EXT4 MAP

const struct file_operations ext4_file_operations = {
    .llseek        = ext4_llseek,
    .read_iter    = ext4_file_read_iter,
    .write_iter    = ext4_file_write_iter,
    .unlocked_ioctl = ext4_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl    = ext4_compat_ioctl,
#endif
    .mmap        = ext4_file_mmap,
    .mmap_supported_flags = MAP_SYNC,
    .open        = ext4_file_open,
    .release    = ext4_release_file,
    .fsync        = ext4_sync_file,
    .get_unmapped_area = thp_get_unmapped_area,
    .splice_read    = generic_file_splice_read,
    .splice_write    = iter_file_splice_write,
    .fallocate    = ext4_fallocate,
};

 

static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
{
    struct inode *inode = file->f_mapping->host;

    if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
        return -EIO;

    /*
     * We don't support synchronous mappings for non-DAX files. At least
     * until someone comes with a sensible use case.
     */
    if (!IS_DAX(file_inode(file)) && (vma->vm_flags & VM_SYNC))
        return -EOPNOTSUPP;

    file_accessed(file);
    dump_stack();
    if (IS_DAX(file_inode(file))) {
        vma->vm_ops = &ext4_dax_vm_ops;
        vma->vm_flags |= VM_HUGEPAGE;
    } else {
        vma->vm_ops = &ext4_file_vm_ops;
    }
    
    return 0;
}

 

static const struct vm_operations_struct ext4_file_vm_ops = {
    .fault        = ext4_filemap_fault,
    .map_pages    = filemap_map_pages,
    .page_mkwrite   = ext4_page_mkwrite,
};

 

文件映射的缺页处理