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FAT: Fix redundant sector read

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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>
This commit is contained in:
Benoît Thébaudeau 2012-07-20 15:20:12 +02:00 committed by Wolfgang Denk
parent 88503ad3bb
commit cd1b042c5c
1 changed files with 33 additions and 26 deletions
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59
fs/fat/fat.c
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@ -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;
@ -874,20 +874,22 @@ 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);