From 43fedb8ae2c2b3bbb43023c118be708226e38179 Mon Sep 17 00:00:00 2001

From: Paolo Bonzini <pbonzini@redhat.com>

Date: Tue, 22 Aug 2017 06:50:55 +0200

Subject: [PATCH 14/15] scsi: add multipath support to qemu-pr-helper

Proper support of persistent reservation for multipath devices requires

communication with the multipath daemon, so that the reservation is

registered and applied when a path comes up.  The device mapper

utilities provide a library to do so; this patch makes qemu-pr-helper.c

detect multipath devices and, when one is found, delegate the operation

to libmpathpersist.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

---

 Makefile              |   3 +

 configure             |  46 +++++++

 docs/pr-manager.rst   |  27 ++++

 include/scsi/utils.h  |   4 +

 scsi/qemu-pr-helper.c | 346 +++++++++++++++++++++++++++++++++++++++++++++++++-

 scsi/utils.c          |  10 ++

 6 files changed, 433 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile

index 8406aeb8cb..4eb40376d2 100644

--- a/Makefile

+++ b/Makefile

@@ -373,6 +373,9 @@ fsdev/virtfs-proxy-helper$(EXESUF): fsdev/virtfs-proxy-helper.o fsdev/9p-marshal

 fsdev/virtfs-proxy-helper$(EXESUF): LIBS += -lcap

 scsi/qemu-pr-helper$(EXESUF): scsi/qemu-pr-helper.o scsi/utils.o $(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)

+ifdef CONFIG_MPATH

+scsi/qemu-pr-helper$(EXESUF): LIBS += -ludev -lmultipath -lmpathpersist

+endif

 qemu-img-cmds.h: $(SRC_PATH)/qemu-img-cmds.hx $(SRC_PATH)/scripts/hxtool

 	$(call quiet-command,sh $(SRC_PATH)/scripts/hxtool -h < $< > $@,"GEN","$@")

diff --git a/configure b/configure

index becc21a0fe..f6edc2a33f 100755

--- a/configure

+++ b/configure

@@ -290,6 +290,7 @@ netmap="no"

 sdl=""

 sdlabi=""

 virtfs=""

+mpath=""

 vnc="yes"

 sparse="no"

 vde=""

@@ -936,6 +937,10 @@ for opt do

   ;;

   --enable-virtfs) virtfs="yes"

   ;;

+  --disable-mpath) mpath="no"

+  ;;

+  --enable-mpath) mpath="yes"

+  ;;

   --disable-vnc) vnc="no"

   ;;

   --enable-vnc) vnc="yes"

@@ -1479,6 +1484,7 @@ disabled with --disable-FEATURE, default is enabled if available:

   vnc-png         PNG compression for VNC server

   cocoa           Cocoa UI (Mac OS X only)

   virtfs          VirtFS

+  mpath           Multipath persistent reservation passthrough

   xen             xen backend driver support

   xen-pci-passthrough

   brlapi          BrlAPI (Braile)

@@ -3300,6 +3306,30 @@ else

 fi

 ##########################################

+# libmpathpersist probe

+

+if test "$mpath" != "no" ; then

+  cat > $TMPC <

+#include <libudev.h>

+#include <mpath_persist.h>

+unsigned mpath_mx_alloc_len = 1024;

+int logsink;

+int main(void) {

+    struct udev *udev = udev_new();

+    mpath_lib_init(udev);

+    return 0;

+}

+EOF

+  if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then

+    mpathpersist=yes

+  else

+    mpathpersist=no

+  fi

+else

+  mpathpersist=no

+fi

+

+##########################################

 # libcap probe

 if test "$cap" != "no" ; then

@@ -5044,12 +5074,24 @@ if test "$softmmu" = yes ; then

       fi

       virtfs=no

     fi

+    if test "$mpath" != no && test "$mpathpersist" = yes ; then

+      mpath=yes

+    else

+      if test "$mpath" = yes; then

+        error_exit "Multipath requires libmpathpersist devel"

+      fi

+      mpath=no

+    fi

     tools="$tools scsi/qemu-pr-helper\$(EXESUF)"

   else

     if test "$virtfs" = yes; then

       error_exit "VirtFS is supported only on Linux"

     fi

     virtfs=no

+    if test "$mpath" = yes; then

+      error_exit "Multipath is supported only on Linux"

