X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=block.c;h=382ea71f4b8c28550d4a798377fd1e6c4bae04ae;hb=60aad298cb6de52f2716b2e82e1353ea9de95fd6;hp=5df17de5a48ea9a5faa2b6028ae7b9304da8f621;hpb=d663640c04f2aab810915c556390211d75457704;p=qemu.git

diff --git a/block.c b/block.c
index 5df17de5a..382ea71f4 100644
--- a/block.c
+++ b/block.c
@@ -394,18 +394,26 @@ typedef struct CreateCo {
     char *filename;
     QEMUOptionParameter *options;
     int ret;
+    Error *err;
 } CreateCo;
 
 static void coroutine_fn bdrv_create_co_entry(void *opaque)
 {
+    Error *local_err = NULL;
+    int ret;
+
     CreateCo *cco = opaque;
     assert(cco->drv);
 
-    cco->ret = cco->drv->bdrv_create(cco->filename, cco->options);
+    ret = cco->drv->bdrv_create(cco->filename, cco->options, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(&cco->err, local_err);
+    }
+    cco->ret = ret;
 }
 
 int bdrv_create(BlockDriver *drv, const char* filename,
-    QEMUOptionParameter *options)
+    QEMUOptionParameter *options, Error **errp)
 {
     int ret;
 
@@ -415,9 +423,11 @@ int bdrv_create(BlockDriver *drv, const char* filename,
         .filename = g_strdup(filename),
         .options = options,
         .ret = NOT_DONE,
+        .err = NULL,
     };
 
     if (!drv->bdrv_create) {
+        error_setg(errp, "Driver '%s' does not support image creation", drv->format_name);
         ret = -ENOTSUP;
         goto out;
     }
@@ -434,22 +444,37 @@ int bdrv_create(BlockDriver *drv, const char* filename,
     }
 
     ret = cco.ret;
+    if (ret < 0) {
+        if (error_is_set(&cco.err)) {
+            error_propagate(errp, cco.err);
+        } else {
+            error_setg_errno(errp, -ret, "Could not create image");
+        }
+    }
 
 out:
     g_free(cco.filename);
     return ret;
 }
 
-int bdrv_create_file(const char* filename, QEMUOptionParameter *options)
+int bdrv_create_file(const char* filename, QEMUOptionParameter *options,
+                     Error **errp)
 {
     BlockDriver *drv;
+    Error *local_err = NULL;
+    int ret;
 
     drv = bdrv_find_protocol(filename, true);
     if (drv == NULL) {
+        error_setg(errp, "Could not find protocol for file '%s'", filename);
         return -ENOENT;
     }
 
-    return bdrv_create(drv, filename, options);
+    ret = bdrv_create(drv, filename, options, &local_err);
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+    }
+    return ret;
 }
 
 /*
@@ -552,7 +577,7 @@ BlockDriver *bdrv_find_protocol(const char *filename,
 }
 
 static int find_image_format(BlockDriverState *bs, const char *filename,
-                             BlockDriver **pdrv)
+                             BlockDriver **pdrv, Error **errp)
 {
     int score, score_max;
     BlockDriver *drv1, *drv;
@@ -563,6 +588,7 @@ static int find_image_format(BlockDriverState *bs, const char *filename,
     if (bs->sg || !bdrv_is_inserted(bs) || bdrv_getlength(bs) == 0) {
         drv = bdrv_find_format("raw");
         if (!drv) {
+            error_setg(errp, "Could not find raw image format");
             ret = -ENOENT;
         }
         *pdrv = drv;
@@ -571,6 +597,8 @@ static int find_image_format(BlockDriverState *bs, const char *filename,
 
     ret = bdrv_pread(bs, 0, buf, sizeof(buf));
     if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not read image for determining its "
+                         "format");
         *pdrv = NULL;
         return ret;
     }
@@ -587,6 +615,8 @@ static int find_image_format(BlockDriverState *bs, const char *filename,
         }
     }
     if (!drv) {
+        error_setg(errp, "Could not determine image format: No compatible "
+                   "driver found");
         ret = -ENOENT;
     }
     *pdrv = drv;
@@ -610,7 +640,7 @@ static int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
         if (length < 0) {
             return length;
         }
-        hint = length >> BDRV_SECTOR_BITS;
+        hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
     }
 
