From 025421eab453fd41a3cc14a0fc48115b0dc4c287 Mon Sep 17 00:00:00 2001
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Date: Fri, 19 Aug 2011 09:37:46 +0000
Subject: [PATCH] fat: replace LINEAR_PREFETCH_SIZE with PREFETCH_BLOCKS
Currently in do_fat_read() when reading FAT sectors, we have to divide down
LINEAR_PREFETCH_SIZE by the sector size, whereas it's defined as 2 sectors
worth of bytes. In order to avoid redundant multiplication/division, introduce
#define PREFETCH_BLOCKS instead of #define LINEAR_PREFETCH_SIZE.
Signed-off-by: Sergei Shtylyov <sshtylyov@mvista.com>
---
fs/fat/fat.c | 9 ++++-----
include/fat.h | 2 +-
2 files changed, 5 insertions(+), 6 deletions(-)
diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index aa0be18b8f3..756ac64a8b7 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -440,10 +440,9 @@ get_vfatname (fsdata *mydata, int curclust, __u8 *cluster,
{
dir_entry *realdent;
dir_slot *slotptr = (dir_slot *)retdent;
- __u8 *buflimit = cluster + ((curclust == 0) ?
- LINEAR_PREFETCH_SIZE :
- (mydata->clust_size * mydata->sect_size)
- );
+ __u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
+ PREFETCH_BLOCKS :
+ mydata->clust_size);
__u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
int idx = 0;
@@ -880,7 +879,7 @@ do_fat_read (const char *filename, void *buffer, unsigned long maxsize,
if (disk_read(cursect,
(mydata->fatsize == 32) ?
(mydata->clust_size) :
- LINEAR_PREFETCH_SIZE / mydata->sect_size,
+ PREFETCH_BLOCKS,
do_fat_read_block) < 0) {
debug("Error: reading rootdir block\n");
goto exit;
diff --git a/include/fat.h b/include/fat.h
index c2465d2d3ea..15dbf1094c3 100644
--- a/include/fat.h
+++ b/include/fat.h
@@ -33,7 +33,7 @@
/* Maximum Long File Name length supported here is 128 UTF-16 code units */
#define VFAT_MAXLEN_BYTES 256 /* Maximum LFN buffer in bytes */
#define VFAT_MAXSEQ 9 /* Up to 9 of 13 2-byte UTF-16 entries */
-#define LINEAR_PREFETCH_SIZE (mydata->sect_size*2) /* Prefetch buffer size */
+#define PREFETCH_BLOCKS 2
#define MAX_CLUSTSIZE 65536
#define DIRENTSPERBLOCK (mydata->sect_size / sizeof(dir_entry))
--
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