[Qemu-devel] [PATCH 1/3] block: Additional info string in ImageInfo and BDI

[Max Reitz]

Add a string for additional information to ImageInfo and
BlockDriverInfo. Also, use this string to emit the compatibility level
and lazy_refcount value (on compat=1.1) for qcow2.

Signed-off-by: Max Reitz <address@hidden>
---
 block.c               |  3 ++-
 block/mirror.c        |  6 ++++--
 block/qapi.c          | 10 +++++++++-
 block/qcow2.c         |  6 ++++++
 include/block/block.h |  2 ++
 qapi-schema.json      |  5 ++++-
 qemu-img.c            |  3 ++-
 qemu-io-cmds.c        |  7 ++++++-
 8 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/block.c b/block.c
index 26639e8..9fd9f3a 100644
--- a/block.c
+++ b/block.c
@@ -1921,7 +1921,7 @@ void bdrv_round_to_clusters(BlockDriverState *bs,
                             int64_t *cluster_sector_num,
                             int *cluster_nb_sectors)
 {
-    BlockDriverInfo bdi;
+    BlockDriverInfo bdi = { .info_string = NULL };
 
     if (bdrv_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) {
         *cluster_sector_num = sector_num;
@@ -1932,6 +1932,7 @@ void bdrv_round_to_clusters(BlockDriverState *bs,
         *cluster_nb_sectors = QEMU_ALIGN_UP(sector_num - *cluster_sector_num +
                                             nb_sectors, c);
     }
+    g_free(bdi.info_string);
 }
 
 static bool tracked_request_overlaps(BdrvTrackedRequest *req,
diff --git a/block/mirror.c b/block/mirror.c
index 86de458..296ad54 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -295,7 +295,7 @@ static void coroutine_fn mirror_run(void *opaque)
     BlockDriverState *bs = s->common.bs;
     int64_t sector_num, end, sectors_per_chunk, length;
     uint64_t last_pause_ns;
-    BlockDriverInfo bdi;
+    BlockDriverInfo bdi = { .info_string = NULL };
     char backing_filename[1024];
     int ret = 0;
     int n;
@@ -325,6 +325,7 @@ static void coroutine_fn mirror_run(void *opaque)
             s->buf_size = MAX(s->buf_size, bdi.cluster_size);
             s->cow_bitmap = bitmap_new(length);
         }
+        g_free(bdi.info_string);
     }
 
     end = s->common.len >> BDRV_SECTOR_BITS;
@@ -544,13 +545,14 @@ void mirror_start(BlockDriverState *bs, BlockDriverState 
*target,
     if (granularity == 0) {
         /* Choose the default granularity based on the target file's cluster
          * size, clamped between 4k and 64k.  */
-        BlockDriverInfo bdi;
+        BlockDriverInfo bdi = { .info_string = NULL };
         if (bdrv_get_info(target, &bdi) >= 0 && bdi.cluster_size != 0) {
             granularity = MAX(4096, bdi.cluster_size);
             granularity = MIN(65536, granularity);
         } else {
             granularity = 65536;
         }
+        g_free(bdi.info_string);
     }
 
