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1 | /* |
2 | * CDDL HEADER START | |
3 | * | |
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. | |
7 | * | |
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. | |
12 | * | |
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] | |
18 | * | |
19 | * CDDL HEADER END | |
20 | */ | |
21 | /* | |
22 | * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. | |
2e528b49 | 23 | * Copyright (c) 2013 by Delphix. All rights reserved. |
572e2857 BB |
24 | */ |
25 | ||
26 | #include <sys/types.h> | |
27 | #include <sys/param.h> | |
28 | #include <sys/errno.h> | |
29 | #include <sys/open.h> | |
30 | #include <sys/kmem.h> | |
31 | #include <sys/conf.h> | |
32 | #include <sys/ddi.h> | |
33 | #include <sys/sunddi.h> | |
34 | #include <sys/zfs_ioctl.h> | |
35 | #include <sys/mkdev.h> | |
36 | #include <sys/zfs_onexit.h> | |
37 | #include <sys/zvol.h> | |
38 | ||
39 | /* | |
40 | * ZFS kernel routines may add/delete callback routines to be invoked | |
41 | * upon process exit (triggered via the close operation from the /dev/zfs | |
42 | * driver). | |
43 | * | |
44 | * These cleanup callbacks are intended to allow for the accumulation | |
45 | * of kernel state across multiple ioctls. User processes participate | |
325f0235 BB |
46 | * simply by opening ZFS_DEV. This causes the ZFS driver to do create |
47 | * some private data for the file descriptor and generating a unique | |
48 | * minor number. The process then passes along that file descriptor to | |
49 | * each ioctl that might have a cleanup operation. | |
572e2857 BB |
50 | * |
51 | * Consumers of the onexit routines should call zfs_onexit_fd_hold() early | |
52 | * on to validate the given fd and add a reference to its file table entry. | |
53 | * This allows the consumer to do its work and then add a callback, knowing | |
54 | * that zfs_onexit_add_cb() won't fail with EBADF. When finished, consumers | |
55 | * should call zfs_onexit_fd_rele(). | |
56 | * | |
57 | * A simple example is zfs_ioc_recv(), where we might create an AVL tree | |
58 | * with dataset/GUID mappings and then reuse that tree on subsequent | |
59 | * zfs_ioc_recv() calls. | |
60 | * | |
61 | * On the first zfs_ioc_recv() call, dmu_recv_stream() will kmem_alloc() | |
62 | * the AVL tree and pass it along with a callback function to | |
63 | * zfs_onexit_add_cb(). The zfs_onexit_add_cb() routine will register the | |
64 | * callback and return an action handle. | |
65 | * | |
66 | * The action handle is then passed from user space to subsequent | |
67 | * zfs_ioc_recv() calls, so that dmu_recv_stream() can fetch its AVL tree | |
68 | * by calling zfs_onexit_cb_data() with the device minor number and | |
69 | * action handle. | |
70 | * | |
71 | * If the user process exits abnormally, the callback is invoked implicitly | |
72 | * as part of the driver close operation. Once the user space process is | |
73 | * finished with the accumulated kernel state, it can also just call close(2) | |
74 | * on the cleanup fd to trigger the cleanup callback. | |
75 | */ | |
76 | ||
77 | void | |
78 | zfs_onexit_init(zfs_onexit_t **zop) | |
79 | { | |
80 | zfs_onexit_t *zo; | |
81 | ||
82 | zo = *zop = kmem_zalloc(sizeof (zfs_onexit_t), KM_SLEEP); | |
83 | mutex_init(&zo->zo_lock, NULL, MUTEX_DEFAULT, NULL); | |
84 | list_create(&zo->zo_actions, sizeof (zfs_onexit_action_node_t), | |
85 | offsetof(zfs_onexit_action_node_t, za_link)); | |
86 | } | |
87 | ||
88 | void | |
89 | zfs_onexit_destroy(zfs_onexit_t *zo) | |
90 | { | |
91 | zfs_onexit_action_node_t *ap; | |
92 | ||
93 | mutex_enter(&zo->zo_lock); | |
94 | while ((ap = list_head(&zo->zo_actions)) != NULL) { | |
95 | list_remove(&zo->zo_actions, ap); | |
96 | mutex_exit(&zo->zo_lock); | |
97 | ap->za_func(ap->za_data); | |
98 | kmem_free(ap, sizeof (zfs_onexit_action_node_t)); | |
99 | mutex_enter(&zo->zo_lock); | |
100 | } | |
101 | mutex_exit(&zo->zo_lock); | |
102 | ||
103 | list_destroy(&zo->zo_actions); | |
104 | mutex_destroy(&zo->zo_lock); | |
105 | kmem_free(zo, sizeof (zfs_onexit_t)); | |
106 | } | |
107 | ||
108 | static int | |
109 | zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo) | |
110 | { | |
325f0235 | 111 | *zo = zfsdev_get_state(minor, ZST_ONEXIT); |
572e2857 | 112 | if (*zo == NULL) |
2e528b49 | 113 | return (SET_ERROR(EBADF)); |
