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