linux/fs/ncpfs/mmap.c

127 lines
2.9 KiB
C
Raw Normal View History

/*
* 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/mm.h>
#include <linux/shm.h>
#include <linux/errno.h>
#include <linux/mman.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/fcntl.h>
#include <linux/ncp_fs.h>
#include "ncplib_kernel.h"
#include <asm/uaccess.h>
#include <asm/system.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
*/
[PATCH] Light weight event counters The remaining counters in page_state after the zoned VM counter patches have been applied are all just for show in /proc/vmstat. They have no essential function for the VM. We use a simple increment of per cpu variables. In order to avoid the most severe races we disable preempt. Preempt does not prevent the race between an increment and an interrupt handler incrementing the same statistics counter. However, that race is exceedingly rare, we may only loose one increment or so and there is no requirement (at least not in kernel) that the vm event counters have to be accurate. In the non preempt case this results in a simple increment for each counter. For many architectures this will be reduced by the compiler to a single instruction. This single instruction is atomic for i386 and x86_64. And therefore even the rare race condition in an interrupt is avoided for both architectures in most cases. The patchset also adds an off switch for embedded systems that allows a building of linux kernels without these counters. The implementation of these counters is through inline code that hopefully results in only a single instruction increment instruction being emitted (i386, x86_64) or in the increment being hidden though instruction concurrency (EPIC architectures such as ia64 can get that done). Benefits: - VM event counter operations usually reduce to a single inline instruction on i386 and x86_64. - No interrupt disable, only preempt disable for the preempt case. Preempt disable can also be avoided by moving the counter into a spinlock. - Handling is similar to zoned VM counters. - Simple and easily extendable. - Can be omitted to reduce memory use for embedded use. References: RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=113512330605497&w=2 RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=114988082814934&w=2 local_t http://marc.theaimsgroup.com/?l=linux-kernel&m=114991748606690&w=2 V2 http://marc.theaimsgroup.com/?t=115014808400007&r=1&w=2 V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767022346&w=2 V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115047968808926&w=2 Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30 16:55:45 +08:00
count_vm_event(PGMAJFAULT);
return VM_FAULT_MAJOR;
}
static struct vm_operations_struct ncp_file_mmap =
{
mm: merge populate and nopage into fault (fixes nonlinear) Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes the virtual address -> file offset differently from linear mappings. ->populate is a layering violation because the filesystem/pagecache code should need to know anything about the virtual memory mapping. The hitch here is that the ->nopage handler didn't pass down enough information (ie. pgoff). But it is more logical to pass pgoff rather than have the ->nopage function calculate it itself anyway (because that's a similar layering violation). Having the populate handler install the pte itself is likewise a nasty thing to be doing. This patch introduces a new fault handler that replaces ->nopage and ->populate and (later) ->nopfn. Most of the old mechanism is still in place so there is a lot of duplication and nice cleanups that can be removed if everyone switches over. The rationale for doing this in the first place is that nonlinear mappings are subject to the pagefault vs invalidate/truncate race too, and it seemed stupid to duplicate the synchronisation logic rather than just consolidate the two. After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in pagecache. Seems like a fringe functionality anyway. NOPAGE_REFAULT is removed. This should be implemented with ->fault, and no users have hit mainline yet. [akpm@linux-foundation.org: cleanup] [randy.dunlap@oracle.com: doc. fixes for readahead] [akpm@linux-foundation.org: build fix] Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 16:46:59 +08:00
.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;
}