On Mon, Aug 03, 2026 at 02:29:16AM +0000, John Groves wrote:
> From: John Groves <[email protected]>
>
> This commit adds vm_operations, plus famfs_mmap() and fault handlers.
> It is still missing iomap_ops, iomap mapping resolution, and
> famfs_ioctl() for setting up file-to-memory mappings.
>
> Signed-off-by: John Groves <[email protected]>
> ---
> fs/famfs/famfs_file.c | 101 +++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 100 insertions(+), 1 deletion(-)
>
> diff --git a/fs/famfs/famfs_file.c b/fs/famfs/famfs_file.c
> index e192b573c51f..678f2035fd5f 100644
> --- a/fs/famfs/famfs_file.c
> +++ b/fs/famfs/famfs_file.c
> @@ -16,6 +16,75 @@
>
> #include "famfs_internal.h"
>
> +/*********************************************************************
> + * vm_operations
> + */
> +static vm_fault_t
> +__famfs_filemap_fault(struct vm_fault *vmf, unsigned int order,
> + bool write_fault)
> +{
> + struct inode *inode = file_inode(vmf->vma->vm_file);
> + struct super_block *sb = inode->i_sb;
> + struct famfs_fs_info *fsi = sb->s_fs_info;
> + vm_fault_t ret;
> + unsigned long pfn;
> +
> + if (fsi->deverror)
> + return VM_FAULT_SIGBUS;
> +
> + if (!IS_DAX(file_inode(vmf->vma->vm_file))) {
> + pr_err("%s: file not marked IS_DAX!!\n", __func__);
> + return VM_FAULT_SIGBUS;
> + }
> +
> + if (write_fault) {
> + sb_start_pagefault(inode->i_sb);
> + file_update_time(vmf->vma->vm_file);
> + }
> +
> + ret = dax_iomap_fault(vmf, order, &pfn, NULL, NULL /*&famfs_iomap_ops
> */);
> + if (ret & VM_FAULT_NEEDDSYNC)
> + ret = dax_finish_sync_fault(vmf, order, pfn);
> +
> + if (write_fault)
> + sb_end_pagefault(inode->i_sb);
> +
> + return ret;
> +}
> +
> +static inline bool
> +famfs_is_write_fault(struct vm_fault *vmf)
> +{
> + return (vmf->flags & FAULT_FLAG_WRITE) &&
> + (vmf->vma->vm_flags & VM_SHARED);
> +}
> +
> +static vm_fault_t
> +famfs_filemap_fault(struct vm_fault *vmf)
> +{
> + return __famfs_filemap_fault(vmf, 0, famfs_is_write_fault(vmf));
> +}
> +
> +static vm_fault_t
> +famfs_filemap_huge_fault(struct vm_fault *vmf, unsigned int order)
> +{
> + return __famfs_filemap_fault(vmf, order, famfs_is_write_fault(vmf));
> +}
> +
> +static vm_fault_t
> +famfs_filemap_mkwrite(struct vm_fault *vmf)
> +{
> + return __famfs_filemap_fault(vmf, 0, true);
Do neither of the conditions in famfs_is_write_fault apply here?
The rest of the patch looks ok to me.
--D
> +}
> +
> +const struct vm_operations_struct famfs_file_vm_ops = {
> + .fault = famfs_filemap_fault,
> + .huge_fault = famfs_filemap_huge_fault,
> + .map_pages = filemap_map_pages,
> + .page_mkwrite = famfs_filemap_mkwrite,
> + .pfn_mkwrite = famfs_filemap_mkwrite,
> +};
> +
> /*********************************************************************
> * file_operations
> */
> @@ -117,6 +186,36 @@ famfs_dax_write_iter(struct kiocb *iocb, struct iov_iter
> *from)
> return rc;
> }
>
> +static int
> +famfs_file_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> + struct inode *inode = file_inode(file);
> + struct super_block *sb = inode->i_sb;
> + struct famfs_fs_info *fsi = sb->s_fs_info;
> + ssize_t rc;
> +
> + if (fsi->deverror)
> + return -ENODEV;
> +
> + /*
> + * Gate shared-writable mappings on FAMFS_OPT_WRITE. This is best
> + * effort: clearing the bit blocks new writable mappings and write(),
> + * but does not revoke mappings that already exist.
> + */
> + if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE) &&
> + !famfs_opt_enabled(fsi, FAMFS_OPT_WRITE))
> + return -EPERM;
> +
> + rc = famfs_file_invalid(inode);
> + if (rc)
> + return (int)rc;
> +
> + file_accessed(file);
> + vma->vm_ops = &famfs_file_vm_ops;
> + vm_flags_set(vma, VM_HUGEPAGE);
> + return 0;
> +}
> +
> const struct file_operations famfs_file_operations = {
> .owner = THIS_MODULE,
>
> @@ -124,7 +223,7 @@ const struct file_operations famfs_file_operations = {
> .write_iter = famfs_dax_write_iter,
> .read_iter = famfs_dax_read_iter,
> .unlocked_ioctl = NULL /*famfs_file_ioctl*/,
> - .mmap = NULL /* famfs_file_mmap */,
> + .mmap = famfs_file_mmap,
>
> /* Force PMD alignment for mmap */
> .get_unmapped_area = thp_get_unmapped_area,
> --
> 2.53.0
>
>
>
