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