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Date: Thu, 26 Feb 2004 17:40:30 +0100
From: Christophe Saout <christophe@saout.de>
To: Andrew Morton <akpm@osdl.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH][2/2] dm-crypt end_io bv_offset fix
Message-ID: <20040226164029.GB12597@leto.cs.pocnet.net>
References: <20040226162324.GA12597@leto.cs.pocnet.net>
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We should copy the bvec array for read requests so that we still
have the unmodified bvec array to decrypt the data afterwards.

(as discussed earlier this day for highmem bounces)

--- linux.orig/drivers/md/dm-crypt.c	2004-02-26 16:54:08.068578768 +0100
+++ linux/drivers/md/dm-crypt.c	2004-02-26 16:59:35.780758944 +0100
@@ -593,8 +593,21 @@
 				return NULL;
 			}
 		}
-	} else
-		clone = bio_clone(bio, GFP_NOIO);
+	} else {
+		/*
+		 * The block layer might modify the bvec array, so always
+		 * copy the required bvecs because we need the original
+		 * one in order to decrypt the whole bio data *afterwards*.
+		 */
+		clone = bio_alloc(GFP_NOIO, bio_segments(bio));
+		if (clone) {
+			clone->bi_idx = 0;
+			clone->bi_vcnt = bio_segments(bio);
+			clone->bi_size = bio->bi_size;
+			memcpy(clone->bi_io_vec, bio_iovec(bio),
+			       sizeof(struct bio_vec) * clone->bi_vcnt);
+		}
+	}
 
 	if (!clone)
 		return NULL;