     bs->total_sectors = hint;
@@ -706,10 +736,11 @@ static int bdrv_open_flags(BlockDriverState *bs, int flags)
  * Removes all processed options from *options.
  */
 static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
-    QDict *options, int flags, BlockDriver *drv)
+    QDict *options, int flags, BlockDriver *drv, Error **errp)
 {
     int ret, open_flags;
     const char *filename;
+    Error *local_err = NULL;
 
     assert(drv != NULL);
     assert(bs->file == NULL);
@@ -738,12 +769,22 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
     bs->read_only = !(open_flags & BDRV_O_RDWR);
 
     if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) {
+        error_setg(errp,
+                   !bs->read_only && bdrv_is_whitelisted(drv, true)
+                        ? "Driver '%s' can only be used for read-only devices"
+                        : "Driver '%s' is not whitelisted",
+                   drv->format_name);
         return -ENOTSUP;
     }
 
     assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */
-    if (!bs->read_only && (flags & BDRV_O_COPY_ON_READ)) {
-        bdrv_enable_copy_on_read(bs);
+    if (flags & BDRV_O_COPY_ON_READ) {
+        if (!bs->read_only) {
+            bdrv_enable_copy_on_read(bs);
+        } else {
+            error_setg(errp, "Can't use copy-on-read on read-only device");
+            return -EINVAL;
+        }
     }
 
     if (filename != NULL) {
@@ -760,33 +801,40 @@ static int bdrv_open_common(BlockDriverState *bs, BlockDriverState *file,
     /* Open the image, either directly or using a protocol */
     if (drv->bdrv_file_open) {
         assert(file == NULL);
-        assert(drv->bdrv_parse_filename || filename != NULL);
-        ret = drv->bdrv_file_open(bs, options, open_flags);
+        assert(!drv->bdrv_needs_filename || filename != NULL);
+        ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
     } else {
         if (file == NULL) {
-            qerror_report(ERROR_CLASS_GENERIC_ERROR, "Can't use '%s' as a "
-                          "block driver for the protocol level",
-                          drv->format_name);
+            error_setg(errp, "Can't use '%s' as a block driver for the "
+                       "protocol level", drv->format_name);
             ret = -EINVAL;
             goto free_and_fail;
         }
         bs->file = file;
-        ret = drv->bdrv_open(bs, options, open_flags);
+        ret = drv->bdrv_open(bs, options, open_flags, &local_err);
     }
 
     if (ret < 0) {
+        if (error_is_set(&local_err)) {
+            error_propagate(errp, local_err);
+        } else if (bs->filename[0]) {
+            error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
+        } else {
+            error_setg_errno(errp, -ret, "Could not open image");
+        }
         goto free_and_fail;
     }
 
     ret = refresh_total_sectors(bs, bs->total_sectors);
     if (ret < 0) {
+        error_setg_errno(errp, -ret, "Could not refresh total sector count");
         goto free_and_fail;
     }
 
 #ifndef _WIN32
     if (bs->is_temporary) {
-        assert(filename != NULL);
-        unlink(filename);
+        assert(bs->filename[0] != '\0');
+        unlink(bs->filename);
     }
 #endif
     return 0;
@@ -808,12 +856,13 @@ free_and_fail:
  * dictionary, it needs to use QINCREF() before calling bdrv_file_open.
  */
 int bdrv_file_open(BlockDriverState **pbs, const char *filename,
-                   QDict *options, int flags)
+                   QDict *options, int flags, Error **errp)
 {
     BlockDriverState *bs;
     BlockDriver *drv;
     const char *drvname;
     bool allow_protocol_prefix = false;
+    Error *local_err = NULL;
     int ret;
 
     /* NULL means an empty set of options */
@@ -832,8 +881,8 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
         qdict_put(options, "filename", qstring_from_str(filename));
         allow_protocol_prefix = true;
     } else {
-        qerror_report(ERROR_CLASS_GENERIC_ERROR, "Can't specify 'file' and "
-                      "'filename' options at the same time");
+        error_setg(errp, "Can't specify 'file' and 'filename' options at the "
+                   "same time");
         ret = -EINVAL;
         goto fail;
     }
@@ -841,54 +890,54 @@ int bdrv_file_open(BlockDriverState **pbs, const char *filename,
     /* Find the right block driver */
     drvname = qdict_get_try_str(options, "driver");
     if (drvname) {
-        drv = bdrv_find_whitelisted_format(drvname, !(flags & BDRV_O_RDWR));
+        drv = bdrv_find_format(drvname);
+        if (!drv) {
+            error_setg(errp, "Unknown driver '%s'", drvname);
+        }
         qdict_del(options, "driver");
     } else if (filename) {
         drv = bdrv_find_protocol(filename, allow_protocol_prefix);
         if (!drv) {
-            qerror_report(ERROR_CLASS_GENERIC_ERROR, "Unknown protocol");
+            error_setg(errp, "Unknown protocol");
         }
     } else {
-        qerror_report(ERROR_CLASS_GENERIC_ERROR,
-                      "Must specify either driver or file");
+        error_setg(errp, "Must specify either driver or file");
         drv = NULL;
     }
 
