On Fri, 5 Feb 2021 17:06:20 -0600 Seth Forshee <seth.forshee@xxxxxxxxxxxxx> wrote: > This feature requires ino_t be 64-bits, which is true for every > 64-bit architecture but s390, so prevent this option from being > selected there. > The previous patch nicely described the end-user impact of the bug. This is especially important when requesting a -stable backport. Here's what I ended up with: From: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx Fixes: ea3271f7196c ("tmpfs: support 64-bit inums per-sb") Signed-off-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> Cc: Chris Down <chris@xxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Amir Goldstein <amir73il@xxxxxxxxx> Cc: Heiko Carstens <hca@xxxxxxxxxxxxx> Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx> Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [5.9+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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 _
