orangefs: hopefully saner op refcounting and locking

* create with refcount 1
* make op_release() decrement and free if zero (i.e. old put_op()
  has become that).
* mark when submitter has given up waiting; from that point nobody
  else can move between the lists, change state, etc.
* have daemon read/write_iter grab a reference when picking op
  and *always* give it up in the end
* don't put into hash until we know it's been successfully passed to
  daemon

* move op->lock _lower_ than htab_in_progress_lock (and make sure
  to take it in purge_inprogress_ops())

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>

fs/orangefs/devorangefs-req.c

@@ -43,9 +43,7 @@ static void orangefs_devreq_add_op(struct orangefs_kernel_op_s *op)
 {
 	int index = hash_func(op->tag, hash_table_size);
 
-	spin_lock(&htable_ops_in_progress_lock);
 	list_add_tail(&op->list, &htable_ops_in_progress[index]);
-	spin_unlock(&htable_ops_in_progress_lock);
 }
 
 static struct orangefs_kernel_op_s *orangefs_devreq_remove_op(__u64 tag)
@@ -60,8 +58,9 @@ static struct orangefs_kernel_op_s *orangefs_devreq_remove_op(__u64 tag)
 				 next,
 				 &htable_ops_in_progress[index],
 				 list) {
-		if (op->tag == tag) {
-			list_del(&op->list);
+		if (op->tag == tag && !op_state_purged(op)) {
+			list_del_init(&op->list);
+			get_op(op); /* increase ref count. */
 			spin_unlock(&htable_ops_in_progress_lock);
 			return op;
 		}
@@ -127,12 +126,17 @@ static ssize_t orangefs_devreq_read(struct file *file,
 		return -EINVAL;
 	}
 
+restart:
 	/* Get next op (if any) from top of list. */
 	spin_lock(&orangefs_request_list_lock);
 	list_for_each_entry_safe(op, temp, &orangefs_request_list, list) {
 		__s32 fsid;
 		/* This lock is held past the end of the loop when we break. */
 		spin_lock(&op->lock);
+		if (unlikely(op_state_purged(op))) {
+			spin_unlock(&op->lock);
+			continue;
+		}
 
 		fsid = fsid_of_op(op);
 		if (fsid != ORANGEFS_FS_ID_NULL) {
@@ -197,16 +201,10 @@ static ssize_t orangefs_devreq_read(struct file *file,
 		spin_unlock(&orangefs_request_list_lock);
 		return -EAGAIN;
 	}
-
-	/*
-	 * Set the operation to be in progress and move it between lists since
-	 * it has been sent to the client.
-	 */
-	set_op_state_inprogress(cur_op);
-
-	list_del(&cur_op->list);
+	list_del_init(&cur_op->list);
+	get_op(op);
 	spin_unlock(&orangefs_request_list_lock);
-	orangefs_devreq_add_op(cur_op);
+
 	spin_unlock(&cur_op->lock);
 
 	/* Push the upcall out. */
@@ -224,6 +222,25 @@ static ssize_t orangefs_devreq_read(struct file *file,
 	if (ret != 0)
 		goto error;
 
+	spin_lock(&htable_ops_in_progress_lock);
+	spin_lock(&cur_op->lock);
+	if (unlikely(op_state_given_up(cur_op))) {
+		spin_unlock(&cur_op->lock);
+		spin_unlock(&htable_ops_in_progress_lock);
+		op_release(cur_op);
+		goto restart;
+	}
+
+	/*
+	 * Set the operation to be in progress and move it between lists since
+	 * it has been sent to the client.
+	 */
+	set_op_state_inprogress(cur_op);
+	orangefs_devreq_add_op(cur_op);
+	spin_unlock(&cur_op->lock);
+	spin_unlock(&htable_ops_in_progress_lock);
+	op_release(cur_op);
+
 	/* The client only asks to read one size buffer. */
 	return MAX_DEV_REQ_UPSIZE;
 error:
@@ -235,11 +252,13 @@ error:
 	gossip_err("orangefs: Failed to copy data to user space\n");
 	spin_lock(&orangefs_request_list_lock);
 	spin_lock(&cur_op->lock);
-	set_op_state_waiting(cur_op);
-	orangefs_devreq_remove_op(cur_op->tag);
-	list_add(&cur_op->list, &orangefs_request_list);
+	if (likely(!op_state_given_up(cur_op))) {
+		set_op_state_waiting(cur_op);
+		list_add(&cur_op->list, &orangefs_request_list);
+	}
 	spin_unlock(&cur_op->lock);
 	spin_unlock(&orangefs_request_list_lock);
+	op_release(cur_op);
 	return -EFAULT;
 }
 
