diff mbox

[V5,2/5] qemu-nbd: support internal snapshot export

Message ID 1384121021-24815-3-git-send-email-xiawenc@linux.vnet.ibm.com
State New
Headers show

Commit Message

Wayne Xia Nov. 10, 2013, 10:03 p.m. UTC 
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 <xiawenc@linux.vnet.ibm.com>
---
 block/snapshot.c         |   18 +++++++++++++++++
 include/block/snapshot.h |    8 +++++++
 qemu-nbd.c               |   47 ++++++++++++++++++++++++++++++++++++++++++++-
 qemu-nbd.texi            |    8 ++++++-
 4 files changed, 78 insertions(+), 3 deletions(-)

Comments

Kevin Wolf Nov. 19, 2013, 11:26 a.m. UTC | #1 
Am 10.11.2013 um 23:03 hat Wenchao Xia geschrieben:
> 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 <xiawenc@linux.vnet.ibm.com>
> ---
>  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) {

You can avoid this ugly line break by using strstart():

    if (strstart(optarg, SNAPSHOT_OPT_BASE, NULL)) {
        ...

Kevin
Wayne Xia Nov. 22, 2013, 1:53 a.m. UTC | #2 
于 2013/11/19 19:26, Kevin Wolf 写道:
> Am 10.11.2013 um 23:03 hat Wenchao Xia geschrieben:
>> 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 <xiawenc@linux.vnet.ibm.com>
>> ---
>>   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) {
>
> You can avoid this ugly line break by using strstart():
>
>      if (strstart(optarg, SNAPSHOT_OPT_BASE, NULL)) {
>          ...
>
> Kevin
>
   Will use strstart(), thanks for tipping.
diff mbox

Patch

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, --partition=@var{num}
   only expose partition @var{num}
 @item -s, --snapshot
-  use snapshot file
+  use @var{filename} as an external snapshot, create a temporary
+  file with backing_file=@var{filename}, redirect the write to
+  the temporary one
+@item -l, --load-snapshot=@var{snapshot_param}
+  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 --cache=@var{cache}
   set cache mode to be used with the file.  See the documentation of