Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches for 2.11.0-rc2

# gpg: Signature made Fri 17 Nov 2017 17:58:36 GMT
# gpg:                using RSA key 0x7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream: (25 commits)
  iotests: Make 087 pass without AIO enabled
  block: Make bdrv_next() keep strong references
  qcow2: Fix overly broad madvise()
  qcow2: Refuse to get unaligned offsets from cache
  qcow2: Add bounds check to get_refblock_offset()
  block: Guard against NULL bs->drv
  qcow2: Unaligned zero cluster in handle_alloc()
  qcow2: check_errors are fatal
  qcow2: reject unaligned offsets in write compressed
  iotests: Add test for failing qemu-img commit
  tests: Add check-qobject for equality tests
  iotests: Add test for non-string option reopening
  block: qobject_is_equal() in bdrv_reopen_prepare()
  qapi: Add qobject_is_equal()
  qapi/qlist: Add qlist_append_null() macro
  qapi/qnull: Add own header
  qcow2: fix image corruption on commit with persistent bitmap
  iotests: test clearing unknown autoclear_features by qcow2
  block: Fix permissions in image activation
  qcow2: fix image corruption after committing qcow2 image into base
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

15 files changed, 244 insertions, 39 deletions

diff --git a/block/block-backend.c b/block/block-backend.c
index f10b1db..5836cb3 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -442,21 +442,37 @@ BlockBackend *blk_next(BlockBackend *blk)
  * the monitor or attached to a BlockBackend */
 BlockDriverState *bdrv_next(BdrvNextIterator *it)
 {
-    BlockDriverState *bs;
+    BlockDriverState *bs, *old_bs;
+
+    /* Must be called from the main loop */
+    assert(qemu_get_current_aio_context() == qemu_get_aio_context());
 
     /* First, return all root nodes of BlockBackends. In order to avoid
      * returning a BDS twice when multiple BBs refer to it, we only return it
      * if the BB is the first one in the parent list of the BDS. */
     if (it->phase == BDRV_NEXT_BACKEND_ROOTS) {
+        BlockBackend *old_blk = it->blk;
+
+        old_bs = old_blk ? blk_bs(old_blk) : NULL;
+
         do {
             it->blk = blk_all_next(it->blk);
             bs = it->blk ? blk_bs(it->blk) : NULL;
         } while (it->blk && (bs == NULL || bdrv_first_blk(bs) != it->blk));
 
+        if (it->blk) {
+            blk_ref(it->blk);
+        }
+        blk_unref(old_blk);
+
         if (bs) {
+            bdrv_ref(bs);
+            bdrv_unref(old_bs);
             return bs;
         }
         it->phase = BDRV_NEXT_MONITOR_OWNED;
+    } else {
+        old_bs = it->bs;
     }
 
     /* Then return the monitor-owned BDSes without a BB attached. Ignore all
@@ -467,18 +483,46 @@ BlockDriverState *bdrv_next(BdrvNextIterator *it)
         bs = it->bs;
     } while (bs && bdrv_has_blk(bs));
 
+    if (bs) {
+        bdrv_ref(bs);
+    }
+    bdrv_unref(old_bs);
+
     return bs;
 }
 
-BlockDriverState *bdrv_first(BdrvNextIterator *it)
+static void bdrv_next_reset(BdrvNextIterator *it)
 {
     *it = (BdrvNextIterator) {
         .phase = BDRV_NEXT_BACKEND_ROOTS,
     };
+}
 
+BlockDriverState *bdrv_first(BdrvNextIterator *it)
+{
+    bdrv_next_reset(it);
     return bdrv_next(it);
 }
 
+/* Must be called when aborting a bdrv_next() iteration before
+ * bdrv_next() returns NULL */
+void bdrv_next_cleanup(BdrvNextIterator *it)
+{
+    /* Must be called from the main loop */
+    assert(qemu_get_current_aio_context() == qemu_get_aio_context());
+
+    if (it->phase == BDRV_NEXT_BACKEND_ROOTS) {
+        if (it->blk) {
+            bdrv_unref(blk_bs(it->blk));
+            blk_unref(it->blk);
+        }
+    } else {
+        bdrv_unref(it->bs);
+    }
+
+    bdrv_next_reset(it);
+}
+
 /*
  * Add a BlockBackend into the list of backends referenced by the monitor, with
  * the given @name acting as the handle for the monitor.
diff --git a/block/bochs.c b/block/bochs.c
index a759b6e..50c6300 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -28,6 +28,7 @@
 #include "block/block_int.h"
 #include "qemu/module.h"
 #include "qemu/bswap.h"
+#include "qemu/error-report.h"
 
