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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 | |
45 | * by opening ZFS_DEV with O_EXCL. This causes the ZFS driver to do a | |
46 | * clone-open, generating a unique minor number. The process then passes | |
47 | * along that file descriptor to each ioctl that might have a cleanup operation. | |
48 | * | |
49 | * Consumers of the onexit routines should call zfs_onexit_fd_hold() early | |
50 | * on to validate the given fd and add a reference to its file table entry. | |
51 | * This allows the consumer to do its work and then add a callback, knowing | |
52 | * that zfs_onexit_add_cb() won't fail with EBADF. When finished, consumers | |
53 | * should call zfs_onexit_fd_rele(). | |
54 | * | |
55 | * A simple example is zfs_ioc_recv(), where we might create an AVL tree | |
56 | * with dataset/GUID mappings and then reuse that tree on subsequent | |
57 | * zfs_ioc_recv() calls. | |
58 | * | |
59 | * On the first zfs_ioc_recv() call, dmu_recv_stream() will kmem_alloc() | |
60 | * the AVL tree and pass it along with a callback function to | |
61 | * zfs_onexit_add_cb(). The zfs_onexit_add_cb() routine will register the | |
62 | * callback and return an action handle. | |
63 | * | |
64 | * The action handle is then passed from user space to subsequent | |
65 | * zfs_ioc_recv() calls, so that dmu_recv_stream() can fetch its AVL tree | |
66 | * by calling zfs_onexit_cb_data() with the device minor number and | |
67 | * action handle. | |
68 | * | |
69 | * If the user process exits abnormally, the callback is invoked implicitly | |
70 | * as part of the driver close operation. Once the user space process is | |
71 | * finished with the accumulated kernel state, it can also just call close(2) | |
72 | * on the cleanup fd to trigger the cleanup callback. | |
73 | */ | |
74 | ||
75 | void | |
76 | zfs_onexit_init(zfs_onexit_t **zop) | |
77 | { | |
78 | zfs_onexit_t *zo; | |
79 | ||
80 | zo = *zop = kmem_zalloc(sizeof (zfs_onexit_t), KM_SLEEP); | |
81 | mutex_init(&zo->zo_lock, NULL, MUTEX_DEFAULT, NULL); | |
82 | list_create(&zo->zo_actions, sizeof (zfs_onexit_action_node_t), | |
83 | offsetof(zfs_onexit_action_node_t, za_link)); | |
84 | } | |
85 | ||
86 | void | |
87 | zfs_onexit_destroy(zfs_onexit_t *zo) | |
88 | { | |
89 | zfs_onexit_action_node_t *ap; | |
90 | ||
91 | mutex_enter(&zo->zo_lock); | |
92 | while ((ap = list_head(&zo->zo_actions)) != NULL) { | |
93 | list_remove(&zo->zo_actions, ap); | |
94 | mutex_exit(&zo->zo_lock); | |
95 | ap->za_func(ap->za_data); | |
96 | kmem_free(ap, sizeof (zfs_onexit_action_node_t)); | |
97 | mutex_enter(&zo->zo_lock); | |
98 | } | |
99 | mutex_exit(&zo->zo_lock); | |
100 | ||
101 | list_destroy(&zo->zo_actions); | |
102 | mutex_destroy(&zo->zo_lock); | |
103 | kmem_free(zo, sizeof (zfs_onexit_t)); | |
104 | } | |
105 | ||
106 | static int | |
107 | zfs_onexit_minor_to_state(minor_t minor, zfs_onexit_t **zo) | |
108 | { | |
109 | *zo = zfsdev_get_soft_state(minor, ZSST_CTLDEV); | |
110 | if (*zo == NULL) | |
111 | return (EBADF); | |
112 | ||
113 | return (0); | |
114 | } | |
115 | ||
116 | /* | |
117 | * Consumers might need to operate by minor number instead of fd, since | |
118 | * they might be running in another thread (e.g. txg_sync_thread). Callers | |
119 | * of this function must call zfs_onexit_fd_rele() when they're finished | |
120 | * using the minor number. | |
121 | */ | |
122 | int | |
123 | zfs_onexit_fd_hold(int fd, minor_t *minorp) | |
124 | { | |
125 | file_t *fp; | |
