From 422ac7d67a7ced985b1beef4b33cc43b48d1f240 Mon Sep 17 00:00:00 2001
From: Jinhua Cao <caojinhua1@huawei.com>
Date: Mon, 18 Mar 2024 10:18:07 +0800
Subject: [PATCH] qemu-img: add qemu-img direct create

Introdue buffer_size while creating raw file, then we
can controll the speed of direct write by:
    qemu-img create -t 'cache' -o buffer_size='num'

Signed-off-by: Jinhua Cao <caojinhua1@huawei.com>
---
 block/file-posix.c               |  65 ++++++++++++++++++--
 include/block/block_int-common.h |   2 +
 qapi/block-core.json             |   6 +-
 qemu-img-cmds.hx                 |   4 +-
 qemu-img.c                       |  14 ++++-
 tests/qemu-iotests/049.out       | 102 +++++++++++++++----------------
 tests/qemu-iotests/099.out       |   2 +-
 7 files changed, 134 insertions(+), 61 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index 4782aba59f..4ac8f684f1 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -128,6 +128,10 @@
 #define FTYPE_CD     1
 
 #define MAX_BLOCKSIZE	4096
+#define DEFAULT_BUFFER_SIZE 65536
+#define BUFFER_ALIGN_SIZE   65536
+#define MIN_BUFFER_SIZE     65536
+#define MAX_BUFFER_SIZE     16777216
 
 /* Posix file locking bytes. Libvirt takes byte 0, we start from higher bytes,
  * leaving a few more bytes for its future use. */
@@ -203,6 +207,8 @@ typedef struct RawPosixAIOData {
     off_t aio_offset;
     uint64_t aio_nbytes;
 
+    size_t buffer_size;
+
     union {
         struct {
             struct iovec *iov;
@@ -2630,7 +2636,8 @@ static void raw_close(BlockDriverState *bs)
  */
 static int coroutine_fn
 raw_regular_truncate(BlockDriverState *bs, int fd, int64_t offset,
-                     PreallocMode prealloc, Error **errp)
+                     PreallocMode prealloc, size_t buffer_size,
+                     Error **errp)
 {
     RawPosixAIOData acb;
 
@@ -2639,6 +2646,7 @@ raw_regular_truncate(BlockDriverState *bs, int fd, int64_t offset,
         .aio_fildes     = fd,
         .aio_type       = QEMU_AIO_TRUNCATE,
         .aio_offset     = offset,
+        .buffer_size    = buffer_size,
         .truncate       = {
             .prealloc       = prealloc,
             .errp           = errp,
@@ -2664,7 +2672,8 @@ static int coroutine_fn raw_co_truncate(BlockDriverState *bs, int64_t offset,
 
     if (S_ISREG(st.st_mode)) {
         /* Always resizes to the exact @offset */
-        return raw_regular_truncate(bs, s->fd, offset, prealloc, errp);
+        return raw_regular_truncate(bs, s->fd, offset, prealloc,
+                                    DEFAULT_BUFFER_SIZE, errp);
     }
 
     if (prealloc != PREALLOC_MODE_OFF) {
@@ -2882,6 +2891,8 @@ raw_co_create(BlockdevCreateOptions *options, Error **errp)
     int fd;
     uint64_t perm, shared;
     int result = 0;
+    int flags = O_RDWR | O_BINARY;
+    size_t buffer_size = DEFAULT_BUFFER_SIZE;
 
     /* Validate options and set default values */
     assert(options->driver == BLOCKDEV_DRIVER_FILE);
@@ -2901,9 +2912,19 @@ raw_co_create(BlockdevCreateOptions *options, Error **errp)
         error_setg(errp, "Extent size hint is too large");
         goto out;
     }
+    if (!file_opts->cache) {
+        file_opts->cache = g_strdup("writeback");
+    }
+    if (file_opts->preallocation == PREALLOC_MODE_FULL &&
+        !strcmp(file_opts->cache, "none")) {
+        flags |= O_DIRECT;
+    }
+    if (file_opts->has_buffersize) {
+        buffer_size = file_opts->buffersize;
+    }
 
