xref: /qemu/scsi/pr-manager-helper.c (revision abff1abf) 
1 /*
2  * Persistent reservation manager that talks to qemu-pr-helper
3  *
4  * Copyright (c) 2017 Red Hat, Inc.
5  *
6  * Author: Paolo Bonzini <pbonzini@redhat.com>
7  *
8  * This code is licensed under the LGPL v2.1 or later.
9  *
10  */
11 
12 #include "qemu/osdep.h"
13 #include "qapi/error.h"
14 #include "scsi/constants.h"
15 #include "scsi/pr-manager.h"
16 #include "scsi/utils.h"
17 #include "io/channel.h"
18 #include "io/channel-socket.h"
19 #include "pr-helper.h"
20 #include "qapi/qapi-events-block.h"
21 #include "qemu/module.h"
22 
23 #include <scsi/sg.h>
24 
25 #define PR_MAX_RECONNECT_ATTEMPTS 5
26 
27 #define TYPE_PR_MANAGER_HELPER "pr-manager-helper"
28 
29 #define PR_MANAGER_HELPER(obj) \
30      OBJECT_CHECK(PRManagerHelper, (obj), \
31                   TYPE_PR_MANAGER_HELPER)
32 
33 typedef struct PRManagerHelper {
34     /* <private> */
35     PRManager parent;
36 
37     char *path;
38 
39     QemuMutex lock;
40     QIOChannel *ioc;
41 } PRManagerHelper;
42 
43 static void pr_manager_send_status_changed_event(PRManagerHelper *pr_mgr)
44 {
45     const char *id = object_get_canonical_path_component(OBJECT(pr_mgr));
46 
47     if (id) {
48         qapi_event_send_pr_manager_status_changed(id, !!pr_mgr->ioc);
49     }
50 }
51 
52 /* Called with lock held.  */
53 static int pr_manager_helper_read(PRManagerHelper *pr_mgr,
54                                   void *buf, int sz, Error **errp)
55 {
56     ssize_t r = qio_channel_read_all(pr_mgr->ioc, buf, sz, errp);
57 
58     if (r < 0) {
59         object_unref(OBJECT(pr_mgr->ioc));
60         pr_mgr->ioc = NULL;
61         pr_manager_send_status_changed_event(pr_mgr);
62         return -EINVAL;
63     }
64 
65     return 0;
66 }
67 
68 /* Called with lock held.  */
69 static int pr_manager_helper_write(PRManagerHelper *pr_mgr,
70                                    int fd,
71                                    const void *buf, int sz, Error **errp)
72 {
73     size_t nfds = (fd != -1);
74     while (sz > 0) {
75         struct iovec iov;
76         ssize_t n_written;
77 
78         iov.iov_base = (void *)buf;
79         iov.iov_len = sz;
80         n_written = qio_channel_writev_full(QIO_CHANNEL(pr_mgr->ioc), &iov, 1,
81                                             nfds ? &fd : NULL, nfds, errp);
82 
83         if (n_written <= 0) {
84             assert(n_written != QIO_CHANNEL_ERR_BLOCK);
85             object_unref(OBJECT(pr_mgr->ioc));
86             pr_mgr->ioc = NULL;
87             pr_manager_send_status_changed_event(pr_mgr);
88             return n_written < 0 ? -EINVAL : 0;
89         }
90 
91         nfds = 0;
92         buf += n_written;
93         sz -= n_written;
94     }
95 
96     return 0;
97 }
98 
99 /* Called with lock held.  */
100 static int pr_manager_helper_initialize(PRManagerHelper *pr_mgr,
101                                         Error **errp)
102 {
103     char *path = g_strdup(pr_mgr->path);
104     SocketAddress saddr = {
105         .type = SOCKET_ADDRESS_TYPE_UNIX,
106         .u.q_unix.path = path
107     };
108     QIOChannelSocket *sioc = qio_channel_socket_new();
109     Error *local_err = NULL;
110 
111     uint32_t flags;
112     int r;
113 
114     assert(!pr_mgr->ioc);
115     qio_channel_set_name(QIO_CHANNEL(sioc), "pr-manager-helper");
116     qio_channel_socket_connect_sync(sioc,
117                                     &saddr,
118                                     &local_err);
119     g_free(path);
120     if (local_err) {
121         object_unref(OBJECT(sioc));
122         error_propagate(errp, local_err);
123         return -ENOTCONN;
124     }
125 
126     qio_channel_set_delay(QIO_CHANNEL(sioc), false);
127     pr_mgr->ioc = QIO_CHANNEL(sioc);
128 
129     /* A simple feature negotation protocol, even though there is
130      * no optional feature right now.