126 | zfs_onexit_t *zo; | |
127 | ||
128 | fp = getf(fd); | |
129 | if (fp == NULL) | |
130 | return (EBADF); | |
131 | ||
132 | *minorp = getminor(fp->f_vnode->v_rdev); | |
133 | return (zfs_onexit_minor_to_state(*minorp, &zo)); | |
134 | } | |
135 | ||
136 | void | |
137 | zfs_onexit_fd_rele(int fd) | |
138 | { | |
139 | releasef(fd); | |
140 | } | |
141 | ||
142 | /* | |
143 | * Add a callback to be invoked when the calling process exits. | |
144 | */ | |
145 | int | |
146 | zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data, | |
147 | uint64_t *action_handle) | |
148 | { | |
149 | zfs_onexit_t *zo; | |
150 | zfs_onexit_action_node_t *ap; | |
151 | int error; | |
152 | ||
153 | error = zfs_onexit_minor_to_state(minor, &zo); | |
154 | if (error) | |
155 | return (error); | |
156 | ||
157 | ap = kmem_alloc(sizeof (zfs_onexit_action_node_t), KM_SLEEP); | |
158 | list_link_init(&ap->za_link); | |
159 | ap->za_func = func; | |
160 | ap->za_data = data; | |
161 | ||
162 | mutex_enter(&zo->zo_lock); | |
163 | list_insert_tail(&zo->zo_actions, ap); | |
164 | mutex_exit(&zo->zo_lock); | |
165 | if (action_handle) | |
166 | *action_handle = (uint64_t)(uintptr_t)ap; | |
167 | ||
168 | return (0); | |
169 | } | |
170 | ||
171 | static zfs_onexit_action_node_t * | |
172 | zfs_onexit_find_cb(zfs_onexit_t *zo, uint64_t action_handle) | |
173 | { | |
174 | zfs_onexit_action_node_t *match; | |
175 | zfs_onexit_action_node_t *ap; | |
176 | list_t *l; | |
177 | ||
178 | ASSERT(MUTEX_HELD(&zo->zo_lock)); | |
179 | ||
180 | match = (zfs_onexit_action_node_t *)(uintptr_t)action_handle; | |
181 | l = &zo->zo_actions; | |
182 | for (ap = list_head(l); ap != NULL; ap = list_next(l, ap)) { | |
183 | if (match == ap) | |
184 | break; | |
185 | } | |
186 | return (ap); | |
187 | } | |
188 | ||
189 | /* | |
190 | * Delete the callback, triggering it first if 'fire' is set. | |
191 | */ | |
192 | int | |
193 | zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire) | |
194 | { | |
195 | zfs_onexit_t *zo; | |
196 | zfs_onexit_action_node_t *ap; | |
197 | int error; | |
198 | ||
199 | error = zfs_onexit_minor_to_state(minor, &zo); | |
200 | if (error) | |
201 | return (error); | |
202 | ||
203 | mutex_enter(&zo->zo_lock); | |
204 | ap = zfs_onexit_find_cb(zo, action_handle); | |
205 | if (ap != NULL) { | |
206 | list_remove(&zo->zo_actions, ap); | |
207 | mutex_exit(&zo->zo_lock); | |
208 | if (fire) | |
209 | ap->za_func(ap->za_data); | |
210 | kmem_free(ap, sizeof (zfs_onexit_action_node_t)); | |
211 | } else { | |
212 | mutex_exit(&zo->zo_lock); | |
213 | error = ENOENT; | |
214 | } | |
215 | ||
216 | return (error); | |
217 | } | |
218 | ||
219 | /* | |
220 | * Return the data associated with this callback. This allows consumers | |
221 | * of the cleanup-on-exit interfaces to stash kernel data across system | |
222 | * calls, knowing that it will be cleaned up if the calling process exits. | |
223 | */ | |
224 | int | |
225 | zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data) | |
226 | { | |
227 | zfs_onexit_t *zo; | |
228 | zfs_onexit_action_node_t *ap; | |
229 | int error; | |
230 | ||
231 | *data = NULL; | |
232 | ||
233 | error = zfs_onexit_minor_to_state(minor, &zo); | |
234 | if (error) | |
235 | return (error); | |
236 | ||
237 | mutex_enter(&zo->zo_lock); | |
238 | ap = zfs_onexit_find_cb(zo, action_handle); | |
239 | if (ap != NULL) | |
240 | *data = ap->za_data; | |
241 | else | |
242 | error = ENOENT; | |
243 | mutex_exit(&zo->zo_lock); | |
244 | ||
245 | return (error); | |
246 | } |