From: Paolo Bonzini <pbonzini@redhat.com>

Date: Mon, 21 Aug 2017 18:58:56 +0200

Subject: [PATCH] scsi: add persistent reservation manager using qemu-pr-helper

This adds a concrete subclass of pr-manager that talks to qemu-pr-helper.

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

---

 scsi/Makefile.objs       |   2 +-

 scsi/pr-manager-helper.c | 302 +++++++++++++++++++++++++++++++++++++++++++++++

 2 files changed, 303 insertions(+), 1 deletion(-)

 create mode 100644 scsi/pr-manager-helper.c

diff --git a/scsi/Makefile.objs b/scsi/Makefile.objs

index 5496d2ae6a..4d25e476cf 100644

--- a/scsi/Makefile.objs

+++ b/scsi/Makefile.objs

@@ -1,3 +1,3 @@

 block-obj-y += utils.o

-block-obj-$(CONFIG_LINUX) += pr-manager.o

+block-obj-$(CONFIG_LINUX) += pr-manager.o pr-manager-helper.o

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

new file mode 100644

index 0000000000..82ff6b6123

--- /dev/null

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

@@ -0,0 +1,302 @@

+/*

+ * Persistent reservation manager that talks to qemu-pr-helper

+ *

+ * Copyright (c) 2017 Red Hat, Inc.

+ *

+ * Author: Paolo Bonzini <pbonzini@redhat.com>

+ *

+ * This code is licensed under the LGPL v2.1 or later.

+ *

+ */

+

+#include "qemu/osdep.h"

+#include "qapi/error.h"

+#include "scsi/constants.h"

+#include "scsi/pr-manager.h"

+#include "scsi/utils.h"

+#include "io/channel.h"

+#include "io/channel-socket.h"

+#include "pr-helper.h"

+

+#include <scsi/sg.h>

+

+#define PR_MAX_RECONNECT_ATTEMPTS 5

+

+#define TYPE_PR_MANAGER_HELPER "pr-manager-helper"

+

+#define PR_MANAGER_HELPER(obj) \

+     OBJECT_CHECK(PRManagerHelper, (obj), \

+                  TYPE_PR_MANAGER_HELPER)

+

+typedef struct PRManagerHelper {

+    /* <private> */

+    PRManager parent;

+

+    char *path;

+

+    QemuMutex lock;

+    QIOChannel *ioc;

+} PRManagerHelper;

+

+/* Called with lock held.  */

+static int pr_manager_helper_read(PRManagerHelper *pr_mgr,

+                                  void *buf, int sz, Error **errp)

+{

+    ssize_t r = qio_channel_read_all(pr_mgr->ioc, buf, sz, errp);

+

+    if (r < 0) {

+        object_unref(OBJECT(pr_mgr->ioc));

+        pr_mgr->ioc = NULL;

+        return -EINVAL;

+    }

+

+    return 0;

+}

+

+/* Called with lock held.  */

+static int pr_manager_helper_write(PRManagerHelper *pr_mgr,

+                                   int fd,

+                                   const void *buf, int sz, Error **errp)

+{

+    size_t nfds = (fd != -1);

+    while (sz > 0) {

+        struct iovec iov;

+        ssize_t n_written;

+

+        iov.iov_base = (void *)buf;

+        iov.iov_len = sz;

+        n_written = qio_channel_writev_full(QIO_CHANNEL(pr_mgr->ioc), &iov, 1,

+                                            nfds ? &fd : NULL, nfds, errp);

+

+        if (n_written <= 0) {

+            assert(n_written != QIO_CHANNEL_ERR_BLOCK);

+            object_unref(OBJECT(pr_mgr->ioc));

+            return n_written < 0 ? -EINVAL : 0;

+        }

+

+        nfds = 0;

+        buf += n_written;

+        sz -= n_written;

+    }

+

+    return 0;