     if (!drv) {
+        /* errp has been set already */
         ret = -ENOENT;
         goto fail;
     }
 
     /* Parse the filename and open it */
     if (drv->bdrv_parse_filename && filename) {
-        Error *local_err = NULL;
         drv->bdrv_parse_filename(filename, options, &local_err);
         if (error_is_set(&local_err)) {
-            qerror_report_err(local_err);
-            error_free(local_err);
+            error_propagate(errp, local_err);
             ret = -EINVAL;
             goto fail;
         }
         qdict_del(options, "filename");
-    } else if (!drv->bdrv_parse_filename && !filename) {
-        qerror_report(ERROR_CLASS_GENERIC_ERROR,
-                      "The '%s' block driver requires a file name",
-                      drv->format_name);
+    } else if (drv->bdrv_needs_filename && !filename) {
+        error_setg(errp, "The '%s' block driver requires a file name",
+                   drv->format_name);
         ret = -EINVAL;
         goto fail;
     }
 
-    ret = bdrv_open_common(bs, NULL, options, flags, drv);
+    ret = bdrv_open_common(bs, NULL, options, flags, drv, &local_err);
     if (ret < 0) {
+        error_propagate(errp, local_err);
         goto fail;
     }
 
     /* Check if any unknown options were used */
     if (qdict_size(options) != 0) {
         const QDictEntry *entry = qdict_first(options);
-        qerror_report(ERROR_CLASS_GENERIC_ERROR, "Block protocol '%s' doesn't "
-                      "support the option '%s'",
-                      drv->format_name, entry->key);
+        error_setg(errp, "Block protocol '%s' doesn't support the option '%s'",
+                   drv->format_name, entry->key);
         ret = -EINVAL;
         goto fail;
     }
@@ -915,11 +964,12 @@ fail:
  * function (even on failure), so if the caller intends to reuse the dictionary,
  * it needs to use QINCREF() before calling bdrv_file_open.
  */
-int bdrv_open_backing_file(BlockDriverState *bs, QDict *options)
+int bdrv_open_backing_file(BlockDriverState *bs, QDict *options, Error **errp)
 {
     char backing_filename[PATH_MAX];
     int back_flags, ret;
     BlockDriver *back_drv = NULL;
+    Error *local_err = NULL;
 
     if (bs->backing_hd != NULL) {
         QDECREF(options);
@@ -937,50 +987,38 @@ int bdrv_open_backing_file(BlockDriverState *bs, QDict *options)
     } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
         QDECREF(options);
         return 0;
+    } else {
+        bdrv_get_full_backing_filename(bs, backing_filename,
+                                       sizeof(backing_filename));
     }
 
     bs->backing_hd = bdrv_new("");
-    bdrv_get_full_backing_filename(bs, backing_filename,
-                                   sizeof(backing_filename));
 
     if (bs->backing_format[0] != '\0') {
         back_drv = bdrv_find_format(bs->backing_format);
     }
 
     /* backing files always opened read-only */
-    back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT);
+    back_flags = bs->open_flags & ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT |
+                                    BDRV_O_COPY_ON_READ);
 
     ret = bdrv_open(bs->backing_hd,
                     *backing_filename ? backing_filename : NULL, options,
-                    back_flags, back_drv);
+                    back_flags, back_drv, &local_err);
     if (ret < 0) {
         bdrv_unref(bs->backing_hd);
         bs->backing_hd = NULL;
         bs->open_flags |= BDRV_O_NO_BACKING;
+        error_setg(errp, "Could not open backing file: %s",
+                   error_get_pretty(local_err));
+        error_free(local_err);
         return ret;
     }
+    pstrcpy(bs->backing_file, sizeof(bs->backing_file),
+            bs->backing_hd->file->filename);
     return 0;
 }
 
