Merge remote-tracking branch 'remotes/stefanha-gitlab/tags/block-pull-request' into staging

Pull request

# gpg: Signature made Thu 08 Jul 2021 14:11:37 BST
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha-gitlab/tags/block-pull-request:
  block/io: Merge discard request alignments
  block: Add backend_defaults property
  block/file-posix: Optimize for macOS
  util/async: print leaked BH name when AioContext finalizes
  util/async: add a human-readable name to BHs for debugging

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

10 files changed, 161 insertions, 17 deletions

diff --git a/block/file-posix.c b/block/file-posix.c
index a26eab0..cb9bffe 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -46,6 +46,7 @@
 #if defined(HAVE_HOST_BLOCK_DEVICE)
 #include <paths.h>
 #include <sys/param.h>
+#include <sys/mount.h>
 #include <IOKit/IOKitLib.h>
 #include <IOKit/IOBSD.h>
 #include <IOKit/storage/IOMediaBSDClient.h>
@@ -1254,6 +1255,15 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
         return;
     }
 
+#if defined(__APPLE__) && (__MACH__)
+    struct statfs buf;
+
+    if (!fstatfs(s->fd, &buf)) {
+        bs->bl.opt_transfer = buf.f_iosize;
+        bs->bl.pdiscard_alignment = buf.f_bsize;
+    }
+#endif
+
     if (bs->sg || S_ISBLK(st.st_mode)) {
         int ret = hdev_get_max_hw_transfer(s->fd, &st);
 
@@ -1591,6 +1601,7 @@ out:
     }
 }
 
+#if defined(CONFIG_FALLOCATE) || defined(BLKZEROOUT) || defined(BLKDISCARD)
 static int translate_err(int err)
 {
     if (err == -ENODEV || err == -ENOSYS || err == -EOPNOTSUPP ||
@@ -1599,6 +1610,7 @@ static int translate_err(int err)
     }
     return err;
 }
+#endif
 
 #ifdef CONFIG_FALLOCATE
 static int do_fallocate(int fd, int mode, off_t offset, off_t len)
@@ -1811,16 +1823,27 @@ static int handle_aiocb_discard(void *opaque)
             }
         } while (errno == EINTR);
 
-        ret = -errno;
+        ret = translate_err(-errno);
 #endif
     } else {
 #ifdef CONFIG_FALLOCATE_PUNCH_HOLE
         ret = do_fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
                            aiocb->aio_offset, aiocb->aio_nbytes);
+        ret = translate_err(-errno);
+#elif defined(__APPLE__) && (__MACH__)
+        fpunchhole_t fpunchhole;
+        fpunchhole.fp_flags = 0;
+        fpunchhole.reserved = 0;
+        fpunchhole.fp_offset = aiocb->aio_offset;
+        fpunchhole.fp_length = aiocb->aio_nbytes;
+        if (fcntl(s->fd, F_PUNCHHOLE, &fpunchhole) == -1) {
+            ret = errno == ENODEV ? -ENOTSUP : -errno;
+        } else {
+            ret = 0;
+        }
 #endif
     }
 
-    ret = translate_err(ret);
     if (ret == -ENOTSUP) {
         s->has_discard = false;
     }
diff --git a/block/io.c b/block/io.c
index cf177a9..e0a689c 100644
--- a/block/io.c
+++ b/block/io.c
@@ -125,6 +125,8 @@ void bdrv_parent_drained_begin_single(BdrvChild *c, bool poll)
 
 static void bdrv_merge_limits(BlockLimits *dst, const BlockLimits *src)
 {
+    dst->pdiscard_alignment = MAX(dst->pdiscard_alignment,
+                                  src->pdiscard_alignment);
     dst->opt_transfer = MAX(dst->opt_transfer, src->opt_transfer);
     dst->max_transfer = MIN_NON_ZERO(dst->max_transfer, src->max_transfer);
     dst->max_hw_transfer = MIN_NON_ZERO(dst->max_hw_transfer,
diff --git a/hw/block/block.c b/hw/block/block.c
index 1e34573..d47ebf0 100644
--- a/hw/block/block.c
+++ b/hw/block/block.c
@@ -65,24 +65,58 @@ bool blkconf_blocksizes(BlockConf *conf, Error **errp)
 {
     BlockBackend *blk = conf->blk;
     BlockSizes blocksizes;
-    int backend_ret;
+    BlockDriverState *bs;
+    bool use_blocksizes;
+    bool use_bs;
+
+    switch (conf->backend_defaults) {
+    case ON_OFF_AUTO_AUTO:
+        use_blocksizes = !blk_probe_blocksizes(blk, &blocksizes);
+        use_bs = false;
+        break;
+
+    case ON_OFF_AUTO_ON:
+        use_blocksizes = !blk_probe_blocksizes(blk, &blocksizes);
+        bs = blk_bs(blk);
+        use_bs = bs;
+        break;
+
+    case ON_OFF_AUTO_OFF:
+        use_blocksizes = false;
+        use_bs = false;
+        break;
+
+    default:
+        abort();
+    }
 
-    backend_ret = blk_probe_blocksizes(blk, &blocksizes);
     /* fill in detected values if they are not defined via qemu command line */
     if (!conf->physical_block_size) {
-        if (!backend_ret) {
+        if (use_blocksizes) {
            conf->physical_block_size = blocksizes.phys;
         } else {
             conf->physical_block_size = BDRV_SECTOR_SIZE;
         }
     }
     if (!conf->logical_block_size) {
-        if (!backend_ret) {
+        if (use_blocksizes) {
             conf->logical_block_size = blocksizes.log;
         } else {
             conf->logical_block_size = BDRV_SECTOR_SIZE;
         }
     }
+    if (use_bs) {
+        if (!conf->opt_io_size) {
+            conf->opt_io_size = bs->bl.opt_transfer;
+        }
+        if (conf->discard_granularity == -1) {
+            if (bs->bl.pdiscard_alignment) {
+                conf->discard_granularity = bs->bl.pdiscard_alignment;
+            } else if (bs->bl.request_alignment != 1) {
+                conf->discard_granularity = bs->bl.request_alignment;
+            }
+        }
+    }
 
     if (conf->logical_block_size > conf->physical_block_size) {
         error_setg(errp,
diff --git a/include/block/aio.h b/include/block/aio.h
index 10fcae1..807edce 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -292,19 +292,44 @@ void aio_context_acquire(AioContext *ctx);
 void aio_context_release(AioContext *ctx);
 
 /**
+ * aio_bh_schedule_oneshot_full: Allocate a new bottom half structure that will
+ * run only once and as soon as possible.
+ *
+ * @name: A human-readable identifier for debugging purposes.
+ */
+void aio_bh_schedule_oneshot_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque,
+                                  const char *name);
+
+/**
  * aio_bh_schedule_oneshot: Allocate a new bottom half structure that will run
  * only once and as soon as possible.
+ *
+ * A convenience wrapper for aio_bh_schedule_oneshot_full() that uses cb as the
+ * name string.
  */
-void aio_bh_schedule_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque);
+#define aio_bh_schedule_oneshot(ctx, cb, opaque) \
+    aio_bh_schedule_oneshot_full((ctx), (cb), (opaque), (stringify(cb)))
 
 /**
- * aio_bh_new: Allocate a new bottom half structure.
+ * aio_bh_new_full: Allocate a new bottom half structure.
  *
  * Bottom halves are lightweight callbacks whose invocation is guaranteed
  * to be wait-free, thread-safe and signal-safe.  The #QEMUBH structure
  * is opaque and must be allocated prior to its use.
+ *
+ * @name: A human-readable identifier for debugging purposes.
+ */
+QEMUBH *aio_bh_new_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque,
+                        const char *name);
+
+/**
+ * aio_bh_new: Allocate a new bottom half structure
+ *
+ * A convenience wrapper for aio_bh_new_full() that uses the cb as the name
+ * string.
  */
-QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque);
+#define aio_bh_new(ctx, cb, opaque) \
+    aio_bh_new_full((ctx), (cb), (opaque), (stringify(cb)))
 
