tree 40d7bbc06ee5e54560ea7e7dabe75ac01a72e00c
parent 6c8b44abc86a3e23dd1a22c0ee187f06bd7c7f5d
author David Woodhouse <dwmw2@infradead.org> 1148138014 +0100
committer David Woodhouse <dwmw2@infradead.org> 1148138014 +0100

[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>