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[Qemu-devel] [PATCH 13/14] qemu-nbd: Add --list option
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH 13/14] qemu-nbd: Add --list option |
Date: |
Fri, 30 Nov 2018 16:03:42 -0600 |
We want to be able to detect whether a given qemu NBD server is
exposing the right export(s) and dirty bitmaps, at least for
regression testing. We could use 'nbd-client -l' from the upstream
NBD project to list exports, but it's annoying to rely on
out-of-tree binaries; furthermore, nbd-client doesn't necessarily
know about all of the qemu NBD extensions. Thus, we plan on adding
a new mode to qemu-nbd that merely sniffs all possible information
from the server during handshake phase, then disconnects and dumps
the information.
This patch actually implements --list/-L, while reusing other
options such as --tls-creds for now designating how to connect
as the client (rather than their non-list usage of how to operate
as the server).
I debated about adding this functionality to something akin to
'qemu-img info' - but that tool does not readily lend itself
to connecting to an arbitrary NBD server without also tying to
a specific export (I may, however, still add ImageInfoSpecificNBD
for reporting the bitmaps available when connecting to a single
export). And, while it may feel a bit odd that normally
qemu-nbd is a server but 'qemu-nbd -L' is a client, we are not
really making the qemu-nbd binary that much larger, because
'qemu-nbd -c' has to operate as both server and client
simultaneously across two threads when feeding the kernel module
for /dev/nbdN access.
Sample output:
$ qemu-nbd -L
exports available: 1
export: ''
size: 65536
flags: 0x4ed ( flush fua trim zeroes df cache )
min block: 512
opt block: 4096
max block: 33554432
available meta contexts: 1
base:allocation
Signed-off-by: Eric Blake <address@hidden>
---
qemu-nbd.c | 153 ++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 141 insertions(+), 12 deletions(-)
diff --git a/qemu-nbd.c b/qemu-nbd.c
index c57053a0795..e19a841b869 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -76,6 +76,7 @@ static void usage(const char *name)
{
(printf) (
"Usage: %s [OPTIONS] FILE\n"
+" or: %s -L [OPTIONS]\n"
"QEMU Disk Network Block Device Server\n"
"\n"
" -h, --help display this help and exit\n"
@@ -97,6 +98,7 @@ static void usage(const char *name)
" -P, --partition=NUM only expose partition NUM\n"
"\n"
"General purpose options:\n"
+" -L, --list list NBD exports visible to client\n"
" --object type,id=ID,... define an object such as 'secret' for providing\n"
" passwords and/or encryption keys\n"
" --tls-creds=ID use id of an earlier --object to provide TLS\n"
@@ -130,7 +132,7 @@ static void usage(const char *name)
" --image-opts treat FILE as a full set of image options\n"
"\n"
QEMU_HELP_BOTTOM "\n"
- , name, NBD_DEFAULT_PORT, "DEVICE");
+ , name, name, NBD_DEFAULT_PORT, "DEVICE");
}
static void version(const char *name)
@@ -242,6 +244,92 @@ static void termsig_handler(int signum)
}
+static int qemu_nbd_client_list(SocketAddress *saddr, QCryptoTLSCreds *tls,
+ const char *hostname)
+{
+ int ret = EXIT_FAILURE;
+ int rc;
+ Error *err = NULL;
+ QIOChannelSocket *sioc;
+ NBDExportInfo *list;
+ int i, j;
+
+ sioc = qio_channel_socket_new();
+ if (qio_channel_socket_connect_sync(sioc, saddr, &err) < 0) {
+ error_report_err(err);
+ goto out;
+ }
+ rc = nbd_receive_export_list(QIO_CHANNEL(sioc), tls, hostname, &list,
+ &err);
+ if (rc < 0) {
+ if (err) {
+ error_report_err(err);
+ }
+ goto out_socket;
+ }
+ printf("exports available: %d\n", rc);
