[PATCH v2 2/2] qemu-img: add support for rate limit in qemu-img convert

[Zhengui li]

From: Zhengui <lizhengui@huawei.com>

Currently, there is no rate limit for qemu-img convert. This may
cause the task of qemu-img convert to consume all the bandwidth
of the storage. This will affect the IO performance of other processes
and virtual machines under shared storage. So we add support for
offline rate limit in qemu-img convert to get better quality of sevice.

Signed-off-by: Zhengui <lizhengui@huawei.com>
---
 docs/tools/qemu-img.rst |  6 +++++-
 qemu-img-cmds.hx        |  4 ++--
 qemu-img.c              | 30 +++++++++++++++++++++++++++++-
 3 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index bcb11b0..b615aa8 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -188,6 +188,10 @@ Parameters to convert subcommand:
   allocated target image depending on the host support for getting allocation
   information.
 
+.. option:: -r
+
+   Rate limit for the convert process
+
 .. option:: --salvage
 
   Try to ignore I/O errors when reading.  Unless in quiet mode (``-q``), errors
@@ -410,7 +414,7 @@ Command description:
   4
     Error on reading data
 
-.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] 
[--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t 
CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l 
SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-m NUM_COROUTINES] [-W] FILENAME [FILENAME2 
[...]] OUTPUT_FILENAME
+.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] 
[--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t 
CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l 
SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-r RATE_LIMIT] [-m NUM_COROUTINES] [-W] 
FILENAME [FILENAME2 [...]] OUTPUT_FILENAME
 
   Convert the disk image *FILENAME* or a snapshot *SNAPSHOT_PARAM*
   to disk image *OUTPUT_FILENAME* using format *OUTPUT_FMT*. It can
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index 2a31806..7eb489b 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -46,9 +46,9 @@ SRST
 ERST
 
 DEF("convert", img_convert,
-    "convert [--object objectdef] [--image-opts] [--target-image-opts] 
[--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f fmt] [-t 
cache] [-T src_cache] [-O output_fmt] [-B backing_file] [-o options] [-l 
snapshot_param] [-S sparse_size] [-m num_coroutines] [-W] [--salvage] filename 
[filename2 [...]] output_filename")
+    "convert [--object objectdef] [--image-opts] [--target-image-opts] 
[--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f fmt] [-t 
cache] [-T src_cache] [-O output_fmt] [-B backing_file] [-o options] [-l 
snapshot_param] [-S sparse_size] [-r rate_limit] [-m num_coroutines] [-W] 
[--salvage] filename [filename2 [...]] output_filename")
 SRST
-.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] 
[--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t 
CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l 
SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-m NUM_COROUTINES] [-W] [--salvage] FILENAME 
[FILENAME2 [...]] OUTPUT_FILENAME
+.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] 
[--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t 
CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l 
SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-r RATE_LIMIT] [-m NUM_COROUTINES] [-W] 
[--salvage] FILENAME [FILENAME2 [...]] OUTPUT_FILENAME
 ERST
 
 DEF("create", img_create,
diff --git a/qemu-img.c b/qemu-img.c
index ea66139..8dfe1c4 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -50,6 +50,8 @@
 #include "block/qapi.h"
 #include "crypto/init.h"
 #include "trace/control.h"
+#include "qemu/throttle.h"
+#include "block/throttle-groups.h"
 
 #define QEMU_IMG_VERSION "qemu-img version " QEMU_FULL_VERSION \
                           "\n" QEMU_COPYRIGHT "\n"
@@ -1672,6 +1674,7 @@ enum ImgConvertBlockStatus {
 };
 
 #define MAX_COROUTINES 16
+#define CONVERT_THROTTLE_GROUP "img_convert"
 
 typedef struct ImgConvertState {
     BlockBackend **src;
@@ -2187,6 +2190,17 @@ static int convert_copy_bitmaps(BlockDriverState *src, 
BlockDriverState *dst)
 
 #define MAX_BUF_SECTORS 32768
 
+static void set_rate_limit(BlockBackend *blk, int64_t rate_limit)
+{
+    ThrottleConfig cfg;
+
+    throttle_config_init(&cfg);
+    cfg.buckets[THROTTLE_BPS_WRITE].avg = rate_limit;
+
+    blk_io_limits_enable(blk, CONVERT_THROTTLE_GROUP);
+    blk_set_io_limits(blk, &cfg);
+}
+
 static int img_convert(int argc, char **argv)
 {
     int c, bs_i, flags, src_flags = 0;
@@ -2207,6 +2221,7 @@ static int img_convert(int argc, char **argv)
     bool force_share = false;
     bool explict_min_sparse = false;
     bool bitmaps = false;
+    int64_t rate_limit = 0;
 
     ImgConvertState s = (ImgConvertState) {
         /* Need at least 4k of zeros for sparse detection */
@@ -2229,7 +2244,7 @@ static int img_convert(int argc, char **argv)
             {"bitmaps", no_argument, 0, OPTION_BITMAPS},
             {0, 0, 0, 0}
         };
-        c = getopt_long(argc, argv, ":hf:O:B:Cco:l:S:pt:T:qnm:WU",
+        c = getopt_long(argc, argv, ":hf:O:B:Cco:l:S:pt:T:qnm:WUr:",
                         long_options, NULL);
         if (c == -1) {
             break;
@@ -2326,6 +2341,15 @@ static int img_convert(int argc, char **argv)
         case 'U':
             force_share = true;
             break;
+        case 'r': {
+            int64_t sval;
+
+            sval = cvtnum("rate limit", optarg);
+            if (sval < 0) {
+                goto fail_getopt;
+            }
+            rate_limit = sval;
+        }   break;
         case OPTION_OBJECT: {
             QemuOpts *object_opts;
             object_opts = qemu_opts_parse_noisily(&qemu_object_opts,
@@ -2715,6 +2739,10 @@ static int img_convert(int argc, char **argv)
         s.cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE;
     }
 
+    if (rate_limit) {
+        set_rate_limit(s.target, rate_limit);
+    }
+
     ret = convert_do_copy(&s);
 
     /* Now copy the bitmaps */
-- 
2.6.4.windows.1