Re: [PATCH 01/23] mm/shmem: introduce shmem_file_setup_with_mnt

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

Hi Andrew,

This patch has been floating around for a while now Acked and without
further comments. It is blocking us from merging huge page support to
drm/i915.

Would you mind merging it, or prodding the right people to get it in?

Regards, Joonas

On Mon, 2017-08-21 at 19:34 +0100, Matthew Auld wrote:
> We are planning to use our own tmpfs mnt in i915 in place of the
> shm_mnt, such that we can control the mount options, in particular
> huge=, which we require to support huge-gtt-pages. So rather than roll
> our own version of __shmem_file_setup, it would be preferred if we could
> just give shmem our mnt, and let it do the rest.
> 
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Kirill A. Shutemov <kirill@shutemov.name>
> Cc: Hugh Dickins <hughd@google.com>
> Cc: linux-mm@kvack.org
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
>  include/linux/shmem_fs.h |  2 ++
>  mm/shmem.c               | 30 ++++++++++++++++++++++--------
>  2 files changed, 24 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index a7d6bd2a918f..27de676f0b63 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -53,6 +53,8 @@ extern struct file *shmem_file_setup(const char *name,
>  					loff_t size, unsigned long flags);
>  extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
>  					    unsigned long flags);
> +extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
> +		const char *name, loff_t size, unsigned long flags);
>  extern int shmem_zero_setup(struct vm_area_struct *);
>  extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
>  		unsigned long len, unsigned long pgoff, unsigned long flags);
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 6540e5982444..0975e65ea61c 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -4141,7 +4141,7 @@ static const struct dentry_operations anon_ops = {
>  	.d_dname = simple_dname
>  };
>  
> -static struct file *__shmem_file_setup(const char *name, loff_t size,
> +static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
>  				       unsigned long flags, unsigned int i_flags)
>  {
>  	struct file *res;
> @@ -4150,8 +4150,8 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
>  	struct super_block *sb;
>  	struct qstr this;
>  
> -	if (IS_ERR(shm_mnt))
> -		return ERR_CAST(shm_mnt);
> +	if (IS_ERR(mnt))
> +		return ERR_CAST(mnt);
>  
>  	if (size < 0 || size > MAX_LFS_FILESIZE)
>  		return ERR_PTR(-EINVAL);
> @@ -4163,8 +4163,8 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
>  	this.name = name;
>  	this.len = strlen(name);
>  	this.hash = 0; /* will go */
> -	sb = shm_mnt->mnt_sb;
> -	path.mnt = mntget(shm_mnt);
> +	sb = mnt->mnt_sb;
> +	path.mnt = mntget(mnt);
>  	path.dentry = d_alloc_pseudo(sb, &this);
>  	if (!path.dentry)
>  		goto put_memory;
> @@ -4209,7 +4209,7 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
>   */
>  struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
>  {
> -	return __shmem_file_setup(name, size, flags, S_PRIVATE);
> +	return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
>  }
>  
>  /**
> @@ -4220,11 +4220,25 @@ struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned lon
>   */
>  struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
>  {
> -	return __shmem_file_setup(name, size, flags, 0);
> +	return __shmem_file_setup(shm_mnt, name, size, flags, 0);
>  }
>  EXPORT_SYMBOL_GPL(shmem_file_setup);
>  
>  /**
> + * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
> + * @mnt: the tmpfs mount where the file will be created
> + * @name: name for dentry (to be seen in /proc/<pid>/maps
> + * @size: size to be set for the file
> + * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
> + */
> +struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
> +				       loff_t size, unsigned long flags)
> +{
> +	return __shmem_file_setup(mnt, name, size, flags, 0);
> +}
> +EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
> +
> +/**
>   * shmem_zero_setup - setup a shared anonymous mapping
>   * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
>   */
> @@ -4239,7 +4253,7 @@ int shmem_zero_setup(struct vm_area_struct *vma)
>  	 * accessible to the user through its mapping, use S_PRIVATE flag to
>  	 * bypass file security, in the same way as shmem_kernel_file_setup().
>  	 */
> -	file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE);
> +	file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
>  	if (IS_ERR(file))
>  		return PTR_ERR(file);
>  
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation

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