Re: [PATCH 2/6] shmem: rename functions that are memfd-related

From: Marc-Andrà Lureau
Date: Fri Nov 03 2017 - 12:36:19 EST


Hi

----- Original Message -----
> On 11/03/2017 09:02 AM, Marc-Andrà Lureau wrote:
> > Hi
> >
> > ----- Original Message -----
> >> On 10/31/2017 11:40 AM, Marc-Andrà Lureau wrote:
> >>> Those functions are called for memfd files, backed by shmem or
> >>> hugetlb (the next patches will handle hugetlb).
> >>>
> >>> Signed-off-by: Marc-Andrà Lureau <marcandre.lureau@xxxxxxxxxx>
> >>> ---
> >>> fs/fcntl.c | 2 +-
> >>> include/linux/shmem_fs.h | 4 ++--
> >>> mm/shmem.c | 10 +++++-----
> >>> 3 files changed, 8 insertions(+), 8 deletions(-)
> >>>
> >>> diff --git a/fs/fcntl.c b/fs/fcntl.c
> >>> index 448a1119f0be..752c23743616 100644
> >>> --- a/fs/fcntl.c
> >>> +++ b/fs/fcntl.c
> >>> @@ -417,7 +417,7 @@ static long do_fcntl(int fd, unsigned int cmd,
> >>> unsigned
> >>> long arg,
> >>> break;
> >>> case F_ADD_SEALS:
> >>> case F_GET_SEALS:
> >>> - err = shmem_fcntl(filp, cmd, arg);
> >>> + err = memfd_fcntl(filp, cmd, arg);
> >>> break;
> >>> case F_GET_RW_HINT:
> >>> case F_SET_RW_HINT:
> >>> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> >>> index 557d0c3b6eca..0dac8c0f4aa4 100644
> >>> --- a/include/linux/shmem_fs.h
> >>> +++ b/include/linux/shmem_fs.h
> >>> @@ -109,11 +109,11 @@ extern void shmem_uncharge(struct inode *inode,
> >>> long
> >>> pages);
> >>>
> >>> #ifdef CONFIG_TMPFS
> >>>
> >>> -extern long shmem_fcntl(struct file *file, unsigned int cmd, unsigned
> >>> long
> >>> arg);
> >>> +extern long memfd_fcntl(struct file *file, unsigned int cmd, unsigned
> >>> long
> >>> arg);
> >>>
> >>> #else
> >>>
> >>> -static inline long shmem_fcntl(struct file *f, unsigned int c, unsigned
> >>> long a)
> >>> +static inline long memfd_fcntl(struct file *f, unsigned int c, unsigned
> >>> long a)
> >>> {
> >>> return -EINVAL;
> >>> }
> >>
> >> Do we want memfd_fcntl() to work for hugetlbfs if CONFIG_TMPFS is not
> >> defined? I admit that having CONFIG_HUGETLBFS defined without
> >> CONFIG_TMPFS
> >> is unlikely, but I think possible. Based on the above #ifdef/#else, I
> >> think hugetlbfs seals will not work if CONFIG_TMPFS is not defined.
> >
> > Good point, memfd_create() will not exists either.
> >
> > I think this is a separate concern, and preexisting from this patch series
> > though.
>
> Ah yes. I should have addressed this when adding hugetlbfs memfd_create
> support.
>
> Of course, one 'simple' way to address this would be to make CONFIG_HUGETLBFS
> depend on CONFIG_TMPFS. Not sure what people think about this?
>

I can't say much about that. But compiling the hugetlb seal support while TPMFS/memfd is disabled should not break anything. You won't be able to add seals, that's it.

I suppose memfd could be splitted off TPMFS, and depend on either HUGETLBFS || TPMFS?

> > Ack the function renaming part?
>
> Yes, the remaining code looks fine to me.

Should I add your Review-by: for this patch then?

>
> --
> Mike Kravetz
>
> >
> >> --
> >> Mike Kravetz
> >>
> >>> diff --git a/mm/shmem.c b/mm/shmem.c
> >>> index 37260c5e12fa..b7811979611f 100644
> >>> --- a/mm/shmem.c
> >>> +++ b/mm/shmem.c
> >>> @@ -2722,7 +2722,7 @@ static int shmem_wait_for_pins(struct address_space
> >>> *mapping)
> >>> F_SEAL_GROW | \
> >>> F_SEAL_WRITE)
> >>>
> >>> -static int shmem_add_seals(struct file *file, unsigned int seals)
> >>> +static int memfd_add_seals(struct file *file, unsigned int seals)
> >>> {
> >>> struct inode *inode = file_inode(file);
> >>> struct shmem_inode_info *info = SHMEM_I(inode);
> >>> @@ -2792,7 +2792,7 @@ static int shmem_add_seals(struct file *file,
> >>> unsigned int seals)
> >>> return error;
> >>> }
> >>>
> >>> -static int shmem_get_seals(struct file *file)
> >>> +static int memfd_get_seals(struct file *file)
> >>> {
> >>> if (file->f_op != &shmem_file_operations)
> >>> return -EINVAL;
> >>> @@ -2800,7 +2800,7 @@ static int shmem_get_seals(struct file *file)
> >>> return SHMEM_I(file_inode(file))->seals;
> >>> }
> >>>
> >>> -long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
> >>> +long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
> >>> {
> >>> long error;
> >>>
> >>> @@ -2810,10 +2810,10 @@ long shmem_fcntl(struct file *file, unsigned int
> >>> cmd, unsigned long arg)
> >>> if (arg > UINT_MAX)
> >>> return -EINVAL;
> >>>
> >>> - error = shmem_add_seals(file, arg);
> >>> + error = memfd_add_seals(file, arg);
> >>> break;
> >>> case F_GET_SEALS:
> >>> - error = shmem_get_seals(file);
> >>> + error = memfd_get_seals(file);
> >>> break;
> >>> default:
> >>> error = -EINVAL;
> >>>
> >>
> >> --
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>
> --
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