From 111ebb6e6f7bd7de6d722c5848e95621f43700d9 Mon Sep 17 00:00:00 2001 From: OGAWA Hirofumi Date: Fri, 23 Jun 2006 02:03:26 -0700 Subject: [PATCH] writeback: fix range handling When a writeback_control's `start' and `end' fields are used to indicate a one-byte-range starting at file offset zero, the required values of .start=0,.end=0 mean that the ->writepages() implementation has no way of telling that it is being asked to perform a range request. Because we're currently overloading (start == 0 && end == 0) to mean "this is not a write-a-range request". To make all this sane, the patch changes range of writeback_control. So caller does: If it is calling ->writepages() to write pages, it sets range (range_start/end or range_cyclic) always. And if range_cyclic is true, ->writepages() thinks the range is cyclic, otherwise it just uses range_start and range_end. This patch does, - Add LLONG_MAX, LLONG_MIN, ULLONG_MAX to include/linux/kernel.h -1 is usually ok for range_end (type is long long). But, if someone did, range_end += val; range_end is "val - 1" u64val = range_end >> bits; u64val is "~(0ULL)" or something, they are wrong. So, this adds LLONG_MAX to avoid nasty things, and uses LLONG_MAX for range_end. - All callers of ->writepages() sets range_start/end or range_cyclic. - Fix updates of ->writeback_index. It seems already bit strange. If it starts at 0 and ended by check of nr_to_write, this last index may reduce chance to scan end of file. So, this updates ->writeback_index only if range_cyclic is true or whole-file is scanned. Signed-off-by: OGAWA Hirofumi Cc: Nathan Scott Cc: Anton Altaparmakov Cc: Steven French Cc: "Vladimir V. Saveliev" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index f4fc576ed4c4..25fccd859fbf 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -24,6 +24,9 @@ extern const char linux_banner[]; #define LONG_MAX ((long)(~0UL>>1)) #define LONG_MIN (-LONG_MAX - 1) #define ULONG_MAX (~0UL) +#define LLONG_MAX ((long long)(~0ULL>>1)) +#define LLONG_MIN (-LLONG_MAX - 1) +#define ULLONG_MAX (~0ULL) #define STACK_MAGIC 0xdeadbeef -- cgit v1.2.3 From 368a5fa1f28589e6b54588a139ea872d5b4b1914 Mon Sep 17 00:00:00 2001 From: Hua Zhong Date: Fri, 23 Jun 2006 02:05:42 -0700 Subject: [PATCH] remove unlikely() in might_sleep_if() The likely() profiling tools show that __alloc_page() causes a lot of misses: ! 132 119193 __alloc_pages():mm/page_alloc.c@937 Because most __alloc_page() calls are not atomic. Signed-off-by: Hua Zhong Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 25fccd859fbf..8c21aaa248b4 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -78,7 +78,7 @@ extern int cond_resched(void); # define might_sleep() do { might_resched(); } while (0) #endif -#define might_sleep_if(cond) do { if (unlikely(cond)) might_sleep(); } while (0) +#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) #define abs(x) ({ \ int __x = (x); \ -- cgit v1.2.3