+}

+

+/* Called with lock held.  */

+static int pr_manager_helper_initialize(PRManagerHelper *pr_mgr,

+                                        Error **errp)

+{

+    char *path = g_strdup(pr_mgr->path);

+    SocketAddress saddr = {

+        .type = SOCKET_ADDRESS_TYPE_UNIX,

+        .u.q_unix.path = path

+    };

+    QIOChannelSocket *sioc = qio_channel_socket_new();

+    Error *local_err = NULL;

+

+    uint32_t flags;

+    int r;

+

+    assert(!pr_mgr->ioc);

+    qio_channel_set_name(QIO_CHANNEL(sioc), "pr-manager-helper");

+    qio_channel_socket_connect_sync(sioc,

+                                    &saddr,

+                                    &local_err);

+    g_free(path);

+    if (local_err) {

+        object_unref(OBJECT(sioc));

+        error_propagate(errp, local_err);

+        return -ENOTCONN;

+    }

+

+    qio_channel_set_delay(QIO_CHANNEL(sioc), false);

+    pr_mgr->ioc = QIO_CHANNEL(sioc);

+

+    /* A simple feature negotation protocol, even though there is

+     * no optional feature right now.

+     */

+    r = pr_manager_helper_read(pr_mgr, &flags, sizeof(flags), errp);

+    if (r < 0) {

+        goto out_close;

+    }

+

+    flags = 0;

+    r = pr_manager_helper_write(pr_mgr, -1, &flags, sizeof(flags), errp);

+    if (r < 0) {

+        goto out_close;

+    }

+

+    return 0;

+

+out_close:

+    object_unref(OBJECT(pr_mgr->ioc));

+    pr_mgr->ioc = NULL;

+    return r;

+}

+

+static int pr_manager_helper_run(PRManager *p,

+                                 int fd, struct sg_io_hdr *io_hdr)

+{

+    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);

+

+    uint32_t len;

+    PRHelperResponse resp;

+    int ret;

+    int expected_dir;

+    int attempts;

+    uint8_t cdb[PR_HELPER_CDB_SIZE] = { 0 };

+

+    if (!io_hdr->cmd_len || io_hdr->cmd_len > PR_HELPER_CDB_SIZE) {

+        return -EINVAL;

+    }

+

+    memcpy(cdb, io_hdr->cmdp, io_hdr->cmd_len);

+    assert(cdb[0] == PERSISTENT_RESERVE_OUT || cdb[0] == PERSISTENT_RESERVE_IN);

+    expected_dir =

+        (cdb[0] == PERSISTENT_RESERVE_OUT ? SG_DXFER_TO_DEV : SG_DXFER_FROM_DEV);

+    if (io_hdr->dxfer_direction != expected_dir) {

+        return -EINVAL;

+    }

+

+    len = scsi_cdb_xfer(cdb);

+    if (io_hdr->dxfer_len < len || len > PR_HELPER_DATA_SIZE) {

+        return -EINVAL;

+    }

+

+    qemu_mutex_lock(&pr_mgr->lock);

+

+    /* Try to reconnect while sending the CDB.  */

+    for (attempts = 0; attempts < PR_MAX_RECONNECT_ATTEMPTS; attempts++) {

+        if (!pr_mgr->ioc) {

+            ret = pr_manager_helper_initialize(pr_mgr, NULL);

+            if (ret < 0) {

+                qemu_mutex_unlock(&pr_mgr->lock);

+                g_usleep(G_USEC_PER_SEC);

+                qemu_mutex_lock(&pr_mgr->lock);

+                continue;

+            }

+        }

+

+        ret = pr_manager_helper_write(pr_mgr, fd, cdb, ARRAY_SIZE(cdb), NULL);

+        if (ret >= 0) {

+            break;

+        }

+    }

+    if (ret < 0) {

+        goto out;

+    }

+

+    /* After sending the CDB, any communications failure causes the

+     * command to fail.  The failure is transient, retrying the command

+     * will invoke pr_manager_helper_initialize again.

