From: NeilBrown <neilb@suse.de>
Date: Tue, 7 Feb 2012 00:55:18 +0000 (+1100)
Subject: super1: make aread/awrite always use an aligned buffer.
X-Git-Tag: mdadm-3.2.4~93
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6ef89052d85b8137b8a7100f761d896ae6f61001;p=thirdparty%2Fmdadm.git

super1: make aread/awrite always use an aligned buffer.

A recently change to write_bitmap1 meant awrite would sometimes
write from a non-aligned buffer which of course break.

So change awrite (and aread) to always use their own aligned
buffer to ensure safety.

Reported-by: Alexander Lyakas <alex.bolshoy@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/super1.c b/super1.c
index d23d6e8e..cfa237a0 100644
--- a/super1.c
+++ b/super1.c
@@ -143,17 +143,19 @@ static int aread(int fd, void *buf, int len)
 	 * the full sector and copy relevant bits into
 	 * the buffer
 	 */
-	int bsize;
+	int bsize, iosize;
 	char *b;
 	int n;
-	if (ioctl(fd, BLKSSZGET, &bsize) != 0 ||
-	    bsize <= len)
-		return read(fd, buf, len);
-	if (bsize > 4096)
+	if (ioctl(fd, BLKSSZGET, &bsize) != 0)
+		bsize = 512;
+
+	if (bsize > 4096 || len > 4096)
 		return -1;
 	b = (char*)(((long)(abuf+4096))&~4095UL);
 
-	n = read(fd, b, bsize);
+	for (iosize = 0; iosize < len; iosize += bsize)
+		;
+	n = read(fd, b, iosize);
 	if (n <= 0)
 		return n;
 	lseek(fd, len - n, 1);
@@ -171,22 +173,27 @@ static int awrite(int fd, void *buf, int len)
 	 * than the write.
 	 * The address must be sector-aligned.
 	 */
-	int bsize;
+	int bsize, iosize;
 	char *b;
 	int n;
-	if (ioctl(fd, BLKSSZGET, &bsize) != 0 ||
-	    bsize <= len)
-		return write(fd, buf, len);
-	if (bsize > 4096)
+	if (ioctl(fd, BLKSSZGET, &bsize) != 0)
+		bsize = 512;
+	if (bsize > 4096 || len > 4096)
 		return -1;
 	b = (char*)(((long)(abuf+4096))&~4095UL);
 
-	n = read(fd, b, bsize);
-	if (n <= 0)
-		return n;
-	lseek(fd, -n, 1);
+	for (iosize = 0; iosize < len ; iosize += bsize)
+		;
+
+	if (len != iosize) {
+		n = read(fd, b, iosize);
+		if (n <= 0)
+			return n;
+		lseek(fd, -n, 1);
+	}
+
 	memcpy(b, buf, len);
-	n = write(fd, b, bsize);
+	n = write(fd, b, iosize);
 	if (n <= 0)
 		return n;
 	lseek(fd, len - n, 1);