diff mbox

[v5,12/15] drive-backup: added support for data compression

Message ID 1467635306-31875-13-git-send-email-den@openvz.org
State New, archived
Headers show

Commit Message

Denis V. Lunev July 4, 2016, 12:28 p.m. UTC
From: Pavel Butsykin <pbutsykin@virtuozzo.com>

The idea is simple - backup is "written-once" data. It is written block
by block and it is large enough. It would be nice to save storage
space and compress it.

The patch adds a flag to the qmp/hmp drive-backup command which enables
block compression. Compression should be implemented in the format driver
to enable this feature.

There are some limitations of the format driver to allow compressed writes.
We can write data only once. Though for backup this is perfectly fine.
These limitations are maintained by the driver and the error will be
reported if we are doing something wrong.

Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Jeff Cody <jcody@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: John Snow <jsnow@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
---
 block/backup.c            | 12 +++++++++++-
 blockdev.c                |  9 ++++++---
 hmp-commands.hx           |  8 +++++---
 hmp.c                     |  3 +++
 include/block/block_int.h |  1 +
 qapi/block-core.json      |  5 ++++-
 qmp-commands.hx           |  5 ++++-
 7 files changed, 34 insertions(+), 9 deletions(-)

Comments

Stefan Hajnoczi July 14, 2016, 12:17 p.m. UTC | #1
On Mon, Jul 04, 2016 at 03:28:23PM +0300, Denis V. Lunev wrote:
> From: Pavel Butsykin <pbutsykin@virtuozzo.com>
> 
> The idea is simple - backup is "written-once" data. It is written block
> by block and it is large enough. It would be nice to save storage
> space and compress it.
> 
> The patch adds a flag to the qmp/hmp drive-backup command which enables
> block compression. Compression should be implemented in the format driver
> to enable this feature.
> 
> There are some limitations of the format driver to allow compressed writes.
> We can write data only once. Though for backup this is perfectly fine.
> These limitations are maintained by the driver and the error will be
> reported if we are doing something wrong.
> 
> Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Jeff Cody <jcody@redhat.com>
> CC: Markus Armbruster <armbru@redhat.com>
> CC: Eric Blake <eblake@redhat.com>
> CC: John Snow <jsnow@redhat.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> ---
>  block/backup.c            | 12 +++++++++++-
>  blockdev.c                |  9 ++++++---
>  hmp-commands.hx           |  8 +++++---
>  hmp.c                     |  3 +++
>  include/block/block_int.h |  1 +
>  qapi/block-core.json      |  5 ++++-
>  qmp-commands.hx           |  5 ++++-
>  7 files changed, 34 insertions(+), 9 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
diff mbox

Patch

diff --git a/block/backup.c b/block/backup.c
index 581269b..6adca5e 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -47,6 +47,7 @@  typedef struct BackupBlockJob {
     uint64_t sectors_read;
     unsigned long *done_bitmap;
     int64_t cluster_size;
+    bool compress;
     NotifierWithReturn before_write;
     QLIST_HEAD(, CowRequest) inflight_reqs;
 } BackupBlockJob;
@@ -154,7 +155,8 @@  static int coroutine_fn backup_do_cow(BackupBlockJob *job,
                                        bounce_qiov.size, BDRV_REQ_MAY_UNMAP);
         } else {
             ret = blk_co_pwritev(job->target, start * job->cluster_size,
-                                 bounce_qiov.size, &bounce_qiov, 0);
+                                 bounce_qiov.size, &bounce_qiov,
+                                 job->compress ? BDRV_REQ_WRITE_COMPRESSED : 0);
         }
         if (ret < 0) {
             trace_backup_do_cow_write_fail(job, start, ret);
@@ -477,6 +479,7 @@  static void coroutine_fn backup_run(void *opaque)
 void backup_start(BlockDriverState *bs, BlockDriverState *target,
                   int64_t speed, MirrorSyncMode sync_mode,
                   BdrvDirtyBitmap *sync_bitmap,
+                  bool compress,
                   BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
                   BlockCompletionFunc *cb, void *opaque,
@@ -508,6 +511,12 @@  void backup_start(BlockDriverState *bs, BlockDriverState *target,
         return;
     }
 
+    if (compress && target->drv->bdrv_co_pwritev_compressed == NULL) {
+        error_setg(errp, "Compression is not supported for this drive %s",
+                   bdrv_get_device_name(target));
+        return;
+    }
+
     if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
         return;
     }
@@ -555,6 +564,7 @@  void backup_start(BlockDriverState *bs, BlockDriverState *target,
     job->sync_mode = sync_mode;
     job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
                        sync_bitmap : NULL;
+    job->compress = compress;
 