+     */

+    if (expected_dir == SG_DXFER_TO_DEV) {

+        io_hdr->resid = io_hdr->dxfer_len - len;

+        ret = pr_manager_helper_write(pr_mgr, -1, io_hdr->dxferp, len, NULL);

+        if (ret < 0) {

+            goto out;

+        }

+    }

+    ret = pr_manager_helper_read(pr_mgr, &resp, sizeof(resp), NULL);

+    if (ret < 0) {

+        goto out;

+    }

+

+    resp.result = be32_to_cpu(resp.result);

+    resp.sz = be32_to_cpu(resp.sz);

+    if (io_hdr->dxfer_direction == SG_DXFER_FROM_DEV) {

+        assert(resp.sz <= io_hdr->dxfer_len);

+        ret = pr_manager_helper_read(pr_mgr, io_hdr->dxferp, resp.sz, NULL);

+        if (ret < 0) {

+            goto out;

+        }

+        io_hdr->resid = io_hdr->dxfer_len - resp.sz;

+    } else {

+        assert(resp.sz == 0);

+    }

+

+    io_hdr->status = resp.result;

+    if (resp.result == CHECK_CONDITION) {

+        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;

+        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, PR_HELPER_SENSE_SIZE);

+        memcpy(io_hdr->sbp, resp.sense, io_hdr->sb_len_wr);

+    }

+

+out:

+    if (ret < 0) {

+        int sense_len = scsi_build_sense(io_hdr->sbp,

+                                         SENSE_CODE(LUN_COMM_FAILURE));

+        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;

+        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len);

+        io_hdr->status = CHECK_CONDITION;

+    }

+    qemu_mutex_unlock(&pr_mgr->lock);

+    return ret;

+}

+

+static void pr_manager_helper_complete(UserCreatable *uc, Error **errp)

+{

+    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(uc);

+

+    qemu_mutex_lock(&pr_mgr->lock);

+    pr_manager_helper_initialize(pr_mgr, errp);

+    qemu_mutex_unlock(&pr_mgr->lock);

+}

+

+static char *get_path(Object *obj, Error **errp)

+{

+    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);

+

+    return g_strdup(pr_mgr->path);

+}

+

+static void set_path(Object *obj, const char *str, Error **errp)

+{

+    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);

+

+    g_free(pr_mgr->path);

+    pr_mgr->path = g_strdup(str);

+}

+

+static void pr_manager_helper_instance_finalize(Object *obj)

+{

+    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);

+

+    object_unref(OBJECT(pr_mgr->ioc));

+    qemu_mutex_destroy(&pr_mgr->lock);

+}

+

+static void pr_manager_helper_instance_init(Object *obj)

+{

+    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);

+

+    qemu_mutex_init(&pr_mgr->lock);

+}

+

+static void pr_manager_helper_class_init(ObjectClass *klass,

+                                         void *class_data G_GNUC_UNUSED)

+{

+    PRManagerClass *prmgr_klass = PR_MANAGER_CLASS(klass);

+    UserCreatableClass *uc_klass = USER_CREATABLE_CLASS(klass);

+

+    object_class_property_add_str(klass, "path", get_path, set_path,

+                                  &error_abort);

+    uc_klass->complete = pr_manager_helper_complete;

+    prmgr_klass->run = pr_manager_helper_run;

+}

+

+static const TypeInfo pr_manager_helper_info = {

+    .parent = TYPE_PR_MANAGER,

+    .name = TYPE_PR_MANAGER_HELPER,

+    .instance_size = sizeof(PRManagerHelper),

+    .instance_init = pr_manager_helper_instance_init,

+    .instance_finalize = pr_manager_helper_instance_finalize,

+    .class_init = pr_manager_helper_class_init,

+};

+

+static void pr_manager_helper_register_types(void)

+{

+    type_register_static(&pr_manager_helper_info);

+}

+

+type_init(pr_manager_helper_register_types);