[PATCH v2] 9p: move P9_XATTR_SIZE_MAX from 9p.h to 9p.c

[Will Cohen <wwcohen@gmail.com>]

The patch set adding 9p functionality to darwin introduced an issue
where limits.h, which defines XATTR_SIZE_MAX, is included in 9p.c,
though the referenced constant is needed in 9p.h. This commit fixes that
issue by moving the definition of P9_XATTR_SIZE_MAX, which uses
XATTR_SIZE_MAX, to also be in 9p.c.

Additionally, this commit moves the location of the system headers
include in 9p.c to occur before the project headers.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/950
Fixes: 38d7fd68b0 ("9p: darwin: Move XATTR_SIZE_MAX->P9_XATTR_SIZE_MAX")

Signed-off-by: Will Cohen <wwcohen@gmail.com>
---
 hw/9pfs/9p.c | 28 +++++++++++++++++++++++-----
 hw/9pfs/9p.h | 18 ------------------
 2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index dcaa602d4c..b9152c7882 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -16,6 +16,11 @@
  * https://wiki.qemu.org/Documentation/9p
  */
 
+#ifdef CONFIG_LINUX
+#include <linux/limits.h>
+#else
+#include <limits.h>
+#endif
 #include "qemu/osdep.h"
 #include <glib/gprintf.h>
 #include "hw/virtio/virtio.h"
@@ -33,11 +38,6 @@
 #include "migration/blocker.h"
 #include "qemu/xxhash.h"
 #include <math.h>
-#ifdef CONFIG_LINUX
-#include <linux/limits.h>
-#else
-#include <limits.h>
-#endif
 
 int open_fd_hw;
 int total_open_fd;
@@ -3925,6 +3925,24 @@ out_nofid:
     v9fs_string_free(&name);
 }
 
+#if defined(CONFIG_LINUX)
+/* Currently, only Linux has XATTR_SIZE_MAX */
+#define P9_XATTR_SIZE_MAX XATTR_SIZE_MAX
+#elif defined(CONFIG_DARWIN)
+/*
+ * Darwin doesn't seem to define a maximum xattr size in its user
+ * space header, so manually configure it across platforms as 64k.
+ *
+ * Having no limit at all can lead to QEMU crashing during large g_malloc()
+ * calls. Because QEMU does not currently support macOS guests, the below
+ * preliminary solution only works due to its being a reflection of the limit of
+ * Linux guests.
+ */
+#define P9_XATTR_SIZE_MAX 65536
+#else
+#error Missing definition for P9_XATTR_SIZE_MAX for this host system
+#endif
+
 static void coroutine_fn v9fs_xattrcreate(void *opaque)
 {
     int flags, rflags = 0;
diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
index af2635fae9..994f952600 100644
--- a/hw/9pfs/9p.h
+++ b/hw/9pfs/9p.h
@@ -479,22 +479,4 @@ struct V9fsTransport {
     void        (*push_and_notify)(V9fsPDU *pdu);
 };
 
-#if defined(XATTR_SIZE_MAX)
-/* Linux */
-#define P9_XATTR_SIZE_MAX XATTR_SIZE_MAX
-#elif defined(CONFIG_DARWIN)
-/*
- * Darwin doesn't seem to define a maximum xattr size in its user
- * space header, so manually configure it across platforms as 64k.
- *
- * Having no limit at all can lead to QEMU crashing during large g_malloc()
- * calls. Because QEMU does not currently support macOS guests, the below
- * preliminary solution only works due to its being a reflection of the limit of
- * Linux guests.
- */
-#define P9_XATTR_SIZE_MAX 65536
-#else
-#error Missing definition for P9_XATTR_SIZE_MAX for this host system
-#endif
-
 #endif
-- 
2.35.1