[5/5] [CRYPTO] Optimise kmap calls in crypt()

[Herbert Xu]

Hi:
 
Perform kmap once (or twice if the buffer is not aligned correctly)
per page in crypt() instead of the current code which does it once
per block.  Consequently it will yield once per page instead of once
per block.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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diff -Nru a/crypto/cipher.c b/crypto/cipher.c
--- a/crypto/cipher.c	2005-03-21 18:44:41 +11:00
+++ b/crypto/cipher.c	2005-03-21 18:44:41 +11:00
@@ -117,17 +117,21 @@
 
 		in_place = scatterwalk_samebuf(&walk_in, &walk_out);
 
-		src_p = prepare_src(&walk_in, bsize, tmp_src, in_place);
-		dst_p = prepare_dst(&walk_out, bsize, tmp_dst, in_place);
+		do {
+			src_p = prepare_src(&walk_in, bsize, tmp_src,
+					    in_place);
+			dst_p = prepare_dst(&walk_out, bsize, tmp_dst,
+					    in_place);
 
-		nbytes -= bsize;
+			prfn(tfm, dst_p, src_p, crfn, enc, info);
 
-		prfn(tfm, dst_p, src_p, crfn, enc, info);
+			complete_src(&walk_in, bsize, src_p, in_place);
+			complete_dst(&walk_out, bsize, dst_p, in_place);
 
-		complete_src(&walk_in, bsize, src_p, in_place);
-		scatterwalk_done(&walk_in, 0, nbytes);
+			nbytes -= bsize;
+		} while (nbytes && !scatterwalk_across_pages(&walk_in, bsize));
 
-		complete_dst(&walk_out, bsize, dst_p, in_place);
+		scatterwalk_done(&walk_in, 0, nbytes);
 		scatterwalk_done(&walk_out, 1, nbytes);
 
 		if (!nbytes)