mmap.c

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/*
 *  mmap.c
 *
 *  Copyright (C) 1995, 1996 by Volker Lendecke
 *  Modified 1997 Peter Waltenberg, Bill Hawes, David Woodhouse for 2.1 dcache
 *
 */

#include <linux/stat.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/errno.h>
#include <linux/mman.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/memcontrol.h>

#include <asm/uaccess.h>

#include "ncp_fs.h"

/*
 * Fill in the supplied page for mmap
 * XXX: how are we excluding truncate/invalidate here? Maybe need to lock
 * page?
 */
static int ncp_file_mmap_fault(struct vm_area_struct *area,
                    struct vm_fault *vmf)
{
    struct file *file = area->vm_file;
    struct dentry *dentry = file->f_path.dentry;
    struct inode *inode = dentry->d_inode;
    char *pg_addr;
    unsigned int already_read;
    unsigned int count;
    int bufsize;
    int pos; /* XXX: loff_t ? */

    /*
     * ncpfs has nothing against high pages as long
     * as recvmsg and memset works on it
     */
    vmf->page = alloc_page(GFP_HIGHUSER);
    if (!vmf->page)
        return VM_FAULT_OOM;
    pg_addr = kmap(vmf->page);
    pos = vmf->pgoff << PAGE_SHIFT;

    count = PAGE_SIZE;
    /* what we can read in one go */
    bufsize = NCP_SERVER(inode)->buffer_size;

    already_read = 0;
    if (ncp_make_open(inode, O_RDONLY) >= 0) {
        while (already_read < count) {
            int read_this_time;
            int to_read;

            to_read = bufsize - (pos % bufsize);

            to_read = min_t(unsigned int, to_read, count - already_read);

            if (ncp_read_kernel(NCP_SERVER(inode),
                     NCP_FINFO(inode)->file_handle,
                     pos, to_read,
                     pg_addr + already_read,
                     &read_this_time) != 0) {
                read_this_time = 0;
            }
            pos += read_this_time;
            already_read += read_this_time;

            if (read_this_time < to_read) {
                break;
            }
        }
        ncp_inode_close(inode);

    }

    if (already_read < PAGE_SIZE)
        memset(pg_addr + already_read, 0, PAGE_SIZE - already_read);
    flush_dcache_page(vmf->page);
    kunmap(vmf->page);

    /*
     * If I understand ncp_read_kernel() properly, the above always
     * fetches from the network, here the analogue of disk.
     * -- wli
     */
    count_vm_event(PGMAJFAULT);
    mem_cgroup_count_vm_event(area->vm_mm, PGMAJFAULT);
    return VM_FAULT_MAJOR;
}

static const struct vm_operations_struct ncp_file_mmap =
{
    .fault = ncp_file_mmap_fault,
};


/* This is used for a general mmap of a ncp file */
int ncp_mmap(struct file *file, struct vm_area_struct *vma)
{
    struct inode *inode = file->f_path.dentry->d_inode;
    
    DPRINTK("ncp_mmap: called\n");

    if (!ncp_conn_valid(NCP_SERVER(inode)))
        return -EIO;

    /* only PAGE_COW or read-only supported now */
    if (vma->vm_flags & VM_SHARED)
        return -EINVAL;
    /* we do not support files bigger than 4GB... We eventually 
       supports just 4GB... */
    if (((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff 
       > (1U << (32 - PAGE_SHIFT)))
        return -EFBIG;

    vma->vm_ops = &ncp_file_mmap;
    file_accessed(file);
    return 0;
}