readahead: increase interleaved readahead size

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

Reported-by: Xu Chenfeng <xcf@ustc.edu.cn>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/mm/readahead.c b/mm/readahead.c
index 56731158309b..16378b90843e 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -403,6 +403,7 @@ ondemand_readahead(struct address_space *mapping,
 
                 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;