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>
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 * by opening ZFS_DEV with O_EXCL. This causes the ZFS driver to do a
43 * clone-open, generating a unique minor number. The process then passes
44 * along that file descriptor to each ioctl that might have a cleanup operation.
46 * Consumers of the onexit routines should call zfs_onexit_fd_hold() early
47 * on to validate the given fd and add a reference to its file table entry.
48 * This allows the consumer to do its work and then add a callback, knowing
49 * that zfs_onexit_add_cb() won't fail with EBADF. When finished, consumers
50 * should call zfs_onexit_fd_rele().
52 * A simple example is zfs_ioc_recv(), where we might create an AVL tree
53 * with dataset/GUID mappings and then reuse that tree on subsequent
54 * zfs_ioc_recv() calls.
56 * On the first zfs_ioc_recv() call, dmu_recv_stream() will kmem_alloc()
57 * the AVL tree and pass it along with a callback function to
58 * zfs_onexit_add_cb(). The zfs_onexit_add_cb() routine will register the
59 * callback and return an action handle.
61 * The action handle is then passed from user space to subsequent
62 * zfs_ioc_recv() calls, so that dmu_recv_stream() can fetch its AVL tree
63 * by calling zfs_onexit_cb_data() with the device minor number and
66 * If the user process exits abnormally, the callback is invoked implicitly
67 * as part of the driver close operation. Once the user space process is
68 * finished with the accumulated kernel state, it can also just call close(2)
69 * on the cleanup fd to trigger the cleanup callback.
73 zfs_onexit_init(zfs_onexit_t **zop)
77 zo = *zop = kmem_zalloc(sizeof (zfs_onexit_t), KM_SLEEP);
78 mutex_init(&zo->zo_lock, NULL, MUTEX_DEFAULT, NULL);
79 list_create(&zo->zo_actions, sizeof (zfs_onexit_action_node_t),
80 offsetof(zfs_onexit_action_node_t, za_link));
84 zfs_onexit_destroy(zfs_onexit_t *zo)
86 zfs_onexit_action_node_t *ap;
88 mutex_enter(&zo->zo_lock);
89 while ((ap = list_head(&zo->zo_actions)) != NULL) {
90 list_remove(&zo->zo_actions, ap);
91 mutex_exit(&zo->zo_lock);
92 ap->za_func(ap->za_data);
93 kmem_free(ap, sizeof (zfs_onexit_action_node_t));
94 mutex_enter(&zo->zo_lock);
96 mutex_exit(&zo->zo_lock);
98 list_destroy(&zo->zo_actions);
99 mutex_destroy(&zo->zo_lock);
100 kmem_free(zo, sizeof (zfs_onexit_t));
104 zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo)
106 *zo = zfsdev_get_soft_state(minor, ZSST_CTLDEV);
114 * Consumers might need to operate by minor number instead of fd, since
115 * they might be running in another thread (e.g. txg_sync_thread). Callers
116 * of this function must call zfs_onexit_fd_rele() when they're finished
117 * using the minor number.
120 zfs_onexit_fd_hold(int fd, minor_t *minorp)
131 tmpfp = curthread->td_fpop;
132 curthread->td_fpop = fp;
133 error = devfs_get_cdevpriv(&data);
135 *minorp = (minor_t)(uintptr_t)data;
136 curthread->td_fpop = tmpfp;
139 return (zfs_onexit_minor_to_state(*minorp, &zo));
143 zfs_onexit_fd_rele(int fd)
149 * Add a callback to be invoked when the calling process exits.
152 zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data,
153 uint64_t *action_handle)
156 zfs_onexit_action_node_t *ap;
159 error = zfs_onexit_minor_to_state(minor, &zo);
163 ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP);
164 list_link_init(&ap->za_link);
168 mutex_enter(&zo->zo_lock);
169 list_insert_tail(&zo->zo_actions, ap);
170 mutex_exit(&zo->zo_lock);
172 *action_handle = (uint64_t)(uintptr_t)ap;
177 static zfs_onexit_action_node_t *
178 zfs_onexit_find_cb(zfs_onexit_t *zo, uint64_t action_handle)
180 zfs_onexit_action_node_t *match;
181 zfs_onexit_action_node_t *ap;
184 ASSERT(MUTEX_HELD(&zo->zo_lock));
186 match = (zfs_onexit_action_node_t *)(uintptr_t)action_handle;
188 for (ap = list_head(l); ap != NULL; ap = list_next(l, ap)) {
196 * Delete the callback, triggering it first if 'fire' is set.
199 zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire)
202 zfs_onexit_action_node_t *ap;
205 error = zfs_onexit_minor_to_state(minor, &zo);
209 mutex_enter(&zo->zo_lock);
210 ap = zfs_onexit_find_cb(zo, action_handle);
212 list_remove(&zo->zo_actions, ap);
213 mutex_exit(&zo->zo_lock);
215 ap->za_func(ap->za_data);
216 kmem_free(ap, sizeof (zfs_onexit_action_node_t));
218 mutex_exit(&zo->zo_lock);
226 * Return the data associated with this callback. This allows consumers
227 * of the cleanup-on-exit interfaces to stash kernel data across system
228 * calls, knowing that it will be cleaned up if the calling process exits.
231 zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data)
234 zfs_onexit_action_node_t *ap;
239 error = zfs_onexit_minor_to_state(minor, &zo);
243 mutex_enter(&zo->zo_lock);
244 ap = zfs_onexit_find_cb(zo, action_handle);
249 mutex_exit(&zo->zo_lock);