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block: Take graph lock for most of .bdrv_open

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Most implementations of .bdrv_open first open their file child (which is
an operation that internally takes the write lock and therefore we
shouldn't hold the graph lock while calling it), and afterwards many
operations that require holding the graph lock, e.g. for accessing
bs->file.

This changes block drivers that follow this pattern to take the graph
lock after opening the child node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-24-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2023-10-27 17:53:32 +02:00
parent 65ff757df0
commit a4b740db5e
16 changed files with 60 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

11
block/qcow.c
View file

@ -124,9 +124,11 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
ret = bdrv_open_file_child(NULL, options, "file", bs, errp);
if (ret < 0) {
goto fail;
goto fail_unlocked;
}
bdrv_graph_rdlock_main_loop();
ret = bdrv_pread(bs->file, 0, sizeof(header), &header, 0);
if (ret < 0) {
goto fail;
@ -301,11 +303,9 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
}
/* Disable migration when qcow images are used */
bdrv_graph_rdlock_main_loop();
error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
"does not support live migration",
bdrv_get_device_or_node_name(bs));
bdrv_graph_rdunlock_main_loop();
ret = migrate_add_blocker_normal(&s->migration_blocker, errp);
if (ret < 0) {
@ -315,9 +315,12 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
qobject_unref(encryptopts);
qapi_free_QCryptoBlockOpenOptions(crypto_opts);
qemu_co_mutex_init(&s->lock);
bdrv_graph_rdunlock_main_loop();
return 0;
fail:
fail:
bdrv_graph_rdunlock_main_loop();
fail_unlocked:
g_free(s->l1_table);
qemu_vfree(s->l2_cache);
g_free(s->cluster_cache);