stat: fix inconsistency between struct stat and struct compat_stat

struct stat (defined in arch/x86/include/uapi/asm/stat.h) has 32-bit
st_dev and st_rdev; struct compat_stat (defined in
arch/x86/include/asm/compat.h) has 16-bit st_dev and st_rdev followed by
a 16-bit padding.

This patch fixes struct compat_stat to match struct stat.

[ Historical note: the old x86 'struct stat' did have that 16-bit field
  that the compat layer had kept around, but it was changes back in 2003
  by "struct stat - support larger dev_t":

    https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=e95b2065677fe32512a597a79db94b77b90c968d

  and back in those days, the x86_64 port was still new, and separate
  from the i386 code, and had already picked up the old version with a
  16-bit st_dev field ]

Note that we can't change compat_dev_t because it is used by
compat_loop_info.

Also, if the st_dev and st_rdev values are 32-bit, we don't have to use
old_valid_dev to test if the value fits into them.  This fixes
-EOVERFLOW on filesystems that are on NVMe because NVMe uses the major
number 259.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 7516e4199b3c..20fd0acd7d80 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -28,15 +28,13 @@ typedef u16		compat_ipc_pid_t;
 typedef __kernel_fsid_t	compat_fsid_t;
 
 struct compat_stat {
-	compat_dev_t	st_dev;
-	u16		__pad1;
+	u32		st_dev;
 	compat_ino_t	st_ino;
 	compat_mode_t	st_mode;
 	compat_nlink_t	st_nlink;
 	__compat_uid_t	st_uid;
 	__compat_gid_t	st_gid;
-	compat_dev_t	st_rdev;
-	u16		__pad2;
+	u32		st_rdev;
 	u32		st_size;
 	u32		st_blksize;
 	u32		st_blocks;