kernel-fxtec-pro1x/include/linux/highmem.h
Christoph Lameter eebd2aa355 Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user
Simplify page cache zeroing of segments of pages through 3 functions

zero_user_segments(page, start1, end1, start2, end2)

        Zeros two segments of the page. It takes the position where to
        start and end the zeroing which avoids length calculations and
	makes code clearer.

zero_user_segment(page, start, end)

        Same for a single segment.

zero_user(page, start, length)

        Length variant for the case where we know the length.

We remove the zero_user_page macro. Issues:

1. Its a macro. Inline functions are preferable.

2. The KM_USER0 macro is only defined for HIGHMEM.

   Having to treat this special case everywhere makes the
   code needlessly complex. The parameter for zeroing is always
   KM_USER0 except in one single case that we open code.

Avoiding KM_USER0 makes a lot of code not having to be dealing
with the special casing for HIGHMEM anymore. Dealing with
kmap is only necessary for HIGHMEM configurations. In those
configurations we use KM_USER0 like we do for a series of other
functions defined in highmem.h.

Since KM_USER0 is depends on HIGHMEM the existing zero_user_page
function could not be a macro. zero_user_* functions introduced
here can be be inline because that constant is not used when these
functions are called.

Also extract the flushing of the caches to be outside of the kmap.

[akpm@linux-foundation.org: fix nfs and ntfs build]
[akpm@linux-foundation.org: fix ntfs build some more]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Steven French <sfrench@us.ibm.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Anton Altaparmakov <aia21@cantab.net>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Cc: David Chinner <dgc@sgi.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Steven French <sfrench@us.ibm.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-05 09:44:13 -08:00

192 lines
4.9 KiB
C

#ifndef _LINUX_HIGHMEM_H
#define _LINUX_HIGHMEM_H
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#ifndef ARCH_HAS_FLUSH_ANON_PAGE
static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
{
}
#endif
#ifndef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
static inline void flush_kernel_dcache_page(struct page *page)
{
}
#endif
#ifdef CONFIG_HIGHMEM
#include <asm/highmem.h>
/* declarations for linux/mm/highmem.c */
unsigned int nr_free_highpages(void);
extern unsigned long totalhigh_pages;
void kmap_flush_unused(void);
#else /* CONFIG_HIGHMEM */
static inline unsigned int nr_free_highpages(void) { return 0; }
#define totalhigh_pages 0
#ifndef ARCH_HAS_KMAP
static inline void *kmap(struct page *page)
{
might_sleep();
return page_address(page);
}
#define kunmap(page) do { (void) (page); } while (0)
#include <asm/kmap_types.h>
static inline void *kmap_atomic(struct page *page, enum km_type idx)
{
pagefault_disable();
return page_address(page);
}
#define kmap_atomic_prot(page, idx, prot) kmap_atomic(page, idx)
#define kunmap_atomic(addr, idx) do { pagefault_enable(); } while (0)
#define kmap_atomic_pfn(pfn, idx) kmap_atomic(pfn_to_page(pfn), (idx))
#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
#define kmap_flush_unused() do {} while(0)
#endif
#endif /* CONFIG_HIGHMEM */
/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
{
void *addr = kmap_atomic(page, KM_USER0);
clear_user_page(addr, vaddr, page);
kunmap_atomic(addr, KM_USER0);
/* Make sure this page is cleared on other CPU's too before using it */
smp_wmb();
}
#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
/**
* __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags
* @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE
* @vma: The VMA the page is to be allocated for
* @vaddr: The virtual address the page will be inserted into
*
* This function will allocate a page for a VMA but the caller is expected
* to specify via movableflags whether the page will be movable in the
* future or not
*
* An architecture may override this function by defining
* __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own
* implementation.
*/
static inline struct page *
__alloc_zeroed_user_highpage(gfp_t movableflags,
struct vm_area_struct *vma,
unsigned long vaddr)
{
struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags,
vma, vaddr);
if (page)
clear_user_highpage(page, vaddr);
return page;
}
#endif
/**
* alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
* @vma: The VMA the page is to be allocated for
* @vaddr: The virtual address the page will be inserted into
*
* This function will allocate a page for a VMA that the caller knows will
* be able to migrate in the future using move_pages() or reclaimed
*/
static inline struct page *
alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
unsigned long vaddr)
{
return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
}
static inline void clear_highpage(struct page *page)
{
void *kaddr = kmap_atomic(page, KM_USER0);
clear_page(kaddr);
kunmap_atomic(kaddr, KM_USER0);
}
static inline void zero_user_segments(struct page *page,
unsigned start1, unsigned end1,
unsigned start2, unsigned end2)
{
void *kaddr = kmap_atomic(page, KM_USER0);
BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE);
if (end1 > start1)
memset(kaddr + start1, 0, end1 - start1);
if (end2 > start2)
memset(kaddr + start2, 0, end2 - start2);
kunmap_atomic(kaddr, KM_USER0);
flush_dcache_page(page);
}
static inline void zero_user_segment(struct page *page,
unsigned start, unsigned end)
{
zero_user_segments(page, start, end, 0, 0);
}
static inline void zero_user(struct page *page,
unsigned start, unsigned size)
{
zero_user_segments(page, start, start + size, 0, 0);
}
static inline void __deprecated memclear_highpage_flush(struct page *page,
unsigned int offset, unsigned int size)
{
zero_user(page, offset, size);
}
#ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE
static inline void copy_user_highpage(struct page *to, struct page *from,
unsigned long vaddr, struct vm_area_struct *vma)
{
char *vfrom, *vto;
vfrom = kmap_atomic(from, KM_USER0);
vto = kmap_atomic(to, KM_USER1);
copy_user_page(vto, vfrom, vaddr, to);
kunmap_atomic(vfrom, KM_USER0);
kunmap_atomic(vto, KM_USER1);
/* Make sure this page is cleared on other CPU's too before using it */
smp_wmb();
}
#endif
static inline void copy_highpage(struct page *to, struct page *from)
{
char *vfrom, *vto;
vfrom = kmap_atomic(from, KM_USER0);
vto = kmap_atomic(to, KM_USER1);
copy_page(vto, vfrom);
kunmap_atomic(vfrom, KM_USER0);
kunmap_atomic(vto, KM_USER1);
}
#endif /* _LINUX_HIGHMEM_H */