Btrfs: Make ACLs return EOPNOTSUPP for now

There was a slight problem with ACL's returning EINVAL when you tried to set an
ACL.  This isn't correct, we should be returning EOPNOTSUPP, so I did a very
ugly thing and just commented everybody out and made them return EOPNOTSUPP.
This is only temporary, I'm going back to implement ACL's, but Chris wants to
push out a release so this will suffice for now.

Also Yan suggested setting reada to -1 in the delete case to enable backwards
readahead, and in the listxattr case I moved path->reada = 2; to after the if
(!path) check so we can avoid a possible null dereference.  Thank you,

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/acl.c

@@ -23,32 +23,50 @@
 #include "ctree.h"
 #include "xattr.h"
 
+/*
+ * FIXME: At this point this is all place holder stuff, we just return
+ * -EOPNOTSUPP so cp won't complain when it tries to copy over a file with an
+ *  acl on it.
+ */
+
 static int btrfs_xattr_acl_access_get(struct inode *inode, const char *name,
 				      void *value, size_t size)
 {
+	/*
 	return btrfs_xattr_get(inode, BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS, name,
 			       value, size);
+	*/
+	return -EOPNOTSUPP;
 }
 
 static int btrfs_xattr_acl_access_set(struct inode *inode, const char *name,
 				      const void *value, size_t size, int flags)
 {
+	/*
 	return btrfs_xattr_set(inode, BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS, name,
 			       value, size, flags);
+	*/
+	return -EOPNOTSUPP;
 }
 
 static int btrfs_xattr_acl_default_get(struct inode *inode, const char *name,
 				       void *value, size_t size)
 {
+	/*
 	return btrfs_xattr_get(inode, BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT,
 			       name, value, size);
+	*/
+	return -EOPNOTSUPP;
 }
 
 static int btrfs_xattr_acl_default_set(struct inode *inode, const char *name,
 				       const void *value, size_t size, int flags)
 {
+	/*
 	return btrfs_xattr_set(inode, BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT,
 			       name, value, size, flags);
+	*/
+	return -EOPNOTSUPP;
 }
 
 struct xattr_handler btrfs_xattr_acl_default_handler = {

fs/btrfs/xattr.c

@@ -302,9 +302,9 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 	key.offset = 0;
 
 	path = btrfs_alloc_path();
-	path->reada = 2;
 	if (!path)
 		return -ENOMEM;
+	path->reada = 2;
 
 	mutex_lock(&root->fs_info->fs_mutex);
 
@@ -410,7 +410,7 @@ int btrfs_delete_xattrs(struct btrfs_trans_handle *trans,
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
-
+	path->reada = -1;
 	key.objectid = inode->i_ino;
 	btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 	key.offset = (u64)-1;