     /* Create file */
-    fd = qemu_create(file_opts->filename, O_RDWR | O_BINARY, 0644, errp);
+    fd = qemu_create(file_opts->filename, flags, 0644, errp);
     if (fd < 0) {
         result = -errno;
         goto out;
@@ -2938,7 +2959,8 @@ raw_co_create(BlockdevCreateOptions *options, Error **errp)
     }
 
     /* Clear the file by truncating it to 0 */
-    result = raw_regular_truncate(NULL, fd, 0, PREALLOC_MODE_OFF, errp);
+    result = raw_regular_truncate(NULL, fd, 0, PREALLOC_MODE_OFF,
+                                  buffer_size, errp);
     if (result < 0) {
         goto out_unlock;
     }
@@ -2982,7 +3004,8 @@ raw_co_create(BlockdevCreateOptions *options, Error **errp)
     /* Resize and potentially preallocate the file to the desired
      * final size */
     result = raw_regular_truncate(NULL, fd, file_opts->size,
-                                  file_opts->preallocation, errp);
+                                  file_opts->preallocation,
+                                  buffer_size, errp);
     if (result < 0) {
         goto out_unlock;
     }
@@ -3003,6 +3026,8 @@ out_close:
         error_setg_errno(errp, -result, "Could not close the new file");
     }
 out:
+    g_free(file_opts->cache);
+    file_opts->cache = NULL;
     return result;
 }
 
@@ -3018,6 +3043,8 @@ raw_co_create_opts(BlockDriver *drv, const char *filename,
     PreallocMode prealloc;
     char *buf = NULL;
     Error *local_err = NULL;
+    size_t buffersize = DEFAULT_BUFFER_SIZE;
+    char *cache = NULL;
 
     /* Skip file: protocol prefix */
     strstart(filename, "file:", &filename);
@@ -3040,6 +3067,21 @@ raw_co_create_opts(BlockDriver *drv, const char *filename,
         return -EINVAL;
     }
 
+    buffersize = qemu_opt_get_size_del(opts, BLOCK_OPT_BUFFER_SIZE,
+                                       DEFAULT_BUFFER_SIZE);
+    if (buffersize < MIN_BUFFER_SIZE || buffersize > MAX_BUFFER_SIZE) {
+        error_setg_errno(errp, EINVAL, "Buffer size must be between %d "
+                         "and %d", MIN_BUFFER_SIZE, MAX_BUFFER_SIZE);
+        return -EINVAL;
+    }
+
+    cache = qemu_opt_get_del(opts, BLOCK_OPT_CACHE);
+    if (!cache) {
+        cache = g_strdup("writeback");
+    }
+
+    buffersize = ROUND_UP(buffersize, BUFFER_ALIGN_SIZE);
+
     options = (BlockdevCreateOptions) {
         .driver     = BLOCKDEV_DRIVER_FILE,
         .u.file     = {
@@ -3051,6 +3093,9 @@ raw_co_create_opts(BlockDriver *drv, const char *filename,
             .nocow              = nocow,
             .has_extent_size_hint = has_extent_size_hint,
             .extent_size_hint   = extent_size_hint,
+            .has_buffersize     = true,
+            .buffersize         = buffersize,
+            .cache              = cache,
         },
     };
     return raw_co_create(&options, errp);
@@ -3741,6 +3786,16 @@ static QemuOptsList raw_create_opts = {
             .type = QEMU_OPT_SIZE,
             .help = "Extent size hint for the image file, 0 to disable"
         },
+        {
+            .name = BLOCK_OPT_CACHE,
+            .type = QEMU_OPT_STRING,
+            .help = "Cache mode (allowed values: writeback, none)"
+        },
+        {
+            .name = BLOCK_OPT_BUFFER_SIZE,
+            .type = QEMU_OPT_SIZE,
+            .help = "write buffer size"
+        },
         { /* end of list */ }
     }
 };
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 4e31d161c5..a6e2436524 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -57,6 +57,8 @@
 #define BLOCK_OPT_DATA_FILE_RAW     "data_file_raw"
 #define BLOCK_OPT_COMPRESSION_TYPE  "compression_type"
 #define BLOCK_OPT_EXTL2             "extended_l2"
+#define BLOCK_OPT_CACHE             "cache"
+#define BLOCK_OPT_BUFFER_SIZE       "buffer_size"
 
