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authorBenoît Thébaudeau <benoit.thebaudeau@advansee.com>2012-07-20 15:20:12 +0200
committerWolfgang Denk <wd@denx.de>2012-09-02 17:16:08 +0200
commitcd1b042c5c035719018cffb751714d30513af0a6 (patch)
treeaef17d32566d445ca603ef09715f1744e8fb0f0f
parent88503ad3bb5a21a95fe388a1d45e303c206a4e9d (diff)
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FAT: Fix redundant sector read
With the previous code, the remaining prefetched sectors were read again after each sector. With this patch, each sector is read only once, thus making the prefetch useful. Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com> Cc: Wolfgang Denk <wd@denx.de>
-rw-r--r--fs/fat/fat.c59
1 files changed, 33 insertions, 26 deletions
diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index 48c8844..fbc2d7d 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -775,7 +775,7 @@ do_fat_read(const char *filename, void *buffer, unsigned long maxsize, int dols)
volume_info volinfo;
fsdata datablock;
fsdata *mydata = &datablock;
- dir_entry *dentptr;
+ dir_entry *dentptr = NULL;
__u16 prevcksum = 0xffff;
char *subname = "";
__u32 cursect;
@@ -874,19 +874,21 @@ do_fat_read(const char *filename, void *buffer, unsigned long maxsize, int dols)
while (1) {
int i;
- debug("FAT read sect=%d, clust_size=%d, DIRENTSPERBLOCK=%zd\n",
- cursect, mydata->clust_size, DIRENTSPERBLOCK);
+ if (j == 0) {
+ debug("FAT read sect=%d, clust_size=%d, DIRENTSPERBLOCK=%zd\n",
+ cursect, mydata->clust_size, DIRENTSPERBLOCK);
- if (disk_read(cursect,
- (mydata->fatsize == 32) ?
- (mydata->clust_size) :
- PREFETCH_BLOCKS,
- do_fat_read_block) < 0) {
- debug("Error: reading rootdir block\n");
- goto exit;
- }
+ if (disk_read(cursect,
+ (mydata->fatsize == 32) ?
+ (mydata->clust_size) :
+ PREFETCH_BLOCKS,
+ do_fat_read_block) < 0) {
+ debug("Error: reading rootdir block\n");
+ goto exit;
+ }
- dentptr = (dir_entry *) do_fat_read_block;
+ dentptr = (dir_entry *) do_fat_read_block;
+ }
for (i = 0; i < DIRENTSPERBLOCK; i++) {
char s_name[14], l_name[VFAT_MAXLEN_BYTES];
@@ -1028,28 +1030,33 @@ do_fat_read(const char *filename, void *buffer, unsigned long maxsize, int dols)
* completely processed.
*/
++j;
- int fat32_end = 0;
- if ((mydata->fatsize == 32) && (j == mydata->clust_size)) {
- int nxtsect = 0;
- int nxt_clust = 0;
+ int rootdir_end = 0;
+ if (mydata->fatsize == 32) {
+ if (j == mydata->clust_size) {
+ int nxtsect = 0;
+ int nxt_clust = 0;
- nxt_clust = get_fatent(mydata, root_cluster);
- fat32_end = CHECK_CLUST(nxt_clust, 32);
+ nxt_clust = get_fatent(mydata, root_cluster);
+ rootdir_end = CHECK_CLUST(nxt_clust, 32);
- nxtsect = mydata->data_begin +
- (nxt_clust * mydata->clust_size);
+ nxtsect = mydata->data_begin +
+ (nxt_clust * mydata->clust_size);
- root_cluster = nxt_clust;
+ root_cluster = nxt_clust;
- cursect = nxtsect;
- j = 0;
+ cursect = nxtsect;
+ j = 0;
+ }
} else {
- cursect++;
+ if (j == PREFETCH_BLOCKS)
+ j = 0;
+
+ rootdir_end = (++cursect - mydata->rootdir_sect >=
+ rootdir_size);
}
/* If end of rootdir reached */
- if ((mydata->fatsize == 32 && fat32_end) ||
- (mydata->fatsize != 32 && j == rootdir_size)) {
+ if (rootdir_end) {
if (dols == LS_ROOT) {
printf("\n%d file(s), %d dir(s)\n\n",
files, dirs);