@@ -278,15 +297,13 @@ static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
 			   __func__,
 			   total,
 			   (unsigned int) MAX_DEV_REQ_DOWNSIZE);
-		ret = -EFAULT;
-		goto out;
+		return -EFAULT;
 	}
      
 	n = copy_from_iter(&head, head_size, iter);
 	if (n < head_size) {
 		gossip_err("%s: failed to copy head.\n", __func__);
-		ret = -EFAULT;
-		goto out;
+		return -EFAULT;
 	}
 
 	if (head.version < ORANGEFS_MINIMUM_USERSPACE_VERSION) {
@@ -295,31 +312,26 @@ static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
 			   __func__,
 			   head.version,
 			   ORANGEFS_MINIMUM_USERSPACE_VERSION);
-		ret = -EPROTO;
-		goto out;
+		return -EPROTO;
 	}
 
 	if (head.magic != ORANGEFS_DEVREQ_MAGIC) {
 		gossip_err("Error: Device magic number does not match.\n");
-		ret = -EPROTO;
-		goto out;
+		return -EPROTO;
 	}
 
 	op = orangefs_devreq_remove_op(head.tag);
 	if (!op) {
 		gossip_err("WARNING: No one's waiting for tag %llu\n",
 			   llu(head.tag));
-		goto out;
+		return ret;
 	}
 
-	get_op(op); /* increase ref count. */
-
 	n = copy_from_iter(&op->downcall, downcall_size, iter);
 	if (n != downcall_size) {
 		gossip_err("%s: failed to copy downcall.\n", __func__);
-		put_op(op);
 		ret = -EFAULT;
-		goto out;
+		goto Broken;
 	}
 
 	if (op->downcall.status)
@@ -339,9 +351,8 @@ static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
 			   downcall_size,
 			   op->downcall.trailer_size,
 			   total);
-		put_op(op);
 		ret = -EFAULT;
-		goto out;
+		goto Broken;
 	}
 
 	/* Only READDIR operations should have trailers. */
@@ -350,9 +361,8 @@ static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
 		gossip_err("%s: %x operation with trailer.",
 			   __func__,
 			   op->downcall.type);
-		put_op(op);
 		ret = -EFAULT;
-		goto out;
+		goto Broken;
 	}
 
 	/* READDIR operations should always have trailers. */
@@ -361,9 +371,8 @@ static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
 		gossip_err("%s: %x operation with no trailer.",
 			   __func__,
 			   op->downcall.type);
-		put_op(op);
 		ret = -EFAULT;
-		goto out;
+		goto Broken;
 	}
 
 	if (op->downcall.type != ORANGEFS_VFS_OP_READDIR)
@@ -374,9 +383,8 @@ static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
 	if (op->downcall.trailer_buf == NULL) {
 		gossip_err("%s: failed trailer vmalloc.\n",
 			   __func__);
-		put_op(op);
 		ret = -ENOMEM;
-		goto out;
+		goto Broken;
 	}
 	memset(op->downcall.trailer_buf, 0, op->downcall.trailer_size);
 	n = copy_from_iter(op->downcall.trailer_buf,
@@ -385,9 +393,8 @@ static ssize_t orangefs_devreq_write_iter(struct kiocb *iocb,
 	if (n != op->downcall.trailer_size) {
 		gossip_err("%s: failed to copy trailer.\n", __func__);
 		vfree(op->downcall.trailer_buf);
-		put_op(op);
 		ret = -EFAULT;
-		goto out;
+		goto Broken;
 	}
 
 wakeup:
@@ -404,7 +411,6 @@ wakeup:
 	 * the buffers are done being used.
 	 */
 	if (op->downcall.type == ORANGEFS_VFS_OP_FILE_IO) {
-		int timed_out = 0;
 		DEFINE_WAIT(wait_entry);
 