 /**************************************************************/
 
@@ -110,9 +111,15 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
         return -EINVAL;
     }
 
-    ret = bdrv_set_read_only(bs, true, errp); /* no write support yet */
-    if (ret < 0) {
-        return ret;
+    if (!bdrv_is_read_only(bs)) {
+        error_report("Opening bochs images without an explicit read-only=on "
+                     "option is deprecated. Future versions will refuse to "
+                     "open the image instead of automatically marking the "
+                     "image read-only.");
+        ret = bdrv_set_read_only(bs, true, errp); /* no write support yet */
+        if (ret < 0) {
+            return ret;
+        }
     }
 
     ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
diff --git a/block/cloop.c b/block/cloop.c
index d6597fc..2be6898 100644
--- a/block/cloop.c
+++ b/block/cloop.c
@@ -23,6 +23,7 @@
  */
 #include "qemu/osdep.h"
 #include "qapi/error.h"
+#include "qemu/error-report.h"
 #include "qemu-common.h"
 #include "block/block_int.h"
 #include "qemu/module.h"
@@ -72,9 +73,15 @@ static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
         return -EINVAL;
     }
 
-    ret = bdrv_set_read_only(bs, true, errp);
-    if (ret < 0) {
-        return ret;
+    if (!bdrv_is_read_only(bs)) {
+        error_report("Opening cloop images without an explicit read-only=on "
+                     "option is deprecated. Future versions will refuse to "
+                     "open the image instead of automatically marking the "
+                     "image read-only.");
+        ret = bdrv_set_read_only(bs, true, errp);
+        if (ret < 0) {
+            return ret;
+        }
     }
 
     /* read header */
diff --git a/block/dmg.c b/block/dmg.c
index 6c0711f..c9b3c51 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -419,9 +419,15 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags,
         return -EINVAL;
     }
 
-    ret = bdrv_set_read_only(bs, true, errp);
-    if (ret < 0) {
-        return ret;
+    if (!bdrv_is_read_only(bs)) {
+        error_report("Opening dmg images without an explicit read-only=on "
+                     "option is deprecated. Future versions will refuse to "
+                     "open the image instead of automatically marking the "
+                     "image read-only.");
+        ret = bdrv_set_read_only(bs, true, errp);
+        if (ret < 0) {
+            return ret;
+        }
     }
 
     block_module_load_one("dmg-bz2");
diff --git a/block/io.c b/block/io.c
index 3d5ef2c..4fdf93a 100644
--- a/block/io.c
+++ b/block/io.c
@@ -853,6 +853,10 @@ static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs,
 
     assert(!(flags & ~BDRV_REQ_MASK));
 
+    if (!drv) {
+        return -ENOMEDIUM;
+    }
+
     if (drv->bdrv_co_preadv) {
         return drv->bdrv_co_preadv(bs, offset, bytes, qiov, flags);
     }
@@ -894,6 +898,10 @@ static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs,
 
     assert(!(flags & ~BDRV_REQ_MASK));
 
+    if (!drv) {
+        return -ENOMEDIUM;
+    }
+
     if (drv->bdrv_co_pwritev) {
         ret = drv->bdrv_co_pwritev(bs, offset, bytes, qiov,
                                    flags & bs->supported_write_flags);
@@ -945,6 +953,10 @@ bdrv_driver_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
 {
     BlockDriver *drv = bs->drv;
 
+    if (!drv) {
+        return -ENOMEDIUM;
+    }
+
     if (!drv->bdrv_co_pwritev_compressed) {
         return -ENOTSUP;
     }
@@ -975,6 +987,10 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
                                     BDRV_REQUEST_MAX_BYTES);
     unsigned int progress = 0;
 
