[PATCH 03/14] readahead: state based method: cancel lookahead gracefully

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

[-- Attachment #1: readahead-state-based-method-cancel-lookahead-gracefully.patch --]
[-- Type: text/plain, Size: 1080 bytes --]

When canceling lookahead, update ra->lookahead_index to the next invoke index.
So that we see a consistent state in the next time.

Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
---
 mm/readahead.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- linux-2.6.21-rc3-mm2.orig/mm/readahead.c
+++ linux-2.6.21-rc3-mm2/mm/readahead.c
@@ -1094,7 +1094,7 @@ state_based_readahead(struct address_spa
 
 	if (page && remain_space <= la_size) {
 		rescue_pages(page, la_size);
-		return 0;
+		goto cancel_lookahead;
 	}
 
 	growth_limit = req_size;
@@ -1104,7 +1104,7 @@ state_based_readahead(struct address_spa
 	    growth_limit = ra_max;
 
 	if (!adjust_rala(growth_limit, &ra_size, &la_size))
-		return 0;
+		goto cancel_lookahead;
 
 	limit_rala(growth_limit, la_old, &ra_size, &la_size);
 
@@ -1113,6 +1113,10 @@ state_based_readahead(struct address_spa
 	ra_set_size(ra, ra_size, la_size);
 
 	return ra_submit(ra, mapping, filp);
+
+cancel_lookahead:
+	ra->lookahead_index = ra->readahead_index;
+	return 0;
 }
 
 #endif /* CONFIG_ADAPTIVE_READAHEAD */

--