jffs2: Reduce excessive scan of empty blocks
Scanning 1024 bytes to see if an EB is empty is a bit much.
Lower it to 256 bytes and make sure the while loop is
optimized.
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index 46f870d..b632ddd 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -20,7 +20,7 @@
#include "summary.h"
#include "debug.h"
-#define DEFAULT_EMPTY_SCAN_SIZE 1024
+#define DEFAULT_EMPTY_SCAN_SIZE 256
#define noisy_printk(noise, args...) do { \
if (*(noise)) { \
@@ -435,7 +435,7 @@
unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s) {
struct jffs2_unknown_node *node;
struct jffs2_unknown_node crcnode;
- uint32_t ofs, prevofs;
+ uint32_t ofs, prevofs, max_ofs;
uint32_t hdr_crc, buf_ofs, buf_len;
int err;
int noise = 0;
@@ -550,12 +550,12 @@
/* We temporarily use 'ofs' as a pointer into the buffer/jeb */
ofs = 0;
-
- /* Scan only 4KiB of 0xFF before declaring it's empty */
- while(ofs < EMPTY_SCAN_SIZE(c->sector_size) && *(uint32_t *)(&buf[ofs]) == 0xFFFFFFFF)
+ max_ofs = EMPTY_SCAN_SIZE(c->sector_size);
+ /* Scan only EMPTY_SCAN_SIZE of 0xFF before declaring it's empty */
+ while(ofs < max_ofs && *(uint32_t *)(&buf[ofs]) == 0xFFFFFFFF)
ofs += 4;
- if (ofs == EMPTY_SCAN_SIZE(c->sector_size)) {
+ if (ofs == max_ofs) {
#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
if (jffs2_cleanmarker_oob(c)) {
/* scan oob, take care of cleanmarker */