iomap: remove the length variable in iomap_seek_hole

stable inclusion
from stable-5.10.55
commit 3510b9b41c70e2d51a05e2c6f558b522de8ab646
bugzilla: 175636 https://gitee.com/openeuler/kernel/issues/I4DYWD

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3510b9b41c70e2d51a05e2c6f558b522de8ab646

--------------------------------

[ Upstream commit 49694d14 ]

The length variable is rather pointless given that it can be trivially
deduced from offset and size.  Also the initial calculation can lead
to KASAN warnings.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reported-by: NLeizhen (ThunderTown) <thunder.leizhen@huawei.com>
Reviewed-by: NDarrick J. Wong <djwong@kernel.org>
Signed-off-by: NDarrick J. Wong <djwong@kernel.org>
Reviewed-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/iomap/seek.c

@@ -35,23 +35,20 @@ loff_t
 iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
 {
 	loff_t size = i_size_read(inode);
-	loff_t length = size - offset;
 	loff_t ret;
 
 	/* Nothing to be found before or beyond the end of the file. */
 	if (offset < 0 || offset >= size)
 		return -ENXIO;
 
-	while (length > 0) {
-		ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops,
-				  &offset, iomap_seek_hole_actor);
+	while (offset < size) {
+		ret = iomap_apply(inode, offset, size - offset, IOMAP_REPORT,
+				  ops, &offset, iomap_seek_hole_actor);
 		if (ret < 0)
 			return ret;
 		if (ret == 0)
 			break;
-
 		offset += ret;
-		length -= ret;
 	}
 
 	return offset;