From: Seth Forshee seth.forshee@canonical.com Subject: tmpfs: disallow CONFIG_TMPFS_INODE64 on s390

Currently there is an assumption in tmpfs that 64-bit architectures also have a 64-bit ino_t. This is not true on s390 which has 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, but passing the "inode64" mount option will fail. This leads to the following behavior:

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

As mount sees "inode64" in the mount options and thus passes it in the options for the remount.

So prevent CONFIG_TMPFS_INODE64 from being selected on s390.

Link: https://lkml.kernel.org/r/20210205230620.518245-1-seth.forshee@canonical.com Fixes: ea3271f7196c ("tmpfs: support 64-bit inums per-sb") Signed-off-by: Seth Forshee seth.forshee@canonical.com Acked-by: Hugh Dickins hughd@google.com Cc: Chris Down chris@chrisdown.name Cc: Hugh Dickins hughd@google.com Cc: Amir Goldstein amir73il@gmail.com Cc: Heiko Carstens hca@linux.ibm.com Cc: Vasily Gorbik gor@linux.ibm.com Cc: Christian Borntraeger borntraeger@de.ibm.com Cc: stable@vger.kernel.org [5.9+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/Kconfig~tmpfs-disallow-config_tmpfs_inode64-on-s390 +++ a/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 + depends on TMPFS && 64BIT && !S390 default n help tmpfs has historically used only inode numbers as wide as an unsigned _