[1/2] drive-backup: added support for data compression
diff mbox

Message ID 1461400913-7321-2-git-send-email-den@openvz.org
State New
Headers show

Commit Message

Denis V. Lunev April 23, 2016, 8:41 a.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>
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>
---
 block/backup.c            | 13 +++++++++++++
 blockdev.c                | 12 ++++++++++--
 hmp-commands.hx           |  8 +++++---
 hmp.c                     |  3 ++-
 include/block/block_int.h |  1 +
 qapi/block-core.json      |  2 +-
 qmp-commands.hx           |  4 +++-
 7 files changed, 35 insertions(+), 8 deletions(-)

Patch
diff mbox

diff --git a/block/backup.c b/block/backup.c
index 491fd14..cad0439 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;
     QLIST_HEAD(, CowRequest) inflight_reqs;
 } BackupBlockJob;
 
@@ -157,6 +158,10 @@  static int coroutine_fn backup_do_cow(BlockDriverState *bs,
             ret = bdrv_co_write_zeroes(job->target,
                                        start * sectors_per_cluster,
                                        n, BDRV_REQ_MAY_UNMAP);
+        } else if (job->compress) {
+            ret = bdrv_write_compressed(job->target,
+                                        start * sectors_per_cluster,
+                                        iov.iov_base, n);
         } else {
             ret = bdrv_co_writev(job->target,
                                  start * sectors_per_cluster, n,
@@ -497,6 +502,7 @@  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,
@@ -534,6 +540,12 @@  void backup_start(BlockDriverState *bs, BlockDriverState *target,
         return;
     }
 
+    if (compress && target->drv->bdrv_write_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;
     }
@@ -580,6 +592,7 @@  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 f1f520a..ef72f19 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1856,6 +1856,7 @@  static void do_drive_backup(const char *device, const char *target,
                             bool has_mode, enum NewImageMode mode,
                             bool has_speed, int64_t speed,
                             bool has_bitmap, const char *bitmap,
+                            bool has_compress, bool compress,
                             bool has_on_source_error,
                             BlockdevOnError on_source_error,
                             bool has_on_target_error,
@@ -1896,6 +1897,7 @@  static void drive_backup_prepare(BlkActionState *common, Error **errp)
                     backup->has_mode, backup->mode,
                     backup->has_speed, backup->speed,
                     backup->has_bitmap, backup->bitmap,
+                    backup->has_compress, backup->compress,
                     backup->has_on_source_error, backup->on_source_error,
                     backup->has_on_target_error, backup->on_target_error,
                     common->block_job_txn, &local_err);
@@ -3170,6 +3172,7 @@  static void do_drive_backup(const char *device, const char *target,
                             bool has_mode, enum NewImageMode mode,
                             bool has_speed, int64_t speed,
                             bool has_bitmap, const char *bitmap,
+                            bool has_compress, bool compress,
                             bool has_on_source_error,
                             BlockdevOnError on_source_error,
                             bool has_on_target_error,
@@ -3200,6 +3203,9 @@  static void do_drive_backup(const char *device, const char *target,
     if (!has_mode) {
         mode = NEW_IMAGE_MODE_ABSOLUTE_PATHS;
     }
+    if (!has_compress) {
+        compress = false;
+    }
 
     blk = blk_by_name(device);
     if (!blk) {
@@ -3288,7 +3294,7 @@  static void do_drive_backup(const char *device, const char *target,
         }
     }
 
-    backup_start(bs, target_bs, speed, sync, bmap,
+    backup_start(bs, target_bs, speed, sync, bmap, compress,
                  on_source_error, on_target_error,
                  block_job_cb, bs, txn, &local_err);
     if (local_err != NULL) {
@@ -3307,6 +3313,7 @@  void qmp_drive_backup(const char *device, const char *target,
                       bool has_mode, enum NewImageMode mode,
                       bool has_speed, int64_t speed,
                       bool has_bitmap, const char *bitmap,
+                      bool has_compress, bool compress,
                       bool has_on_source_error, BlockdevOnError on_source_error,
                       bool has_on_target_error, BlockdevOnError on_target_error,
                       Error **errp)
@@ -3314,6 +3321,7 @@  void qmp_drive_backup(const char *device, const char *target,
     return do_drive_backup(device, target, has_format, format, sync,
                            has_mode, mode, has_speed, speed,
                            has_bitmap, bitmap,
+                           has_compress, compress,
                            has_on_source_error, on_source_error,
                            has_on_target_error, on_target_error,
                            NULL, errp);
@@ -3378,7 +3386,7 @@  void do_blockdev_backup(const char *device, const char *target,
 
     bdrv_ref(target_bs);
     bdrv_set_aio_context(target_bs, aio_context);
-    backup_start(bs, target_bs, speed, sync, NULL, on_source_error,
+    backup_start(bs, target_bs, speed, sync, NULL, false, on_source_error,
                  on_target_error, block_job_cb, bs, txn, &local_err);
     if (local_err != NULL) {
         bdrv_unref(target_bs);
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 4f4f60a..4b1d15b 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 d510236..e34593d 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1094,6 +1094,7 @@  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);
     enum NewImageMode mode;
     Error *err = NULL;
 
@@ -1111,7 +1112,7 @@  void hmp_drive_backup(Monitor *mon, const QDict *qdict)
 
     qmp_drive_backup(device, filename, !!format, format,
                      full ? MIRROR_SYNC_MODE_FULL : MIRROR_SYNC_MODE_TOP,
-                     true, mode, false, 0, false, NULL,
+                     true, mode, false, 0, false, NULL, compress, compress,
                      false, 0, false, 0, &err);
     hmp_handle_error(mon, &err);
 }
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 10d8759..142d207 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -701,6 +701,7 @@  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 1d09079..ebedf0d 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -905,7 +905,7 @@ 
 { '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 de896a5..ce36518 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1186,7 +1186,8 @@  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,
     },
 
@@ -1220,6 +1221,7 @@  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": compress data blocks (if the target format supports it).
 - "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.