qemu/scsi/pr-manager-helper.c
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   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
  32typedef struct PRManagerHelper {
  33    /* <private> */
  34    PRManager parent;
  35
  36    char *path;
  37
  38    QemuMutex lock;
  39    QIOChannel *ioc;
  40} PRManagerHelper;
  41
  42static 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                                                  &error_abort);
  49        g_free(id);
  50    }
  51}
  52
  53/* Called with lock held.  */
  54static int pr_manager_helper_read(PRManagerHelper *pr_mgr,
  55                                  void *buf, int sz, Error **errp)
  56{
  57    ssize_t r = qio_channel_read_all(pr_mgr->ioc, buf, sz, errp);
  58
  59    if (r < 0) {
  60        object_unref(OBJECT(pr_mgr->ioc));
  61        pr_mgr->ioc = NULL;
  62        pr_manager_send_status_changed_event(pr_mgr);
  63        return -EINVAL;
  64    }
  65
  66    return 0;
  67}
  68
  69/* Called with lock held.  */
  70static int pr_manager_helper_write(PRManagerHelper *pr_mgr,
  71                                   int fd,
  72                                   const void *buf, int sz, Error **errp)
  73{
  74    size_t nfds = (fd != -1);
  75    while (sz > 0) {
  76        struct iovec iov;
  77        ssize_t n_written;
  78
  79        iov.iov_base = (void *)buf;
  80        iov.iov_len = sz;
  81        n_written = qio_channel_writev_full(QIO_CHANNEL(pr_mgr->ioc), &iov, 1,
  82                                            nfds ? &fd : NULL, nfds, errp);
  83
  84        if (n_written <= 0) {
  85            assert(n_written != QIO_CHANNEL_ERR_BLOCK);
  86            object_unref(OBJECT(pr_mgr->ioc));
  87            pr_mgr->ioc = NULL;
  88            pr_manager_send_status_changed_event(pr_mgr);
  89            return n_written < 0 ? -EINVAL : 0;
  90        }
  91
  92        nfds = 0;
  93        buf += n_written;
  94        sz -= n_written;
  95    }
  96
  97    return 0;
  98}
  99
 100/* Called with lock held.  */
 101static int pr_manager_helper_initialize(PRManagerHelper *pr_mgr,
 102                                        Error **errp)
 103{
 104    char *path = g_strdup(pr_mgr->path);
 105    SocketAddress saddr = {
 106        .type = SOCKET_ADDRESS_TYPE_UNIX,
 107        .u.q_unix.path = path
 108    };
 109    QIOChannelSocket *sioc = qio_channel_socket_new();
 110    Error *local_err = NULL;
 111
 112    uint32_t flags;
 113    int r;
 114
 115    assert(!pr_mgr->ioc);
 116    qio_channel_set_name(QIO_CHANNEL(sioc), "pr-manager-helper");
 117    qio_channel_socket_connect_sync(sioc,
 118                                    &saddr,
 119                                    &local_err);
 120    g_free(path);
 121    if (local_err) {
 122        object_unref(OBJECT(sioc));
 123        error_propagate(errp, local_err);
 124        return -ENOTCONN;
 125    }
 126
 127    qio_channel_set_delay(QIO_CHANNEL(sioc), false);
 128    pr_mgr->ioc = QIO_CHANNEL(sioc);
 129
 130    /* A simple feature negotation protocol, even though there is
 131     * no optional feature right now.
 132     */
 133    r = pr_manager_helper_read(pr_mgr, &flags, sizeof(flags), errp);
 134    if (r < 0) {
 135        goto out_close;
 136    }
 137
 138    flags = 0;
 139    r = pr_manager_helper_write(pr_mgr, -1, &flags, sizeof(flags), errp);
 140    if (r < 0) {
 141        goto out_close;
 142    }
 143
 144    pr_manager_send_status_changed_event(pr_mgr);
 145    return 0;
 146
 147out_close:
 148    object_unref(OBJECT(pr_mgr->ioc));
 149    pr_mgr->ioc = NULL;
 150    return r;
 151}
 152
 153static int pr_manager_helper_run(PRManager *p,
 154                                 int fd, struct sg_io_hdr *io_hdr)
 155{
 156    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
 157
 158    uint32_t len;
 159    PRHelperResponse resp;
 160    int ret;
 161    int expected_dir;
 162    int attempts;
 163    uint8_t cdb[PR_HELPER_CDB_SIZE] = { 0 };
 164
 165    if (!io_hdr->cmd_len || io_hdr->cmd_len > PR_HELPER_CDB_SIZE) {
 166        return -EINVAL;
 167    }
 168
 169    memcpy(cdb, io_hdr->cmdp, io_hdr->cmd_len);
 170    assert(cdb[0] == PERSISTENT_RESERVE_OUT || cdb[0] == PERSISTENT_RESERVE_IN);
 171    expected_dir =
 172        (cdb[0] == PERSISTENT_RESERVE_OUT ? SG_DXFER_TO_DEV : SG_DXFER_FROM_DEV);
 173    if (io_hdr->dxfer_direction != expected_dir) {
 174        return -EINVAL;
 175    }
 176
 177    len = scsi_cdb_xfer(cdb);
 178    if (io_hdr->dxfer_len < len || len > PR_HELPER_DATA_SIZE) {
 179        return -EINVAL;
 180    }
 181
 182    qemu_mutex_lock(&pr_mgr->lock);
 183
 184    /* Try to reconnect while sending the CDB.  */
 185    for (attempts = 0; attempts < PR_MAX_RECONNECT_ATTEMPTS; attempts++) {
 186        if (!pr_mgr->ioc) {
 187            ret = pr_manager_helper_initialize(pr_mgr, NULL);
 188            if (ret < 0) {
 189                qemu_mutex_unlock(&pr_mgr->lock);
 190                g_usleep(G_USEC_PER_SEC);
 191                qemu_mutex_lock(&pr_mgr->lock);
 192                continue;
 193            }
 194        }
 195
 196        ret = pr_manager_helper_write(pr_mgr, fd, cdb, ARRAY_SIZE(cdb), NULL);
 197        if (ret >= 0) {
 198            break;
 199        }
 200    }
 201    if (ret < 0) {
 202        goto out;
 203    }
 204
 205    /* After sending the CDB, any communications failure causes the
 206     * command to fail.  The failure is transient, retrying the command
 207     * will invoke pr_manager_helper_initialize again.
