[PATCH 09/15] block-backend: make global properties write-once

[Paolo Bonzini]

The three global properties allow_aio_context_change,
disable_request_queuing and allow_write_before_eof are
always set for the whole life of a BlockBackend.  Make
this clear by removing the possibility of clearing them,
and by marking the corresponding function GLOBAL_STATE_CODE().

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/block-backend.c             | 24 ++++++++++++++----------
 block/commit.c                    |  4 ++--
 block/export/export.c             |  2 +-
 block/mirror.c                    |  4 ++--
 block/parallels.c                 |  2 +-
 block/qcow.c                      |  2 +-
 block/qcow2.c                     |  2 +-
 block/qed.c                       |  2 +-
 block/stream.c                    |  4 ++--
 block/vdi.c                       |  2 +-
 block/vhdx.c                      |  2 +-
 block/vmdk.c                      |  4 ++--
 block/vpc.c                       |  2 +-
 include/sysemu/block-backend-io.h |  6 +++---
 nbd/server.c                      |  3 +--
 tests/unit/test-bdrv-drain.c      |  4 ++--
 tests/unit/test-block-iothread.c  |  2 +-
 17 files changed, 37 insertions(+), 34 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index c4a884b86c2b..fe42d53d655d 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -73,8 +73,13 @@ struct BlockBackend {
     uint64_t shared_perm;
     bool disable_perm;
 
+    /*
+     * Can only become true; should be written before any requests is
+     * submitted to the BlockBackend.
+     */
     bool allow_aio_context_change;
     bool allow_write_beyond_eof;
+    bool disable_request_queuing;
 
     /* Protected by BQL */
     NotifierList remove_bs_notifiers, insert_bs_notifiers;
@@ -82,7 +87,6 @@ struct BlockBackend {
 
     int quiesce_counter;
     CoQueue queued_requests;
-    bool disable_request_queuing;
 
     VMChangeStateEntry *vmsh;
     bool force_allow_inactivate;
@@ -1217,22 +1221,22 @@ void blk_iostatus_set_err(BlockBackend *blk, int error)
     }
 }
 
-void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow)
+void blk_allow_write_beyond_eof(BlockBackend *blk)
 {
-    IO_CODE();
-    blk->allow_write_beyond_eof = allow;
+    GLOBAL_STATE_CODE();
+    blk->allow_write_beyond_eof = true;
 }
 
-void blk_set_allow_aio_context_change(BlockBackend *blk, bool allow)
+void blk_allow_aio_context_change(BlockBackend *blk)
 {
-    IO_CODE();
-    blk->allow_aio_context_change = allow;
+    GLOBAL_STATE_CODE();
+    blk->allow_aio_context_change = true;
 }
 
-void blk_set_disable_request_queuing(BlockBackend *blk, bool disable)
+void blk_disable_request_queuing(BlockBackend *blk)
 {
-    IO_CODE();
-    blk->disable_request_queuing = disable;
+    GLOBAL_STATE_CODE();
+    blk->disable_request_queuing = true;
 }
 
 static int blk_check_byte_request(BlockBackend *blk, int64_t offset,
diff --git a/block/commit.c b/block/commit.c
index b34634176797..7a448838301b 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -379,7 +379,7 @@ void commit_start(const char *job_id, BlockDriverState *bs,
     if (ret < 0) {
         goto fail;
     }
-    blk_set_disable_request_queuing(s->base, true);
+    blk_disable_request_queuing(s->base);
     s->base_bs = base;
 
     /* Required permissions are already taken with block_job_add_bdrv() */
@@ -388,7 +388,7 @@ void commit_start(const char *job_id, BlockDriverState *bs,
     if (ret < 0) {
         goto fail;
     }
-    blk_set_disable_request_queuing(s->top, true);
+    blk_disable_request_queuing(s->top);
 
     s->backing_file_str = g_strdup(backing_file_str);
     s->on_error = on_error;
diff --git a/block/export/export.c b/block/export/export.c
index 7cc0c25c1c9f..6abfe5becb88 100644
--- a/block/export/export.c
+++ b/block/export/export.c
@@ -155,7 +155,7 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error 
**errp)
     blk = blk_new(ctx, perm, BLK_PERM_ALL);
 
     if (!fixed_iothread) {
-        blk_set_allow_aio_context_change(blk, true);
+        blk_allow_aio_context_change(blk);
     }
 
