4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or https://opensource.org/licenses/CDDL-1.0.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
22 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2013, 2020 by Delphix. All rights reserved.
26 #include <sys/types.h>
27 #include <sys/param.h>
28 #include <sys/errno.h>
30 #include <sys/sunddi.h>
31 #include <sys/zfs_ioctl.h>
32 #include <sys/zfs_onexit.h>
36 * ZFS kernel routines may add/delete callback routines to be invoked
37 * upon process exit (triggered via the close operation from the /dev/zfs
40 * These cleanup callbacks are intended to allow for the accumulation
41 * of kernel state across multiple ioctls. User processes participate
42 * simply by opening ZFS_DEV. This causes the ZFS driver to do create
43 * some private data for the file descriptor and generating a unique
44 * minor number. The process then passes along that file descriptor to
45 * each ioctl that might have a cleanup operation.
47 * Consumers of the onexit routines should call zfs_onexit_fd_hold() early
48 * on to validate the given fd and add a reference to its file table entry.
49 * This allows the consumer to do its work and then add a callback, knowing
50 * that zfs_onexit_add_cb() won't fail with EBADF. When finished, consumers
51 * should call zfs_onexit_fd_rele().
53 * A simple example is zfs_ioc_recv(), where we might create an AVL tree
54 * with dataset/GUID mappings and then reuse that tree on subsequent
55 * zfs_ioc_recv() calls.
57 * On the first zfs_ioc_recv() call, dmu_recv_stream() will kmem_alloc()
58 * the AVL tree and pass it along with a callback function to
59 * zfs_onexit_add_cb(). The zfs_onexit_add_cb() routine will register the
60 * callback and return an action handle.
62 * The action handle is then passed from user space to subsequent
63 * zfs_ioc_recv() calls, so that dmu_recv_stream() can fetch its AVL tree
64 * by calling zfs_onexit_cb_data() with the device minor number and
67 * If the user process exits abnormally, the callback is invoked implicitly
68 * as part of the driver close operation. Once the user space process is
69 * finished with the accumulated kernel state, it can also just call close(2)
70 * on the cleanup fd to trigger the cleanup callback.
74 zfs_onexit_init(zfs_onexit_t **zop)
78 zo = *zop = kmem_zalloc(sizeof (zfs_onexit_t), KM_SLEEP);
79 mutex_init(&zo->zo_lock, NULL, MUTEX_DEFAULT, NULL);
80 list_create(&zo->zo_actions, sizeof (zfs_onexit_action_node_t),
81 offsetof(zfs_onexit_action_node_t, za_link));
85 zfs_onexit_destroy(zfs_onexit_t *zo)
87 zfs_onexit_action_node_t *ap;
89 mutex_enter(&zo->zo_lock);
90 while ((ap = list_head(&zo->zo_actions)) != NULL) {
91 list_remove(&zo->zo_actions, ap);
92 mutex_exit(&zo->zo_lock);
93 ap->za_func(ap->za_data);
94 kmem_free(ap, sizeof (zfs_onexit_action_node_t));
95 mutex_enter(&zo->zo_lock);
97 mutex_exit(&zo->zo_lock);
99 list_destroy(&zo->zo_actions);
100 mutex_destroy(&zo->zo_lock);
101 kmem_free(zo, sizeof (zfs_onexit_t));
105 * Consumers might need to operate by minor number instead of fd, since
106 * they might be running in another thread (e.g. txg_sync_thread). Callers
107 * of this function must call zfs_onexit_fd_rele() when they're finished
108 * using the minor number.
111 zfs_onexit_fd_hold(int fd, minor_t *minorp)
113 zfs_onexit_t *zo = NULL;
115 zfs_file_t *fp = zfs_file_get(fd);
119 int error = zfsdev_getminor(fp, minorp);
121 zfs_onexit_fd_rele(fp);
125 zo = zfsdev_get_state(*minorp, ZST_ONEXIT);
127 zfs_onexit_fd_rele(fp);
134 zfs_onexit_fd_rele(zfs_file_t *fp)
140 zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo)
142 *zo = zfsdev_get_state(minor, ZST_ONEXIT);
144 return (SET_ERROR(EBADF));
150 * Add a callback to be invoked when the calling process exits.
153 zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data,
154 uintptr_t *action_handle)
157 zfs_onexit_action_node_t *ap;
160 error = zfs_onexit_minor_to_state(minor, &zo);
164 ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP);
165 list_link_init(&ap->za_link);
169 mutex_enter(&zo->zo_lock);
170 list_insert_tail(&zo->zo_actions, ap);
171 mutex_exit(&zo->zo_lock);
173 *action_handle = (uintptr_t)ap;