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        g_free(id);
  49    }
  50}
  51
  52/* Called with lock held.  */
  53static 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.  */
  69static 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.  */
 100static 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
 146out_close:
 147    object_unref(OBJECT(pr_mgr->ioc));
 148    pr_mgr->ioc = NULL;
 149    return r;
 150}
 151
 152static 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
 240out:
 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
 252static 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
 264static 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
 273static 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
 280static 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
 288static 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
 296static 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
 303static 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
 316static 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
 325static void pr_manager_helper_register_types(void)
 326{
 327    type_register_static(&pr_manager_helper_info);
 328}
 329
 330type_init(pr_manager_helper_register_types);
 331