From: Dmitry Monakhov <dmonakhov@openvz.org>
Date: Sun, 28 Feb 2016 23:46:42 +0000 (+1100)
Subject: xfs_io: Prevent devide by zero from {pread,pwrite}_random
X-Git-Tag: v4.5.0~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2ab8ecbe62cf4d558a0e37f1c8cc283ab5f7b199;p=thirdparty%2Fxfsprogs-dev.git

xfs_io: Prevent devide by zero from {pread,pwrite}_random

Math is wrong if range requested is less or equals to block size

xfs_io -c 'pwrite -b 4k 8k 4k -R' \
       -c 'pread -b 4k  4k 4k -R' -f file

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
---

diff --git a/io/pread.c b/io/pread.c
index f16c86c1a..b98355f5b 100644
--- a/io/pread.c
+++ b/io/pread.c
@@ -245,7 +245,11 @@ read_random(
 
 	*total = 0;
 	while (count > 0) {
-		off = ((offset + (random() % range)) / buffersize) * buffersize;
+		if (range)
+			off = ((offset + (random() % range)) / buffersize) *
+				buffersize;
+		else
+			off = offset;
 		bytes = do_pread(fd, off, buffersize, buffersize);
 		if (bytes == 0)
 			break;
diff --git a/io/pwrite.c b/io/pwrite.c
index 4fc8de63c..67631ce58 100644
--- a/io/pwrite.c
+++ b/io/pwrite.c
@@ -128,7 +128,11 @@ write_random(
 
 	*total = 0;
 	while (count > 0) {
-		off = ((offset + (random() % range)) / buffersize) * buffersize;
+		if (range)
+			off = ((offset + (random() % range)) / buffersize) *
+				buffersize;
+		else
+			off = offset;
 		bytes = do_pwrite(file->fd, off, buffersize, buffersize);
 		if (bytes == 0)
 			break;