-static void extract_subqdict(QDict *src, QDict **dst, const char *start)
-{
-    const QDictEntry *entry, *next;
-    const char *p;
-
-    *dst = qdict_new();
-    entry = qdict_first(src);
-
-    while (entry != NULL) {
-        next = qdict_next(src, entry);
-        if (strstart(entry->key, start, &p)) {
-            qobject_incref(entry->value);
-            qdict_put_obj(*dst, p, entry->value);
-            qdict_del(src, entry->key);
-        }
-        entry = next;
-    }
-}
-
 /*
  * Opens a disk image (raw, qcow2, vmdk, ...)
  *
@@ -990,7 +1028,7 @@ static void extract_subqdict(QDict *src, QDict **dst, const char *start)
  * dictionary, it needs to use QINCREF() before calling bdrv_open.
  */
 int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
-              int flags, BlockDriver *drv)
+              int flags, BlockDriver *drv, Error **errp)
 {
     int ret;
     /* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
@@ -998,6 +1036,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
     BlockDriverState *file = NULL;
     QDict *file_options = NULL;
     const char *drvname;
+    Error *local_err = NULL;
 
     /* NULL means an empty set of options */
     if (options == NULL) {
@@ -1016,7 +1055,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
         char backing_filename[PATH_MAX];
 
         if (qdict_size(options) != 0) {
-            error_report("Can't use snapshot=on with driver-specific options");
+            error_setg(errp, "Can't use snapshot=on with driver-specific options");
             ret = -EINVAL;
             goto fail;
         }
@@ -1027,7 +1066,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
 
         /* if there is a backing file, use it */
         bs1 = bdrv_new("");
-        ret = bdrv_open(bs1, filename, NULL, 0, drv);
+        ret = bdrv_open(bs1, filename, NULL, 0, drv, &local_err);
         if (ret < 0) {
             bdrv_unref(bs1);
             goto fail;
@@ -1038,6 +1077,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
 
         ret = get_tmp_filename(tmp_filename, sizeof(tmp_filename));
         if (ret < 0) {
+            error_setg_errno(errp, -ret, "Could not get temporary filename");
             goto fail;
         }
 
@@ -1047,6 +1087,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
                      "%s", filename);
         } else if (!realpath(filename, backing_filename)) {
             ret = -errno;
+            error_setg_errno(errp, errno, "Could not resolve path '%s'", filename);
             goto fail;
         }
 
@@ -1062,9 +1103,14 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
                 drv->format_name);
         }
 
-        ret = bdrv_create(bdrv_qcow2, tmp_filename, create_options);
+        ret = bdrv_create(bdrv_qcow2, tmp_filename, create_options, &local_err);
         free_option_parameters(create_options);
         if (ret < 0) {
+            error_setg_errno(errp, -ret, "Could not create temporary overlay "
+                             "'%s': %s", tmp_filename,
+                             error_get_pretty(local_err));
+            error_free(local_err);
+            local_err = NULL;
             goto fail;
         }
 
@@ -1078,10 +1124,10 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
         flags |= BDRV_O_ALLOW_RDWR;
     }
 
-    extract_subqdict(options, &file_options, "file.");
+    qdict_extract_subqdict(options, &file_options, "file.");
 
     ret = bdrv_file_open(&file, filename, file_options,
-                         bdrv_open_flags(bs, flags | BDRV_O_UNMAP));
+                         bdrv_open_flags(bs, flags | BDRV_O_UNMAP), &local_err);
     if (ret < 0) {
         goto fail;
     }
@@ -1089,12 +1135,17 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
     /* Find the right image format driver */
     drvname = qdict_get_try_str(options, "driver");
     if (drvname) {
-        drv = bdrv_find_whitelisted_format(drvname, !(flags & BDRV_O_RDWR));
+        drv = bdrv_find_format(drvname);
         qdict_del(options, "driver");
+        if (!drv) {
+            error_setg(errp, "Invalid driver: '%s'", drvname);
+            ret = -EINVAL;
+            goto unlink_and_fail;
+        }
     }
 
     if (!drv) {
-        ret = find_image_format(file, filename, &drv);
+        ret = find_image_format(file, filename, &drv, &local_err);
     }
 
     if (!drv) {
@@ -1102,7 +1153,7 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
     }
 
