[PATCH v2] Only advertise aio=io_uring if support is actually available

["Dirk Müller" <dmueller@suse.de>]

Change --help output for aio option to only list the aio backend options that
are actually available. io_uring is an optional, linux only backend
option so hide it for cases where it isn't there.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Dirk Müller <dmueller@suse.de>
---
 block/file-posix.c | 4 ++++
 qemu-nbd.c         | 4 ++++
 qemu-options.hx    | 6 +++++-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index 39a3d6dbe6..aec4763862 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -544,7 +544,11 @@ static QemuOptsList raw_runtime_opts = {
         {
             .name = "aio",
             .type = QEMU_OPT_STRING,
+#ifdef CONFIG_LINUX_IO_URING
             .help = "host AIO implementation (threads, native, io_uring)",
+#else
+            .help = "host AIO implementation (threads, native)",
+#endif
         },
         {
             .name = "aio-max-batch",
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 713e7557a9..4634a0fc42 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -147,7 +147,11 @@ static void usage(const char *name)
 "      --cache=MODE          set cache mode used to access the disk image, the\n"
 "                            valid options are: 'none', 'writeback' (default),\n"
 "                            'writethrough', 'directsync' and 'unsafe'\n"
+#ifdef CONFIG_LINUX_IO_URING
 "      --aio=MODE            set AIO mode (native, io_uring or threads)\n"
+#else
+"      --aio=MODE            set AIO mode (native or threads)\n"
+#endif
 "      --discard=MODE        set discard mode (ignore, unmap)\n"
 "      --detect-zeroes=MODE  set detect-zeroes mode (off, on, unmap)\n"
 "      --image-opts          treat FILE as a full set of image options\n"
diff --git a/qemu-options.hx b/qemu-options.hx
index 34e9b32a5c..973125cfca 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1338,7 +1338,11 @@ DEF("drive", HAS_ARG, QEMU_OPTION_drive,
     "       [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
     "       [,snapshot=on|off][,rerror=ignore|stop|report]\n"
     "       [,werror=ignore|stop|report|enospc][,id=name]\n"
-    "       [,aio=threads|native|io_uring]\n"
+    "       [,aio=threads|native"
+#if defined(CONFIG_LINUX_IO_URING)
+    "|io_uring"
+#endif
+    "]\n"
     "       [,readonly=on|off][,copy-on-read=on|off]\n"
     "       [,discard=ignore|unmap][,detect-zeroes=on|off|unmap]\n"
     "       [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]]\n"
-- 
2.35.3