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