linux(4): Uniformly dev_t arguments translation

The two main uses of dev_t are in struct stat and as a parameter of the
mknod system calls.
As of version 2.6.0 of the Linux kernel, dev_t is a 32-bit quantity
with 12 bits set asaid for the major number and 20 for the minor number.
The in-kernel dev_t encoded as MMMmmmmm, where M is a hex digit of the
major number and m is a hex digit of the minor number.
The user-space dev_t encoded as mmmM MMmm, where M and m is the major
and minor numbers accordingly. This is downward compatible with legacy
systems where dev_t is 16 bits wide, encoded as MMmm.
In glibc dev_t is a 64-bit quantity, with 32-bit major and minor numbers,
encoded as MMMM Mmmm mmmM MMmm. This is downward compatible with the Linux
kernel and with legacy systems where dev_t is 16 bits wide.
In the FreeBSD dev_t is a 64-bit quantity. The major and minor numbers
are encoded as MMMmmmMm, therefore conversion of the device numbers between
Linux user-space and FreeBSD kernel required.

(cherry picked from commit 166e2e5a9e87d32dbfc7838903904673873f1e71)

1 files changed, 2 insertions, 1 deletions

diff --git a/sys/compat/linux/linux_util.c b/sys/compat/linux/linux_util.c
index 5995ac5e18af..498320937fd3 100644
--- a/sys/compat/linux/linux_util.c
+++ b/sys/compat/linux/linux_util.c
@@ -35,6 +35,7 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
+#include <sys/types.h>
 #include <sys/bus.h>
 #include <sys/conf.h>
 #include <sys/fcntl.h>
@@ -248,7 +249,7 @@ translate_vnhook_major_minor(struct vnode *vp, struct stat *sb)
 		sb->st_dev = rootdevmp->mnt_stat.f_fsid.val[0];
 
 	if (linux_vn_get_major_minor(vp, &major, &minor) == 0)
-		sb->st_rdev = (major << 8 | minor);
+		sb->st_rdev = makedev(major, minor);
 }
 
 char *