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
  22 #include <scsi/sg.h>
  23
  24 #define PR_MAX_RECONNECT_ATTEMPTS 5
  25
  26 #define TYPE_PR_MANAGER_HELPER "pr-manager-helper"
  27
  28 #define PR_MANAGER_HELPER(obj) \
  29      OBJECT_CHECK(PRManagerHelper, (obj), \
  30                   TYPE_PR_MANAGER_HELPER)
  31
  32 typedef struct PRManagerHelper {
  33     /* <private> */
  34     PRManager parent;
  35
  36     char *path;
  37
  38     QemuMutex lock;
  39     QIOChannel *ioc;
  40 } PRManagerHelper;
  41
  42 static void pr_manager_send_status_changed_event(PRManagerHelper *pr_mgr)
  43 {
  44     char *id = object_get_canonical_path_component(OBJECT(pr_mgr));
  45
  46     if (id) {
  47         qapi_event_send_pr_manager_status_changed(id, !!pr_mgr->ioc);
  48         g_free(id);
  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                                   &error_abort);
 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);