From 56fcb65c7941bdd6824bb090d4a7731af102771d Mon Sep 17 00:00:00 2001
From: Fengguang Wu <wfg@mail.ustc.edu.cn>
Date: Thu, 19 Jul 2007 01:47:58 -0700
Subject: [PATCH] --- yaml --- r: 61567 b: refs/heads/master c:
 f615bfca468c9b80ed2d09be5fdbaf470a32c045 h: refs/heads/master i:   61565:
 78d809193bb46918642745a128a790302c911b9a   61563:
 a569e77b3915d744e0b93a93dfc1b82ec232a199   61559:
 c5712bfaaa32c0594bd7162d87ff3b6ebd334a06   61551:
 94823edf3317a8a6e8f15559f0d9e1981546a77f   61535:
 8fe5d1eace4ba3347471d6da58aa7c95e4f3b31f   61503:
 46bc74b55a6e9132736d27e26689f17587237f21   61439:
 aaeee93866c1bace2aa06b5b76955ea24433af55 v: v3

---
 [refs]               |  2 +-
 trunk/mm/readahead.c | 12 ++++++++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/[refs] b/[refs]
index 826ba05f8c40..d8e3967082c8 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 46fc3e7b4e7233a0ac981ac9084b55217318d04d
+refs/heads/master: f615bfca468c9b80ed2d09be5fdbaf470a32c045
diff --git a/trunk/mm/readahead.c b/trunk/mm/readahead.c
index 88ea0f29aac8..7f9bf588c936 100644
--- a/trunk/mm/readahead.c
+++ b/trunk/mm/readahead.c
@@ -21,8 +21,16 @@ void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
 }
 EXPORT_SYMBOL(default_unplug_io_fn);
 
+/*
+ * Convienent macros for min/max read-ahead pages.
+ * Note that MAX_RA_PAGES is rounded down, while MIN_RA_PAGES is rounded up.
+ * The latter is necessary for systems with large page size(i.e. 64k).
+ */
+#define MAX_RA_PAGES	(VM_MAX_READAHEAD*1024 / PAGE_CACHE_SIZE)
+#define MIN_RA_PAGES	DIV_ROUND_UP(VM_MIN_READAHEAD*1024, PAGE_CACHE_SIZE)
+
 struct backing_dev_info default_backing_dev_info = {
-	.ra_pages	= (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE,
+	.ra_pages	= MAX_RA_PAGES,
 	.state		= 0,
 	.capabilities	= BDI_CAP_MAP_COPY,
 	.unplug_io_fn	= default_unplug_io_fn,
@@ -51,7 +59,7 @@ static inline unsigned long get_max_readahead(struct file_ra_state *ra)
 
 static inline unsigned long get_min_readahead(struct file_ra_state *ra)
 {
-	return (VM_MIN_READAHEAD * 1024) / PAGE_CACHE_SIZE;
+	return MIN_RA_PAGES;
 }
 
 static inline void reset_ahead_window(struct file_ra_state *ra)