tmpfs: disallow CONFIG_TMPFS_INODE64 on alpha

As with s390, alpha is a 64-bit architecture with a 32-bit ino_t.  With
CONFIG_TMPFS_INODE64=y tmpfs mounts will get 64-bit inode numbers and
display "inode64" in the mount options, whereas passing "inode64" in the
mount options will fail.  This leads to erroneous behaviours such as
this:

  # mkdir mnt
  # mount -t tmpfs nodev mnt
  # mount -o remount,rw mnt
  mount: /home/ubuntu/mnt: mount point not mounted or bad option.

Prevent CONFIG_TMPFS_INODE64 from being selected on alpha.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: ea3271f ("tmpfs: support 64-bit inums per-sb")
Signed-off-by: Seth Forshee <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: Chris Down <[email protected]>
Cc: Amir Goldstein <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: <[email protected]>	[5.9+]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/Kconfig

@@ -203,7 +203,7 @@ config TMPFS_XATTR
 
 config TMPFS_INODE64
 	bool "Use 64-bit ino_t by default in tmpfs"
-	depends on TMPFS && 64BIT && !S390
+	depends on TMPFS && 64BIT && !(S390 || ALPHA)
 	default n
 	help
 	  tmpfs has historically used only inode numbers as wide as an unsigned