     ret = blk_insert_bs(blk, bs, errp);
diff --git a/block/mirror.c b/block/mirror.c
index 251adc5ae02a..28e76e9dbf55 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1768,8 +1768,8 @@ static BlockJob *mirror_start_job(
          * ensure that. */
         blk_set_force_allow_inactivate(s->target);
     }
-    blk_set_allow_aio_context_change(s->target, true);
-    blk_set_disable_request_queuing(s->target, true);
+    blk_allow_aio_context_change(s->target);
+    blk_disable_request_queuing(s->target);
 
     s->replaces = g_strdup(replaces);
     s->on_source_error = on_source_error;
diff --git a/block/parallels.c b/block/parallels.c
index bbea2f2221ff..44e18a8cc75d 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -576,7 +576,7 @@ static int coroutine_fn 
parallels_co_create(BlockdevCreateOptions* opts,
         ret = -EPERM;
         goto out;
     }
-    blk_set_allow_write_beyond_eof(blk, true);
+    blk_allow_write_beyond_eof(blk);
 
     /* Create image format */
     bat_entries = DIV_ROUND_UP(total_size, cl_size);
diff --git a/block/qcow.c b/block/qcow.c
index 18e17a5b1235..6165885882dd 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -844,7 +844,7 @@ static int coroutine_fn 
qcow_co_create(BlockdevCreateOptions *opts,
         ret = -EPERM;
         goto exit;
     }
-    blk_set_allow_write_beyond_eof(qcow_blk, true);
+    blk_allow_write_beyond_eof(qcow_blk);
 
     /* Create image format */
     memset(&header, 0, sizeof(header));
diff --git a/block/qcow2.c b/block/qcow2.c
index 7cc49a3a6ce3..133dcef16760 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3634,7 +3634,7 @@ qcow2_co_create(BlockdevCreateOptions *create_options, 
Error **errp)
         ret = -EPERM;
         goto out;
     }
-    blk_set_allow_write_beyond_eof(blk, true);
+    blk_allow_write_beyond_eof(blk);
 
     /* Write the header */
     QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
diff --git a/block/qed.c b/block/qed.c
index 9d54c8eec5b0..6bcbace6f24a 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -687,7 +687,7 @@ static int coroutine_fn 
bdrv_qed_co_create(BlockdevCreateOptions *opts,
         ret = -EPERM;
         goto out;
     }
-    blk_set_allow_write_beyond_eof(blk, true);
+    blk_allow_write_beyond_eof(blk);
 
     /* Prepare image format */
     header = (QEDHeader) {
diff --git a/block/stream.c b/block/stream.c
index 8744ad103f71..660d9dd4fa22 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -331,8 +331,8 @@ void stream_start(const char *job_id, BlockDriverState *bs,
      * Disable request queuing in the BlockBackend to avoid deadlocks on drain:
      * The job reports that it's busy until it reaches a pause point.
      */
-    blk_set_disable_request_queuing(s->blk, true);
-    blk_set_allow_aio_context_change(s->blk, true);
+    blk_disable_request_queuing(s->blk);
+    blk_allow_aio_context_change(s->blk);
 
     /*
      * Prevent concurrent jobs trying to modify the graph structure here, we
diff --git a/block/vdi.c b/block/vdi.c
index 479bcfe820ed..b5f43f42021a 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -812,7 +812,7 @@ static int coroutine_fn 
vdi_co_do_create(BlockdevCreateOptions *create_options,
         goto exit;
     }
 
-    blk_set_allow_write_beyond_eof(blk, true);
+    blk_allow_write_beyond_eof(blk);
 
     /* We need enough blocks to store the given disk size,
        so always round up. */
diff --git a/block/vhdx.c b/block/vhdx.c
index 4c929800feeb..30904dc73978 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -2001,7 +2001,7 @@ static int coroutine_fn 
vhdx_co_create(BlockdevCreateOptions *opts,
         ret = -EPERM;
         goto delete_and_exit;
     }
-    blk_set_allow_write_beyond_eof(blk, true);
+    blk_allow_write_beyond_eof(blk);
 
     /* Create (A) */
 
diff --git a/block/vmdk.c b/block/vmdk.c
index afd347191527..ed9011648ec5 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -2307,7 +2307,7 @@ static int coroutine_fn vmdk_create_extent(const char 
*filename,
         goto exit;
     }
 