     assert ((granularity & (granularity - 1)) == 0);
diff --git a/block/qapi.c b/block/qapi.c
index a4bc411..b63376c 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -110,7 +110,7 @@ void bdrv_query_image_info(BlockDriverState *bs,
     uint64_t total_sectors;
     const char *backing_filename;
     char backing_filename2[1024];
-    BlockDriverInfo bdi;
+    BlockDriverInfo bdi = { .info_string = NULL };
     int ret;
     Error *err = NULL;
     ImageInfo *info = g_new0(ImageInfo, 1);
@@ -133,6 +133,10 @@ void bdrv_query_image_info(BlockDriverState *bs,
         }
         info->dirty_flag = bdi.is_dirty;
         info->has_dirty_flag = true;
+        if (bdi.info_string) {
+            info->info_string = bdi.info_string;
+            info->has_info_string = true;
+        }
     }
     backing_filename = bs->backing_file;
     if (backing_filename[0] != '\0') {
@@ -467,4 +471,8 @@ void bdrv_image_info_dump(fprintf_function func_fprintf, 
void *f,
             func_fprintf(f, "\n");
         }
     }
+
+    if (info->has_info_string) {
+        func_fprintf(f, "additional information: %s\n", info->info_string);
+    }
 }
diff --git a/block/qcow2.c b/block/qcow2.c
index 4bc679a..7351ab1 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1757,6 +1757,12 @@ static int qcow2_get_info(BlockDriverState *bs, 
BlockDriverInfo *bdi)
     BDRVQcowState *s = bs->opaque;
     bdi->cluster_size = s->cluster_size;
     bdi->vm_state_offset = qcow2_vm_state_offset(s);
+    if (s->qcow_version == 2) {
+        bdi->info_string = g_strdup("compat=0.10");
+    } else if (s->qcow_version == 3) {
+        bdi->info_string = g_strdup_printf("compat=1.1,lazy_refcounts=%s",
+                                    s->use_lazy_refcounts ? "on" : "off");
+    }
     return 0;
 }
 
diff --git a/include/block/block.h b/include/block/block.h
index e6b391c..f8335a2 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -18,6 +18,8 @@ typedef struct BlockDriverInfo {
     /* offset at which the VM state can be saved (0 if not possible) */
     int64_t vm_state_offset;
     bool is_dirty;
+    /* additional information; NULL if none */
+    char *info_string;
 } BlockDriverInfo;
 
 typedef struct BlockFragInfo {
diff --git a/qapi-schema.json b/qapi-schema.json
index a51f7d2..15c4f02 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -238,6 +238,9 @@
 #
 # @backing-image: #optional info of the backing image (since 1.6)
 #
+# @info-string: #optional string supplying additional format-specific
+# information (since 1.7)
+#
 # Since: 1.3
 #
 ##
@@ -248,7 +251,7 @@
            '*cluster-size': 'int', '*encrypted': 'bool',
            '*backing-filename': 'str', '*full-backing-filename': 'str',
            '*backing-filename-format': 'str', '*snapshots': ['SnapshotInfo'],
-           '*backing-image': 'ImageInfo' } }
+           '*backing-image': 'ImageInfo', '*info-string': 'str' } }
 
 ##
 # @ImageCheck:
diff --git a/qemu-img.c b/qemu-img.c
index b9a848d..7081d99 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1125,7 +1125,7 @@ static int img_convert(int argc, char **argv)
     uint64_t bs_sectors;
     uint8_t * buf = NULL;
     const uint8_t *buf1;
-    BlockDriverInfo bdi;
+    BlockDriverInfo bdi = { .info_string = NULL };
     QEMUOptionParameter *param = NULL, *create_options = NULL;
     QEMUOptionParameter *out_baseimg_param;
     char *options = NULL;
@@ -1369,6 +1369,7 @@ static int img_convert(int argc, char **argv)
             error_report("could not get block driver info");
             goto out;
         }
+        g_free(bdi.info_string);
         cluster_size = bdi.cluster_size;
         if (cluster_size <= 0 || cluster_size > IO_BUF_SIZE) {
             error_report("invalid cluster size");
diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index f91b6c4..fed0b4b 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -1677,7 +1677,7 @@ static const cmdinfo_t length_cmd = {
 
 static int info_f(BlockDriverState *bs, int argc, char **argv)
 {
-    BlockDriverInfo bdi;
+    BlockDriverInfo bdi = { .info_string = NULL };
     char s1[64], s2[64];
     int ret;
 
@@ -1699,6 +1699,11 @@ static int info_f(BlockDriverState *bs, int argc, char 
**argv)
     printf("cluster size: %s\n", s1);
     printf("vm state offset: %s\n", s2);
 
+    if (bdi.info_string) {
+        printf("additional information: %s\n", bdi.info_string);
+        g_free(bdi.info_string);
+    }
+
     return 0;
 }
 
-- 
1.8.3.1