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linux-next/mm/filemap.h
Carsten Otte eb6fe0c388 [PATCH] xip: reduce code duplication
This patch reworks filemap_xip.c with the goal to reduce code duplication
from mm/filemap.c.  It applies agains 2.6.12-rc6-mm1.  Instead of
implementing the aio functions, this one implements the synchronous
read/write functions only.  For readv and writev, the generic fallback is
used.  For aio, we rely on the application doing the fallback.  Since our
"synchronous" function does memcpy immediately anyway, there is no
performance difference between using the fallbacks or implementing each
operation.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-24 00:06:41 -07:00

95 lines
2.2 KiB
C

/*
* linux/mm/filemap.h
*
* Copyright (C) 1994-1999 Linus Torvalds
*/
#ifndef __FILEMAP_H
#define __FILEMAP_H
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/uio.h>
#include <linux/config.h>
#include <asm/uaccess.h>
size_t
__filemap_copy_from_user_iovec(char *vaddr,
const struct iovec *iov,
size_t base,
size_t bytes);
/*
* Copy as much as we can into the page and return the number of bytes which
* were sucessfully copied. If a fault is encountered then clear the page
* out to (offset+bytes) and return the number of bytes which were copied.
*/
static inline size_t
filemap_copy_from_user(struct page *page, unsigned long offset,
const char __user *buf, unsigned bytes)
{
char *kaddr;
int left;
kaddr = kmap_atomic(page, KM_USER0);
left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
kunmap_atomic(kaddr, KM_USER0);
if (left != 0) {
/* Do it the slow way */
kaddr = kmap(page);
left = __copy_from_user(kaddr + offset, buf, bytes);
kunmap(page);
}
return bytes - left;
}
/*
* This has the same sideeffects and return value as filemap_copy_from_user().
* The difference is that on a fault we need to memset the remainder of the
* page (out to offset+bytes), to emulate filemap_copy_from_user()'s
* single-segment behaviour.
*/
static inline size_t
filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
const struct iovec *iov, size_t base, size_t bytes)
{
char *kaddr;
size_t copied;
kaddr = kmap_atomic(page, KM_USER0);
copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
base, bytes);
kunmap_atomic(kaddr, KM_USER0);
if (copied != bytes) {
kaddr = kmap(page);
copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
base, bytes);
kunmap(page);
}
return copied;
}
static inline void
filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
{
const struct iovec *iov = *iovp;
size_t base = *basep;
while (bytes) {
int copy = min(bytes, iov->iov_len - base);
bytes -= copy;
base += copy;
if (iov->iov_len == base) {
iov++;
base = 0;
}
}
*iovp = iov;
*basep = base;
}
#endif