On Tue, 22 Jul 2014, Jerome Marchand wrote:
> Add a simple helper to check if a vm area belongs to shmem.
>
> Signed-off-by: Jerome Marchand <jmarchan@xxxxxxxxxx>
> ---
> include/linux/mm.h | 6 ++++++
> mm/shmem.c | 8 ++++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 34099fa..04a58d1 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1074,11 +1074,17 @@ int shmem_zero_setup(struct vm_area_struct *);
>
> extern int shmem_locate(struct vm_area_struct *vma, pgoff_t pgoff, int *count);
> bool shmem_mapping(struct address_space *mapping);
> +bool shmem_vma(struct vm_area_struct *vma);
> +
> #else
> static inline bool shmem_mapping(struct address_space *mapping)
> {
> return false;
> }
> +static inline bool shmem_vma(struct vm_area_struct *vma)
> +{
> + return false;
> +}
> #endif
I would prefer include/linux/shmem_fs.h for this (and one of us clean
up where the declarations of shmem_zero_setup and shmem_mapping live).
But if 4/5 goes away, then there will only be one user of shmem_vma(),
so in that case better just declare it (using shmem_mapping()) there
in task_mmu.c in the smaps patch.
>
> extern int can_do_mlock(void);
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 8aa4892..7d16227 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -1483,6 +1483,14 @@ bool shmem_mapping(struct address_space *mapping)
> return mapping->backing_dev_info == &shmem_backing_dev_info;
> }
>
> +bool shmem_vma(struct vm_area_struct *vma)
> +{
> + return (vma->vm_file &&
> + vma->vm_file->f_dentry->d_inode->i_mapping->backing_dev_info
> + == &shmem_backing_dev_info);
> +
I agree with Oleg,
vma->vm_file && shmem_mapping(file_inode(vma->vm_file)->i_mapping);
would be better,
Hugh
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