From 46081b166415acb66d4b3150ecefcd9460bb48a1 Mon Sep 17 00:00:00 2001
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Mon, 20 Dec 2010 18:44:45 +0200
Subject: [SCSI] st: Increase success probability in driver buffer allocation

Modify allocation to try the minimum possible page order allowed by the HBA
scatter/gather segment limit in allocation of the driver's internal
buffer. This increases the probability of successful allocation. The
allocation may still fail if this minimum order is > 0.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Kai Makisara <kai.makisara@kolumbus.fi>
Reported-by: Lukas Kolbe <lkolbe@techfak.uni-bielefeld.de>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 12a36ac..1871b8a 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -3729,7 +3729,8 @@ static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dm
 		b_size = PAGE_SIZE << order;
 	} else {
 		for (b_size = PAGE_SIZE, order = 0;
-		     order < ST_MAX_ORDER && b_size < new_size;
+		     order < ST_MAX_ORDER &&
+			     max_segs * (PAGE_SIZE << order) < new_size;
 		     order++, b_size *= 2)
 			;  /* empty */
 		STbuffer->reserved_page_order = order;
-- 
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