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authorMarkus Armbruster <armbru@redhat.com>2017-03-30 19:43:12 +0200
committerMax Reitz <mreitz@redhat.com>2017-04-03 17:11:39 +0200
commit129c7d1c536d0c67a8781cb09fb5bdb3d0f6a2d0 (patch)
treeada6445881ef92987ad4144741287b9412a7a772 /block/nbd.c
parenta6c76285f2e41535527a46edf4d158a2779545e1 (diff)
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block: Document -drive problematic code and bugs
-blockdev and blockdev_add convert their arguments via QObject to BlockdevOptions for qmp_blockdev_add(), which converts them back to QObject, then to a flattened QDict. The QDict's members are typed according to the QAPI schema. -drive converts its argument via QemuOpts to a (flat) QDict. This QDict's members are all QString. Thus, the QType of a flat QDict member depends on whether it comes from -drive or -blockdev/blockdev_add, except when the QAPI type maps to QString, which is the case for 'str' and enumeration types. The block layer core extracts generic configuration from the flat QDict, and the block driver extracts driver-specific configuration. Both commonly do so by converting (parts of) the flat QDict to QemuOpts, which turns all values into strings. Not exactly elegant, but correct. However, A few places access the flat QDict directly: * Most of them access members that are always QString. Correct. * bdrv_open_inherit() accesses a boolean, carefully. Correct. * nfs_config() uses a QObject input visitor. Correct only because the visited type contains nothing but QStrings. * nbd_config() and ssh_config() use a QObject input visitor, and the visited types contain non-QStrings: InetSocketAddress members @numeric, @to, @ipv4, @ipv6. -drive works as long as you don't try to use them (they're all optional). @to is ignored anyway. Reproducer: -drive driver=ssh,server.host=h,server.port=22,server.ipv4,path=p -drive driver=nbd,server.type=inet,server.data.host=h,server.data.port=22,server.data.ipv4 both fail with "Invalid parameter type for 'data.ipv4', expected: boolean" Add suitable comments to all these places. Mark the buggy ones FIXME. "Fortunately", -drive's driver-specific options are entirely undocumented. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-id: 1490895797-29094-5-git-send-email-armbru@redhat.com [mreitz: Fixed two typos] Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block/nbd.c')
-rw-r--r--block/nbd.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/block/nbd.c b/block/nbd.c
index 36ea617..11e3ba7 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -278,6 +278,14 @@ static SocketAddress *nbd_config(BDRVNBDState *s, QDict *options, Error **errp)
goto done;
}
+ /*
+ * FIXME .numeric, .to, .ipv4 or .ipv6 don't work with -drive
+ * server.type=inet. .to doesn't matter, it's ignored anyway.
+ * That's because when @options come from -blockdev or
+ * blockdev_add, members are typed according to the QAPI schema,
+ * but when they come from -drive, they're all QString. The
+ * visitor expects the former.
+ */
iv = qobject_input_visitor_new(crumpled_addr);
visit_type_SocketAddress(iv, NULL, &saddr, &local_err);
if (local_err) {