+ for (i = 0; i < rc; i++) {
+ printf(" export: '%s'\n", list[i].name);
+ if (list[i].description && *list[i].description) {
+ printf(" description: %s\n", list[i].description);
+ }
+ if (list[i].flags & NBD_FLAG_HAS_FLAGS) {
+ printf(" size: %" PRIu64 "\n", list[i].size);
+ printf(" flags: 0x%x (", list[i].flags);
+ if (list[i].flags & NBD_FLAG_READ_ONLY) {
+ printf(" readonly");
+ }
+ if (list[i].flags & NBD_FLAG_SEND_FLUSH) {
+ printf(" flush");
+ }
+ if (list[i].flags & NBD_FLAG_SEND_FUA) {
+ printf(" fua");
+ }
+ if (list[i].flags & NBD_FLAG_ROTATIONAL) {
+ printf(" rotational");
+ }
+ if (list[i].flags & NBD_FLAG_SEND_TRIM) {
+ printf(" trim");
+ }
+ if (list[i].flags & NBD_FLAG_SEND_WRITE_ZEROES) {
+ printf(" zeroes");
+ }
+ if (list[i].flags & NBD_FLAG_SEND_DF) {
+ printf(" df");
+ }
+ if (list[i].flags & NBD_FLAG_CAN_MULTI_CONN) {
+ printf(" multi");
+ }
+ if (list[i].flags & NBD_FLAG_SEND_RESIZE) {
+ printf(" resize");
+ }
+ if (list[i].flags & NBD_FLAG_SEND_CACHE) {
+ printf(" cache");
+ }
+ printf(" )\n");
+ }
+ if (list[i].min_block) {
+ printf(" min block: %u\n", list[i].min_block);
+ printf(" opt block: %u\n", list[i].opt_block);
+ printf(" max block: %u\n", list[i].max_block);
+ }
+ if (list[i].n_contexts) {
+ printf(" available meta contexts: %d\n", list[i].n_contexts);
+ for (j = 0; j < list[i].n_contexts; j++) {
+ printf(" %s\n", list[i].contexts[j]);
+ }
+ }
+ }
+ nbd_free_export_list(list, rc);
+
+ ret = EXIT_SUCCESS;
+ out_socket:
+ object_unref(OBJECT(sioc));
+ out:
+ return ret;
+}
+
+
#if HAVE_NBD_DEVICE
static void *show_parts(void *arg)
{
@@ -424,7 +512,8 @@ static QemuOptsList qemu_object_opts = {
-static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, Error **errp)
+static QCryptoTLSCreds *nbd_get_tls_creds(const char *id, bool list,
+ Error **errp)
{
Object *obj;
QCryptoTLSCreds *creds;
@@ -444,10 +533,18 @@ static QCryptoTLSCreds *nbd_get_tls_creds(const char *id,
Error **errp)
return NULL;
}
- if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
- error_setg(errp,
- "Expecting TLS credentials with a server endpoint");
- return NULL;
+ if (list) {
+ if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT) {
+ error_setg(errp,
+ "Expecting TLS credentials with a client endpoint");
+ return NULL;
+ }
+ } else {
+ if (creds->endpoint != QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
+ error_setg(errp,
+ "Expecting TLS credentials with a server endpoint");
+ return NULL;
+ }
}
object_ref(obj);
return creds;
@@ -470,7 +567,8 @@ static void setup_address_and_port(const char **address,
const char **port)
static const char *socket_activation_validate_opts(const char *device,
const char *sockpath,
const char *address,
- const char *port)
+ const char *port,
+ bool list)
{
if (device != NULL) {
return "NBD device can't be set when using socket activation";
@@ -488,6 +586,10 @@ static const char *socket_activation_validate_opts(const
char *device,
return "TCP port number can't be set when using socket activation";
}
+ if (list) {
+ return "List mode is incompatible with socket activation";
+ }
+
return NULL;
}
@@ -511,7 +613,7 @@ int main(int argc, char **argv)
off_t fd_size;
QemuOpts *sn_opts = NULL;
const char *sn_id_or_name = NULL;
- const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:D:";
+ const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:x:T:D:L";
struct option lopt[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, 'V' },
@@ -523,6 +625,7 @@ int main(int argc, char **argv)
{ "partition", required_argument, NULL, 'P' },
{ "connect", required_argument, NULL, 'c' },