 		/*
@@ -412,7 +418,8 @@ wakeup:
 		 * that this op is done
 		 */
 		spin_lock(&op->lock);
-		set_op_state_serviced(op);
+		if (!op_state_given_up(op))
+			set_op_state_serviced(op);
 		spin_unlock(&op->lock);
 
 		while (1) {
@@ -435,7 +442,6 @@ wakeup:
 					gossip_debug(GOSSIP_DEV_DEBUG,
 						"%s: timed out.\n",
 						__func__);
-					timed_out = 1;
 					break;
 				}
 				continue;
@@ -450,15 +456,6 @@ wakeup:
 		spin_lock(&op->lock);
 		finish_wait(&op->io_completion_waitq, &wait_entry);
 		spin_unlock(&op->lock);
-
-		/* NOTE: for I/O operations we handle releasing the op
-		 * object except in the case of timeout.  the reason we
-		 * can't free the op in timeout cases is that the op
-		 * service logic in the vfs retries operations using
-		 * the same op ptr, thus it can't be freed.
-		 */
-		if (!timed_out)
-			op_release(op);
 	} else {
 		/*
 		 * tell the vfs op waiting on a waitqueue that
@@ -468,11 +465,22 @@ wakeup:
 		 * notification
 		 */
 		spin_lock(&op->lock);
-		set_op_state_serviced(op);
+		if (!op_state_given_up(op))
+			set_op_state_serviced(op);
 		spin_unlock(&op->lock);
 	}
 out:
+	op_release(op);
 	return ret;
+
+Broken:
+	spin_lock(&op->lock);
+	if (!op_state_given_up(op)) {
+		op->downcall.status = ret;
+		set_op_state_serviced(op);
+	}
+	spin_unlock(&op->lock);
+	goto out;
 }
 
 /* Returns whether any FS are still pending remounted */

fs/orangefs/file.c

@@ -105,10 +105,9 @@ static ssize_t wait_for_direct_io(enum ORANGEFS_io_type type, struct inode *inod
 	ssize_t ret;
 
 	new_op = op_alloc(ORANGEFS_VFS_OP_FILE_IO);
-	if (!new_op) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!new_op)
+		return -ENOMEM;
+
 	/* synchronous I/O */
 	new_op->upcall.req.io.async_vfs_io = ORANGEFS_VFS_SYNC_IO;
 	new_op->upcall.req.io.readahead_size = readahead_size;
@@ -234,12 +233,9 @@ populate_shared_memory:
 
 	/*
 	 * tell the device file owner waiting on I/O that this read has
-	 * completed and it can return now.  in this exact case, on
-	 * wakeup the daemon will free the op, so we *cannot* touch it
-	 * after this.
+	 * completed and it can return now.
 	 */
 	wake_up_daemon_for_return(new_op);
-	new_op = NULL;
 
 out:
 	if (buffer_index >= 0) {
@@ -249,10 +245,7 @@ out:
 			     __func__, handle, buffer_index);
 		buffer_index = -1;
 	}
-	if (new_op) {
-		op_release(new_op);
-		new_op = NULL;
-	}
+	op_release(new_op);
 	return ret;
 }
 

fs/orangefs/orangefs-cache.c

@@ -120,7 +120,7 @@ struct orangefs_kernel_op_s *op_alloc(__s32 type)
 		init_waitqueue_head(&new_op->waitq);
 
 		init_waitqueue_head(&new_op->io_completion_waitq);
-		atomic_set(&new_op->ref_count, 0);
+		atomic_set(&new_op->ref_count, 1);
 
 		orangefs_op_initialize(new_op);
 
@@ -149,14 +149,13 @@ struct orangefs_kernel_op_s *op_alloc(__s32 type)
 	return new_op;
 }
 
-void op_release(struct orangefs_kernel_op_s *orangefs_op)
+void __op_release(struct orangefs_kernel_op_s *orangefs_op)
 {
 	if (orangefs_op) {
 		gossip_debug(GOSSIP_CACHE_DEBUG,
 			     "Releasing OP (%p: %llu)\n",
 			     orangefs_op,
 			     llu(orangefs_op->tag));
-		orangefs_op_initialize(orangefs_op);
 		kmem_cache_free(op_cache, orangefs_op);
 	} else {
 		gossip_err("NULL pointer in op_release\n");

fs/orangefs/orangefs-kernel.h

@@ -94,6 +94,7 @@ sizeof(__u64) + sizeof(struct orangefs_downcall_s))
  * serviced - op has matching downcall; ok
  * purged   - op has to start a timer since client-core
  *            exited uncleanly before servicing op
+ * given up - submitter has given up waiting for it
  */
 enum orangefs_vfs_op_states {
 	OP_VFS_STATE_UNKNOWN = 0,
@@ -101,30 +102,9 @@ enum orangefs_vfs_op_states {
 	OP_VFS_STATE_INPROGR = 2,
 	OP_VFS_STATE_SERVICED = 4,
 	OP_VFS_STATE_PURGED = 8,
+	OP_VFS_STATE_GIVEN_UP = 16,
 };
 
