Make sure interleaved readahead size is larger than request size.
This also makes readahead window grow up more quickly.

Reported-by: Xu Chenfeng <xcf@ustc.edu.cn>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 mm/readahead.c |    1 +
 1 file changed, 1 insertion(+)

--- mm.orig/mm/readahead.c
+++ mm/mm/readahead.c
@@ -428,6 +428,7 @@ ondemand_readahead(struct address_space 
 
 		ra->start = start;
 		ra->size = start - offset;	/* old async_size */
+		ra->size += req_size;
 		ra->size = get_next_ra_size(ra, max);
 		ra->async_size = ra->size;
 		goto readit;

--