[PULL,09/58] block: introduce bdrv_open_file_child() helper

diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index 21265e3966..29a38d7e18 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -76,6 +76,9 @@  BdrvChild *bdrv_open_child(const char *filename,
                            const BdrvChildClass *child_class,
                            BdrvChildRole child_role,
                            bool allow_none, Error **errp);
+int bdrv_open_file_child(const char *filename,
+                         QDict *options, const char *bdref_key,
+                         BlockDriverState *parent, Error **errp);
 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp);
 int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
                         Error **errp);
diff --git a/block.c b/block.c
index c8374dac4f..25a596a612 100644
--- a/block.c
+++ b/block.c
@@ -3673,6 +3673,27 @@  BdrvChild *bdrv_open_child(const char *filename,
                              errp);
 }
 
+/*
+ * Wrapper on bdrv_open_child() for most popular case: open primary child of bs.
+ */
+int bdrv_open_file_child(const char *filename,
+                         QDict *options, const char *bdref_key,
+                         BlockDriverState *parent, Error **errp)
+{
+    BdrvChildRole role;
+
+    /* commit_top and mirror_top don't use this function */
+    assert(!parent->drv->filtered_child_is_backing);
+
+    role = parent->drv->is_filter ?
+        (BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE;
+
+    parent->file = bdrv_open_child(filename, options, bdref_key, parent,
+                                   &child_of_bds, role, false, errp);
+
+    return parent->file ? 0 : -EINVAL;
+}
+
 /*
  * TODO Future callers may need to specify parent/child_class in order for
  * option inheritance to work. Existing callers use it for the root node.
diff --git a/block/blkdebug.c b/block/blkdebug.c
index bbf2948703..5fcfc8ac6f 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -503,12 +503,9 @@  static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Open the image file */
-    bs->file = bdrv_open_child(qemu_opt_get(opts, "x-image"), options, "image",
-                               bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(qemu_opt_get(opts, "x-image"), options, "image",
+                               bs, errp);
+    if (ret < 0) {
         goto out;
     }
 
diff --git a/block/blklogwrites.c b/block/blklogwrites.c
index e3c6c4039c..12b4c3c8cf 100644
--- a/block/blklogwrites.c
+++ b/block/blklogwrites.c
@@ -155,11 +155,8 @@  static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Open the file */
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, false,
-                               errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
         goto fail;
     }
 
diff --git a/block/blkreplay.c b/block/blkreplay.c
index dcbe780ddb..76a0b8d12a 100644
--- a/block/blkreplay.c
+++ b/block/blkreplay.c
@@ -26,11 +26,8 @@  static int blkreplay_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
 
     /* Open the image file */
-    bs->file = bdrv_open_child(NULL, options, "image", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "image", bs, errp);
+    if (ret < 0) {
         goto fail;
     }
 
diff --git a/block/blkverify.c b/block/blkverify.c
index 020b1ae7b6..43a2d94f7b 100644
--- a/block/blkverify.c
+++ b/block/blkverify.c
@@ -122,12 +122,9 @@  static int blkverify_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     /* Open the raw file */
-    bs->file = bdrv_open_child(qemu_opt_get(opts, "x-raw"), options, "raw",
-                               bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(qemu_opt_get(opts, "x-raw"), options, "raw",
+                               bs, errp);
+    if (ret < 0) {
         goto fail;
     }
 
diff --git a/block/bochs.c b/block/bochs.c
index b76f34fe03..e30e3908d9 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -110,10 +110,9 @@  static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
         return ret;
     }
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     ret = bdrv_pread(bs->file, 0, sizeof(bochs), &bochs, 0);
diff --git a/block/cloop.c b/block/cloop.c
index 40b146e714..3ff975a94d 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -71,10 +71,9 @@  static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
         return ret;
     }
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     /* read header */
diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index afbdd04489..4abaa7339e 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -412,6 +412,7 @@  static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
     int64_t cluster_size;
     g_autoptr(BlockdevOptions) full_opts = NULL;
     BlockdevOptionsCbw *opts;
+    int ret;
 
     full_opts = cbw_parse_options(options, errp);
     if (!full_opts) {
@@ -420,11 +421,9 @@  static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
     assert(full_opts->driver == BLOCKDEV_DRIVER_COPY_BEFORE_WRITE);
     opts = &full_opts->u.copy_before_write;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     s->target = bdrv_open_child(NULL, options, "target", bs, &child_of_bds,
diff --git a/block/copy-on-read.c b/block/copy-on-read.c
index 1fc7fb3333..815ac1d835 100644
--- a/block/copy-on-read.c
+++ b/block/copy-on-read.c
@@ -41,12 +41,11 @@  static int cor_open(BlockDriverState *bs, QDict *options, int flags,
     BDRVStateCOR *state = bs->opaque;
     /* Find a bottom node name, if any */
     const char *bottom_node = qdict_get_try_str(options, "bottom");
+    int ret;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     bs->supported_read_flags = BDRV_REQ_PREFETCH;
diff --git a/block/crypto.c b/block/crypto.c
index 7a57774b76..396e529bb2 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -261,15 +261,14 @@  static int block_crypto_open_generic(QCryptoBlockFormat format,
 {
     BlockCrypto *crypto = bs->opaque;
     QemuOpts *opts = NULL;
-    int ret = -EINVAL;
+    int ret;
     QCryptoBlockOpenOptions *open_opts = NULL;
     unsigned int cflags = 0;
     QDict *cryptoopts = NULL;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     bs->supported_write_flags = BDRV_REQ_FUA &
@@ -277,6 +276,7 @@  static int block_crypto_open_generic(QCryptoBlockFormat format,
 
     opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);
     if (!qemu_opts_absorb_qdict(opts, options, errp)) {
+        ret = -EINVAL;
         goto cleanup;
     }
 
