qemu/scsi/pr-manager-helper.c
Leonardo Bras b88651cb4d QIOChannel: Add flags on io_writev and introduce io_flush callback
Add flags to io_writev and introduce io_flush as optional callback to
QIOChannelClass, allowing the implementation of zero copy writes by
subclasses.

How to use them:
- Write data using qio_channel_writev*(...,QIO_CHANNEL_WRITE_FLAG_ZERO_COPY),
- Wait write completion with qio_channel_flush().

Notes:
As some zero copy write implementations work asynchronously, it's
recommended to keep the write buffer untouched until the return of
qio_channel_flush(), to avoid the risk of sending an updated buffer
instead of the buffer state during write.

As io_flush callback is optional, if a subclass does not implement it, then:
- io_flush will return 0 without changing anything.

Also, some functions like qio_channel_writev_full_all() were adapted to
receive a flag parameter. That allows shared code between zero copy and
non-zero copy writev, and also an easier implementation on new flags.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20220513062836.965425-3-leobras@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2022-05-16 13:56:24 +01:00

329 lines
8.9 KiB
C

/*
* 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 "qapi/qapi-events-block.h"
#include "qemu/module.h"
#include <scsi/sg.h>
#include "qom/object.h"
#define PR_MAX_RECONNECT_ATTEMPTS 5
#define TYPE_PR_MANAGER_HELPER "pr-manager-helper"
OBJECT_DECLARE_SIMPLE_TYPE(PRManagerHelper, PR_MANAGER_HELPER)
struct PRManagerHelper {
/* <private> */
PRManager parent;
char *path;
QemuMutex lock;
QIOChannel *ioc;
};
static void pr_manager_send_status_changed_event(PRManagerHelper *pr_mgr)
{
const char *id = object_get_canonical_path_component(OBJECT(pr_mgr));
if (id) {
qapi_event_send_pr_manager_status_changed(id, !!pr_mgr->ioc);
}
}
/* 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;
pr_manager_send_status_changed_event(pr_mgr);
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, 0, errp);
if (n_written <= 0) {
assert(n_written != QIO_CHANNEL_ERR_BLOCK);
object_unref(OBJECT(pr_mgr->ioc));
pr_mgr->ioc = NULL;
pr_manager_send_status_changed_event(pr_mgr);
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 negotiation 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;
}
pr_manager_send_status_changed_event(pr_mgr);
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 bool pr_manager_helper_is_connected(PRManager *p)
{
PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
bool result;
qemu_mutex_lock(&pr_mgr->lock);
result = (pr_mgr->ioc != NULL);
qemu_mutex_unlock(&pr_mgr->lock);
return result;
}
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);
uc_klass->complete = pr_manager_helper_complete;
prmgr_klass->run = pr_manager_helper_run;
prmgr_klass->is_connected = pr_manager_helper_is_connected;
}
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);