+    if (!drv) {
+        return -ENOMEDIUM;
+    }
+
     /* FIXME We cannot require callers to have write permissions when all they
      * are doing is a read request. If we did things right, write permissions
      * would be obtained anyway, but internally by the copy-on-read code. As
@@ -1291,6 +1307,10 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
                         bs->bl.request_alignment);
     int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, MAX_BOUNCE_BUFFER);
 
+    if (!drv) {
+        return -ENOMEDIUM;
+    }
+
     assert(alignment % bs->bl.request_alignment == 0);
     head = offset % alignment;
     tail = (offset + bytes) % alignment;
@@ -1397,6 +1417,10 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
     uint64_t bytes_remaining = bytes;
     int max_transfer;
 
+    if (!drv) {
+        return -ENOMEDIUM;
+    }
+
     if (bdrv_has_readonly_bitmaps(bs)) {
         return -EPERM;
     }
@@ -1863,6 +1887,8 @@ static int coroutine_fn bdrv_co_block_status(BlockDriverState *bs,
         bytes = n;
     }
 
+    /* Must be non-NULL or bdrv_getlength() would have failed */
+    assert(bs->drv);
     if (!bs->drv->bdrv_co_get_block_status) {
         *pnum = bytes;
         ret = BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED;
@@ -2373,6 +2399,12 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
     }
 
     BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
+    if (!bs->drv) {
+        /* bs->drv->bdrv_co_flush() might have ejected the BDS
+         * (even in case of apparent success) */
+        ret = -ENOMEDIUM;
+        goto out;
+    }
     if (bs->drv->bdrv_co_flush_to_disk) {
         ret = bs->drv->bdrv_co_flush_to_disk(bs);
     } else if (bs->drv->bdrv_aio_flush) {
@@ -2542,6 +2574,10 @@ int coroutine_fn bdrv_co_pdiscard(BlockDriverState *bs, int64_t offset,
             num = max_pdiscard;
         }
 
+        if (!bs->drv) {
+            ret = -ENOMEDIUM;
+            goto out;
+        }
         if (bs->drv->bdrv_co_pdiscard) {
             ret = bs->drv->bdrv_co_pdiscard(bs, offset, num);
         } else {
diff --git a/block/qapi.c b/block/qapi.c
index 7fa2437..fc10f0a 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -39,8 +39,14 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
 {
     ImageInfo **p_image_info;
     BlockDriverState *bs0;
-    BlockDeviceInfo *info = g_malloc0(sizeof(*info));
+    BlockDeviceInfo *info;
 
+    if (!bs->drv) {
+        error_setg(errp, "Block device %s is ejected", bs->node_name);
+        return NULL;
+    }
+
+    info = g_malloc0(sizeof(*info));
     info->file                   = g_strdup(bs->filename);
     info->ro                     = bs->read_only;
     info->drv                    = g_strdup(bs->drv->format_name);
diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 75746a7..c48ffeb 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -62,6 +62,18 @@ static inline int qcow2_cache_get_table_idx(BlockDriverState *bs,
     return idx;
 }
 
+static inline const char *qcow2_cache_get_name(BDRVQcow2State *s, Qcow2Cache *c)
+{
+    if (c == s->refcount_block_cache) {
+        return "refcount block";
+    } else if (c == s->l2_table_cache) {
+        return "L2 table";
+    } else {
+        /* Do not abort, because this is not critical */
+        return "unknown";
+    }
+}
+
 static void qcow2_cache_table_release(BlockDriverState *bs, Qcow2Cache *c,
                                       int i, int num_tables)
 {
@@ -73,7 +85,7 @@ static void qcow2_cache_table_release(BlockDriverState *bs, Qcow2Cache *c,
     size_t mem_size = (size_t) s->cluster_size * num_tables;
     size_t offset = QEMU_ALIGN_UP((uintptr_t) t, align) - (uintptr_t) t;
     size_t length = QEMU_ALIGN_DOWN(mem_size - offset, align);
-    if (length > 0) {
+    if (mem_size > offset && length > 0) {
         madvise((uint8_t *) t + offset, length, MADV_DONTNEED);
     }
 #endif
@@ -314,9 +326,18 @@ static int qcow2_cache_do_get(BlockDriverState *bs, Qcow2Cache *c,
     uint64_t min_lru_counter = UINT64_MAX;
     int min_lru_index = -1;
 
