[JFFS2] Speed up mount for directly-mapped NOR flash

Remove excessive scanning of empty flash after a clean
marker for users of the point/unpoint method. cfi_cmdset_0001
uses point/unpoint by default iff flash mapping is linear.
The speedup is several orders of magnitude if FS is less than
half full.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 11 insertions, 4 deletions

diff --git a/fs/jffs2/scan.c b/fs/jffs2/scan.c
index a5103df5242e..7a46a436edfc 100644
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -636,16 +636,17 @@ scan_more:
 
                 if (*(uint32_t *)(&buf[ofs-buf_ofs]) == 0xffffffff) {
                         uint32_t inbuf_ofs;
-                        uint32_t empty_start;
+                        uint32_t empty_start, scan_end;
 
                         empty_start = ofs;
                         ofs += 4;
+                        scan_end = min_t(uint32_t, EMPTY_SCAN_SIZE(c->sector_size)/8, buf_len);
 
                         D1(printk(KERN_DEBUG "Found empty flash at 0x%08x\n", ofs));
                 more_empty:
                         inbuf_ofs = ofs - buf_ofs;
-                        while (inbuf_ofs < buf_len) {
-                                if (*(uint32_t *)(&buf[inbuf_ofs]) != 0xffffffff) {
+                        while (inbuf_ofs < scan_end) {
+                                if (unlikely(*(uint32_t *)(&buf[inbuf_ofs]) != 0xffffffff)) {
                                         printk(KERN_WARNING "Empty flash at 0x%08x ends at 0x%08x\n",
                                                empty_start, ofs);
                                         if ((err = jffs2_scan_dirty_space(c, jeb, ofs-empty_start)))
@@ -666,7 +667,11 @@ scan_more:
                                 D1(printk(KERN_DEBUG "%d bytes at start of block seems clean... assuming all clean\n", EMPTY_SCAN_SIZE(c->sector_size)));
                                 return BLK_STATE_CLEANMARKER;
                         }
-
+                        if (!buf_size && (scan_end != buf_len)) {/* XIP/point case */
+                                scan_end = buf_len;
+                                goto more_empty;
+                        }
+                        
                         /* See how much more there is to read in this eraseblock... */
                         buf_len = min_t(uint32_t, buf_size, jeb->offset + c->sector_size - ofs);
                         if (!buf_len) {
@@ -676,6 +681,8 @@ scan_more:
                                           empty_start));
                                 break;
                         }
+                        /* point never reaches here */
+                        scan_end = buf_len;
                         D1(printk(KERN_DEBUG "Reading another 0x%x at 0x%08x\n", buf_len, ofs));
                         err = jffs2_fill_scan_buf(c, buf, ofs, buf_len);
                         if (err)