 #define BLOCK_PROBE_BUF_SIZE        512
 
diff --git a/qapi/block-core.json b/qapi/block-core.json
index ca390c5700..1444624590 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -4906,6 +4906,8 @@
 #
 # @extent-size-hint: Extent size hint to add to the image file; 0 for
 #     not adding an extent size hint (default: 1 MB, since 5.1)
+# @cache: Cache mode used to write the output disk image
+# @buffersize: Buffer size for creating image
 #
 # Since: 2.12
 ##
@@ -4914,7 +4916,9 @@
             'size':                 'size',
             '*preallocation':       'PreallocMode',
             '*nocow':               'bool',
-            '*extent-size-hint':    'size'} }
+            '*extent-size-hint':    'size',
+            '*cache':               'str',
+            '*buffersize':          'size'} }
 
 ##
 # @BlockdevCreateOptionsGluster:
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index 068692d13e..20bdcd7b82 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -52,9 +52,9 @@ SRST
 ERST
 
 DEF("create", img_create,
-    "create [--object objectdef] [-q] [-f fmt] [-b backing_file [-F backing_fmt]] [-u] [-o options] filename [size]")
+    "create [--object objectdef] [-q] [-f fmt] [-b backing_file [-F backing_fmt]] [-u] [-t cache] [-o options] filename [size]")
 SRST
-.. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE [-F BACKING_FMT]] [-u] [-o OPTIONS] FILENAME [SIZE]
+.. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE [-F BACKING_FMT]] [-u] [-t CACHE] [-o OPTIONS] FILENAME [SIZE]
 ERST
 
 DEF("dd", img_dd,
diff --git a/qemu-img.c b/qemu-img.c
index 5a77f67719..80adee2620 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -516,6 +516,7 @@ static int img_create(int argc, char **argv)
     const char *base_fmt = NULL;
     const char *filename;
     const char *base_filename = NULL;
+    const char *cache = BDRV_DEFAULT_CACHE;
     char *options = NULL;
     Error *local_err = NULL;
     bool quiet = false;
@@ -527,7 +528,7 @@ static int img_create(int argc, char **argv)
             {"object", required_argument, 0, OPTION_OBJECT},
             {0, 0, 0, 0}
         };
-        c = getopt_long(argc, argv, ":F:b:f:ho:qu",
+        c = getopt_long(argc, argv, ":F:b:f:t:ho:qu",
                         long_options, NULL);
         if (c == -1) {
             break;
@@ -551,6 +552,9 @@ static int img_create(int argc, char **argv)
         case 'f':
             fmt = optarg;
             break;
+        case 't':
+            cache = optarg;
+            break;
         case 'o':
             if (accumulate_options(&options, optarg) < 0) {
                 goto fail;
@@ -594,6 +598,14 @@ static int img_create(int argc, char **argv)
         error_exit("Unexpected argument: %s", argv[optind]);
     }
 
+    if (!options) {
+        options = g_strdup_printf(BLOCK_OPT_CACHE"=%s", cache);
+    } else {
+        char *old_options = options;
+        options = g_strdup_printf("%s,"BLOCK_OPT_CACHE"=%s", options, cache);
+        g_free(old_options);
+    }
+
     bdrv_img_create(filename, fmt, base_filename, base_fmt,
                     options, img_size, flags, quiet, &local_err);
     if (local_err) {
diff --git a/tests/qemu-iotests/049.out b/tests/qemu-iotests/049.out
index 34e1b452e6..b4a9705ec2 100644
--- a/tests/qemu-iotests/049.out
+++ b/tests/qemu-iotests/049.out
@@ -4,90 +4,90 @@ QA output created by 049
 == 1. Traditional size parameter ==
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1024
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1024b
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1k
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1K
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1G
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1073741824 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1073741824 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1T
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1099511627776 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1099511627776 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1024.0
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1024.0b
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1.5k
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1536 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1536 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1.5K
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1536 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1536 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1.5M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1572864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1572864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1.5G
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1610612736 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1610612736 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 TEST_DIR/t.qcow2 1.5T
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1649267441664 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1649267441664 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 == 2. Specifying size via -o ==
 