+    assert(offset != 0);
+
     trace_qcow2_cache_get(qemu_coroutine_self(), c == s->l2_table_cache,
                           offset, read_from_disk);
 
+    if (offset_into_cluster(s, offset)) {
+        qcow2_signal_corruption(bs, true, -1, -1, "Cannot get entry from %s "
+                                "cache: Offset %#" PRIx64 " is unaligned",
+                                qcow2_cache_get_name(s, c), offset);
+        return -EIO;
+    }
+
     /* Check if the table is already cached */
     i = lookup_index = (offset / s->cluster_size * 4) % c->size;
     do {
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 2e072ed..a3fec27 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1308,10 +1308,21 @@ static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
         (!*host_offset ||
          start_of_cluster(s, *host_offset) == (entry & L2E_OFFSET_MASK)))
     {
+        int preallocated_nb_clusters;
+
+        if (offset_into_cluster(s, entry & L2E_OFFSET_MASK)) {
+            qcow2_signal_corruption(bs, true, -1, -1, "Preallocated zero "
+                                    "cluster offset %#llx unaligned (guest "
+                                    "offset: %#" PRIx64 ")",
+                                    entry & L2E_OFFSET_MASK, guest_offset);
+            ret = -EIO;
+            goto fail;
+        }
+
         /* Try to reuse preallocated zero clusters; contiguous normal clusters
          * would be fine, too, but count_cow_clusters() above has limited
          * nb_clusters already to a range of COW clusters */
-        int preallocated_nb_clusters =
+        preallocated_nb_clusters =
             count_contiguous_clusters(nb_clusters, s->cluster_size,
                                       &l2_table[l2_index], QCOW_OFLAG_COPIED);
         assert(preallocated_nb_clusters > 0);
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 60b8eef..3de1ab5 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -3077,16 +3077,40 @@ done:
     return ret;
 }
 
+static int64_t get_refblock_offset(BlockDriverState *bs, uint64_t offset)
+{
+    BDRVQcow2State *s = bs->opaque;
+    uint32_t index = offset_to_reftable_index(s, offset);
+    int64_t covering_refblock_offset = 0;
+
+    if (index < s->refcount_table_size) {
+        covering_refblock_offset = s->refcount_table[index] & REFT_OFFSET_MASK;
+    }
+    if (!covering_refblock_offset) {
+        qcow2_signal_corruption(bs, true, -1, -1, "Refblock at %#" PRIx64 " is "
+                                "not covered by the refcount structures",
+                                offset);
+        return -EIO;
+    }
+
+    return covering_refblock_offset;
+}
+
 static int qcow2_discard_refcount_block(BlockDriverState *bs,
                                         uint64_t discard_block_offs)
 {
     BDRVQcow2State *s = bs->opaque;
-    uint64_t refblock_offs = get_refblock_offset(s, discard_block_offs);
+    int64_t refblock_offs;
     uint64_t cluster_index = discard_block_offs >> s->cluster_bits;
     uint32_t block_index = cluster_index & (s->refcount_block_size - 1);
     void *refblock;
     int ret;
 
+    refblock_offs = get_refblock_offset(bs, discard_block_offs);
+    if (refblock_offs < 0) {
+        return refblock_offs;
+    }
+
     assert(discard_block_offs != 0);
 
     ret = qcow2_cache_get(bs, s->refcount_block_cache, refblock_offs,
diff --git a/block/qcow2.c b/block/qcow2.c
index b3d66a0..1914a94 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -376,6 +376,8 @@ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
 
         default:
             /* unknown magic - save it in case we need to rewrite the header */
+            /* If you add a new feature, make sure to also update the fast
+             * path of qcow2_make_empty() to deal with it. */
             {
                 Qcow2UnknownHeaderExtension *uext;
 
@@ -1475,7 +1477,10 @@ static int qcow2_do_open(BlockDriverState *bs, QDict *options, int flags,
         BdrvCheckResult result = {0};
 
         ret = qcow2_check(bs, &result, BDRV_FIX_ERRORS | BDRV_FIX_LEAKS);
-        if (ret < 0) {
+        if (ret < 0 || result.check_errors) {
+            if (ret >= 0) {
+                ret = -EIO;
+            }
             error_setg_errno(errp, -ret, "Could not repair dirty image");
             goto fail;
         }
@@ -3356,6 +3361,10 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
         return bdrv_truncate(bs->file, cluster_offset, PREALLOC_MODE_OFF, NULL);
     }
 
