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[Qemu-devel] [PATCH V4 2/5] qemu-nbd: support internal snapshot export
From: |
Wenchao Xia |
Subject: |
[Qemu-devel] [PATCH V4 2/5] qemu-nbd: support internal snapshot export |
Date: |
Fri, 11 Oct 2013 10:33:28 +0800 |
Now it is possible to directly export an internal snapshot, which
can be used to probe the snapshot's contents without qemu-img
convert.
Signed-off-by: Wenchao Xia <address@hidden>
---
block/snapshot.c | 18 +++++++++++++++++
include/block/snapshot.h | 8 +++++++
qemu-nbd.c | 47 ++++++++++++++++++++++++++++++++++++++++++++-
qemu-nbd.texi | 8 ++++++-
4 files changed, 78 insertions(+), 3 deletions(-)
diff --git a/block/snapshot.c b/block/snapshot.c
index e51a7db..7cc45fa 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -25,6 +25,24 @@
#include "block/snapshot.h"
#include "block/block_int.h"
+QemuOptsList internal_snapshot_opts = {
+ .name = "snapshot",
+ .head = QTAILQ_HEAD_INITIALIZER(internal_snapshot_opts.head),
+ .desc = {
+ {
+ .name = SNAPSHOT_OPT_ID,
+ .type = QEMU_OPT_STRING,
+ .help = "snapshot id"
+ },{
+ .name = SNAPSHOT_OPT_NAME,
+ .type = QEMU_OPT_STRING,
+ .help = "snapshot name"
+ },{
+ /* end of list */
+ }
+ },
+};
+
int bdrv_snapshot_find(BlockDriverState *bs, QEMUSnapshotInfo *sn_info,
const char *name)
{
diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index d05bea7..770d9bb 100644
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -27,6 +27,14 @@
#include "qemu-common.h"
#include "qapi/error.h"
+#include "qemu/option.h"
+
+
+#define SNAPSHOT_OPT_BASE "snapshot."
+#define SNAPSHOT_OPT_ID "snapshot.id"
+#define SNAPSHOT_OPT_NAME "snapshot.name"
+
+extern QemuOptsList internal_snapshot_opts;
typedef struct QEMUSnapshotInfo {
char id_str[128]; /* unique snapshot id */
diff --git a/qemu-nbd.c b/qemu-nbd.c
index c26c98e..f934eaa 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -20,6 +20,7 @@
#include "block/block.h"
#include "block/nbd.h"
#include "qemu/main-loop.h"
+#include "block/snapshot.h"
#include <stdarg.h>
#include <stdio.h>
@@ -79,7 +80,14 @@ static void usage(const char *name)
"\n"
"Block device options:\n"
" -r, --read-only export read-only\n"
-" -s, --snapshot use snapshot file\n"
+" -s, --snapshot use FILE as an external snapshot, create a temporary\n"
+" file with backing_file=FILE, redirect the write to\n"
+" the temporary one\n"
+" -l, --load-snapshot=SNAPSHOT_PARAM\n"
+" load an internal snapshot inside FILE and export it\n"
+" as an read-only device, SNAPSHOT_PARAM format is\n"
+" 'snapshot.id=[ID],snapshot.name=[NAME]', or\n"
+" '[ID_OR_NAME]'\n"
" -n, --nocache disable host cache\n"
" --cache=MODE set cache mode (none, writeback, ...)\n"
#ifdef CONFIG_LINUX_AIO
@@ -315,7 +323,9 @@ int main(int argc, char **argv)
char *device = NULL;
int port = NBD_DEFAULT_PORT;
off_t fd_size;
- const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:t";
+ QemuOpts *sn_opts = NULL;
+ const char *sn_id_or_name = NULL;
+ const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:";