     /* Open the image */
-    ret = bdrv_open_common(bs, file, options, flags, drv);
+    ret = bdrv_open_common(bs, file, options, flags, drv, &local_err);
     if (ret < 0) {
         goto unlink_and_fail;
     }
@@ -1116,8 +1167,8 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
     if ((flags & BDRV_O_NO_BACKING) == 0) {
         QDict *backing_options;
 
-        extract_subqdict(options, &backing_options, "backing.");
-        ret = bdrv_open_backing_file(bs, backing_options);
+        qdict_extract_subqdict(options, &backing_options, "backing.");
+        ret = bdrv_open_backing_file(bs, backing_options, &local_err);
         if (ret < 0) {
             goto close_and_fail;
         }
@@ -1126,9 +1177,9 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
     /* Check if any unknown options were used */
     if (qdict_size(options) != 0) {
         const QDictEntry *entry = qdict_first(options);
-        qerror_report(ERROR_CLASS_GENERIC_ERROR, "Block format '%s' used by "
-            "device '%s' doesn't support the option '%s'",
-            drv->format_name, bs->device_name, entry->key);
+        error_setg(errp, "Block format '%s' used by device '%s' doesn't "
+                   "support the option '%s'", drv->format_name, bs->device_name,
+                   entry->key);
 
         ret = -EINVAL;
         goto close_and_fail;
@@ -1152,11 +1203,17 @@ fail:
     QDECREF(bs->options);
     QDECREF(options);
     bs->options = NULL;
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+    }
     return ret;
 
 close_and_fail:
     bdrv_close(bs);
     QDECREF(options);
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+    }
     return ret;
 }
 
@@ -2613,7 +2670,7 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
             goto out;
         }
 
-        total_sectors = len >> BDRV_SECTOR_BITS;
+        total_sectors = DIV_ROUND_UP(len, BDRV_SECTOR_SIZE);
         max_nb_sectors = MAX(0, total_sectors - sector_num);
         if (max_nb_sectors > 0) {
             ret = drv->bdrv_co_readv(bs, sector_num,
@@ -2819,9 +2876,10 @@ int64_t bdrv_getlength(BlockDriverState *bs)
     if (!drv)
         return -ENOMEDIUM;
 
-    if (bdrv_dev_has_removable_media(bs)) {
-        if (drv->bdrv_getlength) {
-            return drv->bdrv_getlength(bs);
+    if (drv->has_variable_length) {
+        int ret = refresh_total_sectors(bs, bs->total_sectors);
+        if (ret < 0) {
+            return ret;
         }
     }
     return bs->total_sectors * BDRV_SECTOR_SIZE;
@@ -3031,6 +3089,11 @@ int bdrv_has_zero_init(BlockDriverState *bs)
 {
     assert(bs->drv);
 
+    /* If BS is a copy on write image, it is initialized to
+       the contents of the base image, which may not be zeroes.  */
+    if (bs->backing_hd) {
+        return 0;
+    }
     if (bs->drv->bdrv_has_zero_init) {
         return bs->drv->bdrv_has_zero_init(bs);
     }
@@ -3039,15 +3102,15 @@ int bdrv_has_zero_init(BlockDriverState *bs)
     return 0;
 }
 
-typedef struct BdrvCoIsAllocatedData {
+typedef struct BdrvCoGetBlockStatusData {
     BlockDriverState *bs;
     BlockDriverState *base;
     int64_t sector_num;
     int nb_sectors;
     int *pnum;
-    int ret;
+    int64_t ret;
     bool done;
-} BdrvCoIsAllocatedData;
+} BdrvCoGetBlockStatusData;
 
 /*
  * Returns true iff the specified sector is present in the disk image. Drivers
@@ -3064,12 +3127,13 @@ typedef struct BdrvCoIsAllocatedData {
  * 'nb_sectors' is the max value 'pnum' should be set to.  If nb_sectors goes
  * beyond the end of the disk image it will be clamped.
  */
-static int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs,
-                                             int64_t sector_num,
-                                             int nb_sectors, int *pnum)
+static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
+                                                     int64_t sector_num,
+                                                     int nb_sectors, int *pnum)
 {
     int64_t length;
     int64_t n;
+    int64_t ret, ret2;
 
     length = bdrv_getlength(bs);
     if (length < 0) {
@@ -3086,35 +3150,76 @@ static int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs,
         nb_sectors = n;
     }
 
