stale_objects),
+		   atomic_read(&fscache_n_cache_retired_objects),
+		   atomic_read(&fscache_n_cache_culled_objects));
 	return 0;
 }
 

include/linux/fscache-cache.h

···
  */
 typedef void (*fscache_operation_release_t)(struct fscache_operation *op);
 typedef void (*fscache_operation_processor_t)(struct fscache_operation *op);
+typedef void (*fscache_operation_cancel_t)(struct fscache_operation *op);
 
 enum fscache_operation_state {
 	FSCACHE_OP_ST_BLANK,		/* Op is not yet submitted */
···
 	 *   the op in a non-pool thread */
 	fscache_operation_processor_t processor;
 
+	/* Operation cancellation cleanup (optional) */
+	fscache_operation_cancel_t cancel;
+
 	/* operation releaser */
 	fscache_operation_release_t release;
 };
···
 extern void fscache_enqueue_operation(struct fscache_operation *);
 extern void fscache_op_complete(struct fscache_operation *, bool);
 extern void fscache_put_operation(struct fscache_operation *);
-
-/**
- * fscache_operation_init - Do basic initialisation of an operation
- * @op: The operation to initialise
- * @release: The release function to assign
- *
- * Do basic initialisation of an operation.  The caller must still set flags,
- * object and processor if needed.
- */
-static inline void fscache_operation_init(struct fscache_operation *op,
-					fscache_operation_processor_t processor,
-					fscache_operation_release_t release)
-{
-	INIT_WORK(&op->work, fscache_op_work_func);
-	atomic_set(&op->usage, 1);
-	op->state = FSCACHE_OP_ST_INITIALISED;
-	op->debug_id = atomic_inc_return(&fscache_op_debug_id);
-	op->processor = processor;
-	op->release = release;
-	INIT_LIST_HEAD(&op->pend_link);
-}
+extern void fscache_operation_init(struct fscache_operation *,
+				   fscache_operation_processor_t,
+				   fscache_operation_cancel_t,
+				   fscache_operation_release_t);
 
 /*
  * data read operation
  */
 struct fscache_retrieval {
 	struct fscache_operation op;
+	struct fscache_cookie	*cookie;	/* The netfs cookie */
 	struct address_space	*mapping;	/* netfs pages */
 	fscache_rw_complete_t	end_io_func;	/* function to call on I/O completion */
 	void			*context;	/* netfs read context (pinned) */
···
 #define FSCACHE_OBJECT_IS_LOOKED_UP	4	/* T if object has been looked up */
 #define FSCACHE_OBJECT_IS_AVAILABLE	5	/* T if object has become active */
 #define FSCACHE_OBJECT_RETIRED		6	/* T if object was retired on relinquishment */
+#define FSCACHE_OBJECT_KILLED_BY_CACHE	7	/* T if object was killed by the cache */
 
 	struct list_head	cache_link;	/* link in cache->object_list */
 	struct hlist_node	cookie_link;	/* link in cookie->backing_objects */
···
 	return test_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags);
 }
 
+static inline bool fscache_cache_is_broken(struct fscache_object *object)
+{
+	return test_bit(FSCACHE_IOERROR, &object->cache->flags);
+}
+
 static inline bool fscache_object_is_active(struct fscache_object *object)
 {
 	return fscache_object_is_available(object) &&
 		fscache_object_is_live(object) &&
-		!test_bit(FSCACHE_IOERROR, &object->cache->flags);
-}
-
-static inline bool fscache_object_is_dead(struct fscache_object *object)
-{
-	return fscache_object_is_dying(object) &&
-		test_bit(FSCACHE_IOERROR, &object->cache->flags);
+		!fscache_cache_is_broken(object);
 }
 
 /**
···
 extern enum fscache_checkaux fscache_check_aux(struct fscache_object *object,
 					       const void *data,
 					       uint16_t datalen);
+
+extern void fscache_object_retrying_stale(struct fscache_object *object);
+
+enum fscache_why_object_killed {
+	FSCACHE_OBJECT_IS_STALE,
+	FSCACHE_OBJECT_NO_SPACE,
+	FSCACHE_OBJECT_WAS_RETIRED,
+	FSCACHE_OBJECT_WAS_CULLED,
+};
+extern void fscache_object_mark_killed(struct fscache_object *object,
+				       enum fscache_why_object_killed why);
 
 #endif /* _LINUX_FSCACHE_CACHE_H */