-#define get_op(op)					\
-	do {						\
-		atomic_inc(&(op)->ref_count);	\
-		gossip_debug(GOSSIP_DEV_DEBUG,	\
-			"(get) Alloced OP (%p:%llu)\n",	\
-			op,				\
-			llu((op)->tag));		\
-	} while (0)
-
-#define put_op(op)							\
-	do {								\
-		if (atomic_sub_and_test(1, &(op)->ref_count) == 1) {  \
-			gossip_debug(GOSSIP_DEV_DEBUG,		\
-				"(put) Releasing OP (%p:%llu)\n",	\
-				op,					\
-				llu((op)->tag));			\
-			op_release(op);					\
-			}						\
-	} while (0)
-
-#define op_wait(op) (atomic_read(&(op)->ref_count) <= 2 ? 0 : 1)
-
 /*
  * Defines for controlling whether I/O upcalls are for async or sync operations
  */
@@ -258,6 +238,25 @@ static inline void set_op_state_purged(struct orangefs_kernel_op_s *op)
 #define op_state_in_progress(op) ((op)->op_state & OP_VFS_STATE_INPROGR)
 #define op_state_serviced(op)    ((op)->op_state & OP_VFS_STATE_SERVICED)
 #define op_state_purged(op)      ((op)->op_state & OP_VFS_STATE_PURGED)
+#define op_state_given_up(op)    ((op)->op_state & OP_VFS_STATE_GIVEN_UP)
+
+static inline void get_op(struct orangefs_kernel_op_s *op)
+{
+	atomic_inc(&op->ref_count);
+	gossip_debug(GOSSIP_DEV_DEBUG,
+			"(get) Alloced OP (%p:%llu)\n",	op, llu(op->tag));
+}
+
+void __op_release(struct orangefs_kernel_op_s *op);
+
+static inline void op_release(struct orangefs_kernel_op_s *op)
+{
+	if (atomic_dec_and_test(&op->ref_count)) {
+		gossip_debug(GOSSIP_DEV_DEBUG,
+			"(put) Releasing OP (%p:%llu)\n", op, llu((op)->tag));
+		__op_release(op);
+	}
+}
 
 /* per inode private orangefs info */
 struct orangefs_inode_s {
@@ -459,7 +458,6 @@ int op_cache_initialize(void);
 int op_cache_finalize(void);
 struct orangefs_kernel_op_s *op_alloc(__s32 type);
 char *get_opname_string(struct orangefs_kernel_op_s *new_op);
-void op_release(struct orangefs_kernel_op_s *op);
 
 int dev_req_cache_initialize(void);
 int dev_req_cache_finalize(void);
@@ -665,11 +663,9 @@ int service_operation(struct orangefs_kernel_op_s *op,
 do {								\
 	if (!op_state_serviced(new_op)) {			\
 		orangefs_cancel_op_in_progress(new_op->tag);	\
-		op_release(new_op);				\
 	} else {						\
 		wake_up_daemon_for_return(new_op);		\
 	}							\
-	new_op = NULL;						\
 	orangefs_bufmap_put(bufmap, buffer_index);				\
 	buffer_index = -1;					\
 } while (0)

fs/orangefs/orangefs-mod.c

@@ -271,6 +271,7 @@ void purge_inprogress_ops(void)
 		struct orangefs_kernel_op_s *op;
 		struct orangefs_kernel_op_s *next;
 
+		spin_lock(&htable_ops_in_progress_lock);
 		list_for_each_entry_safe(op,
 					 next,
 					 &htable_ops_in_progress[i],
@@ -284,6 +285,7 @@ void purge_inprogress_ops(void)
 			set_op_state_purged(op);
 			spin_unlock(&op->lock);
 		}
+		spin_unlock(&htable_ops_in_progress_lock);
 	}
 }
 

fs/orangefs/orangefs-sysfs.c

@@ -773,10 +773,8 @@ static int sysfs_service_op_show(char *kobj_id, char *buf, void *attr)
 		op_alloc_type = ORANGEFS_VFS_OP_PERF_COUNT;
 
 	new_op = op_alloc(op_alloc_type);
-	if (!new_op) {
-		rc = -ENOMEM;
-		goto out;
-	}
+	if (!new_op)
+		return -ENOMEM;
 
