From 9c905966c4d8c03ea21d230b277b7ea1e492f3c9 Mon Sep 17 00:00:00 2001
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Thu, 18 Dec 2008 14:49:39 +0900
Subject: [SCSI] st: make all the fragment buffers the same size

This patch simiplifies the fragment buffer management a bit, all the
buffers in the fragment list become the same size. This is necessary
to use the block layer API (sg driver was modified in the same way)
since the block layer API takes the same size page frames instead of
scatter gatter.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Kai Makisara <Kai.Makisara@kolumbus.fi>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 7f3f317..3984cd8 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -3747,20 +3747,20 @@ static int enlarge_buffer(struct st_buffer * STbuffer, int new_size, int need_dm
 	priority = GFP_KERNEL | __GFP_NOWARN;
 	if (need_dma)
 		priority |= GFP_DMA;
-	for (b_size = PAGE_SIZE, order=0; order <= 6 &&
-	     b_size < new_size - STbuffer->buffer_size;
-	     order++, b_size *= 2)
-		;  /* empty */
+
+	if (STbuffer->frp_segs) {
+		b_size = STbuffer->frp[0].length;
+		order = get_order(b_size);
+	} else {
+		for (b_size = PAGE_SIZE, order = 0;
+		     order <= 6 && b_size < new_size; order++, b_size *= 2)
+			;  /* empty */
+	}
 
 	for (segs = STbuffer->frp_segs, got = STbuffer->buffer_size;
 	     segs < max_segs && got < new_size;) {
 		STbuffer->frp[segs].page = alloc_pages(priority, order);
 		if (STbuffer->frp[segs].page == NULL) {
-			if (new_size - got <= (max_segs - segs) * b_size / 2) {
-				b_size /= 2; /* Large enough for the rest of the buffers */
-				order--;
-				continue;
-			}
 			DEB(STbuffer->buffer_size = got);
 			normalize_buffer(STbuffer);
 			return 0;
-- 
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