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pr-manager-helper.c (9076B)

      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, 0, 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);