Re: [Qemu-block] [PATCH v2 3/4] block-stream: add compress option

[Stefan Hajnoczi]

On Thu, Nov 16, 2017 at 07:54:57PM +0300, Anton Nefedov wrote:
> It might be useful to compress images during block-stream;
> this way the user can merge compressed images of a backing chain and
> the result will remain compressed.
> 
> Signed-off-by: Anton Nefedov 
> ---
>  qapi/block-core.json  |  4 
>  include/block/block_int.h |  4 +++-
>  block/stream.c| 16 
>  blockdev.c| 13 -
>  hmp.c |  2 ++
>  hmp-commands.hx   |  4 ++--
>  6 files changed, 35 insertions(+), 8 deletions(-)

Reviewed-by: Stefan Hajnoczi 


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[Qemu-block] [PATCH v2 3/4] block-stream: add compress option

[Anton Nefedov]

It might be useful to compress images during block-stream;
this way the user can merge compressed images of a backing chain and
the result will remain compressed.

Signed-off-by: Anton Nefedov 
---
 qapi/block-core.json  |  4 
 include/block/block_int.h |  4 +++-
 block/stream.c| 16 
 blockdev.c| 13 -
 hmp.c |  2 ++
 hmp-commands.hx   |  4 ++--
 6 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/qapi/block-core.json b/qapi/block-core.json
index ab96e34..b7282cd 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2007,6 +2007,9 @@
 #
 # @speed:  the maximum speed, in bytes per second
 #
+# @compress: true to compress data; may only be set if the target format
+#supports it (default: false). (Since 2.12)
+#
 # @on-error: the action to take on an error (default report).
 #'stop' and 'enospc' can only be used if the block device
 #supports io-status (see BlockInfo).  Since 1.3.
@@ -2026,6 +2029,7 @@
 { 'command': 'block-stream',
   'data': { '*job-id': 'str', 'device': 'str', '*base': 'str',
 '*base-node': 'str', '*backing-file': 'str', '*speed': 'int',
+'*compress': 'bool',
 '*on-error': 'BlockdevOnError' } }
 
 ##
diff --git a/include/block/block_int.h b/include/block/block_int.h
index a548277..093bf9b 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -863,6 +863,7 @@ int is_windows_drive(const char *filename);
  * @backing_file_str: The file name that will be written to @bs as the
  * the new backing file if the job completes. Ignored if @base is %NULL.
  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
+ * @compress: True to compress data.
  * @on_error: The action to take upon error.
  * @errp: Error object.
  *
@@ -875,7 +876,8 @@ int is_windows_drive(const char *filename);
  */
 void stream_start(const char *job_id, BlockDriverState *bs,
   BlockDriverState *base, const char *backing_file_str,
-  int64_t speed, BlockdevOnError on_error, Error **errp);
+  int64_t speed, bool compress,
+  BlockdevOnError on_error, Error **errp);
 
 /**
  * commit_start:
diff --git a/block/stream.c b/block/stream.c
index e6f7234..75c9d66 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -38,23 +38,29 @@ typedef struct StreamBlockJob {
 BlockdevOnError on_error;
 char *backing_file_str;
 int bs_flags;
+bool compress;
 } StreamBlockJob;
 
 static int coroutine_fn stream_populate(BlockBackend *blk,
 int64_t offset, uint64_t bytes,
-void *buf)
+void *buf, bool compress)
 {
 struct iovec iov = {
 .iov_base = buf,
 .iov_len  = bytes,
 };
 QEMUIOVector qiov;
+int flags = BDRV_REQ_COPY_ON_READ;
+
+if (compress) {
+flags |= BDRV_REQ_WRITE_COMPRESSED;
+}
 
 assert(bytes < SIZE_MAX);
 qemu_iovec_init_external(, , 1);
 
 /* Copy-on-read the unallocated clusters */
-return blk_co_preadv(blk, offset, qiov.size, , BDRV_REQ_COPY_ON_READ);
+return blk_co_preadv(blk, offset, qiov.size, , flags);
 }
 
 typedef struct {
@@ -166,7 +172,7 @@ static void coroutine_fn stream_run(void *opaque)
 }
 trace_stream_one_iteration(s, offset, n, ret);
 if (copy) {
-ret = stream_populate(blk, offset, n, buf);
+ret = stream_populate(blk, offset, n, buf, s->compress);
 }
 if (ret < 0) {
 BlockErrorAction action =
@@ -227,7 +233,8 @@ static const BlockJobDriver stream_job_driver = {
 
 void stream_start(const char *job_id, BlockDriverState *bs,
   BlockDriverState *base, const char *backing_file_str,
-  int64_t speed, BlockdevOnError on_error, Error **errp)
+  int64_t speed, bool compress,
+  BlockdevOnError on_error, Error **errp)
 {
 StreamBlockJob *s;
 BlockDriverState *iter;
@@ -267,6 +274,7 @@ void stream_start(const char *job_id, BlockDriverState *bs,
 s->base = base;
 s->backing_file_str = g_strdup(backing_file_str);
 s->bs_flags = orig_bs_flags;
+s->compress = compress;
 
 s->on_error = on_error;
 trace_stream_start(bs, base, s);
diff --git a/blockdev.c b/blockdev.c
index 56a6b24..ae2a1d2 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2968,6 +2968,7 @@ void qmp_block_stream(bool has_job_id, const char 
*job_id, const char *device,
   bool has_base_node, const char *base_node,
   bool has_backing_file, const char *backing_file,
   bool has_speed, int64_t speed,
+  bool has_compress, bool compress,
   bool has_on_error, BlockdevOnError on_error,