eCryptfs: Fix data corruption when using ecryptfs_passthrough

ecryptfs_passthrough is a mount option that allows eCryptfs to allow
data to be written to non-eCryptfs files in the lower filesystem.  The
passthrough option was causing data corruption due to it not always
being treated as a non-eCryptfs file.

The first 8 bytes of an eCryptfs file contains the decrypted file size.
This value was being written to the non-eCryptfs files, too.  Also,
extra 0x00 characters were being written to make the file size a
multiple of PAGE_CACHE_SIZE.

Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 8b65f28..b91851f 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -483,15 +483,7 @@
 	ecryptfs_inode = page->mapping->host;
 	crypt_stat =
 		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
-	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
-		rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page,
-						       0, PAGE_CACHE_SIZE);
-		if (rc)
-			printk(KERN_ERR "%s: Error attempting to copy "
-			       "page at index [%ld]\n", __func__,
-			       page->index);
-		goto out;
-	}
+	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 	enc_extent_page = alloc_page(GFP_USER);
 	if (!enc_extent_page) {
 		rc = -ENOMEM;
@@ -620,16 +612,7 @@
 	ecryptfs_inode = page->mapping->host;
 	crypt_stat =
 		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
-	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
-		rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
-						      PAGE_CACHE_SIZE,
-						      ecryptfs_inode);
-		if (rc)
-			printk(KERN_ERR "%s: Error attempting to copy "
-			       "page at index [%ld]\n", __func__,
-			       page->index);
-		goto out;
-	}
+	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
 	enc_extent_page = alloc_page(GFP_USER);
 	if (!enc_extent_page) {
 		rc = -ENOMEM;