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fat: replace LINEAR_PREFETCH_SIZE with PREFETCH_BLOCKS

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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>
This commit is contained in:
Sergei Shtylyov 2011-08-19 09:37:46 +00:00 committed by Wolfgang Denk
parent 40e219165b
commit 025421eab4
2 changed files with 5 additions and 6 deletions
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9
fs/fat/fat.c
View file

@ -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;

2
include/fat.h
View file

@ -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))