[Qemu-devel] [PATCH] block: char devices on FreeBSD are not behind a pager

[Roger Pau Monne <roger.pau@citrix.com>]

Acknowledge this and forcefully set BDRV_O_NOCACHE and O_DIRECT in order to
force QEMU to use aligned buffers.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/raw-posix.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 86ce4f2..63841dd 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -472,6 +472,18 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
         }
 #endif
     }
+#ifdef __FreeBSD__
+    if (S_ISCHR(st.st_mode)) {
+        /*
+         * The file is a char device (disk), which on FreeBSD isn't behind
+         * a pager, so set BDRV_O_NOCACHE unconditionally. This is needed
+         * so Qemu makes sure all IO operations on the device are aligned
+         * to sector size, or else FreeBSD will reject them with EINVAL.
+         */
+        bs->open_flags |= BDRV_O_NOCACHE;
+        s->open_flags |= O_DIRECT;
+    }
+#endif
 
 #ifdef CONFIG_XFS
     if (platform_test_xfs_fd(s->fd)) {
-- 
1.9.3 (Apple Git-50)