[JFFS2] Optimise reading of eraseblock summary nodes

This improves the time to mount 512MiB of NAND flash on my OLPC prototype
by about 4%. We used to read the last page of the eraseblock twice -- once
to find the offset of the summary node, and again to actually _read_ the
summary node. Now we read the last page only once, and read more only if
we need to.

We also don't allocate a new buffer just for the summary code -- we use
the buffer which was already allocated for the scan. Better still, if the
'buffer' for the scan is actually just a pointer directly into NOR flash,
we use that too, avoiding the memcpy() which we used to do.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/jffs2/summary.h b/fs/jffs2/summary.h
index b7a678be1709..afff4bd551a1 100644
--- a/fs/jffs2/summary.h
+++ b/fs/jffs2/summary.h
@@ -160,7 +160,8 @@ int jffs2_sum_add_padding_mem(struct jffs2_summary *s, uint32_t size);
 int jffs2_sum_add_inode_mem(struct jffs2_summary *s, struct jffs2_raw_inode *ri, uint32_t ofs);
 int jffs2_sum_add_dirent_mem(struct jffs2_summary *s, struct jffs2_raw_dirent *rd, uint32_t ofs);
 int jffs2_sum_scan_sumnode(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
-                        uint32_t ofs, uint32_t *pseudo_random);
+                           struct jffs2_raw_summary *summary, uint32_t sumlen,
+                           uint32_t *pseudo_random);
 
 #else                           /* SUMMARY DISABLED */