-    if (!bs->drv->bdrv_co_is_allocated) {
+    if (!bs->drv->bdrv_co_get_block_status) {
         *pnum = nb_sectors;
-        return 1;
+        ret = BDRV_BLOCK_DATA;
+        if (bs->drv->protocol_name) {
+            ret |= BDRV_BLOCK_OFFSET_VALID | (sector_num * BDRV_SECTOR_SIZE);
+        }
+        return ret;
+    }
+
+    ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum);
+    if (ret < 0) {
+        *pnum = 0;
+        return ret;
+    }
+
+    if (ret & BDRV_BLOCK_RAW) {
+        assert(ret & BDRV_BLOCK_OFFSET_VALID);
+        return bdrv_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
+                                     *pnum, pnum);
+    }
+
+    if (!(ret & BDRV_BLOCK_DATA)) {
+        if (bdrv_has_zero_init(bs)) {
+            ret |= BDRV_BLOCK_ZERO;
+        } else if (bs->backing_hd) {
+            BlockDriverState *bs2 = bs->backing_hd;
+            int64_t length2 = bdrv_getlength(bs2);
+            if (length2 >= 0 && sector_num >= (length2 >> BDRV_SECTOR_BITS)) {
+                ret |= BDRV_BLOCK_ZERO;
+            }
+        }
+    }
+
+    if (bs->file &&
+        (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
+        (ret & BDRV_BLOCK_OFFSET_VALID)) {
+        ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
+                                        *pnum, pnum);
+        if (ret2 >= 0) {
+            /* Ignore errors.  This is just providing extra information, it
+             * is useful but not necessary.
+             */
+            ret |= (ret2 & BDRV_BLOCK_ZERO);
+        }
     }
 
-    return bs->drv->bdrv_co_is_allocated(bs, sector_num, nb_sectors, pnum);
+    return ret;
 }
 
-/* Coroutine wrapper for bdrv_is_allocated() */
-static void coroutine_fn bdrv_is_allocated_co_entry(void *opaque)
+/* Coroutine wrapper for bdrv_get_block_status() */
+static void coroutine_fn bdrv_get_block_status_co_entry(void *opaque)
 {
-    BdrvCoIsAllocatedData *data = opaque;
+    BdrvCoGetBlockStatusData *data = opaque;
     BlockDriverState *bs = data->bs;
 
-    data->ret = bdrv_co_is_allocated(bs, data->sector_num, data->nb_sectors,
-                                     data->pnum);
+    data->ret = bdrv_co_get_block_status(bs, data->sector_num, data->nb_sectors,
+                                         data->pnum);
     data->done = true;
 }
 
 /*
- * Synchronous wrapper around bdrv_co_is_allocated().
+ * Synchronous wrapper around bdrv_co_get_block_status().
  *
- * See bdrv_co_is_allocated() for details.
+ * See bdrv_co_get_block_status() for details.
  */
-int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
-                      int *pnum)
+int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
+                              int nb_sectors, int *pnum)
 {
     Coroutine *co;
-    BdrvCoIsAllocatedData data = {
+    BdrvCoGetBlockStatusData data = {
         .bs = bs,
         .sector_num = sector_num,
         .nb_sectors = nb_sectors,
@@ -3124,9 +3229,9 @@ int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
 
     if (qemu_in_coroutine()) {
         /* Fast-path if already in coroutine context */
-        bdrv_is_allocated_co_entry(&data);
+        bdrv_get_block_status_co_entry(&data);
     } else {
-        co = qemu_coroutine_create(bdrv_is_allocated_co_entry);
+        co = qemu_coroutine_create(bdrv_get_block_status_co_entry);
         qemu_coroutine_enter(co, &data);
         while (!data.done) {
             qemu_aio_wait();
@@ -3135,6 +3240,18 @@ int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
     return data.ret;
 }
 
+int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
+                                   int nb_sectors, int *pnum)
+{
+    int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum);
+    if (ret < 0) {
+        return ret;
+    }
+    return
+        (ret & BDRV_BLOCK_DATA) ||
+        ((ret & BDRV_BLOCK_ZERO) && !bdrv_has_zero_init(bs));
+}
+
 /*
  * Given an image chain: ... -> [BASE] -> [INTER1] -> [INTER2] -> [TOP]
  *
@@ -3229,6 +3346,15 @@ int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     return drv->bdrv_get_info(bs, bdi);
 }
 
+ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs)
+{
+    BlockDriver *drv = bs->drv;
+    if (drv && drv->bdrv_get_specific_info) {
+        return drv->bdrv_get_specific_info(bs);
+    }
+    return NULL;
+}
+
 int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
                       int64_t pos, int size)
 {
@@ -4381,6 +4507,7 @@ void bdrv_img_create(const char *filename, const char *fmt,
     BlockDriverState *bs = NULL;
     BlockDriver *drv, *proto_drv;
     BlockDriver *backing_drv = NULL;
+    Error *local_err = NULL;
     int ret = 0;
 
     /* Find driver and parse its options */
@@ -4467,10 +4594,13 @@ void bdrv_img_create(const char *filename, const char *fmt,
             bs = bdrv_new("");
 
             ret = bdrv_open(bs, backing_file->value.s, NULL, back_flags,
-                            backing_drv);
+                            backing_drv, &local_err);
             if (ret < 0) {
-                error_setg_errno(errp, -ret, "Could not open '%s'",
-                                 backing_file->value.s);
+                error_setg_errno(errp, -ret, "Could not open '%s': %s",
+                                 backing_file->value.s,
+                                 error_get_pretty(local_err));
+                error_free(local_err);
+                local_err = NULL;
                 goto out;
             }
             bdrv_get_geometry(bs, &size);
@@ -4489,22 +4619,19 @@ void bdrv_img_create(const char *filename, const char *fmt,
         print_option_parameters(param);
         puts("");
     }
-    ret = bdrv_create(drv, filename, param);
-    if (ret < 0) {
-        if (ret == -ENOTSUP) {
-            error_setg(errp,"Formatting or formatting option not supported for "
-                            "file format '%s'", fmt);
-        } else if (ret == -EFBIG) {
-            const char *cluster_size_hint = "";
-            if (get_option_parameter(create_options, BLOCK_OPT_CLUSTER_SIZE)) {
-                cluster_size_hint = " (try using a larger cluster size)";
-            }
-            error_setg(errp, "The image size is too large for file format '%s'%s",
-                       fmt, cluster_size_hint);
-        } else {
-            error_setg(errp, "%s: error while creating %s: %s", filename, fmt,
-                       strerror(-ret));
+    ret = bdrv_create(drv, filename, param, &local_err);
+    if (ret == -EFBIG) {
+        /* This is generally a better message than whatever the driver would
+         * deliver (especially because of the cluster_size_hint), since that
+         * is most probably not much different from "image too large". */
+        const char *cluster_size_hint = "";
+        if (get_option_parameter(create_options, BLOCK_OPT_CLUSTER_SIZE)) {
+            cluster_size_hint = " (try using a larger cluster size)";
         }
+        error_setg(errp, "The image size is too large for file format '%s'"
+                   "%s", fmt, cluster_size_hint);
+        error_free(local_err);
+        local_err = NULL;
     }
 
 out:
@@ -4514,6 +4641,9 @@ out:
     if (bs) {
         bdrv_unref(bs);
     }
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
+    }
 }
 
 AioContext *bdrv_get_aio_context(BlockDriverState *bs)
@@ -4527,3 +4657,30 @@ void bdrv_add_before_write_notifier(BlockDriverState *bs,
 {
     notifier_with_return_list_add(&bs->before_write_notifiers, notifier);
 }
+
+int bdrv_amend_options(BlockDriverState *bs, QEMUOptionParameter *options)
+{
+    if (bs->drv->bdrv_amend_options == NULL) {
+        return -ENOTSUP;
+    }
+    return bs->drv->bdrv_amend_options(bs, options);
+}
+
+ExtSnapshotPerm bdrv_check_ext_snapshot(BlockDriverState *bs)
+{
+    if (bs->drv->bdrv_check_ext_snapshot) {
+        return bs->drv->bdrv_check_ext_snapshot(bs);
+    }
+
+    if (bs->file && bs->file->drv && bs->file->drv->bdrv_check_ext_snapshot) {
+        return bs->file->drv->bdrv_check_ext_snapshot(bs);
+    }
+
+    /* external snapshots are allowed by default */
+    return EXT_SNAPSHOT_ALLOWED;
+}
+
+ExtSnapshotPerm bdrv_check_ext_snapshot_forbidden(BlockDriverState *bs)
+{
+    return EXT_SNAPSHOT_FORBIDDEN;
+}