 	/* Can't do a service_operation if the client is not running... */
 	rc = is_daemon_in_service();
@@ -931,11 +929,7 @@ out:
 		}
 	}
 
-	/*
-	 * if we got ENOMEM, then op_alloc probably failed...
-	 */
-	if (rc != -ENOMEM)
-		op_release(new_op);
+	op_release(new_op);
 
 	return rc;
 
@@ -1039,10 +1033,8 @@ static int sysfs_service_op_store(char *kobj_id, const char *buf, void *attr)
 		     kobj_id);
 
 	new_op = op_alloc(ORANGEFS_VFS_OP_PARAM);
-	if (!new_op) {
-		rc = -ENOMEM;
-		goto out;
-	}
+	if (!new_op)
+		return -EINVAL; /* sic */
 
 	/* Can't do a service_operation if the client is not running... */
 	rc = is_daemon_in_service();
@@ -1269,15 +1261,9 @@ static int sysfs_service_op_store(char *kobj_id, const char *buf, void *attr)
 	}
 
 out:
-	/*
-	 * if we got ENOMEM, then op_alloc probably failed...
-	 */
-	if (rc == -ENOMEM)
-		rc = 0;
-	else
-		op_release(new_op);
+	op_release(new_op);
 
-	if (rc == 0)
+	if (rc == -ENOMEM || rc == 0)
 		rc = -EINVAL;
 
 	return rc;

fs/orangefs/orangefs-utils.c

@@ -429,19 +429,15 @@ int orangefs_inode_setattr(struct inode *inode, struct iattr *iattr)
 	ret = copy_attributes_from_inode(inode,
 		       &new_op->upcall.req.setattr.attributes,
 		       iattr);
-	if (ret < 0) {
-		op_release(new_op);
-		return ret;
-	}
-
-	ret = service_operation(new_op, __func__,
+	if (ret >= 0) {
+		ret = service_operation(new_op, __func__,
 				get_interruptible_flag(inode));
 
-	gossip_debug(GOSSIP_UTILS_DEBUG,
-		     "orangefs_inode_setattr: returning %d\n",
-		     ret);
+		gossip_debug(GOSSIP_UTILS_DEBUG,
+			     "orangefs_inode_setattr: returning %d\n",
+			     ret);
+	}
 
-	/* when request is serviced properly, free req op struct */
 	op_release(new_op);
 
 	/*

fs/orangefs/waitqueue.c

@@ -279,25 +279,6 @@ retry_servicing:
 	return ret;
 }
 
-static inline void remove_op_from_request_list(struct orangefs_kernel_op_s *op)
-{
-	struct list_head *tmp = NULL;
-	struct list_head *tmp_safe = NULL;
-	struct orangefs_kernel_op_s *tmp_op = NULL;
-
-	spin_lock(&orangefs_request_list_lock);
-	list_for_each_safe(tmp, tmp_safe, &orangefs_request_list) {
-		tmp_op = list_entry(tmp,
-				    struct orangefs_kernel_op_s,
-				    list);
-		if (tmp_op && (tmp_op == op)) {
-			list_del(&tmp_op->list);
-			break;
-		}
-	}
-	spin_unlock(&orangefs_request_list_lock);
-}
-
 static void orangefs_clean_up_interrupted_operation(struct orangefs_kernel_op_s *op)
 {
 	/*
@@ -334,6 +315,7 @@ static void orangefs_clean_up_interrupted_operation(struct orangefs_kernel_op_s
 	}
 
 	spin_lock(&op->lock);
+	op->op_state |= OP_VFS_STATE_GIVEN_UP;
 
 	if (op_state_waiting(op)) {
 		/*
@@ -341,7 +323,9 @@ static void orangefs_clean_up_interrupted_operation(struct orangefs_kernel_op_s
 		 * list.
 		 */
 		spin_unlock(&op->lock);
-		remove_op_from_request_list(op);
+		spin_lock(&orangefs_request_list_lock);
+		list_del(&op->list);
+		spin_unlock(&orangefs_request_list_lock);
 		gossip_debug(GOSSIP_WAIT_DEBUG,
 			     "Interrupted: Removed op %p from request_list\n",
 			     op);