-    blk_set_allow_write_beyond_eof(blk, true);
+    blk_allow_write_beyond_eof(blk);
 
     ret = vmdk_init_extent(blk, filesize, flat, compress, zeroed_grain, errp);
 exit:
@@ -2807,7 +2807,7 @@ static BlockBackend * coroutine_fn 
vmdk_co_create_cb(int64_t size, int idx,
     if (!blk) {
         return NULL;
     }
-    blk_set_allow_write_beyond_eof(blk, true);
+    blk_allow_write_beyond_eof(blk);
     bdrv_unref(bs);
 
     if (size != -1) {
diff --git a/block/vpc.c b/block/vpc.c
index 6ee95dcb9600..e5c420a8cb76 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -1015,7 +1015,7 @@ static int coroutine_fn 
vpc_co_create(BlockdevCreateOptions *opts,
         ret = -EPERM;
         goto out;
     }
-    blk_set_allow_write_beyond_eof(blk, true);
+    blk_allow_write_beyond_eof(blk);
 
     /* Get geometry and check that it matches the image size*/
     ret = calculate_rounded_image_size(vpc_opts, &cyls, &heads, &secs_per_cyl,
diff --git a/include/sysemu/block-backend-io.h 
b/include/sysemu/block-backend-io.h
index 7ec6d978d408..f77adb1fe294 100644
--- a/include/sysemu/block-backend-io.h
+++ b/include/sysemu/block-backend-io.h
@@ -26,9 +26,9 @@ const char *blk_name(const BlockBackend *blk);
 
 BlockDriverState *blk_bs(BlockBackend *blk);
 
-void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow);
-void blk_set_allow_aio_context_change(BlockBackend *blk, bool allow);
-void blk_set_disable_request_queuing(BlockBackend *blk, bool disable);
+void blk_allow_write_beyond_eof(BlockBackend *blk);
+void blk_allow_aio_context_change(BlockBackend *blk);
+void blk_disable_request_queuing(BlockBackend *blk);
 bool blk_iostatus_is_enabled(const BlockBackend *blk);
 
 char *blk_get_attached_dev_id(BlockBackend *blk);
diff --git a/nbd/server.c b/nbd/server.c
index 462ddb0e4adb..5c92bec6d005 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1778,7 +1778,7 @@ static int nbd_export_create(BlockExport *blk_exp, 
BlockExportOptions *exp_args,
      * be properly quiesced when entering a drained section, as our coroutines
      * servicing pending requests might enter blk_pread().
      */
-    blk_set_disable_request_queuing(blk, true);
+    blk_disable_request_queuing(blk);
 
     blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
 
@@ -1854,7 +1854,6 @@ static void nbd_export_delete(BlockExport *blk_exp)
     }
     blk_remove_aio_context_notifier(exp->common.blk, blk_aio_attached,
                                     blk_aio_detach, exp);
-    blk_set_disable_request_queuing(exp->common.blk, false);
 
     for (i = 0; i < exp->nr_export_bitmaps; i++) {
         bdrv_dirty_bitmap_set_busy(exp->export_bitmaps[i], false);
diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index f677f1d9fc25..d44fa1728589 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -541,7 +541,7 @@ static void test_iothread_common(enum drain_type 
drain_type, int drain_thread)
                               &error_abort);
     s = bs->opaque;
     blk_insert_bs(blk, bs, &error_abort);
-    blk_set_disable_request_queuing(blk, true);
+    blk_disable_request_queuing(blk);
 
     blk_set_aio_context(blk, ctx_a, &error_abort);
     aio_context_acquire(ctx_a);
@@ -767,7 +767,7 @@ static void test_blockjob_common_drain_node(enum drain_type 
drain_type,
                                   &error_abort);
     blk_target = blk_new(qemu_get_aio_context(), BLK_PERM_ALL, BLK_PERM_ALL);
     blk_insert_bs(blk_target, target, &error_abort);
-    blk_set_allow_aio_context_change(blk_target, true);
+    blk_allow_aio_context_change(blk_target);
 
     aio_context_acquire(ctx);
     tjob = block_job_create("job0", &test_job_driver, NULL, src,
diff --git a/tests/unit/test-block-iothread.c b/tests/unit/test-block-iothread.c
index 8ca5adec5e82..68df827cddd8 100644
--- a/tests/unit/test-block-iothread.c
+++ b/tests/unit/test-block-iothread.c
@@ -793,7 +793,7 @@ static void test_propagate_mirror(void)
 
     /* ...unless we explicitly allow it */
     aio_context_acquire(ctx);
-    blk_set_allow_aio_context_change(blk, true);
+    blk_allow_aio_context_change(blk);
     bdrv_try_change_aio_context(target, ctx, NULL, &error_abort);
     aio_context_release(ctx);
 
-- 
2.38.1