+    fi

+    mpath=no

   fi

 fi

@@ -5295,6 +5337,7 @@ echo "Audio drivers     $audio_drv_list"

 echo "Block whitelist (rw) $block_drv_rw_whitelist"

 echo "Block whitelist (ro) $block_drv_ro_whitelist"

 echo "VirtFS support    $virtfs"

+echo "Multipath support $mpath"

 echo "VNC support       $vnc"

 if test "$vnc" = "yes" ; then

     echo "VNC SASL support  $vnc_sasl"

@@ -5738,6 +5781,9 @@ fi

 if test "$virtfs" = "yes" ; then

   echo "CONFIG_VIRTFS=y" >> $config_host_mak

 fi

+if test "$mpath" = "yes" ; then

+  echo "CONFIG_MPATH=y" >> $config_host_mak

+fi

 if test "$vhost_scsi" = "yes" ; then

   echo "CONFIG_VHOST_SCSI=y" >> $config_host_mak

 fi

diff --git a/docs/pr-manager.rst b/docs/pr-manager.rst

index 7107e59fb8..9b1de198b1 100644

--- a/docs/pr-manager.rst

+++ b/docs/pr-manager.rst

@@ -60,6 +60,7 @@ system service and supports the following option:

 -d, --daemon              run in the background

 -q, --quiet               decrease verbosity

+-v, --verbose             increase verbosity

 -f, --pidfile=path        PID file when running as a daemon

 -k, --socket=path         path to the socket

 -T, --trace=trace-opts    tracing options

@@ -82,3 +83,29 @@ its operation.  To do this, add the following options:

 -u, --user=user           user to drop privileges to

 -g, --group=group         group to drop privileges to

+

+---------------------------------------------

+Multipath devices and persistent reservations

+---------------------------------------------

+

+Proper support of persistent reservation for multipath devices requires

+communication with the multipath daemon, so that the reservation is

+registered and applied when a path is newly discovered or becomes online

+again.  :command:`qemu-pr-helper` can do this if the ``libmpathpersist``

+library was available on the system at build time.

+

+As of August 2017, a reservation key must be specified in ``multipath.conf``

+for ``multipathd`` to check for persistent reservation for newly

+discovered paths or reinstated paths.  The attribute can be added

+to the ``defaults`` section or the ``multipaths`` section; for example::

+

+    multipaths {

+        multipath {

+            wwid   XXXXXXXXXXXXXXXX

+            alias      yellow

+            reservation_key  0x123abc

+        }

+    }

+

+Linking :program:`qemu-pr-helper` to ``libmpathpersist`` does not impede

+its usage on regular SCSI devices.

diff --git a/include/scsi/utils.h b/include/scsi/utils.h

index d301b31768..00a4bdb080 100644

--- a/include/scsi/utils.h

+++ b/include/scsi/utils.h

@@ -72,10 +72,14 @@ extern const struct SCSISense sense_code_IO_ERROR;

 extern const struct SCSISense sense_code_I_T_NEXUS_LOSS;

 /* Command aborted, Logical Unit failure */

 extern const struct SCSISense sense_code_LUN_FAILURE;

+/* Command aborted, LUN Communication failure */

+extern const struct SCSISense sense_code_LUN_COMM_FAILURE;

 /* Command aborted, Overlapped Commands Attempted */

 extern const struct SCSISense sense_code_OVERLAPPED_COMMANDS;

 /* LUN not ready, Capacity data has changed */

 extern const struct SCSISense sense_code_CAPACITY_CHANGED;

+/* Unit attention, SCSI bus reset */

+extern const struct SCSISense sense_code_SCSI_BUS_RESET;

 /* LUN not ready, Medium not present */

 extern const struct SCSISense sense_code_UNIT_ATTENTION_NO_MEDIUM;

 /* Unit attention, Power on, reset or bus device reset occurred */

diff --git a/scsi/qemu-pr-helper.c b/scsi/qemu-pr-helper.c

index e39efbd529..5f77c873e1 100644

--- a/scsi/qemu-pr-helper.c

+++ b/scsi/qemu-pr-helper.c

@@ -30,6 +30,12 @@

 #include <pwd.h>

 #include <grp.h>

+#ifdef CONFIG_MPATH

+#include <libudev.h>

+#include <mpath_cmd.h>

+#include <mpath_persist.h>

+#endif

+

 #include "qapi/error.h"

