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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. | |
23 | */ | |
24 | ||
25 | #include <sys/types.h> | |
26 | #include <sys/param.h> | |
27 | #include <sys/errno.h> | |
28 | #include <sys/open.h> | |
29 | #include <sys/kmem.h> | |
30 | #include <sys/conf.h> | |
31 | #include <sys/ddi.h> | |
32 | #include <sys/sunddi.h> | |
33 | #include <sys/zfs_ioctl.h> | |
34 | #include <sys/mkdev.h> | |
35 | #include <sys/zfs_onexit.h> | |
36 | #include <sys/zvol.h> | |
37 | ||
38 | /* | |
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 | |
41 | * driver). | |
42 | * | |
43 | * These cleanup callbacks are intended to allow for the accumulation | |
44 | * of kernel state across multiple ioctls. User processes participate | |
325f0235 BB |
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. | |
572e2857 BB |
49 | * |
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(). | |
55 | * | |
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. | |
59 | * | |
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. | |
64 | * | |
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 | |
68 | * action handle. | |
69 | * | |
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. | |
74 | */ | |
75 | ||
76 | void | |
77 | zfs_onexit_init(zfs_onexit_t **zop) | |
78 | { | |
79 | zfs_onexit_t *zo; | |
80 | ||
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)); | |
85 | } | |
86 | ||
87 | void | |
88 | zfs_onexit_destroy(zfs_onexit_t *zo) | |
89 | { | |
90 | zfs_onexit_action_node_t *ap; | |
91 | ||
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); | |
99 | } | |
100 | mutex_exit(&zo->zo_lock); | |
101 | ||
102 | list_destroy(&zo->zo_actions); | |
103 | mutex_destroy(&zo->zo_lock); | |
104 | kmem_free(zo, sizeof (zfs_onexit_t)); | |
105 | } | |
106 | ||
107 | static int | |
108 | zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo) | |
109 | { | |
325f0235 | 110 | *zo = zfsdev_get_state(minor, ZST_ONEXIT); |
572e2857 BB |
111 | if (*zo == NULL) |
112 | return (EBADF); | |
113 | ||
114 | return (0); | |
115 | } | |
116 | ||
117 | /* | |
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. | |
122 | */ | |
123 | int | |
124 | zfs_onexit_fd_hold(int fd, minor_t *minorp) | |
125 | { | |
126 | file_t *fp; | |
127 | zfs_onexit_t *zo; | |
128 | ||
129 | fp = getf(fd); | |
130 | if (fp == NULL) | |
131 | return (EBADF); | |
132 | ||
325f0235 | 133 | *minorp = zfsdev_getminor(fp->f_file); |
572e2857 BB |
134 | return (zfs_onexit_minor_to_state(*minorp, &zo)); |
135 | } | |
136 | ||
137 | void | |
138 | zfs_onexit_fd_rele(int fd) | |
139 | { | |
140 | releasef(fd); | |
141 | } | |
142 | ||
143 | /* | |
144 | * Add a callback to be invoked when the calling process exits. | |
145 | */ | |
146 | int | |
147 | zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data, | |
148 | uint64_t *action_handle) | |
149 | { | |
150 | zfs_onexit_t *zo; | |
151 | zfs_onexit_action_node_t *ap; | |
152 | int error; | |
153 | ||
154 | error = zfs_onexit_minor_to_state(minor, &zo); | |
155 | if (error) | |
156 | return (error); | |
157 | ||
158 | ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP); | |
159 | list_link_init(&ap->za_link); | |
160 | ap->za_func = func; | |
161 | ap->za_data = data; | |
162 | ||
163 | mutex_enter(&zo->zo_lock); | |
164 | list_insert_tail(&zo->zo_actions, ap); | |
165 | mutex_exit(&zo->zo_lock); | |
166 | if (action_handle) | |
167 | *action_handle = (uint64_t)(uintptr_t)ap; | |
168 | ||
169 | return (0); | |
170 | } | |
171 | ||
172 | static zfs_onexit_action_node_t * | |
173 | zfs_onexit_find_cb(zfs_onexit_t *zo, uint64_t action_handle) | |
174 | { | |
175 | zfs_onexit_action_node_t *match; | |
176 | zfs_onexit_action_node_t *ap; | |
177 | list_t *l; | |
178 | ||
179 | ASSERT(MUTEX_HELD(&zo->zo_lock)); | |
180 | ||
181 | match = (zfs_onexit_action_node_t *)(uintptr_t)action_handle; | |
182 | l = &zo->zo_actions; | |
183 | for (ap = list_head(l); ap != NULL; ap = list_next(l, ap)) { | |
184 | if (match == ap) | |
185 | break; | |
186 | } | |
187 | return (ap); | |
188 | } | |
189 | ||
190 | /* | |
191 | * Delete the callback, triggering it first if 'fire' is set. | |
192 | */ | |
193 | int | |
194 | zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire) | |
195 | { | |
196 | zfs_onexit_t *zo; | |
197 | zfs_onexit_action_node_t *ap; | |
198 | int error; | |
199 | ||
200 | error = zfs_onexit_minor_to_state(minor, &zo); | |
201 | if (error) | |
202 | return (error); | |
203 | ||
204 | mutex_enter(&zo->zo_lock); | |
205 | ap = zfs_onexit_find_cb(zo, action_handle); | |
206 | if (ap != NULL) { | |
207 | list_remove(&zo->zo_actions, ap); | |
208 | mutex_exit(&zo->zo_lock); | |
209 | if (fire) | |
210 | ap->za_func(ap->za_data); | |
211 | kmem_free(ap, sizeof (zfs_onexit_action_node_t)); | |
212 | } else { | |
213 | mutex_exit(&zo->zo_lock); | |
214 | error = ENOENT; | |
215 | } | |
216 | ||
217 | return (error); | |
218 | } | |
219 | ||
220 | /* | |
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. | |
224 | */ | |
225 | int | |
226 | zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data) | |
227 | { | |
228 | zfs_onexit_t *zo; | |
229 | zfs_onexit_action_node_t *ap; | |
230 | int error; | |
231 | ||
232 | *data = NULL; | |
233 | ||
234 | error = zfs_onexit_minor_to_state(minor, &zo); | |
235 | if (error) | |
236 | return (error); | |
237 | ||
238 | mutex_enter(&zo->zo_lock); | |
239 | ap = zfs_onexit_find_cb(zo, action_handle); | |
240 | if (ap != NULL) | |
241 | *data = ap->za_data; | |
242 | else | |
243 | error = ENOENT; | |
244 | mutex_exit(&zo->zo_lock); | |
245 | ||
246 | return (error); | |
247 | } |