131      */
132     r = pr_manager_helper_read(pr_mgr, &flags, sizeof(flags), errp);
133     if (r < 0) {
134         goto out_close;
135     }
136 
137     flags = 0;
138     r = pr_manager_helper_write(pr_mgr, -1, &flags, sizeof(flags), errp);
139     if (r < 0) {
140         goto out_close;
141     }
142 
143     pr_manager_send_status_changed_event(pr_mgr);
144     return 0;
145 
146 out_close:
147     object_unref(OBJECT(pr_mgr->ioc));
148     pr_mgr->ioc = NULL;
149     return r;
150 }
151 
152 static int pr_manager_helper_run(PRManager *p,
153                                  int fd, struct sg_io_hdr *io_hdr)
154 {
155     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
156 
157     uint32_t len;
158     PRHelperResponse resp;
159     int ret;
160     int expected_dir;
161     int attempts;
162     uint8_t cdb[PR_HELPER_CDB_SIZE] = { 0 };
163 
164     if (!io_hdr->cmd_len || io_hdr->cmd_len > PR_HELPER_CDB_SIZE) {
165         return -EINVAL;
166     }
167 
168     memcpy(cdb, io_hdr->cmdp, io_hdr->cmd_len);
169     assert(cdb[0] == PERSISTENT_RESERVE_OUT || cdb[0] == PERSISTENT_RESERVE_IN);
170     expected_dir =
171         (cdb[0] == PERSISTENT_RESERVE_OUT ? SG_DXFER_TO_DEV : SG_DXFER_FROM_DEV);
172     if (io_hdr->dxfer_direction != expected_dir) {
173         return -EINVAL;
174     }
175 
176     len = scsi_cdb_xfer(cdb);
177     if (io_hdr->dxfer_len < len || len > PR_HELPER_DATA_SIZE) {
178         return -EINVAL;
179     }
180 
181     qemu_mutex_lock(&pr_mgr->lock);
182 
183     /* Try to reconnect while sending the CDB.  */
184     for (attempts = 0; attempts < PR_MAX_RECONNECT_ATTEMPTS; attempts++) {
185         if (!pr_mgr->ioc) {
186             ret = pr_manager_helper_initialize(pr_mgr, NULL);
187             if (ret < 0) {
188                 qemu_mutex_unlock(&pr_mgr->lock);
189                 g_usleep(G_USEC_PER_SEC);
190                 qemu_mutex_lock(&pr_mgr->lock);
191                 continue;
192             }
193         }
194 
195         ret = pr_manager_helper_write(pr_mgr, fd, cdb, ARRAY_SIZE(cdb), NULL);
196         if (ret >= 0) {
197             break;
198         }
199     }
200     if (ret < 0) {
201         goto out;
202     }
203 
204     /* After sending the CDB, any communications failure causes the
205      * command to fail.  The failure is transient, retrying the command
206      * will invoke pr_manager_helper_initialize again.
207      */
208     if (expected_dir == SG_DXFER_TO_DEV) {
209         io_hdr->resid = io_hdr->dxfer_len - len;
210         ret = pr_manager_helper_write(pr_mgr, -1, io_hdr->dxferp, len, NULL);
211         if (ret < 0) {
212             goto out;
213         }
214     }
215     ret = pr_manager_helper_read(pr_mgr, &resp, sizeof(resp), NULL);
216     if (ret < 0) {
217         goto out;
218     }
219 
220     resp.result = be32_to_cpu(resp.result);
221     resp.sz = be32_to_cpu(resp.sz);
222     if (io_hdr->dxfer_direction == SG_DXFER_FROM_DEV) {
223         assert(resp.sz <= io_hdr->dxfer_len);
224         ret = pr_manager_helper_read(pr_mgr, io_hdr->dxferp, resp.sz, NULL);
225         if (ret < 0) {
226             goto out;
227         }
228         io_hdr->resid = io_hdr->dxfer_len - resp.sz;
229     } else {
230         assert(resp.sz == 0);
231     }
232 
233     io_hdr->status = resp.result;
234     if (resp.result == CHECK_CONDITION) {
235         io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
236         io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, PR_HELPER_SENSE_SIZE);
237         memcpy(io_hdr->sbp, resp.sense, io_hdr->sb_len_wr);
238     }
239 
240 out:
241     if (ret < 0) {
242         int sense_len = scsi_build_sense(io_hdr->sbp,
243                                          SENSE_CODE(LUN_COMM_FAILURE));
244         io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
245         io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len);
246         io_hdr->status = CHECK_CONDITION;
247     }
248     qemu_mutex_unlock(&pr_mgr->lock);
249     return ret;
250 }
251 
252 static bool pr_manager_helper_is_connected(PRManager *p)
253 {
254     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
255     bool result;
256 
257     qemu_mutex_lock(&pr_mgr->lock);
258     result = (pr_mgr->ioc != NULL);
259     qemu_mutex_unlock(&pr_mgr->lock);
260 
261     return result;
262 }
263 
264 static void pr_manager_helper_complete(UserCreatable *uc, Error **errp)
265 {
266     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(uc);
267 
268     qemu_mutex_lock(&pr_mgr->lock);
269     pr_manager_helper_initialize(pr_mgr, errp);
270     qemu_mutex_unlock(&pr_mgr->lock);
271 }
272 
273 static char *get_path(Object *obj, Error **errp)
274 {
275     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
276 
277     return g_strdup(pr_mgr->path);
278 }
279 
280 static void set_path(Object *obj, const char *str, Error **errp)
281 {
282     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
283 
284     g_free(pr_mgr->path);
285     pr_mgr->path = g_strdup(str);
286 }
287 
288 static void pr_manager_helper_instance_finalize(Object *obj)
289 {
290     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
291 
292     object_unref(OBJECT(pr_mgr->ioc));
293     qemu_mutex_destroy(&pr_mgr->lock);
294 }
295 
296 static void pr_manager_helper_instance_init(Object *obj)
297 {
298     PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
299 
300     qemu_mutex_init(&pr_mgr->lock);
301 }
302 
303 static void pr_manager_helper_class_init(ObjectClass *klass,
304                                          void *class_data G_GNUC_UNUSED)
305 {
306     PRManagerClass *prmgr_klass = PR_MANAGER_CLASS(klass);
307     UserCreatableClass *uc_klass = USER_CREATABLE_CLASS(klass);
308 
309     object_class_property_add_str(klass, "path", get_path, set_path);
310     uc_klass->complete = pr_manager_helper_complete;
311     prmgr_klass->run = pr_manager_helper_run;
312     prmgr_klass->is_connected = pr_manager_helper_is_connected;
313 }
314 
315 static const TypeInfo pr_manager_helper_info = {
316     .parent = TYPE_PR_MANAGER,
317     .name = TYPE_PR_MANAGER_HELPER,
318     .instance_size = sizeof(PRManagerHelper),
319     .instance_init = pr_manager_helper_instance_init,
320     .instance_finalize = pr_manager_helper_instance_finalize,
321     .class_init = pr_manager_helper_class_init,
322 };
323 
324 static void pr_manager_helper_register_types(void)
325 {
326     type_register_static(&pr_manager_helper_info);
327 }
328 
329 type_init(pr_manager_helper_register_types);
330