 #include "qemu-common.h"

 #include "qemu/cutils.h"

@@ -60,6 +66,7 @@ static enum { RUNNING, TERMINATE, TERMINATING } state;

 static QIOChannelSocket *server_ioc;

 static int server_watch;

 static int num_active_sockets = 1;

+static int noisy;

 static int verbose;

 #ifdef CONFIG_LIBCAP

@@ -204,9 +211,316 @@ static int do_sgio(int fd, const uint8_t *cdb, uint8_t *sense,

     return r;

 }

+/* Device mapper interface */

+

+#ifdef CONFIG_MPATH

+#define CONTROL_PATH "/dev/mapper/control"

+

+typedef struct DMData {

+    struct dm_ioctl dm;

+    uint8_t data[1024];

+} DMData;

+

+static int control_fd;

+

+static void *dm_ioctl(int ioc, struct dm_ioctl *dm)

+{

+    static DMData d;

+    memcpy(&d.dm, dm, sizeof(d.dm));

+    QEMU_BUILD_BUG_ON(sizeof(d.data) < sizeof(struct dm_target_spec));

+

+    d.dm.version[0] = DM_VERSION_MAJOR;

+    d.dm.version[1] = 0;

+    d.dm.version[2] = 0;

+    d.dm.data_size = 1024;

+    d.dm.data_start = offsetof(DMData, data);

+    if (ioctl(control_fd, ioc, &d) < 0) {

+        return NULL;

+    }

+    memcpy(dm, &d.dm, sizeof(d.dm));

+    return &d.data;

+}

+

+static void *dm_dev_ioctl(int fd, int ioc, struct dm_ioctl *dm)

+{

+    struct stat st;

+    int r;

+

+    r = fstat(fd, &st);

+    if (r < 0) {

+        perror("fstat");

+        exit(1);

+    }

+

+    dm->dev = st.st_rdev;

+    return dm_ioctl(ioc, dm);

+}

+

+static void dm_init(void)

+{

+    control_fd = open(CONTROL_PATH, O_RDWR);

+    if (control_fd < 0) {

+        perror("Cannot open " CONTROL_PATH);

+        exit(1);

+    }

+    struct dm_ioctl dm = { 0 };

+    if (!dm_ioctl(DM_VERSION, &dm)) {

+        perror("ioctl");

+        exit(1);

+    }

+    if (dm.version[0] != DM_VERSION_MAJOR) {

+        fprintf(stderr, "Unsupported device mapper interface");

+        exit(1);

+    }

+}

+

+/* Variables required by libmultipath and libmpathpersist.  */

+QEMU_BUILD_BUG_ON(PR_HELPER_DATA_SIZE > MPATH_MAX_PARAM_LEN);

+unsigned mpath_mx_alloc_len = PR_HELPER_DATA_SIZE;

+int logsink;

+

+static void multipath_pr_init(void)

+{

+    static struct udev *udev;

+

+    udev = udev_new();

+    mpath_lib_init(udev);

+}

+

+static int is_mpath(int fd)

+{

+    struct dm_ioctl dm = { .flags = DM_NOFLUSH_FLAG };

+    struct dm_target_spec *tgt;

+

+    tgt = dm_dev_ioctl(fd, DM_TABLE_STATUS, &dm;;

+    if (!tgt) {

+        if (errno == ENXIO) {

+            return 0;

+        }

+        perror("ioctl");

+        exit(EXIT_FAILURE);

+    }

+    return !strncmp(tgt->target_type, "multipath", DM_MAX_TYPE_NAME);

+}

+

+static int mpath_reconstruct_sense(int fd, int r, uint8_t *sense)

+{

+    switch (r) {

+    case MPATH_PR_SUCCESS:

+        return GOOD;

+    case MPATH_PR_SENSE_NOT_READY:

+    case MPATH_PR_SENSE_MEDIUM_ERROR:

+    case MPATH_PR_SENSE_HARDWARE_ERROR:

+    case MPATH_PR_SENSE_ABORTED_COMMAND:

+        {

+            /* libmpathpersist ate the exact sense.  Try to find it by

+             * issuing TEST UNIT READY.