572e2857 BB |
114 | |
115 | return (0); | |
116 | } | |
117 | ||
118 | /* | |
119 | * Consumers might need to operate by minor number instead of fd, since | |
120 | * they might be running in another thread (e.g. txg_sync_thread). Callers | |
121 | * of this function must call zfs_onexit_fd_rele() when they're finished | |
122 | * using the minor number. | |
123 | */ | |
124 | int | |
125 | zfs_onexit_fd_hold(int fd, minor_t *minorp) | |
126 | { | |
127 | file_t *fp; | |
128 | zfs_onexit_t *zo; | |
72540ea3 | 129 | int error; |
572e2857 BB |
130 | |
131 | fp = getf(fd); | |
132 | if (fp == NULL) | |
2e528b49 | 133 | return (SET_ERROR(EBADF)); |
572e2857 | 134 | |
72540ea3 RY |
135 | error = zfsdev_getminor(fp->f_file, minorp); |
136 | if (error == 0) | |
137 | error = zfs_onexit_minor_to_state(*minorp, &zo); | |
138 | ||
139 | if (error) | |
140 | zfs_onexit_fd_rele(fd); | |
141 | ||
142 | return (error); | |
572e2857 BB |
143 | } |
144 | ||
145 | void | |
146 | zfs_onexit_fd_rele(int fd) | |
147 | { | |
148 | releasef(fd); | |
149 | } | |
150 | ||
151 | /* | |
152 | * Add a callback to be invoked when the calling process exits. | |
153 | */ | |
154 | int | |
155 | zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data, | |
156 | uint64_t *action_handle) | |
157 | { | |
158 | zfs_onexit_t *zo; | |
159 | zfs_onexit_action_node_t *ap; | |
160 | int error; | |
161 | ||
162 | error = zfs_onexit_minor_to_state(minor, &zo); | |
163 | if (error) | |
164 | return (error); | |
165 | ||
79c76d5b | 166 | ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP); |
572e2857 BB |
167 | list_link_init(&ap->za_link); |
168 | ap->za_func = func; | |
169 | ap->za_data = data; | |
170 | ||
171 | mutex_enter(&zo->zo_lock); | |
172 | list_insert_tail(&zo->zo_actions, ap); | |
173 | mutex_exit(&zo->zo_lock); | |
174 | if (action_handle) | |
175 | *action_handle = (uint64_t)(uintptr_t)ap; | |
176 | ||
177 | return (0); | |
178 | } | |
179 | ||
180 | static zfs_onexit_action_node_t * | |
181 | zfs_onexit_find_cb(zfs_onexit_t *zo, uint64_t action_handle) | |
182 | { | |
183 | zfs_onexit_action_node_t *match; | |
184 | zfs_onexit_action_node_t *ap; | |
185 | list_t *l; | |
186 | ||
187 | ASSERT(MUTEX_HELD(&zo->zo_lock)); | |
188 | ||
189 | match = (zfs_onexit_action_node_t *)(uintptr_t)action_handle; | |
190 | l = &zo->zo_actions; | |
191 | for (ap = list_head(l); ap != NULL; ap = list_next(l, ap)) { | |
192 | if (match == ap) | |
193 | break; | |
194 | } | |
195 | return (ap); | |
196 | } | |
197 | ||
198 | /* | |
199 | * Delete the callback, triggering it first if 'fire' is set. | |
200 | */ | |
201 | int | |
202 | zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire) | |
203 | { | |
204 | zfs_onexit_t *zo; | |
205 | zfs_onexit_action_node_t *ap; | |
206 | int error; | |
207 | ||
208 | error = zfs_onexit_minor_to_state(minor, &zo); | |
209 | if (error) | |
210 | return (error); | |
211 | ||
212 | mutex_enter(&zo->zo_lock); | |
213 | ap = zfs_onexit_find_cb(zo, action_handle); | |
214 | if (ap != NULL) { | |
215 | list_remove(&zo->zo_actions, ap); | |
216 | mutex_exit(&zo->zo_lock); | |
217 | if (fire) | |
218 | ap->za_func(ap->za_data); | |
219 | kmem_free(ap, sizeof (zfs_onexit_action_node_t)); | |
220 | } else { | |
221 | mutex_exit(&zo->zo_lock); | |
2e528b49 | 222 | error = SET_ERROR(ENOENT); |
572e2857 BB |
223 | } |
224 | ||
225 | return (error); | |
226 | } | |
227 | ||
228 | /* | |
229 | * Return the data associated with this callback. This allows consumers | |
230 | * of the cleanup-on-exit interfaces to stash kernel data across system | |
231 | * calls, knowing that it will be cleaned up if the calling process exits. | |
232 | */ | |
233 | int | |
234 | zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data) | |
235 | { | |
236 | zfs_onexit_t *zo; | |
237 | zfs_onexit_action_node_t *ap; | |
238 | int error; | |
239 | ||
240 | *data = NULL; | |
241 | ||
242 | error = zfs_onexit_minor_to_state(minor, &zo); | |
243 | if (error) | |
244 | return (error); | |
245 | ||
246 | mutex_enter(&zo->zo_lock); | |
247 | ap = zfs_onexit_find_cb(zo, action_handle); | |
248 | if (ap != NULL) | |
249 | *data = ap->za_data; | |
250 | else | |
2e528b49 | 251 | error = SET_ERROR(ENOENT); |
572e2857 BB |
252 | mutex_exit(&zo->zo_lock); |
253 | ||
254 | return (error); | |
255 | } |