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572e2857 BB |
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> | |
572e2857 | 29 | #include <sys/kmem.h> |
572e2857 BB |
30 | #include <sys/sunddi.h> |
31 | #include <sys/zfs_ioctl.h> | |
572e2857 BB |
32 | #include <sys/zfs_onexit.h> |
33 | #include <sys/zvol.h> | |
34 | ||
35 | /* | |
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 | |
38 | * driver). | |
39 | * | |
40 | * These cleanup callbacks are intended to allow for the accumulation | |
41 | * of kernel state across multiple ioctls. User processes participate | |
325f0235 BB |
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. | |
572e2857 BB |
46 | * |
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(). | |
52 | * | |
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. | |
56 | * | |
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. | |
61 | * | |
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 | |
65 | * action handle. | |
66 | * | |
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. | |
71 | */ | |
72 | ||
73 | void | |
74 | zfs_onexit_init(zfs_onexit_t **zop) | |
75 | { | |
76 | zfs_onexit_t *zo; | |
77 | ||
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)); | |
82 | } | |
83 | ||
84 | void | |
85 | zfs_onexit_destroy(zfs_onexit_t *zo) | |
86 | { | |
87 | zfs_onexit_action_node_t *ap; | |
88 | ||
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); | |
96 | } | |
97 | mutex_exit(&zo->zo_lock); | |
98 | ||
99 | list_destroy(&zo->zo_actions); | |
100 | mutex_destroy(&zo->zo_lock); | |
101 | kmem_free(zo, sizeof (zfs_onexit_t)); | |
102 | } | |
103 | ||
104 | static int | |
105 | zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo) | |
106 | { | |
325f0235 | 107 | *zo = zfsdev_get_state(minor, ZST_ONEXIT); |
572e2857 | 108 | if (*zo == NULL) |
2e528b49 | 109 | return (SET_ERROR(EBADF)); |
572e2857 BB |
110 | |
111 | return (0); | |
112 | } | |
113 | ||
114 | /* | |
115 | * Consumers might need to operate by minor number instead of fd, since | |
116 | * they might be running in another thread (e.g. txg_sync_thread). Callers | |
117 | * of this function must call zfs_onexit_fd_rele() when they're finished | |
118 | * using the minor number. | |
119 | */ | |
120 | int | |
121 | zfs_onexit_fd_hold(int fd, minor_t *minorp) | |
122 | { | |
123 | file_t *fp; | |
124 | zfs_onexit_t *zo; | |
72540ea3 | 125 | int error; |
572e2857 BB |
126 | |
127 | fp = getf(fd); | |
128 | if (fp == NULL) | |
2e528b49 | 129 | return (SET_ERROR(EBADF)); |
572e2857 | 130 | |
72540ea3 RY |
131 | error = zfsdev_getminor(fp->f_file, minorp); |
132 | if (error == 0) | |
133 | error = zfs_onexit_minor_to_state(*minorp, &zo); | |
134 | ||
135 | if (error) | |
136 | zfs_onexit_fd_rele(fd); | |
137 | ||
138 | return (error); | |
572e2857 BB |
139 | } |
140 | ||
141 | void | |
142 | zfs_onexit_fd_rele(int fd) | |
143 | { | |
144 | releasef(fd); | |
145 | } | |
146 | ||
147 | /* | |
148 | * Add a callback to be invoked when the calling process exits. | |
149 | */ | |
150 | int | |
151 | zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data, | |
152 | uint64_t *action_handle) | |
153 | { | |
154 | zfs_onexit_t *zo; | |
155 | zfs_onexit_action_node_t *ap; | |
156 | int error; | |
157 | ||
158 | error = zfs_onexit_minor_to_state(minor, &zo); | |
159 | if (error) | |
160 | return (error); | |
161 | ||
79c76d5b | 162 | ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP); |
572e2857 BB |
163 | list_link_init(&ap->za_link); |
164 | ap->za_func = func; | |
165 | ap->za_data = data; | |
166 | ||
167 | mutex_enter(&zo->zo_lock); | |
168 | list_insert_tail(&zo->zo_actions, ap); | |
169 | mutex_exit(&zo->zo_lock); | |
170 | if (action_handle) | |
171 | *action_handle = (uint64_t)(uintptr_t)ap; | |
172 | ||
173 | return (0); | |
174 | } | |
175 | ||
176 | static zfs_onexit_action_node_t * | |
177 | zfs_onexit_find_cb(zfs_onexit_t *zo, uint64_t action_handle) | |
178 | { | |
179 | zfs_onexit_action_node_t *match; | |
180 | zfs_onexit_action_node_t *ap; | |
181 | list_t *l; | |
182 | ||
183 | ASSERT(MUTEX_HELD(&zo->zo_lock)); | |
184 | ||
185 | match = (zfs_onexit_action_node_t *)(uintptr_t)action_handle; | |
186 | l = &zo->zo_actions; | |
187 | for (ap = list_head(l); ap != NULL; ap = list_next(l, ap)) { | |
188 | if (match == ap) | |
189 | break; | |
190 | } | |
191 | return (ap); | |
192 | } | |
193 | ||
194 | /* | |
195 | * Delete the callback, triggering it first if 'fire' is set. | |
196 | */ | |
197 | int | |
198 | zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire) | |
199 | { | |
200 | zfs_onexit_t *zo; | |
201 | zfs_onexit_action_node_t *ap; | |
202 | int error; | |
203 | ||
204 | error = zfs_onexit_minor_to_state(minor, &zo); | |
205 | if (error) | |
206 | return (error); | |
207 | ||
208 | mutex_enter(&zo->zo_lock); | |
209 | ap = zfs_onexit_find_cb(zo, action_handle); | |
210 | if (ap != NULL) { | |
211 | list_remove(&zo->zo_actions, ap); | |
212 | mutex_exit(&zo->zo_lock); | |
213 | if (fire) | |
214 | ap->za_func(ap->za_data); | |
215 | kmem_free(ap, sizeof (zfs_onexit_action_node_t)); | |
216 | } else { | |
217 | mutex_exit(&zo->zo_lock); | |
2e528b49 | 218 | error = SET_ERROR(ENOENT); |
572e2857 BB |
219 | } |
220 | ||
221 | return (error); | |
222 | } | |
223 | ||
224 | /* | |
225 | * Return the data associated with this callback. This allows consumers | |
226 | * of the cleanup-on-exit interfaces to stash kernel data across system | |
227 | * calls, knowing that it will be cleaned up if the calling process exits. | |
228 | */ | |
229 | int | |
230 | zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data) | |
231 | { | |
232 | zfs_onexit_t *zo; | |
233 | zfs_onexit_action_node_t *ap; | |
234 | int error; | |
235 | ||
236 | *data = NULL; | |
237 | ||
238 | error = zfs_onexit_minor_to_state(minor, &zo); | |
239 | if (error) | |
240 | return (error); | |
241 | ||
242 | mutex_enter(&zo->zo_lock); | |
243 | ap = zfs_onexit_find_cb(zo, action_handle); | |
244 | if (ap != NULL) | |
245 | *data = ap->za_data; | |
246 | else | |
2e528b49 | 247 | error = SET_ERROR(ENOENT); |
572e2857 BB |
248 | mutex_exit(&zo->zo_lock); |
249 | ||
250 | return (error); | |
251 | } |