+             */

+            uint8_t cdb[6] = { TEST_UNIT_READY };

+            int sz = 0;

+            return do_sgio(fd, cdb, sense, NULL, &sz, SG_DXFER_NONE);

+        }

+

+    case MPATH_PR_SENSE_UNIT_ATTENTION:

+        /* Congratulations libmpathpersist, you ruined the Unit Attention...

+         * Return a heavyweight one.

+         */

+        scsi_build_sense(sense, SENSE_CODE(SCSI_BUS_RESET));

+        return CHECK_CONDITION;

+    case MPATH_PR_SENSE_INVALID_OP:

+        /* Only one valid sense.  */

+        scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));

+        return CHECK_CONDITION;

+    case MPATH_PR_ILLEGAL_REQ:

+        /* Guess.  */

+        scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));

+        return CHECK_CONDITION;

+    case MPATH_PR_NO_SENSE:

+        scsi_build_sense(sense, SENSE_CODE(NO_SENSE));

+        return CHECK_CONDITION;

+

+    case MPATH_PR_RESERV_CONFLICT:

+        return RESERVATION_CONFLICT;

+

+    case MPATH_PR_OTHER:

+    default:

+        scsi_build_sense(sense, SENSE_CODE(LUN_COMM_FAILURE));

+        return CHECK_CONDITION;

+    }

+}

+

+static int multipath_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,

+                           uint8_t *data, int sz)

+{

+    int rq_servact = cdb[1];

+    struct prin_resp resp;

+    size_t written;

+    int r;

+

+    switch (rq_servact) {

+    case MPATH_PRIN_RKEY_SA:

+    case MPATH_PRIN_RRES_SA:

+    case MPATH_PRIN_RCAP_SA:

+        break;

+    case MPATH_PRIN_RFSTAT_SA:

+        /* Nobody implements it anyway, so bail out. */

+    default:

+        /* Cannot parse any other output.  */

+        scsi_build_sense(sense, SENSE_CODE(INVALID_FIELD));

+        return CHECK_CONDITION;

+    }

+

+    r = mpath_persistent_reserve_in(fd, rq_servact, &resp, noisy, verbose);

+    if (r == MPATH_PR_SUCCESS) {

+        switch (rq_servact) {

+        case MPATH_PRIN_RKEY_SA:

+        case MPATH_PRIN_RRES_SA: {

+            struct prin_readdescr *out = &resp.prin_descriptor.prin_readkeys;

+            assert(sz >= 8);

+            written = MIN(out->additional_length + 8, sz);

+            stl_be_p(&data[0], out->prgeneration);

+            stl_be_p(&data[4], out->additional_length);

+            memcpy(&data[8], out->key_list, written - 8);

+            break;

+        }

+        case MPATH_PRIN_RCAP_SA: {

+            struct prin_capdescr *out = &resp.prin_descriptor.prin_readcap;

+            assert(sz >= 6);

+            written = 6;

+            stw_be_p(&data[0], out->length);

+            data[2] = out->flags[0];

+            data[3] = out->flags[1];

+            stw_be_p(&data[4], out->pr_type_mask);

+            break;

+        }

+        default:

+            scsi_build_sense(sense, SENSE_CODE(INVALID_OPCODE));

+            return CHECK_CONDITION;

+        }

+        assert(written <= sz);

+        memset(data + written, 0, sz - written);

+    }

+

+    return mpath_reconstruct_sense(fd, r, sense);

+}

+

+static int multipath_pr_out(int fd, const uint8_t *cdb, uint8_t *sense,

+                            const uint8_t *param, int sz)

+{

+    int rq_servact = cdb[1];

+    int rq_scope = cdb[2] >> 4;

+    int rq_type = cdb[2] & 0xf;

+    struct prout_param_descriptor paramp;

+    char transportids[PR_HELPER_DATA_SIZE];

+    int r;

+

+    switch (rq_servact) {

+    case MPATH_PROUT_REG_SA:

+    case MPATH_PROUT_RES_SA:

+    case MPATH_PROUT_REL_SA:

+    case MPATH_PROUT_CLEAR_SA:

+    case MPATH_PROUT_PREE_SA:

+    case MPATH_PROUT_PREE_AB_SA:

+    case MPATH_PROUT_REG_IGN_SA:

+        break;

+    case MPATH_PROUT_REG_MOV_SA:

+        /* Not supported by struct prout_param_descriptor.  */

+    default:

+        /* Cannot parse any other input.  */

+        scsi_build_sense(sense, SENSE_CODE(INVALID_FIELD));

+        return CHECK_CONDITION;

+    }

+

+    /* Convert input data, especially transport IDs, to the structs

+     * used by libmpathpersist (which, of course, will immediately

+     * do the opposite).

