[PATCH 6/9] readahead: save mmap read-around states in file_ra_state

[Fengguang Wu <wfg@mail.ustc.edu.cn>]

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Change mmap read-around to share the same code style and data structure
with readahead code.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
---
 mm/filemap.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- linux-2.6.24-rc5-mm1.orig/mm/filemap.c
+++ linux-2.6.24-rc5-mm1/mm/filemap.c
@@ -1334,13 +1334,15 @@ static void do_sync_mmap_readahead(struc
 	if (ra->mmap_miss > MMAP_LOTSAMISS)
 		return;
 
+	/*
+	 * mmap read-around
+	 */
 	ra_pages = max_sane_readahead(ra->ra_pages);
 	if (ra_pages) {
-		pgoff_t start = 0;
-
-		if (offset > ra_pages / 2)
-			start = offset - ra_pages / 2;
-		do_page_cache_readahead(mapping, file, start, ra_pages);
+		ra->start = max_t(long, 0, offset - ra_pages / 2);
+		ra->size = ra_pages;
+		ra->async_size = 0;
+		ra_submit(ra, mapping, file);
 	}
 }
 

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