ecryptfs: fix truncation error in ecryptfs_read_update_atime

This is similar to the bug found in direct-io not so long ago.

Fix up truncation (ssize_t->int).  This only matters with >2G
reads/writes, which the kernel doesn't permit.
Signed-off-by: Edward Shishkin <edward.shishkin@gmail.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Eric Sandeen <esandeen@redhat.com>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

fs/ecryptfs/file.c

@@ -47,7 +47,7 @@ static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
 				const struct iovec *iov,
 				unsigned long nr_segs, loff_t pos)
 {
-	int rc;
+	ssize_t rc;
 	struct dentry *lower_dentry;
 	struct vfsmount *lower_vfsmount;
 	struct file *file = iocb->ki_filp;