[PATCH 2/3] qemu-img: Add convert --bitmaps option

[Eric Blake]

Make it easier to copy all the persistent bitmaps of a source image
along with the contents, by adding a boolean flag for use with
qemu-img convert.

See also https://bugzilla.redhat.com/show_bug.cgi?id=1779893

Signed-off-by: Eric Blake <address@hidden>
---
 docs/tools/qemu-img.rst |  6 ++-
 qemu-img.c              | 81 +++++++++++++++++++++++++++++++++++++++--
 qemu-img-cmds.hx        |  4 +-
 3 files changed, 85 insertions(+), 6 deletions(-)

diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index 0080f83a76c9..8c4d85e0b835 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -186,6 +186,10 @@ Parameters to convert subcommand:

 .. program:: qemu-img-convert

+.. option:: --bitmaps
+
+  Additionally copy all bitmaps
+
 .. option:: -n

   Skip the creation of the target volume
@@ -373,7 +377,7 @@ Command description:
   4
     Error on reading data

-.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] 
[--target-is-zero] [-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] [-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.c b/qemu-img.c
index 821cbf610e5f..6541357179c2 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -28,6 +28,7 @@
 #include "qemu-common.h"
 #include "qemu-version.h"
 #include "qapi/error.h"
+#include "qapi/qapi-commands-block-core.h"
 #include "qapi/qapi-visit-block-core.h"
 #include "qapi/qobject-output-visitor.h"
 #include "qapi/qmp/qjson.h"
@@ -71,6 +72,7 @@ enum {
     OPTION_SHRINK = 266,
     OPTION_SALVAGE = 267,
     OPTION_TARGET_IS_ZERO = 268,
+    OPTION_BITMAPS = 269,
 };

 typedef enum OutputFormat {
@@ -176,6 +178,7 @@ static void QEMU_NORETURN help(void)
            "       hiding corruption that has already occurred.\n"
            "\n"
            "Parameters to convert subcommand:\n"
+           "  '--bitmaps' copies all persistent bitmaps to destination\n"
            "  '-m' specifies how many coroutines work in parallel during the 
convert\n"
            "       process (defaults to 8)\n"
            "  '-W' allow to write to the target out of order rather than 
sequential\n"
@@ -2054,6 +2057,47 @@ static int convert_do_copy(ImgConvertState *s)
     return s->ret;
 }

+static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst)
+{
+    BdrvDirtyBitmap *bm;
+    Error *err = NULL;
+    BlockDirtyBitmapMergeSource *merge;
+    BlockDirtyBitmapMergeSourceList *list;
+
+    FOR_EACH_DIRTY_BITMAP(src, bm) {
+        const char *name;
+
+        if (!bdrv_dirty_bitmap_get_persistence(bm)) {
+            continue;
+        }
+        name = bdrv_dirty_bitmap_name(bm);
+        qmp_block_dirty_bitmap_add(dst->node_name, name,
+                                   true, bdrv_dirty_bitmap_granularity(bm),
+                                   true, true,
+                                   true, !bdrv_dirty_bitmap_enabled(bm),
+                                   &err);
+        if (err) {
+            error_reportf_err(err, "Failed to create bitmap %s: ", name);
+            return -1;
+        }
+
+        merge = g_new0(BlockDirtyBitmapMergeSource, 1);
+        merge->type = QTYPE_QDICT;
+        merge->u.external.node = g_strdup(src->node_name);
+        merge->u.external.name = g_strdup(name);
+        list = g_new0(BlockDirtyBitmapMergeSourceList, 1);
+        list->value = merge;
+        qmp_block_dirty_bitmap_merge(dst->node_name, name, list, &err);
+        qapi_free_BlockDirtyBitmapMergeSourceList(list);
+        if (err) {
+            error_reportf_err(err, "Failed to populate bitmap %s: ", name);
+            return -1;
+        }
+    }
+
+    return 0;
+}
+
 #define MAX_BUF_SECTORS 32768

 static int img_convert(int argc, char **argv)
@@ -2075,6 +2119,8 @@ static int img_convert(int argc, char **argv)
     int64_t ret = -EINVAL;
     bool force_share = false;
     bool explict_min_sparse = false;
+    bool bitmaps = false;
+    size_t nbitmaps = 0;

     ImgConvertState s = (ImgConvertState) {
         /* Need at least 4k of zeros for sparse detection */
@@ -2094,6 +2140,7 @@ static int img_convert(int argc, char **argv)
             {"target-image-opts", no_argument, 0, OPTION_TARGET_IMAGE_OPTS},
             {"salvage", no_argument, 0, OPTION_SALVAGE},
             {"target-is-zero", no_argument, 0, OPTION_TARGET_IS_ZERO},
+            {"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",
@@ -2225,6 +2272,9 @@ static int img_convert(int argc, char **argv)
              */
             s.has_zero_init = true;
             break;
+        case OPTION_BITMAPS:
+            bitmaps = true;
+            break;
         }
     }

@@ -2286,7 +2336,6 @@ static int img_convert(int argc, char **argv)
         goto fail_getopt;
     }

-
     /* ret is still -EINVAL until here */
     ret = bdrv_parse_cache_mode(src_cache, &src_flags, &src_writethrough);
     if (ret < 0) {
@@ -2446,6 +2495,28 @@ static int img_convert(int argc, char **argv)
         }
     }

+    /* Determine how many bitmaps need copying */
+    if (bitmaps) {
+        BdrvDirtyBitmap *bm;
+
+        if (s.src_num > 1) {
+            error_report("Copying bitmaps only possible with single source");
+            ret = -1;
+            goto out;
+        }
+        FOR_EACH_DIRTY_BITMAP(blk_bs(s.src[0]), bm) {
+            if (bdrv_dirty_bitmap_get_persistence(bm)) {
+                nbitmaps++;
+            }
+        }
+        if (nbitmaps > 0 && drv && !drv->bdrv_co_can_store_new_dirty_bitmap) {
+            error_report("Format driver '%s' does not support bitmaps",
+                         out_fmt);
+            ret = -1;
+            goto out;
+        }
+    }
+
     /*
      * The later open call will need any decryption secrets, and
      * bdrv_create() will purge "opts", so extract them now before
@@ -2454,9 +2525,7 @@ static int img_convert(int argc, char **argv)
     if (!skip_create) {
         open_opts = qdict_new();
         qemu_opt_foreach(opts, img_add_key_secrets, open_opts, &error_abort);
-    }

-    if (!skip_create) {
         /* Create the new image */
         ret = bdrv_create(drv, out_filename, opts, &local_err);
         if (ret < 0) {
@@ -2553,6 +2622,12 @@ static int img_convert(int argc, char **argv)
     }

     ret = convert_do_copy(&s);
+
+    /* Now copy the bitmaps */
+    if (nbitmaps > 0 && ret == 0) {
+        ret = convert_copy_bitmaps(blk_bs(s.src[0]), out_bs);
+    }
+
 out:
     if (!ret) {
         qemu_progress_print(100, 0);
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index c9c54de1df40..37cb36335218 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -39,9 +39,9 @@ SRST
 ERST

 DEF("convert", img_convert,
-    "convert [--object objectdef] [--image-opts] [--target-image-opts] 
[--target-is-zero] [-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] [-m num_coroutines] [-W] [--salvage] filename 
[filename2 [...]] output_filename")
 SRST
-.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] 
[--target-is-zero] [-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] [-m NUM_COROUTINES] [-W] [--salvage] FILENAME 
[FILENAME2 [...]] OUTPUT_FILENAME
 ERST

 DEF("create", img_create,
-- 
2.26.0