+    if (offset_into_cluster(s, offset)) {
+        return -EINVAL;
+    }
+
     buf = qemu_blockalign(bs, s->cluster_size);
     if (bytes != s->cluster_size) {
         if (bytes > s->cluster_size ||
@@ -3600,13 +3609,16 @@ static int qcow2_make_empty(BlockDriverState *bs)
 
     l1_clusters = DIV_ROUND_UP(s->l1_size, s->cluster_size / sizeof(uint64_t));
 
-    if (s->qcow_version >= 3 && !s->snapshots &&
-        3 + l1_clusters <= s->refcount_block_size) {
-        /* The following function only works for qcow2 v3 images (it requires
-         * the dirty flag) and only as long as there are no snapshots (because
-         * it completely empties the image). Furthermore, the L1 table and three
-         * additional clusters (image header, refcount table, one refcount
-         * block) have to fit inside one refcount block. */
+    if (s->qcow_version >= 3 && !s->snapshots && !s->nb_bitmaps &&
+        3 + l1_clusters <= s->refcount_block_size &&
+        s->crypt_method_header != QCOW_CRYPT_LUKS) {
+        /* The following function only works for qcow2 v3 images (it
+         * requires the dirty flag) and only as long as there are no
+         * features that reserve extra clusters (such as snapshots,
+         * LUKS header, or persistent bitmaps), because it completely
+         * empties the image.  Furthermore, the L1 table and three
+         * additional clusters (image header, refcount table, one
+         * refcount block) have to fit inside one refcount block. */
         return make_completely_empty(bs);
     }
 
@@ -4069,6 +4081,9 @@ static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
                 error_report("Changing the encryption format is not supported");
                 return -ENOTSUP;
             }
+        } else if (g_str_has_prefix(desc->name, "encrypt.")) {
+            error_report("Changing the encryption parameters is not supported");
+            return -ENOTSUP;
         } else if (!strcmp(desc->name, BLOCK_OPT_CLUSTER_SIZE)) {
             cluster_size = qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE,
                                              cluster_size);
diff --git a/block/qcow2.h b/block/qcow2.h
index 782a206..6f0ff15 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -527,12 +527,6 @@ uint32_t offset_to_reftable_index(BDRVQcow2State *s, uint64_t offset)
     return offset >> (s->refcount_block_bits + s->cluster_bits);
 }
 
-static inline uint64_t get_refblock_offset(BDRVQcow2State *s, uint64_t offset)
-{
-    uint32_t index = offset_to_reftable_index(s, offset);
-    return s->refcount_table[index] & REFT_OFFSET_MASK;
-}
-
 /* qcow2.c functions */
 int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
                   int64_t sector_num, int nb_sectors);
diff --git a/block/rbd.c b/block/rbd.c
index 144f350..a76a5e8 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -665,10 +665,16 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,
     /* If we are using an rbd snapshot, we must be r/o, otherwise
      * leave as-is */
     if (s->snap != NULL) {
-        r = bdrv_set_read_only(bs, true, &local_err);
-        if (r < 0) {
-            error_propagate(errp, local_err);
-            goto failed_open;
+        if (!bdrv_is_read_only(bs)) {
+            error_report("Opening rbd snapshots without an explicit "
+                         "read-only=on option is deprecated. Future versions "
+                         "will refuse to open the image instead of "
+                         "automatically marking the image read-only.");
+            r = bdrv_set_read_only(bs, true, &local_err);
+            if (r < 0) {
+                error_propagate(errp, local_err);
+                goto failed_open;
+            }
         }
     }
 
diff --git a/block/replication.c b/block/replication.c
index 3a4e682..e41e293 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -161,10 +161,13 @@ static void replication_child_perm(BlockDriverState *bs, BdrvChild *c,
                                    uint64_t perm, uint64_t shared,
                                    uint64_t *nperm, uint64_t *nshared)
 {
-    *nperm = *nshared = BLK_PERM_CONSISTENT_READ \
-                        | BLK_PERM_WRITE \
-                        | BLK_PERM_WRITE_UNCHANGED;
-
+    *nperm = BLK_PERM_CONSISTENT_READ;
+    if ((bs->open_flags & (BDRV_O_INACTIVE | BDRV_O_RDWR)) == BDRV_O_RDWR) {
+        *nperm |= BLK_PERM_WRITE;
+    }
+    *nshared = BLK_PERM_CONSISTENT_READ \
+               | BLK_PERM_WRITE \
+               | BLK_PERM_WRITE_UNCHANGED;
     return;
 }
 
@@ -339,12 +342,24 @@ static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp)
         return;
     }
 
+    if (!s->active_disk->bs->drv) {
+        error_setg(errp, "Active disk %s is ejected",
+                   s->active_disk->bs->node_name);
+        return;
+    }
+
     ret = s->active_disk->bs->drv->bdrv_make_empty(s->active_disk->bs);
     if (ret < 0) {
         error_setg(errp, "Cannot make active disk empty");
         return;
     }
 
+    if (!s->hidden_disk->bs->drv) {
+        error_setg(errp, "Hidden disk %s is ejected",
+                   s->hidden_disk->bs->node_name);
+        return;
+    }
+
     ret = s->hidden_disk->bs->drv->bdrv_make_empty(s->hidden_disk->bs);
     if (ret < 0) {
         error_setg(errp, "Cannot make hidden disk empty");
@@ -508,6 +523,9 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
             return;
         }
 
+        /* Must be true, or the bdrv_getlength() calls would have failed */
+        assert(s->active_disk->bs->drv && s->hidden_disk->bs->drv);
+
         if (!s->active_disk->bs->drv->bdrv_make_empty ||
             !s->hidden_disk->bs->drv->bdrv_make_empty) {
             error_setg(errp,
diff --git a/block/snapshot.c b/block/snapshot.c
index 1d5ab5f..be0743a 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -417,6 +417,7 @@ bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
         }
         aio_context_release(ctx);
         if (!ok) {
+            bdrv_next_cleanup(&it);
             goto fail;
         }
     }
@@ -444,6 +445,7 @@ int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
         }
         aio_context_release(ctx);
         if (ret < 0) {
+            bdrv_next_cleanup(&it);
             goto fail;
         }
     }
@@ -469,6 +471,7 @@ int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs)
         }
         aio_context_release(ctx);
         if (err < 0) {
+            bdrv_next_cleanup(&it);
             goto fail;
         }
     }
@@ -494,6 +497,7 @@ int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
         }
         aio_context_release(ctx);
         if (err < 0) {
+            bdrv_next_cleanup(&it);
             goto fail;
         }
     }
@@ -525,6 +529,7 @@ int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
         }
         aio_context_release(ctx);
         if (err < 0) {
+            bdrv_next_cleanup(&it);
             goto fail;
         }
     }
@@ -548,6 +553,7 @@ BlockDriverState *bdrv_all_find_vmstate_bs(void)
         aio_context_release(ctx);
 
         if (found) {
+            bdrv_next_cleanup(&it);
             break;
         }
     }
diff --git a/block/vvfat.c b/block/vvfat.c
index a0f2335..a690595 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -1259,7 +1259,11 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
                        "Unable to set VVFAT to 'rw' when drive is read-only");
             goto fail;
         }
-    } else  {
+    } else  if (!bdrv_is_read_only(bs)) {
+        error_report("Opening non-rw vvfat images without an explicit "
+                     "read-only=on option is deprecated. Future versions "
+                     "will refuse to open the image instead of "
+                     "automatically marking the image read-only.");
         /* read only is the default for safety */
         ret = bdrv_set_read_only(bs, true, &local_err);
         if (ret < 0) {
@@ -2943,7 +2947,7 @@ static int do_commit(BDRVVVFATState* s)
         return ret;
     }
 
-    if (s->qcow->bs->drv->bdrv_make_empty) {
+    if (s->qcow->bs->drv && s->qcow->bs->drv->bdrv_make_empty) {
         s->qcow->bs->drv->bdrv_make_empty(s->qcow->bs);
     }