+     */

+    memset(&paramp, 0, sizeof(paramp));

+    memcpy(&paramp.key, &param[0], 8);

+    memcpy(&paramp.sa_key, &param[8], 8);

+    paramp.sa_flags = param[10];

+    if (sz > PR_OUT_FIXED_PARAM_SIZE) {

+        size_t transportid_len;

+        int i, j;

+        if (sz < PR_OUT_FIXED_PARAM_SIZE + 4) {

+            scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM_LEN));

+            return CHECK_CONDITION;

+        }

+        transportid_len = ldl_be_p(&param[24]) + PR_OUT_FIXED_PARAM_SIZE + 4;

+        if (transportid_len > sz) {

+            scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));

+            return CHECK_CONDITION;

+        }

+        for (i = PR_OUT_FIXED_PARAM_SIZE + 4, j = 0; i < transportid_len; ) {

+            struct transportid *id = (struct transportid *) &transportids[j];

+            int len;

+

+            id->format_code = param[i] & 0xc0;

+            id->protocol_id = param[i] & 0x0f;

+            switch (param[i] & 0xcf) {

+            case 0:

+                /* FC transport.  */

+                if (i + 24 > transportid_len) {

+                    goto illegal_req;

+                }

+                memcpy(id->n_port_name, &param[i + 8], 8);

+                j += offsetof(struct transportid, n_port_name[8]);

+                i += 24;

+                break;

+            case 3:

+            case 0x43:

+                /* iSCSI transport.  */

+                len = lduw_be_p(&param[i + 2]);

+                if (len > 252 || (len & 3) || i + len + 4 > transportid_len) {

+                    /* For format code 00, the standard says the maximum is 223

+                     * plus the NUL terminator.  For format code 01 there is no

+                     * maximum length, but libmpathpersist ignores the first

+                     * byte of id->iscsi_name so our maximum is 252.

+                     */

+                    goto illegal_req;

+                }

+                if (memchr(&param[i + 4], 0, len) == NULL) {

+                    goto illegal_req;

+                }

+                memcpy(id->iscsi_name, &param[i + 2], len + 2);

+                j += offsetof(struct transportid, iscsi_name[len + 2]);

+                i += len + 4;

+                break;

+            case 6:

+                /* SAS transport.  */

+                if (i + 24 > transportid_len) {

+                    goto illegal_req;

+                }

+                memcpy(id->sas_address, &param[i + 4], 8);

+                j += offsetof(struct transportid, sas_address[8]);

+                i += 24;

+                break;

+            default:

+            illegal_req:

+                scsi_build_sense(sense, SENSE_CODE(INVALID_PARAM));

+                return CHECK_CONDITION;

+            }

+

+            paramp.trnptid_list[paramp.num_transportid++] = id;

+        }

+    }

+

+    r = mpath_persistent_reserve_out(fd, rq_servact, rq_scope, rq_type,

+                                     &paramp, noisy, verbose);

+    return mpath_reconstruct_sense(fd, r, sense);

+}

+#endif

+

 static int do_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,

                     uint8_t *data, int *resp_sz)

 {

+#ifdef CONFIG_MPATH

+    if (is_mpath(fd)) {

+        /* multipath_pr_in fills the whole input buffer.  */

+        return multipath_pr_in(fd, cdb, sense, data, *resp_sz);

+    }

+#endif

+

     return do_sgio(fd, cdb, sense, data, resp_sz,

                    SG_DXFER_FROM_DEV);

 }

@@ -214,7 +528,14 @@ static int do_pr_in(int fd, const uint8_t *cdb, uint8_t *sense,

 static int do_pr_out(int fd, const uint8_t *cdb, uint8_t *sense,

                      const uint8_t *param, int sz)

 {

-    int resp_sz = sz;

+    int resp_sz;

