| Message ID | 20210205202159.505612-1-seth.forshee@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tmpfs: Don't use 64-bit inodes by defulat with 32-bit ino_t | expand |
On Fri, 5 Feb 2021 14:21:59 -0600 Seth Forshee <seth.forshee@canonical.com> 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 <seth.forshee@canonical.com> 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 <seth.forshee@canonical.com> 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 <seth.forshee@canonical.com> > > With a cc:stable, I assume? Yes, I forgot that. Thanks. Seth
On Fri, 5 Feb 2021 14:55:43 -0600 Seth Forshee <seth.forshee@canonical.com> 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 <seth.forshee@canonical.com> 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 <seth.forshee@canonical.com> 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 <seth.forshee@canonical.com> 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
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;
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 <seth.forshee@canonical.com> --- mm/shmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)