struct option lopt[] = {
{ "help", 0, NULL, 'h' },
{ "version", 0, NULL, 'V' },
@@ -328,6 +338,7 @@ int main(int argc, char **argv)
{ "connect", 1, NULL, 'c' },
{ "disconnect", 0, NULL, 'd' },
{ "snapshot", 0, NULL, 's' },
+ { "load-snapshot", 1, NULL, 'l' },
{ "nocache", 0, NULL, 'n' },
{ "cache", 1, NULL, QEMU_NBD_OPT_CACHE },
#ifdef CONFIG_LINUX_AIO
@@ -428,6 +439,18 @@ int main(int argc, char **argv)
errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
}
break;
+ case 'l':
+ if (strncmp(optarg, SNAPSHOT_OPT_BASE, strlen(SNAPSHOT_OPT_BASE))
+ == 0) {
+ sn_opts = qemu_opts_parse(&internal_snapshot_opts, optarg, 0);
+ if (!sn_opts) {
+ errx(EXIT_FAILURE, "Failed in parsing snapshot param `%s'",
+ optarg);
+ }
+ } else {
+ sn_id_or_name = optarg;
+ }
+ /* fall through */
case 'r':
nbdflags |= NBD_FLAG_READ_ONLY;
flags &= ~BDRV_O_RDWR;
@@ -581,6 +604,22 @@ int main(int argc, char **argv)
error_get_pretty(local_err));
}
+ if (sn_opts) {
+ ret = bdrv_snapshot_load_tmp(bs,
+ qemu_opt_get(sn_opts, SNAPSHOT_OPT_ID),
+ qemu_opt_get(sn_opts, SNAPSHOT_OPT_NAME),
+ &local_err);
+ } else if (sn_id_or_name) {
+ ret = bdrv_snapshot_load_tmp_by_id_or_name(bs, sn_id_or_name,
+ &local_err);
+ }
+ if (ret < 0) {
+ errno = -ret;
+ err(EXIT_FAILURE,
+ "Failed to load snapshot: %s",
+ error_get_pretty(local_err));
+ }
+
fd_size = bdrv_getlength(bs);
if (partition != -1) {
@@ -641,6 +680,10 @@ int main(int argc, char **argv)
unlink(sockpath);
}
+ if (sn_opts) {
+ qemu_opts_del(sn_opts);
+ }
+
if (device) {
void *ret;
pthread_join(client_thread, &ret);
diff --git a/qemu-nbd.texi b/qemu-nbd.texi
index 6055ec6..5b55f76 100644
--- a/qemu-nbd.texi
+++ b/qemu-nbd.texi
@@ -27,7 +27,13 @@ Export QEMU disk image using NBD protocol.
@item -P, address@hidden
only expose partition @var{num}
@item -s, --snapshot
- use snapshot file
+ use @var{filename} as an external snapshot, create a temporary
+ file with address@hidden, redirect the write to
+ the temporary one
address@hidden -l, address@hidden
+ load an internal snapshot inside @var{filename} and export it
+ as an read-only device, @var{snapshot_param} format is
+ 'snapshot.id=[ID],snapshot.name=[NAME]' or '[ID_OR_NAME]'
@item -n, --nocache
@itemx address@hidden
set cache mode to be used with the file. See the documentation of
--
1.7.1
- [Qemu-devel] [PATCH V4 0/5] export internal snapshot by qemu-nbd, Wenchao Xia, 2013/10/11
- [Qemu-devel] [PATCH V4 3/5] qemu-iotests: add 058 internal snapshot export with qemu-nbd case, Wenchao Xia, 2013/10/11
- [Qemu-devel] [PATCH V4 2/5] qemu-nbd: support internal snapshot export,
Wenchao Xia <=
- [Qemu-devel] [PATCH V4 1/5] snapshot: distinguish id and name in load_tmp, Wenchao Xia, 2013/10/11
- [Qemu-devel] [PATCH V4 5/5] qemu-iotests: add test for snapshot in qemu-img convert, Wenchao Xia, 2013/10/11
- [Qemu-devel] [PATCH V4 4/5] qemu-img: add -l for snapshot in convert, Wenchao Xia, 2013/10/11
- Re: [Qemu-devel] [PATCH V4 0/5] export internal snapshot by qemu-nbd, Wenchao Xia, 2013/10/31