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.

Fixes: ea3271f7196c ("tmpfs: support 64-bit inums per-sb")
Cc: stable@vger.kernel.org # v5.9+
Signed-off-by: Seth Forshee <redacted>
---
 fs/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/Kconfig b/fs/Kconfig
index 3347ec7bd837..da524c4d7b7e 100644
--- a/fs/Kconfig
+++ b/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

-- 
2.29.2