 208     */
 209    if (expected_dir == SG_DXFER_TO_DEV) {
 210        io_hdr->resid = io_hdr->dxfer_len - len;
 211        ret = pr_manager_helper_write(pr_mgr, -1, io_hdr->dxferp, len, NULL);
 212        if (ret < 0) {
 213            goto out;
 214        }
 215    }
 216    ret = pr_manager_helper_read(pr_mgr, &resp, sizeof(resp), NULL);
 217    if (ret < 0) {
 218        goto out;
 219    }
 220
 221    resp.result = be32_to_cpu(resp.result);
 222    resp.sz = be32_to_cpu(resp.sz);
 223    if (io_hdr->dxfer_direction == SG_DXFER_FROM_DEV) {
 224        assert(resp.sz <= io_hdr->dxfer_len);
 225        ret = pr_manager_helper_read(pr_mgr, io_hdr->dxferp, resp.sz, NULL);
 226        if (ret < 0) {
 227            goto out;
 228        }
 229        io_hdr->resid = io_hdr->dxfer_len - resp.sz;
 230    } else {
 231        assert(resp.sz == 0);
 232    }
 233
 234    io_hdr->status = resp.result;
 235    if (resp.result == CHECK_CONDITION) {
 236        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
 237        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, PR_HELPER_SENSE_SIZE);
 238        memcpy(io_hdr->sbp, resp.sense, io_hdr->sb_len_wr);
 239    }
 240
 241out:
 242    if (ret < 0) {
 243        int sense_len = scsi_build_sense(io_hdr->sbp,
 244                                         SENSE_CODE(LUN_COMM_FAILURE));
 245        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
 246        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len);
 247        io_hdr->status = CHECK_CONDITION;
 248    }
 249    qemu_mutex_unlock(&pr_mgr->lock);
 250    return ret;
 251}
 252
 253static bool pr_manager_helper_is_connected(PRManager *p)
 254{
 255    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
 256    bool result;
 257
 258    qemu_mutex_lock(&pr_mgr->lock);
 259    result = (pr_mgr->ioc != NULL);
 260    qemu_mutex_unlock(&pr_mgr->lock);
 261
 262    return result;
 263}
 264
 265static void pr_manager_helper_complete(UserCreatable *uc, Error **errp)
 266{
 267    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(uc);
 268
 269    qemu_mutex_lock(&pr_mgr->lock);
 270    pr_manager_helper_initialize(pr_mgr, errp);
 271    qemu_mutex_unlock(&pr_mgr->lock);
 272}
 273
 274static char *get_path(Object *obj, Error **errp)
 275{
 276    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 277
 278    return g_strdup(pr_mgr->path);
 279}
 280
 281static void set_path(Object *obj, const char *str, Error **errp)
 282{
 283    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 284
 285    g_free(pr_mgr->path);
 286    pr_mgr->path = g_strdup(str);
 287}
 288
 289static void pr_manager_helper_instance_finalize(Object *obj)
 290{
 291    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 292
 293    object_unref(OBJECT(pr_mgr->ioc));
 294    qemu_mutex_destroy(&pr_mgr->lock);
 295}
 296
 297static void pr_manager_helper_instance_init(Object *obj)
 298{
 299    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 300
 301    qemu_mutex_init(&pr_mgr->lock);
 302}
 303
 304static void pr_manager_helper_class_init(ObjectClass *klass,
 305                                         void *class_data G_GNUC_UNUSED)
 306{
 307    PRManagerClass *prmgr_klass = PR_MANAGER_CLASS(klass);
 308    UserCreatableClass *uc_klass = USER_CREATABLE_CLASS(klass);
 309
 310    object_class_property_add_str(klass, "path", get_path, set_path,
 311                                  &error_abort);
 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
 317static 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
 326static void pr_manager_helper_register_types(void)
 327{
 328    type_register_static(&pr_manager_helper_info);
 329}
 330
 331type_init(pr_manager_helper_register_types);
 332