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