 qemu-img create -f qcow2 -o size=1024 TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1024b TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1k TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1K TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1M TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1048576 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1G TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1073741824 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1073741824 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1T TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1099511627776 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1099511627776 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1024.0 TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1024.0b TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1024 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1.5k TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1536 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1536 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1.5K TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1536 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1536 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1.5M TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1572864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1572864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1.5G TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1610612736 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1610612736 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o size=1.5T TEST_DIR/t.qcow2
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1649267441664 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=1649267441664 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 == 3. Invalid sizes ==
 
@@ -132,84 +132,84 @@ qemu-img: TEST_DIR/t.qcow2: The image size must be specified only once
 == Check correct interpretation of suffixes for cluster size ==
 
 qemu-img create -f qcow2 -o cluster_size=1024 TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=1024b TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=1k TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=1K TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=1M TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1048576 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1048576 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=1024.0 TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=1024.0b TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=1024 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=0.5k TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=512 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=512 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=0.5K TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=512 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=512 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o cluster_size=0.5M TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=524288 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=524288 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 == Check compat level option ==
 
 qemu-img create -f qcow2 -o compat=0.10 TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.10 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.10 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o compat=1.1 TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=1.1 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=1.1 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o compat=0.42 TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.42 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.42 lazy_refcounts=off refcount_bits=16 cache=writeback
 qemu-img: TEST_DIR/t.qcow2: Parameter 'version' does not accept value '0.42'
 
 qemu-img create -f qcow2 -o compat=foobar TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=foobar lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=foobar lazy_refcounts=off refcount_bits=16 cache=writeback
 qemu-img: TEST_DIR/t.qcow2: Parameter 'version' does not accept value 'foobar'
 
 == Check preallocation option ==
 
 qemu-img create -f qcow2 -o preallocation=off TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o preallocation=metadata TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=metadata compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=metadata compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o preallocation=1234 TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=1234 compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off preallocation=1234 compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 qemu-img: TEST_DIR/t.qcow2: Parameter 'preallocation' does not accept value '1234'
 
 == Check encryption option ==
 
 qemu-img create -f qcow2 -o encryption=off TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 encryption=off cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 encryption=off cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 --object secret,id=sec0,data=123456 -o encryption=on,encrypt.key-secret=sec0 TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 encryption=on encrypt.key-secret=sec0 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 encryption=on encrypt.key-secret=sec0 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 == Check lazy_refcounts option (only with v3) ==
 
 qemu-img create -f qcow2 -o compat=1.1,lazy_refcounts=off TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=1.1 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=1.1 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o compat=1.1,lazy_refcounts=on TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=1.1 lazy_refcounts=on refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=1.1 lazy_refcounts=on refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o compat=0.10,lazy_refcounts=off TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.10 lazy_refcounts=off refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.10 lazy_refcounts=off refcount_bits=16 cache=writeback
 
 qemu-img create -f qcow2 -o compat=0.10,lazy_refcounts=on TEST_DIR/t.qcow2 64M
-Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.10 lazy_refcounts=on refcount_bits=16
+Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.10 lazy_refcounts=on refcount_bits=16 cache=writeback
 qemu-img: TEST_DIR/t.qcow2: Lazy refcounts only supported with compatibility level 1.1 and above (use version=v3 or greater)
 
 == Expect error when backing file name is empty string ==
diff --git a/tests/qemu-iotests/099.out b/tests/qemu-iotests/099.out
index 8cce627529..f6f8f25957 100644
--- a/tests/qemu-iotests/099.out
+++ b/tests/qemu-iotests/099.out
@@ -1,6 +1,6 @@
 QA output created by 099
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072
-Formatting 'TEST_DIR/t.IMGFMT.compare', fmt=raw size=131072
+Formatting 'TEST_DIR/t.IMGFMT.compare', fmt=raw size=131072 cache=writeback
 
 === Testing simple filename for blkverify ===
 
-- 
2.27.0