block: Mark bdrv_amend_options() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_amend_options() need to hold a reader lock for the graph. This
removes an assume_graph_lock() call in crypto's implementation.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-14-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

4 files changed, 16 insertions, 13 deletions

diff --git a/block/crypto.c b/block/crypto.c
index c9c9a39..b3f0233 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -828,7 +828,7 @@ block_crypto_amend_options_generic_luks(BlockDriverState *bs,
                                        errp);
 }
 
-static int
+static int GRAPH_RDLOCK
 block_crypto_amend_options_luks(BlockDriverState *bs,
                                 QemuOpts *opts,
                                 BlockDriverAmendStatusCB *status_cb,
@@ -841,8 +841,6 @@ block_crypto_amend_options_luks(BlockDriverState *bs,
     QCryptoBlockAmendOptions *amend_options = NULL;
     int ret = -EINVAL;
 
-    assume_graph_lock(); /* FIXME */
-
     assert(crypto);
     assert(crypto->block);
 
diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h
index ec623ef..9dc3513 100644
--- a/include/block/block-global-state.h
+++ b/include/block/block-global-state.h
@@ -160,10 +160,10 @@ void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base);
  */
 typedef void BlockDriverAmendStatusCB(BlockDriverState *bs, int64_t offset,
                                       int64_t total_work_size, void *opaque);
-int bdrv_amend_options(BlockDriverState *bs_new, QemuOpts *opts,
-                       BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
-                       bool force,
-                       Error **errp);
+int GRAPH_RDLOCK
+bdrv_amend_options(BlockDriverState *bs_new, QemuOpts *opts,
+                   BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
+                   bool force, Error **errp);
 
 /* check if a named node can be replaced when doing drive-mirror */
 BlockDriverState * GRAPH_RDLOCK
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index be80887..c866177 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -259,12 +259,10 @@ struct BlockDriver {
     int coroutine_fn GRAPH_UNLOCKED_PTR (*bdrv_co_create_opts)(
         BlockDriver *drv, const char *filename, QemuOpts *opts, Error **errp);
 
-    int (*bdrv_amend_options)(BlockDriverState *bs,
-                              QemuOpts *opts,
-                              BlockDriverAmendStatusCB *status_cb,
-                              void *cb_opaque,
-                              bool force,
-                              Error **errp);
+    int GRAPH_RDLOCK_PTR (*bdrv_amend_options)(
+        BlockDriverState *bs, QemuOpts *opts,
+        BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
+        bool force, Error **errp);
 
     int (*bdrv_make_empty)(BlockDriverState *bs);
 
diff --git a/qemu-img.c b/qemu-img.c
index 3ecbc37..585b656 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -4129,6 +4129,8 @@ static int print_amend_option_help(const char *format)
 {
     BlockDriver *drv;
 
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
     /* Find driver and parse its options */
     drv = bdrv_find_format(format);
     if (!drv) {
@@ -4267,9 +4269,11 @@ static int img_amend(int argc, char **argv)
         goto out;
     }
 
+    bdrv_graph_rdlock_main_loop();
     if (!bs->drv->bdrv_amend_options) {
         error_report("Format driver '%s' does not support option amendment",
                      fmt);
+        bdrv_graph_rdunlock_main_loop();
         ret = -1;
         goto out;
     }
@@ -4289,6 +4293,7 @@ static int img_amend(int argc, char **argv)
                               "This option is only supported for image creation\n");
         }
 
+        bdrv_graph_rdunlock_main_loop();
         error_report_err(err);
         ret = -1;
         goto out;
@@ -4298,6 +4303,8 @@ static int img_amend(int argc, char **argv)
     qemu_progress_print(0.f, 0);
     ret = bdrv_amend_options(bs, opts, &amend_status_cb, NULL, force, &err);
     qemu_progress_print(100.f, 0);
+    bdrv_graph_rdunlock_main_loop();
+
     if (ret < 0) {
         error_report_err(err);
         goto out;