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nbd: accept URIs
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The URI syntax is consistent with the Gluster syntax.  Export names
are specified in the path, preceded by one or more (otherwise unused)
slashes.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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@bonzini
bonzini committed Nov 12, 2012
1 parent d04b0bb commit 1d7d2a9
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Showing 2 changed files with 114 additions and 9 deletions.
98 changes: 97 additions & 1 deletion block/nbd.c
View file
Expand Up @@ -28,6 +28,7 @@

#include "qemu-common.h"
#include "nbd.h"
#include "uri.h"
#include "block_int.h"
#include "module.h"
#include "qemu_socket.h"
Expand Down Expand Up @@ -69,6 +70,69 @@ typedef struct BDRVNBDState {
char *export_name; /* An NBD server may export several devices */
} BDRVNBDState;

static int nbd_parse_uri(BDRVNBDState *s, const char *filename)
{
URI *uri;
const char *p;
QueryParams *qp = NULL;
int ret = 0;

uri = uri_parse(filename);
if (!uri) {
return -EINVAL;
}

/* transport */
if (!strcmp(uri->scheme, "nbd")) {
s->is_unix = false;
} else if (!strcmp(uri->scheme, "nbd+tcp")) {
s->is_unix = false;
} else if (!strcmp(uri->scheme, "nbd+unix")) {
s->is_unix = true;
} else {
ret = -EINVAL;
goto out;
}

p = uri->path ? uri->path : "/";
p += strspn(p, "/");
if (p[0]) {
s->export_name = g_strdup(p);
}

qp = query_params_parse(uri->query);
if (qp->n > 1 || (s->is_unix && !qp->n) || (!s->is_unix && qp->n)) {
ret = -EINVAL;
goto out;
}

if (s->is_unix) {
/* nbd+unix:///export?socket=path */
if (uri->server || uri->port || strcmp(qp->p[0].name, "socket")) {
ret = -EINVAL;
goto out;
}
s->host_spec = g_strdup(qp->p[0].value);
} else {
/* nbd[+tcp]://host:port/export */
if (!uri->server) {
ret = -EINVAL;
goto out;
}
if (!uri->port) {
uri->port = NBD_DEFAULT_PORT;
}
s->host_spec = g_strdup_printf("%s:%d", uri->server, uri->port);
}

out:
if (qp) {
query_params_free(qp);
}
uri_free(uri);
return ret;
}

static int nbd_config(BDRVNBDState *s, const char *filename)
{
char *file;
Expand All @@ -77,6 +141,10 @@ static int nbd_config(BDRVNBDState *s, const char *filename)
const char *unixpath;
int err = -EINVAL;

if (strstr(filename, "://")) {
return nbd_parse_uri(s, filename);
}

file = g_strdup(filename);

export_name = strstr(file, EN_OPTSTR);
Expand Down Expand Up @@ -495,6 +563,33 @@ static int64_t nbd_getlength(BlockDriverState *bs)

static BlockDriver bdrv_nbd = {
.format_name = "nbd",
.protocol_name = "nbd",
.instance_size = sizeof(BDRVNBDState),
.bdrv_file_open = nbd_open,
.bdrv_co_readv = nbd_co_readv,
.bdrv_co_writev = nbd_co_writev,
.bdrv_close = nbd_close,
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_discard = nbd_co_discard,
.bdrv_getlength = nbd_getlength,
};

static BlockDriver bdrv_nbd_tcp = {
.format_name = "nbd",
.protocol_name = "nbd+tcp",
.instance_size = sizeof(BDRVNBDState),
.bdrv_file_open = nbd_open,
.bdrv_co_readv = nbd_co_readv,
.bdrv_co_writev = nbd_co_writev,
.bdrv_close = nbd_close,
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_discard = nbd_co_discard,
.bdrv_getlength = nbd_getlength,
};

static BlockDriver bdrv_nbd_unix = {
.format_name = "nbd",
.protocol_name = "nbd+unix",
.instance_size = sizeof(BDRVNBDState),
.bdrv_file_open = nbd_open,
.bdrv_co_readv = nbd_co_readv,
Expand All @@ -503,12 +598,13 @@ static BlockDriver bdrv_nbd = {
.bdrv_co_flush_to_os = nbd_co_flush,
.bdrv_co_discard = nbd_co_discard,
.bdrv_getlength = nbd_getlength,
.protocol_name = "nbd",
};

static void bdrv_nbd_init(void)
{
bdrv_register(&bdrv_nbd);
bdrv_register(&bdrv_nbd_tcp);
bdrv_register(&bdrv_nbd_unix);
}

block_init(bdrv_nbd_init);
25 changes: 17 additions & 8 deletions qemu-doc.texi
View file
Expand Up @@ -610,14 +610,14 @@ QEMU can access directly to block device exported using the Network Block Device
protocol.

@example
qemu-system-i386 linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
qemu-system-i386 linux.img -hdb nbd://my_nbd_server.mydomain.org:1024/
@end example

If the NBD server is located on the same host, you can use an unix socket instead
of an inet socket:

@example
qemu-system-i386 linux.img -hdb nbd:unix:/tmp/my_socket
qemu-system-i386 linux.img -hdb nbd+unix://?socket=/tmp/my_socket
@end example

In this case, the block device must be exported using qemu-nbd:
Expand All @@ -631,17 +631,26 @@ The use of qemu-nbd allows to share a disk between several guests:
qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2
@end example

@noindent
and then you can use it with two guests:
@example
qemu-system-i386 linux1.img -hdb nbd:unix:/tmp/my_socket
qemu-system-i386 linux2.img -hdb nbd:unix:/tmp/my_socket
qemu-system-i386 linux1.img -hdb nbd+unix://?socket=/tmp/my_socket
qemu-system-i386 linux2.img -hdb nbd+unix://?socket=/tmp/my_socket
@end example

If the nbd-server uses named exports (since NBD 2.9.18), you must use the
"exportname" option:
If the nbd-server uses named exports (supported since NBD 2.9.18, or with QEMU's
own embedded NBD server), you must specify an export name in the URI:
@example
qemu-system-i386 -cdrom nbd:localhost:exportname=debian-500-ppc-netinst
qemu-system-i386 -cdrom nbd:localhost:exportname=openSUSE-11.1-ppc-netinst
qemu-system-i386 -cdrom nbd://localhost/debian-500-ppc-netinst
qemu-system-i386 -cdrom nbd://localhost/openSUSE-11.1-ppc-netinst
@end example

The URI syntax for NBD is supported since QEMU 1.3. An alternative syntax is
also available. Here are some example of the older syntax:
@example
qemu-system-i386 linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
qemu-system-i386 linux2.img -hdb nbd:unix:/tmp/my_socket
qemu-system-i386 -cdrom nbd:localhost:10809:exportname=debian-500-ppc-netinst
@end example

@node disk_images_sheepdog
Expand Down

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