     /* If there is no backing file on the target, we cannot rely on COW if our
      * backup cluster size is smaller than the target cluster size. Even for
diff --git a/blockdev.c b/blockdev.c
index 8f55590..fa88900 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3147,6 +3147,9 @@  static void do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, Error **errp)
     if (!backup->has_mode) {
         backup->mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
     }
+    if (!backup->has_compress) {
+        backup->compress = false;
+    }
 
     blk = blk_by_name(backup->device);
     if (!blk) {
@@ -3235,8 +3238,8 @@  static void do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, Error **errp)
     }
 
     backup_start(bs, target_bs, backup->speed, backup->sync, bmap,
-                 backup->on_source_error, backup->on_target_error,
-                 block_job_cb, bs, txn, &local_err);
+                 backup->compress, backup->on_source_error,
+                 backup->on_target_error, block_job_cb, bs, txn, &local_err);
     bdrv_unref(target_bs);
     if (local_err != NULL) {
         error_propagate(errp, local_err);
@@ -3306,7 +3309,7 @@  void do_blockdev_backup(BlockdevBackup *backup, BlockJobTxn *txn, Error **errp)
             goto out;
         }
     }
-    backup_start(bs, target_bs, backup->speed, backup->sync, NULL,
+    backup_start(bs, target_bs, backup->speed, backup->sync, NULL, false,
                  backup->on_source_error, backup->on_target_error, block_job_cb,
                  bs, txn, &local_err);
     if (local_err != NULL) {
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 98b4b1a..f91c7ba 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1181,8 +1181,8 @@  ETEXI
 
     {
         .name       = "drive_backup",
-        .args_type  = "reuse:-n,full:-f,device:B,target:s,format:s?",
-        .params     = "[-n] [-f] device target [format]",
+        .args_type  = "reuse:-n,full:-f,compress:-c,device:B,target:s,format:s?",
+        .params     = "[-n] [-f] [-c] device target [format]",
         .help       = "initiates a point-in-time\n\t\t\t"
                       "copy for a device. The device's contents are\n\t\t\t"
                       "copied to the new image file, excluding data that\n\t\t\t"
@@ -1190,7 +1190,9 @@  ETEXI
                       "The -n flag requests QEMU to reuse the image found\n\t\t\t"
                       "in new-image-file, instead of recreating it from scratch.\n\t\t\t"
                       "The -f flag requests QEMU to copy the whole disk,\n\t\t\t"
-                      "so that the result does not need a backing file.\n\t\t\t",
+                      "so that the result does not need a backing file.\n\t\t\t"
+                      "The -c flag requests QEMU to compress backup data\n\t\t\t"
+                      "(if the target format supports it).\n\t\t\t",
         .mhandler.cmd = hmp_drive_backup,
     },
 STEXI
diff --git a/hmp.c b/hmp.c
index 818519e..0de28b3 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1109,6 +1109,7 @@  void hmp_drive_backup(Monitor *mon, const QDict *qdict)
     const char *format = qdict_get_try_str(qdict, "format");
     bool reuse = qdict_get_try_bool(qdict, "reuse", false);
     bool full = qdict_get_try_bool(qdict, "full", false);
+    bool compress = qdict_get_try_bool(qdict, "compress", false);
     Error *err = NULL;
     DriveBackup backup = {
         .device = (char *)device,
@@ -1122,6 +1123,8 @@  void hmp_drive_backup(Monitor *mon, const QDict *qdict)
         .speed = 0,
         .has_bitmap = false,
         .bitmap = NULL,
+        .has_compress = !!compress,
+        .compress = compress,
         .has_on_source_error = false,
         .on_source_error = 0,
         .has_on_target_error = false,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index d8048e3..d5f063c 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -729,6 +729,7 @@  void mirror_start(BlockDriverState *bs, BlockDriverState *target,
 void backup_start(BlockDriverState *bs, BlockDriverState *target,
                   int64_t speed, MirrorSyncMode sync_mode,
                   BdrvDirtyBitmap *sync_bitmap,
+                  bool compress,
                   BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
                   BlockCompletionFunc *cb, void *opaque,
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 8e0750a..0cbad5a 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -888,6 +888,9 @@ 
 #          Must be present if sync is "incremental", must NOT be present
 #          otherwise. (Since 2.4)
 #
+# @compress: #optional true to compress data, if the target format supports it.
+#            (default: false) (since 2.7)
+#
 # @on-source-error: #optional the action to take on an error on the source,
 #                   default 'report'.  'stop' and 'enospc' can only be used
 #                   if the block device supports io-status (see BlockInfo).
@@ -905,7 +908,7 @@ 
 { 'struct': 'DriveBackup',
   'data': { 'device': 'str', 'target': 'str', '*format': 'str',
             'sync': 'MirrorSyncMode', '*mode': 'NewImageMode',
-            '*speed': 'int', '*bitmap': 'str',
+            '*speed': 'int', '*bitmap': 'str', '*compress': 'bool',
             '*on-source-error': 'BlockdevOnError',
             '*on-target-error': 'BlockdevOnError' } }
 
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 09b1e38..810d0fe 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1213,7 +1213,8 @@  EQMP
     {
         .name       = "drive-backup",
         .args_type  = "sync:s,device:B,target:s,speed:i?,mode:s?,format:s?,"
-                      "bitmap:s?,on-source-error:s?,on-target-error:s?",
+                      "bitmap:s?,compress:b?,"
+                      "on-source-error:s?,on-target-error:s?",
         .mhandler.cmd_new = qmp_marshal_drive_backup,
     },
 
@@ -1247,6 +1248,8 @@  Arguments:
 - "mode": whether and how QEMU should create a new image
           (NewImageMode, optional, default 'absolute-paths')
 - "speed": the maximum speed, in bytes per second (json-int, optional)
+- "compress": true to compress data, if the target format supports it.
+              (json-bool, optional, default false)
 - "on-source-error": the action to take on an error on the source, default
                      'report'.  'stop' and 'enospc' can only be used
                      if the block device supports io-status.