[PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[Seth Forshee]

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.

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

diff --git a/fs/Kconfig b/fs/Kconfig
index aa4c12282301..3347ec7bd837 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
+	depends on TMPFS && 64BIT && !S390
 	default n
 	help
 	  tmpfs has historically used only inode numbers as wide as an unsigned
-- 
2.29.2

Re: [PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[Andrew Morton]

On Fri,  5 Feb 2021 17:06:20 -0600 Seth Forshee <seth.forshee@canonical.com> 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@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>
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
_

Re: [PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[Chris Down]

Andrew Morton writes:
>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>
>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>

Either of the two ways presented looks fine to me, no real preference. Thanks!

Acked-by: Chris Down <chris@chrisdown.name>

>---
>
> 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
>_
>

Re: [PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[Heiko Carstens]

On Fri, Feb 05, 2021 at 04:05:51PM -0800, Andrew Morton wrote:
> On Fri,  5 Feb 2021 17:06:20 -0600 Seth Forshee <seth.forshee@canonical.com> 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@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>
> 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

Heh, it's sort of funny that we have a similar patch, which
unfortunately was/is not yet on our external features branch,
which does exactly the same.

In any case:

Acked-by: Heiko Carstens <hca@linux.ibm.com>

Re: [PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[Hugh Dickins]

On Fri, 5 Feb 2021, Andrew Morton wrote:
> On Fri,  5 Feb 2021 17:06:20 -0600 Seth Forshee <seth.forshee@canonical.com> 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@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>
> Cc: Chris Down <chris@chrisdown.name>
> Cc: Hugh Dickins <hughd@google.com>

Thank you Seth: now that you've fixed Kirill's alpha observation too,
Acked-by: 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
> _
> 
> 

Re: [PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[Kirill A. Shutemov]

On Fri, Feb 05, 2021 at 05:06:20PM -0600, Seth Forshee 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.

Quick grep suggests the same for alpha. Am I wrong?

-- 
 Kirill A. Shutemov

Re: [PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[Seth Forshee]

On Sun, Feb 07, 2021 at 05:48:31PM +0300, Kirill A. Shutemov wrote:
> On Fri, Feb 05, 2021 at 05:06:20PM -0600, Seth Forshee 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.
> 
> Quick grep suggests the same for alpha. Am I wrong?

No, it appears you are right. Looks like my grep missed alpha somehow.

Andrew, do you prefer an additional patch or an updated version of the
previous patch?

Re: [PATCH] tmpfs: Disallow CONFIG_TMPFS_INODE64 on s390

[Andrew Morton]

On Mon, 8 Feb 2021 07:06:58 -0600 Seth Forshee <seth.forshee@canonical.com> wrote:

> On Sun, Feb 07, 2021 at 05:48:31PM +0300, Kirill A. Shutemov wrote:
> > On Fri, Feb 05, 2021 at 05:06:20PM -0600, Seth Forshee 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.
> > 
> > Quick grep suggests the same for alpha. Am I wrong?
> 
> No, it appears you are right. Looks like my grep missed alpha somehow.
> 
> Andrew, do you prefer an additional patch or an updated version of the
> previous patch?

Doesn't matter much.  A second patch for Alpha would be best, I guess. 
Thanks.