block/file-posix: update .help of BLOCK_OPT_PREALLOC option

Show 'falloc' among the allowed values of 'preallocation'
option, only when it is supported (if defined CONFIG_POSIX_FALLOCATE)

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190524075848.23781-3-sgarzare@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

diff --git a/block/file-posix.c b/block/file-posix.c
index 6e6bf3f4a57b63edcf5cdf4c7fa94c5c5a41231d..83ab1b78efa3f632df89b6caff5fe4810aac6bd4 100644 (file)
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -2752,7 +2752,11 @@ static QemuOptsList raw_create_opts = {
         {
             .name = BLOCK_OPT_PREALLOC,
             .type = QEMU_OPT_STRING,
-            .help = "Preallocation mode (allowed values: off, falloc, full)"
+            .help = "Preallocation mode (allowed values: off"
+#ifdef CONFIG_POSIX_FALLOCATE
+                    ", falloc"
+#endif
+                    ", full)"
         },
         { /* end of list */ }
     }