+#ifdef CONFIG_MPATH

+    if (is_mpath(fd)) {

+        return multipath_pr_out(fd, cdb, sense, param, sz);

+    }

+#endif

+

+    resp_sz = sz;

     return do_sgio(fd, cdb, sense, (uint8_t *)param, &resp_sz,

                    SG_DXFER_TO_DEV);

 }

@@ -525,6 +846,14 @@ static int drop_privileges(void)

         return -1;

     }

+#ifdef CONFIG_MPATH

+    /* For /dev/mapper/control ioctls */

+    if (capng_update(CAPNG_ADD, CAPNG_EFFECTIVE | CAPNG_PERMITTED,

+                     CAP_SYS_ADMIN) < 0) {

+        return -1;

+    }

+#endif

+

     /* Change user/group id, retaining the capabilities.  Because file descriptors

      * are passed via SCM_RIGHTS, we don't need supplementary groups (and in

      * fact the helper can run as "nobody").

@@ -541,7 +870,7 @@ static int drop_privileges(void)

 int main(int argc, char **argv)

 {

-    const char *sopt = "hVk:fdT:u:g:q";

+    const char *sopt = "hVk:fdT:u:g:vq";

     struct option lopt[] = {

         { "help", no_argument, NULL, 'h' },

         { "version", no_argument, NULL, 'V' },

@@ -551,10 +880,12 @@ int main(int argc, char **argv)

         { "trace", required_argument, NULL, 'T' },

         { "user", required_argument, NULL, 'u' },

         { "group", required_argument, NULL, 'g' },

+        { "verbose", no_argument, NULL, 'v' },

         { "quiet", no_argument, NULL, 'q' },

         { NULL, 0, NULL, 0 }

     };

     int opt_ind = 0;

+    int loglevel = 1;

     int quiet = 0;

     char ch;

     Error *local_err = NULL;

@@ -631,6 +962,9 @@ int main(int argc, char **argv)

         case 'q':

             quiet = 1;

             break;

+        case 'v':

+            ++loglevel;

+            break;

         case 'T':

             g_free(trace_file);

             trace_file = trace_opt_parse(optarg);

@@ -650,7 +984,8 @@ int main(int argc, char **argv)

     }

     /* set verbosity */

-    verbose = !quiet;

+    noisy = !quiet && (loglevel >= 3);

+    verbose = quiet ? 0 : MIN(loglevel, 3);

     if (!trace_init_backends()) {

         exit(EXIT_FAILURE);

@@ -658,6 +993,11 @@ int main(int argc, char **argv)

     trace_init_file(trace_file);

     qemu_set_log(LOG_TRACE);

+#ifdef CONFIG_MPATH

+    dm_init();

+    multipath_pr_init();

+#endif

+

     socket_activation = check_socket_activation();

     if (socket_activation == 0) {

         SocketAddress saddr;

diff --git a/scsi/utils.c b/scsi/utils.c

index fab60bdf20..5684951b12 100644

--- a/scsi/utils.c

+++ b/scsi/utils.c

@@ -206,6 +206,11 @@ const struct SCSISense sense_code_OVERLAPPED_COMMANDS = {

     .key = ABORTED_COMMAND, .asc = 0x4e, .ascq = 0x00

 };

+/* Command aborted, LUN Communication Failure */

+const struct SCSISense sense_code_LUN_COMM_FAILURE = {

+    .key = ABORTED_COMMAND, .asc = 0x08, .ascq = 0x00

+};

+

 /* Unit attention, Capacity data has changed */

 const struct SCSISense sense_code_CAPACITY_CHANGED = {

     .key = UNIT_ATTENTION, .asc = 0x2a, .ascq = 0x09

@@ -216,6 +221,11 @@ const struct SCSISense sense_code_RESET = {

     .key = UNIT_ATTENTION, .asc = 0x29, .ascq = 0x00

 };

+/* Unit attention, SCSI bus reset */

+const struct SCSISense sense_code_SCSI_BUS_RESET = {

+    .key = UNIT_ATTENTION, .asc = 0x29, .ascq = 0x02

+};

+

 /* Unit attention, No medium */

 const struct SCSISense sense_code_UNIT_ATTENTION_NO_MEDIUM = {

     .key = UNIT_ATTENTION, .asc = 0x3a, .ascq = 0x00

-- 

2.13.5