Currently there seems to be an assumption in tmpfs that 64-bit
architectures also have a 64-bit ino_t. This is not true; s390 at
least 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.
Ideally CONFIG_TMPFS_INODE64 would depend on sizeof(ino_t) < 8,
but I don't think it's possible to test for this (potentially
CONFIG_ARCH_HAS_64BIT_INO_T or similar could be added, but I'm
not sure whether or not that is wanted). So fix this by simply
refusing to honor the CONFIG_TMPFS_INODE64 setting when
sizeof(ino_t) < 8.
Fixes: ea3271f7196c ("tmpfs: support 64-bit inums per-sb")
Signed-off-by: Seth Forshee <[email protected]>
---
mm/shmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 7c6b6d8f6c39..efde42acdc7a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3733,7 +3733,7 @@ static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
ctx->blocks = shmem_default_max_blocks();
if (!(ctx->seen & SHMEM_SEEN_INODES))
ctx->inodes = shmem_default_max_inodes();
- if (!(ctx->seen & SHMEM_SEEN_INUMS))
+ if (!(ctx->seen & SHMEM_SEEN_INUMS) && sizeof(ino_t) >= 8)
ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
} else {
sb->s_flags |= SB_NOUSER;
--
2.29.2
On Fri, 5 Feb 2021 14:21:59 -0600 Seth Forshee <[email protected]> wrote:
> Currently there seems to be an assumption in tmpfs that 64-bit
> architectures also have a 64-bit ino_t. This is not true; s390 at
> least 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.
>
> Ideally CONFIG_TMPFS_INODE64 would depend on sizeof(ino_t) < 8,
> but I don't think it's possible to test for this (potentially
> CONFIG_ARCH_HAS_64BIT_INO_T or similar could be added, but I'm
> not sure whether or not that is wanted). So fix this by simply
> refusing to honor the CONFIG_TMPFS_INODE64 setting when
> sizeof(ino_t) < 8.
How about changing s390 Kconfig so that CONFIG_TMPFS_INODE64 is not enabled?
> Fixes: ea3271f7196c ("tmpfs: support 64-bit inums per-sb")
> Signed-off-by: Seth Forshee <[email protected]>
With a cc:stable, I assume?
On Fri, Feb 05, 2021 at 12:41:57PM -0800, Andrew Morton wrote:
> On Fri, 5 Feb 2021 14:21:59 -0600 Seth Forshee <[email protected]> wrote:
>
> > Currently there seems to be an assumption in tmpfs that 64-bit
> > architectures also have a 64-bit ino_t. This is not true; s390 at
> > least 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.
> >
> > Ideally CONFIG_TMPFS_INODE64 would depend on sizeof(ino_t) < 8,
> > but I don't think it's possible to test for this (potentially
> > CONFIG_ARCH_HAS_64BIT_INO_T or similar could be added, but I'm
> > not sure whether or not that is wanted). So fix this by simply
> > refusing to honor the CONFIG_TMPFS_INODE64 setting when
> > sizeof(ino_t) < 8.
>
> How about changing s390 Kconfig so that CONFIG_TMPFS_INODE64 is not enabled?
I did do that for our config. I see the s390 defconfig has it enabled,
so I will send a patch for that too. But the fact that it can be
configured that way and that the code behaves badly still seems
problematic.
>
> > Fixes: ea3271f7196c ("tmpfs: support 64-bit inums per-sb")
> > Signed-off-by: Seth Forshee <[email protected]>
>
> With a cc:stable, I assume?
Yes, I forgot that. Thanks.
Seth
On Fri, 5 Feb 2021 14:55:43 -0600 Seth Forshee <[email protected]> wrote:
> On Fri, Feb 05, 2021 at 12:41:57PM -0800, Andrew Morton wrote:
> > On Fri, 5 Feb 2021 14:21:59 -0600 Seth Forshee <[email protected]> wrote:
> >
> > > Currently there seems to be an assumption in tmpfs that 64-bit
> > > architectures also have a 64-bit ino_t. This is not true; s390 at
> > > least 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.
> > >
> > > Ideally CONFIG_TMPFS_INODE64 would depend on sizeof(ino_t) < 8,
> > > but I don't think it's possible to test for this (potentially
> > > CONFIG_ARCH_HAS_64BIT_INO_T or similar could be added, but I'm
> > > not sure whether or not that is wanted). So fix this by simply
> > > refusing to honor the CONFIG_TMPFS_INODE64 setting when
> > > sizeof(ino_t) < 8.
> >
> > How about changing s390 Kconfig so that CONFIG_TMPFS_INODE64 is not enabled?
>
> I did do that for our config. I see the s390 defconfig has it enabled,
> so I will send a patch for that too. But the fact that it can be
> configured that way and that the code behaves badly still seems
> problematic.
I meant
--- a/fs/Kconfig~a
+++ 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
_
On Fri, Feb 05, 2021 at 01:23:13PM -0800, Andrew Morton wrote:
> On Fri, 5 Feb 2021 14:55:43 -0600 Seth Forshee <[email protected]> wrote:
>
> > On Fri, Feb 05, 2021 at 12:41:57PM -0800, Andrew Morton wrote:
> > > On Fri, 5 Feb 2021 14:21:59 -0600 Seth Forshee <[email protected]> wrote:
> > >
> > > > Currently there seems to be an assumption in tmpfs that 64-bit
> > > > architectures also have a 64-bit ino_t. This is not true; s390 at
> > > > least 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.
> > > >
> > > > Ideally CONFIG_TMPFS_INODE64 would depend on sizeof(ino_t) < 8,
> > > > but I don't think it's possible to test for this (potentially
> > > > CONFIG_ARCH_HAS_64BIT_INO_T or similar could be added, but I'm
> > > > not sure whether or not that is wanted). So fix this by simply
> > > > refusing to honor the CONFIG_TMPFS_INODE64 setting when
> > > > sizeof(ino_t) < 8.
> > >
> > > How about changing s390 Kconfig so that CONFIG_TMPFS_INODE64 is not enabled?
> >
> > I did do that for our config. I see the s390 defconfig has it enabled,
> > so I will send a patch for that too. But the fact that it can be
> > configured that way and that the code behaves badly still seems
> > problematic.
>
> I meant
>
> --- a/fs/Kconfig~a
> +++ 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
> _
Ah. s390 does appear to be the only architecture that doesn't use
unsigned long for ino_t, so that seems good to me. I can send a patch if
you want, but seems like you've already got one ...
Seth