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nbd: allow reconnect on open, with corresponding new options 

It is useful when start of vm and start of nbd server are not
simple to sync.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2021-09-06 22:06:48 +03:00
parent 2bf40d0841
commit be16b8bf9f
2 changed files with 52 additions and 2 deletions
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45
block/nbd.c
View File

@ -80,6 +80,7 @@ typedef struct BDRVNBDState {
NBDClientState state;
QEMUTimer *reconnect_delay_timer;
QEMUTimer *open_timer;
NBDClientRequest requests[MAX_NBD_REQUESTS];
NBDReply reply;
@ -87,6 +88,7 @@ typedef struct BDRVNBDState {
/* Connection parameters */
uint32_t reconnect_delay;
uint32_t open_timeout;
SocketAddress *saddr;
char *export, *tlscredsid;
QCryptoTLSCreds *tlscreds;
@ -218,6 +220,32 @@ static void nbd_teardown_connection(BlockDriverState *bs)
s->state = NBD_CLIENT_QUIT;
}
static void open_timer_del(BDRVNBDState *s)
{
if (s->open_timer) {
timer_free(s->open_timer);
s->open_timer = NULL;
}
}
static void open_timer_cb(void *opaque)
{
BDRVNBDState *s = opaque;
nbd_co_establish_connection_cancel(s->conn);
open_timer_del(s);
}
static void open_timer_init(BDRVNBDState *s, uint64_t expire_time_ns)
{
assert(!s->open_timer);
s->open_timer = aio_timer_new(bdrv_get_aio_context(s->bs),
QEMU_CLOCK_REALTIME,
SCALE_NS,
open_timer_cb, s);
timer_mod(s->open_timer, expire_time_ns);
}
static bool nbd_client_connecting(BDRVNBDState *s)
{
NBDClientState state = qatomic_load_acquire(&s->state);
@ -1742,6 +1770,15 @@ static QemuOptsList nbd_runtime_opts = {
"future requests before a successful reconnect will "
"immediately fail. Default 0",
},
{
.name = "open-timeout",
.type = QEMU_OPT_NUMBER,
.help = "In seconds. If zero, the nbd driver tries the connection "
"only once, and fails to open if the connection fails. "
"If non-zero, the nbd driver will repeat connection "
"attempts until successful or until @open-timeout seconds "
"have elapsed. Default 0",
},
{ /* end of list */ }
},
};
@ -1797,6 +1834,7 @@ static int nbd_process_options(BlockDriverState *bs, QDict *options,
}
s->reconnect_delay = qemu_opt_get_number(opts, "reconnect-delay", 0);
s->open_timeout = qemu_opt_get_number(opts, "open-timeout", 0);
ret = 0;
@ -1828,7 +1866,12 @@ static int nbd_open(BlockDriverState *bs, QDict *options, int flags,
s->conn = nbd_client_connection_new(s->saddr, true, s->export,
s->x_dirty_bitmap, s->tlscreds);
/* TODO: Configurable retry-until-timeout behaviour. */
if (s->open_timeout) {
nbd_client_connection_enable_retry(s->conn);
open_timer_init(s, qemu_clock_get_ns(QEMU_CLOCK_REALTIME) +
s->open_timeout * NANOSECONDS_PER_SECOND);
}
s->state = NBD_CLIENT_CONNECTING_WAIT;
ret = nbd_do_establish_connection(bs, errp);
if (ret < 0) {

9
qapi/block-core.json
View File

@ -4096,6 +4096,12 @@
# future requests before a successful reconnect will
# immediately fail. Default 0 (Since 4.2)
#
# @open-timeout: In seconds. If zero, the nbd driver tries the connection
# only once, and fails to open if the connection fails.
# If non-zero, the nbd driver will repeat connection attempts
# until successful or until @open-timeout seconds have elapsed.
# Default 0 (Since 7.0)
#
# Features:
# @unstable: Member @x-dirty-bitmap is experimental.
#
@ -4106,7 +4112,8 @@
'*export': 'str',
'*tls-creds': 'str',
'*x-dirty-bitmap': { 'type': 'str', 'features': [ 'unstable' ] },
'*reconnect-delay': 'uint32' } }
'*reconnect-delay': 'uint32',
'*open-timeout': 'uint32' } }
##
# @BlockdevOptionsRaw: