dquot: cleanup dquot transfer routine

Get rid of the transfer dquot operation - it is now always called from
the filesystem and if a filesystem really needs it's own (which none
currently does) it can just call into it's own routine directly.

Rename the now static low-level dquot_transfer helper to __dquot_transfer
and vfs_dq_transfer to dquot_transfer to have a consistent namespace,
and make the new dquot_transfer return a normal negative errno value
which all callers expect.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 6cf3d8d..472e8f8 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1020,7 +1020,7 @@
 		/*
 		 * Gather pointers to quota structures so that allocation /
 		 * freeing of quota structures happens here and not inside
-		 * vfs_dq_transfer() where we have problems with lock ordering
+		 * dquot_transfer() where we have problems with lock ordering
 		 */
 		if (attr->ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid
 		    && OCFS2_HAS_RO_COMPAT_FEATURE(sb,
@@ -1053,7 +1053,7 @@
 			mlog_errno(status);
 			goto bail_unlock;
 		}
-		status = vfs_dq_transfer(inode, attr) ? -EDQUOT : 0;
+		status = dquot_transfer(inode, attr);
 		if (status < 0)
 			goto bail_commit;
 	} else {