@@ -285,6 +285,7 @@  static int block_crypto_open_generic(QCryptoBlockFormat format,
 
     open_opts = block_crypto_open_opts_init(cryptoopts, errp);
     if (!open_opts) {
+        ret = -EINVAL;
         goto cleanup;
     }
 
diff --git a/block/dmg.c b/block/dmg.c
index 98db18d82a..422136276a 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -440,10 +440,9 @@  static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
         return ret;
     }
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     block_module_load_one("dmg-bz2");
diff --git a/block/filter-compress.c b/block/filter-compress.c
index d5be538619..305716c86c 100644
--- a/block/filter-compress.c
+++ b/block/filter-compress.c
@@ -30,11 +30,9 @@ 
 static int compress_open(BlockDriverState *bs, QDict *options, int flags,
                          Error **errp)
 {
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    int ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     if (!bs->file->bs->drv || !block_driver_can_compress(bs->file->bs->drv)) {
diff --git a/block/parallels.c b/block/parallels.c
index c1523e7dab..27c81cee40 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -737,10 +737,9 @@  static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
     Error *local_err = NULL;
     char *buf;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     ret = bdrv_pread(bs->file, 0, sizeof(ph), &ph, 0);
diff --git a/block/preallocate.c b/block/preallocate.c
index e15cb8c74a..d50ee7f49b 100644
--- a/block/preallocate.c
+++ b/block/preallocate.c
@@ -134,6 +134,7 @@  static int preallocate_open(BlockDriverState *bs, QDict *options, int flags,
                             Error **errp)
 {
     BDRVPreallocateState *s = bs->opaque;
+    int ret;
 
     /*
      * s->data_end and friends should be initialized on permission update.
@@ -141,11 +142,9 @@  static int preallocate_open(BlockDriverState *bs, QDict *options, int flags,
      */
     s->file_end = s->zero_start = s->data_end = -EINVAL;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     if (!preallocate_absorb_opts(&s->opts, options, bs->file->bs, errp)) {
diff --git a/block/qcow.c b/block/qcow.c
index 311aaa8705..72ed4c3321 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -121,10 +121,8 @@  static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
     qdict_extract_subqdict(options, &encryptopts, "encrypt.");
     encryptfmt = qdict_get_try_str(encryptopts, "format");
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        ret = -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
         goto fail;
     }
 
diff --git a/block/qcow2.c b/block/qcow2.c
index b57f7cc8ee..b47016cf61 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1905,11 +1905,11 @@  static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
         .errp = errp,
         .ret = -EINPROGRESS
     };
+    int ret;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     /* Initialise locks */
diff --git a/block/qed.c b/block/qed.c
index bda00e6257..4627169348 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -561,11 +561,11 @@  static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
         .errp = errp,
         .ret = -EINPROGRESS
     };
+    int ret;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     bdrv_qed_init_state(bs);
diff --git a/block/replication.c b/block/replication.c
index c67f931f37..ee33dc4598 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -88,11 +88,9 @@  static int replication_open(BlockDriverState *bs, QDict *options,
     const char *mode;
     const char *top_id;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     ret = -EINVAL;
diff --git a/block/throttle.c b/block/throttle.c
index ddd450593a..131eba3ab4 100644
--- a/block/throttle.c
+++ b/block/throttle.c
@@ -78,11 +78,9 @@  static int throttle_open(BlockDriverState *bs, QDict *options,
     char *group;
     int ret;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
-                               false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
     bs->supported_write_flags = bs->file->bs->supported_write_flags |
                                 BDRV_REQ_WRITE_UNCHANGED;
diff --git a/block/vdi.c b/block/vdi.c
index e942325455..a9bafb5a9e 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -377,10 +377,9 @@  static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
     QemuUUID uuid_link, uuid_parent;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     logout("\n");
diff --git a/block/vhdx.c b/block/vhdx.c
index e10e78ebfd..ce1e75f5ec 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -1001,10 +1001,9 @@  static int vhdx_open(BlockDriverState *bs, QDict *options, int flags,
     uint64_t signature;
     Error *local_err = NULL;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     s->bat = NULL;
diff --git a/block/vmdk.c b/block/vmdk.c
index f7d8856dfb..d75a87cb85 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1308,10 +1308,9 @@  static int vmdk_open(BlockDriverState *bs, QDict *options, int flags,
     BDRVVmdkState *s = bs->opaque;
     uint32_t magic;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     buf = vmdk_read_desc(bs->file, 0, errp);
diff --git a/block/vpc.c b/block/vpc.c
index 4f49ef207f..95841f259a 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -233,10 +233,9 @@  static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
     int ret;
     int64_t bs_size;
 
-    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
-                               BDRV_CHILD_IMAGE, false, errp);
-    if (!bs->file) {
-        return -EINVAL;
+    ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
+    if (ret < 0) {
+        return ret;
     }
 
     opts = qemu_opts_create(&vpc_runtime_opts, NULL, 0, &error_abort);