{ "disconnect", no_argument, NULL, 'd' },
+ { "list", no_argument, NULL, 'L' },
{ "snapshot", no_argument, NULL, 's' },
{ "load-snapshot", required_argument, NULL, 'l' },
{ "nocache", no_argument, NULL, 'n' },
@@ -558,13 +661,14 @@ int main(int argc, char **argv)
Error *local_err = NULL;
BlockdevDetectZeroesOptions detect_zeroes =
BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF;
QDict *options = NULL;
- const char *export_name = ""; /* Default export name */
+ const char *export_name = NULL;
const char *export_description = NULL;
const char *tlscredsid = NULL;
bool imageOpts = false;
bool writethrough = true;
char *trace_file = NULL;
bool fork_process = false;
+ bool list = false;
int old_stderr = -1;
unsigned socket_activation;
@@ -764,13 +868,32 @@ int main(int argc, char **argv)
case QEMU_NBD_OPT_FORK:
fork_process = true;
break;
+ case 'L':
+ list = true;
+ break;
}
}
- if ((argc - optind) != 1) {
+ if (list) {
+ if (argc != optind) {
+ error_report("List mode is incompatible with a file name");
+ exit(EXIT_FAILURE);
+ }
+ if (export_name || export_description || dev_offset || partition ||
+ device || disconnect || fmt || sn_id_or_name) {
+ error_report("List mode is incompatible with per-device settings");
+ exit(EXIT_FAILURE);
+ }
+ if (fork_process) {
+ error_report("List mode is incompatible with forking");
+ exit(EXIT_FAILURE);
+ }
+ } else if ((argc - optind) != 1) {
error_report("Invalid number of arguments");
error_printf("Try `%s --help' for more information.\n", argv[0]);
exit(EXIT_FAILURE);
+ } else if (!export_name) {
+ export_name = "";
}
qemu_opts_foreach(&qemu_object_opts,
@@ -789,7 +912,8 @@ int main(int argc, char **argv)
} else {
/* Using socket activation - check user didn't use -p etc. */
const char *err_msg = socket_activation_validate_opts(device, sockpath,
- bindto, port);
+ bindto, port,
+ list);
if (err_msg != NULL) {
error_report("%s", err_msg);
exit(EXIT_FAILURE);
@@ -812,7 +936,7 @@ int main(int argc, char **argv)
error_report("TLS is not supported with a host device");
exit(EXIT_FAILURE);
}
- tlscreds = nbd_get_tls_creds(tlscredsid, &local_err);
+ tlscreds = nbd_get_tls_creds(tlscredsid, list, &local_err);
if (local_err) {
error_report("Failed to get TLS creds %s",
error_get_pretty(local_err));
@@ -820,6 +944,11 @@ int main(int argc, char **argv)
}
}
+ if (list) {
+ saddr = nbd_build_socket_address(sockpath, bindto, port);
+ return qemu_nbd_client_list(saddr, tlscreds, bindto);
+ }
+
if (disconnect) {
#if HAVE_NBD_DEVICE
int nbdfd = open(argv[optind], O_RDWR);
--
2.17.2
- Re: [Qemu-devel] [PATCH 02/14] nbd/client: More consistent error messages, (continued)
- [Qemu-devel] [PATCH 03/14] qemu-nbd: Fail earlier for -c/-d on non-linux, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 10/14] nbd/client: Split handshake into two functions, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 08/14] nbd/client: Refactor nbd_receive_list(), Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 07/14] nbd/client: Refactor nbd_negotiate_simple_meta_context(), Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 09/14] nbd/client: Refactor return of nbd_receive_negotiate(), Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 14/14] iotests: Enhance 223, 233 to cover 'qemu-nbd --list', Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 11/14] nbd/client: Add nbd_receive_export_list(), Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 12/14] nbd/client: Work around 3.0 bug for listing meta contexts, Eric Blake, 2018/11/30
- [Qemu-devel] [PATCH 13/14] qemu-nbd: Add --list option,
Eric Blake <=