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 http://www.opensolaris.org/os/licensing.
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.
25 #include <sys/types.h>
26 #include <sys/param.h>
27 #include <sys/errno.h>
32 #include <sys/sunddi.h>
33 #include <sys/zfs_ioctl.h>
34 #include <sys/mkdev.h>
35 #include <sys/zfs_onexit.h>
39 * ZFS kernel routines may add/delete callback routines to be invoked
40 * upon process exit (triggered via the close operation from the /dev/zfs
43 * These cleanup callbacks are intended to allow for the accumulation
44 * of kernel state across multiple ioctls. User processes participate
45 * simply by opening ZFS_DEV. This causes the ZFS driver to do create
46 * some private data for the file descriptor and generating a unique
47 * minor number. The process then passes along that file descriptor to
48 * each ioctl that might have a cleanup operation.
50 * Consumers of the onexit routines should call zfs_onexit_fd_hold() early
51 * on to validate the given fd and add a reference to its file table entry.
52 * This allows the consumer to do its work and then add a callback, knowing
53 * that zfs_onexit_add_cb() won't fail with EBADF. When finished, consumers
54 * should call zfs_onexit_fd_rele().
56 * A simple example is zfs_ioc_recv(), where we might create an AVL tree
57 * with dataset/GUID mappings and then reuse that tree on subsequent
58 * zfs_ioc_recv() calls.
60 * On the first zfs_ioc_recv() call, dmu_recv_stream() will kmem_alloc()
61 * the AVL tree and pass it along with a callback function to
62 * zfs_onexit_add_cb(). The zfs_onexit_add_cb() routine will register the
63 * callback and return an action handle.
65 * The action handle is then passed from user space to subsequent
66 * zfs_ioc_recv() calls, so that dmu_recv_stream() can fetch its AVL tree
67 * by calling zfs_onexit_cb_data() with the device minor number and
70 * If the user process exits abnormally, the callback is invoked implicitly
71 * as part of the driver close operation. Once the user space process is
72 * finished with the accumulated kernel state, it can also just call close(2)
73 * on the cleanup fd to trigger the cleanup callback.
77 zfs_onexit_init(zfs_onexit_t **zop)
81 zo = *zop = kmem_zalloc(sizeof (zfs_onexit_t), KM_SLEEP);
82 mutex_init(&zo->zo_lock, NULL, MUTEX_DEFAULT, NULL);
83 list_create(&zo->zo_actions, sizeof (zfs_onexit_action_node_t),
84 offsetof(zfs_onexit_action_node_t, za_link));
88 zfs_onexit_destroy(zfs_onexit_t *zo)
90 zfs_onexit_action_node_t *ap;
92 mutex_enter(&zo->zo_lock);
93 while ((ap = list_head(&zo->zo_actions)) != NULL) {
94 list_remove(&zo->zo_actions, ap);
95 mutex_exit(&zo->zo_lock);
96 ap->za_func(ap->za_data);
97 kmem_free(ap, sizeof (zfs_onexit_action_node_t));
98 mutex_enter(&zo->zo_lock);
100 mutex_exit(&zo->zo_lock);
102 list_destroy(&zo->zo_actions);
103 mutex_destroy(&zo->zo_lock);
104 kmem_free(zo, sizeof (zfs_onexit_t));
108 zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo)
110 *zo = zfsdev_get_state(minor, ZST_ONEXIT);
118 * Consumers might need to operate by minor number instead of fd, since
119 * they might be running in another thread (e.g. txg_sync_thread). Callers
120 * of this function must call zfs_onexit_fd_rele() when they're finished
121 * using the minor number.
124 zfs_onexit_fd_hold(int fd, minor_t *minorp)
133 *minorp = zfsdev_getminor(fp->f_file);
134 return (zfs_onexit_minor_to_state(*minorp, &zo));
138 zfs_onexit_fd_rele(int fd)
144 * Add a callback to be invoked when the calling process exits.
147 zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data,
148 uint64_t *action_handle)
151 zfs_onexit_action_node_t *ap;
154 error = zfs_onexit_minor_to_state(minor, &zo);
158 ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP);
159 list_link_init(&ap->za_link);
163 mutex_enter(&zo->zo_lock);
164 list_insert_tail(&zo->zo_actions, ap);
165 mutex_exit(&zo->zo_lock);
167 *action_handle = (uint64_t)(uintptr_t)ap;
172 static zfs_onexit_action_node_t *
173 zfs_onexit_find_cb(zfs_onexit_t *zo, uint64_t action_handle)
175 zfs_onexit_action_node_t *match;
176 zfs_onexit_action_node_t *ap;
179 ASSERT(MUTEX_HELD(&zo->zo_lock));
181 match = (zfs_onexit_action_node_t *)(uintptr_t)action_handle;
183 for (ap = list_head(l); ap != NULL; ap = list_next(l, ap)) {
191 * Delete the callback, triggering it first if 'fire' is set.
194 zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire)
197 zfs_onexit_action_node_t *ap;
200 error = zfs_onexit_minor_to_state(minor, &zo);
204 mutex_enter(&zo->zo_lock);
205 ap = zfs_onexit_find_cb(zo, action_handle);
207 list_remove(&zo->zo_actions, ap);
208 mutex_exit(&zo->zo_lock);
210 ap->za_func(ap->za_data);
211 kmem_free(ap, sizeof (zfs_onexit_action_node_t));
213 mutex_exit(&zo->zo_lock);
221 * Return the data associated with this callback. This allows consumers
222 * of the cleanup-on-exit interfaces to stash kernel data across system
223 * calls, knowing that it will be cleaned up if the calling process exits.
226 zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data)
229 zfs_onexit_action_node_t *ap;
234 error = zfs_onexit_minor_to_state(minor, &zo);
238 mutex_enter(&zo->zo_lock);
239 ap = zfs_onexit_find_cb(zo, action_handle);
244 mutex_exit(&zo->zo_lock);