scsi/pr-manager-helper.c

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