From eebd2aa355692afaf9906f62118620f1a1c19dbb Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Mon, 4 Feb 2008 22:28:29 -0800 Subject: 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 Cc: Steven French Cc: Michael Halcrow Cc: Cc: Steven Whitehouse Cc: Trond Myklebust Cc: "J. Bruce Fields" Cc: Anton Altaparmakov Cc: Mark Fasheh Cc: David Chinner Cc: Michael Halcrow Cc: Steven French Cc: Steven Whitehouse Cc: Trond Myklebust Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/highmem.h | 48 ++++++++++++++++++++++++++++++------------------ 1 file changed, 30 insertions(+), 18 deletions(-) (limited to 'include') diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 1fcb0033179..61a5e5eb27f 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -124,28 +124,40 @@ static inline void clear_highpage(struct page *page) kunmap_atomic(kaddr, KM_USER0); } -/* - * Same but also flushes aliased cache contents to RAM. - * - * This must be a macro because KM_USER0 and friends aren't defined if - * !CONFIG_HIGHMEM - */ -#define zero_user_page(page, offset, size, km_type) \ - do { \ - void *kaddr; \ - \ - BUG_ON((offset) + (size) > PAGE_SIZE); \ - \ - kaddr = kmap_atomic(page, km_type); \ - memset((char *)kaddr + (offset), 0, (size)); \ - flush_dcache_page(page); \ - kunmap_atomic(kaddr, (km_type)); \ - } while (0) +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(page, offset, size, KM_USER0); + zero_user(page, offset, size); } #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE -- cgit v1.2.3-18-g5258