 /**
  * aio_notify: Force processing of pending events.
diff --git a/include/hw/block/block.h b/include/hw/block/block.h
index c172cbe..5902c04 100644
--- a/include/hw/block/block.h
+++ b/include/hw/block/block.h
@@ -19,6 +19,7 @@
 
 typedef struct BlockConf {
     BlockBackend *blk;
+    OnOffAuto backend_defaults;
     uint32_t physical_block_size;
     uint32_t logical_block_size;
     uint32_t min_io_size;
@@ -48,6 +49,8 @@ static inline unsigned int get_physical_block_exp(BlockConf *conf)
 }
 
 #define DEFINE_BLOCK_PROPERTIES_BASE(_state, _conf)                     \
+    DEFINE_PROP_ON_OFF_AUTO("backend_defaults", _state,                 \
+                            _conf.backend_defaults, ON_OFF_AUTO_AUTO),  \
     DEFINE_PROP_BLOCKSIZE("logical_block_size", _state,                 \
                           _conf.logical_block_size),                    \
     DEFINE_PROP_BLOCKSIZE("physical_block_size", _state,                \
diff --git a/include/qemu/main-loop.h b/include/qemu/main-loop.h
index 98aef56..8dbc6fc 100644
--- a/include/qemu/main-loop.h
+++ b/include/qemu/main-loop.h
@@ -294,7 +294,9 @@ void qemu_cond_timedwait_iothread(QemuCond *cond, int ms);
 
 void qemu_fd_register(int fd);
 
-QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque);
+#define qemu_bh_new(cb, opaque) \
+    qemu_bh_new_full((cb), (opaque), (stringify(cb)))
+QEMUBH *qemu_bh_new_full(QEMUBHFunc *cb, void *opaque, const char *name);
 void qemu_bh_schedule_idle(QEMUBH *bh);
 
 enum {
diff --git a/tests/qemu-iotests/172.out b/tests/qemu-iotests/172.out
index d53f61d..4cf4d53 100644
--- a/tests/qemu-iotests/172.out
+++ b/tests/qemu-iotests/172.out
@@ -21,6 +21,7 @@ Testing:
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -48,6 +49,7 @@ Testing: -fda TEST_DIR/t.qcow2
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -85,6 +87,7 @@ Testing: -fdb TEST_DIR/t.qcow2
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "floppy1"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -96,6 +99,7 @@ Testing: -fdb TEST_DIR/t.qcow2
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -137,6 +141,7 @@ Testing: -fda TEST_DIR/t.qcow2 -fdb TEST_DIR/t.qcow2.2
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "floppy1"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -148,6 +153,7 @@ Testing: -fda TEST_DIR/t.qcow2 -fdb TEST_DIR/t.qcow2.2
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -190,6 +196,7 @@ Testing: -fdb
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "floppy1"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -201,6 +208,7 @@ Testing: -fdb
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -228,6 +236,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -265,6 +274,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2,index=1
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "floppy1"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -276,6 +286,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2,index=1
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -317,6 +328,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=floppy,file=TEST_DIR/t
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "floppy1"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -328,6 +340,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=floppy,file=TEST_DIR/t
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -373,6 +386,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -410,6 +424,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,unit=1
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -447,6 +462,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qco
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "none1"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -458,6 +474,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qco
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -509,6 +526,7 @@ Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device fl
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -520,6 +538,7 @@ Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device fl
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -562,6 +581,7 @@ Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device fl
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -573,6 +593,7 @@ Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device fl
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -615,6 +636,7 @@ Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device fl
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -626,6 +648,7 @@ Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device fl
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "floppy1"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -668,6 +691,7 @@ Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device fl
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -679,6 +703,7 @@ Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device fl
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "floppy1"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -730,6 +755,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.q
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -741,6 +767,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.q
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -783,6 +810,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.q
               dev: floppy, id ""
                 unit = 1 (0x1)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -794,6 +822,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.q
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "floppy0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -842,6 +871,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -global floppy.drive=none0 -device
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -909,6 +939,7 @@ Testing: -device floppy
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = ""
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -933,6 +964,7 @@ Testing: -device floppy,drive-type=120
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = ""
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -957,6 +989,7 @@ Testing: -device floppy,drive-type=144
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = ""
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -981,6 +1014,7 @@ Testing: -device floppy,drive-type=288
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = ""
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -1008,6 +1042,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,drive-t
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -1045,6 +1080,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,drive-t
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -1085,6 +1121,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,logical
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
@@ -1122,6 +1159,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,physica
               dev: floppy, id ""
                 unit = 0 (0x0)
                 drive = "none0"
+                backend_defaults = "auto"
                 logical_block_size = 512 (512 B)
                 physical_block_size = 512 (512 B)
                 min_io_size = 0 (0 B)
diff --git a/tests/unit/ptimer-test-stubs.c b/tests/unit/ptimer-test-stubs.c
index 7f801a4..2a3ef58 100644
--- a/tests/unit/ptimer-test-stubs.c
+++ b/tests/unit/ptimer-test-stubs.c
@@ -108,7 +108,7 @@ int64_t qemu_clock_deadline_ns_all(QEMUClockType type, int attr_mask)
     return deadline;
 }
 
-QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
+QEMUBH *qemu_bh_new_full(QEMUBHFunc *cb, void *opaque, const char *name)
 {
     QEMUBH *bh = g_new(QEMUBH, 1);
 
diff --git a/util/async.c b/util/async.c
index 5d9b7cc..9a41591 100644
--- a/util/async.c
+++ b/util/async.c
@@ -57,6 +57,7 @@ enum {
 
 struct QEMUBH {
     AioContext *ctx;
+    const char *name;
     QEMUBHFunc *cb;
     void *opaque;
     QSLIST_ENTRY(QEMUBH) next;
@@ -107,7 +108,8 @@ static QEMUBH *aio_bh_dequeue(BHList *head, unsigned *flags)
     return bh;
 }
 
-void aio_bh_schedule_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
+void aio_bh_schedule_oneshot_full(AioContext *ctx, QEMUBHFunc *cb,
+                                  void *opaque, const char *name)
 {
     QEMUBH *bh;
     bh = g_new(QEMUBH, 1);
@@ -115,11 +117,13 @@ void aio_bh_schedule_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
         .ctx = ctx,
         .cb = cb,
         .opaque = opaque,
+        .name = name,
     };
     aio_bh_enqueue(bh, BH_SCHEDULED | BH_ONESHOT);
 }
 
-QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
+QEMUBH *aio_bh_new_full(AioContext *ctx, QEMUBHFunc *cb, void *opaque,
+                        const char *name)
 {
     QEMUBH *bh;
     bh = g_new(QEMUBH, 1);
@@ -127,6 +131,7 @@ QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
         .ctx = ctx,
         .cb = cb,
         .opaque = opaque,
+        .name = name,
     };
     return bh;
 }
@@ -339,8 +344,20 @@ aio_ctx_finalize(GSource     *source)
     assert(QSIMPLEQ_EMPTY(&ctx->bh_slice_list));
 
     while ((bh = aio_bh_dequeue(&ctx->bh_list, &flags))) {
-        /* qemu_bh_delete() must have been called on BHs in this AioContext */
-        assert(flags & BH_DELETED);
+        /*
+         * qemu_bh_delete() must have been called on BHs in this AioContext. In
+         * many cases memory leaks, hangs, or inconsistent state occur when a
+         * BH is leaked because something still expects it to run.
+         *
+         * If you hit this, fix the lifecycle of the BH so that
+         * qemu_bh_delete() and any associated cleanup is called before the
+         * AioContext is finalized.
+         */
+        if (unlikely(!(flags & BH_DELETED))) {
+            fprintf(stderr, "%s: BH '%s' leaked, aborting...\n",
+                    __func__, bh->name);
+            abort();
+        }
 
         g_free(bh);
     }
diff --git a/util/main-loop.c b/util/main-loop.c
index 4ae5b23..06b18b1 100644
--- a/util/main-loop.c
+++ b/util/main-loop.c
@@ -544,9 +544,9 @@ void main_loop_wait(int nonblocking)
 
 /* Functions to operate on the main QEMU AioContext.  */
 
-QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
+QEMUBH *qemu_bh_new_full(QEMUBHFunc *cb, void *opaque, const char *name)
 {
-    return aio_bh_new(qemu_aio_context, cb, opaque);
+    return aio_bh_new_full(qemu_aio_context, cb, opaque, name);
 }
 
 /*