| /* |
| * CDDL HEADER START |
| * |
| * The contents of this file are subject to the terms of the |
| * Common Development and Distribution License (the "License"). |
| * You may not use this file except in compliance with the License. |
| * |
| * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE |
| * or http://www.opensolaris.org/os/licensing. |
| * See the License for the specific language governing permissions |
| * and limitations under the License. |
| * |
| * When distributing Covered Code, include this CDDL HEADER in each |
| * file and include the License file at usr/src/OPENSOLARIS.LICENSE. |
| * If applicable, add the following below this CDDL HEADER, with the |
| * fields enclosed by brackets "[]" replaced with your own identifying |
| * information: Portions Copyright [yyyy] [name of copyright owner] |
| * |
| * CDDL HEADER END |
| */ |
| /* |
| * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. |
| * Copyright (c) 2013, 2020 by Delphix. All rights reserved. |
| */ |
| |
| #include <sys/types.h> |
| #include <sys/param.h> |
| #include <sys/errno.h> |
| #include <sys/kmem.h> |
| #include <sys/sunddi.h> |
| #include <sys/zfs_ioctl.h> |
| #include <sys/zfs_onexit.h> |
| #include <sys/zvol.h> |
| |
| /* |
| * ZFS kernel routines may add/delete callback routines to be invoked |
| * upon process exit (triggered via the close operation from the /dev/zfs |
| * driver). |
| * |
| * These cleanup callbacks are intended to allow for the accumulation |
| * of kernel state across multiple ioctls. User processes participate |
| * simply by opening ZFS_DEV. This causes the ZFS driver to do create |
| * some private data for the file descriptor and generating a unique |
| * minor number. The process then passes along that file descriptor to |
| * each ioctl that might have a cleanup operation. |
| * |
| * Consumers of the onexit routines should call zfs_onexit_fd_hold() early |
| * on to validate the given fd and add a reference to its file table entry. |
| * This allows the consumer to do its work and then add a callback, knowing |
| * that zfs_onexit_add_cb() won't fail with EBADF. When finished, consumers |
| * should call zfs_onexit_fd_rele(). |
| * |
| * A simple example is zfs_ioc_recv(), where we might create an AVL tree |
| * with dataset/GUID mappings and then reuse that tree on subsequent |
| * zfs_ioc_recv() calls. |
| * |
| * On the first zfs_ioc_recv() call, dmu_recv_stream() will kmem_alloc() |
| * the AVL tree and pass it along with a callback function to |
| * zfs_onexit_add_cb(). The zfs_onexit_add_cb() routine will register the |
| * callback and return an action handle. |
| * |
| * The action handle is then passed from user space to subsequent |
| * zfs_ioc_recv() calls, so that dmu_recv_stream() can fetch its AVL tree |
| * by calling zfs_onexit_cb_data() with the device minor number and |
| * action handle. |
| * |
| * If the user process exits abnormally, the callback is invoked implicitly |
| * as part of the driver close operation. Once the user space process is |
| * finished with the accumulated kernel state, it can also just call close(2) |
| * on the cleanup fd to trigger the cleanup callback. |
| */ |
| |
| void |
| zfs_onexit_init(zfs_onexit_t **zop) |
| { |
| zfs_onexit_t *zo; |
| |
| zo = *zop = kmem_zalloc(sizeof (zfs_onexit_t), KM_SLEEP); |
| mutex_init(&zo->zo_lock, NULL, MUTEX_DEFAULT, NULL); |
| list_create(&zo->zo_actions, sizeof (zfs_onexit_action_node_t), |
| offsetof(zfs_onexit_action_node_t, za_link)); |
| } |
| |
| void |
| zfs_onexit_destroy(zfs_onexit_t *zo) |
| { |
| zfs_onexit_action_node_t *ap; |
| |
| mutex_enter(&zo->zo_lock); |
| while ((ap = list_head(&zo->zo_actions)) != NULL) { |
| list_remove(&zo->zo_actions, ap); |
| mutex_exit(&zo->zo_lock); |
| ap->za_func(ap->za_data); |
| kmem_free(ap, sizeof (zfs_onexit_action_node_t)); |
| mutex_enter(&zo->zo_lock); |
| } |
| mutex_exit(&zo->zo_lock); |
| |
| list_destroy(&zo->zo_actions); |
| mutex_destroy(&zo->zo_lock); |
| kmem_free(zo, sizeof (zfs_onexit_t)); |
| } |
| |
| /* |
| * Consumers might need to operate by minor number instead of fd, since |
| * they might be running in another thread (e.g. txg_sync_thread). Callers |
| * of this function must call zfs_onexit_fd_rele() when they're finished |
| * using the minor number. |
| */ |
| zfs_file_t * |
| zfs_onexit_fd_hold(int fd, minor_t *minorp) |
| { |
| zfs_onexit_t *zo = NULL; |
| |
| zfs_file_t *fp = zfs_file_get(fd); |
| if (fp == NULL) |
| return (NULL); |
| |
| int error = zfsdev_getminor(fp, minorp); |
| if (error) { |
| zfs_onexit_fd_rele(fp); |
| return (NULL); |
| } |
| |
| zo = zfsdev_get_state(*minorp, ZST_ONEXIT); |
| if (zo == NULL) { |
| zfs_onexit_fd_rele(fp); |
| return (NULL); |
| } |
| return (fp); |
| } |
| |
| void |
| zfs_onexit_fd_rele(zfs_file_t *fp) |
| { |
| zfs_file_put(fp); |
| } |
| |
| static int |
| zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo) |
| { |
| *zo = zfsdev_get_state(minor, ZST_ONEXIT); |
| if (*zo == NULL) |
| return (SET_ERROR(EBADF)); |
| |
| return (0); |
| } |
| |
| /* |
| * Add a callback to be invoked when the calling process exits. |
| */ |
| int |
| zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data, |
| uint64_t *action_handle) |
| { |
| zfs_onexit_t *zo; |
| zfs_onexit_action_node_t *ap; |
| int error; |
| |
| error = zfs_onexit_minor_to_state(minor, &zo); |
| if (error) |
| return (error); |
| |
| ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP); |
| list_link_init(&ap->za_link); |
| ap->za_func = func; |
| ap->za_data = data; |
| |
| mutex_enter(&zo->zo_lock); |
| list_insert_tail(&zo->zo_actions, ap); |
| mutex_exit(&zo->zo_lock); |
| if (action_handle) |
| *action_handle = (uint64_t)(uintptr_t)ap; |
| |
| return (0); |
| } |