ext4: add project quota support

This patch adds mount options for enabling/disabling project quota
accounting and enforcement. A new specific inode is also used for
project quota accounting.

[ Includes fix from Dan Carpenter to crrect error checking from dqget(). ]

Signed-off-by: Li Xi <lixi@ddn.com>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0237811..96cc151 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1261,7 +1261,7 @@
 #endif
 
 /* Number of quota types we support */
-#define EXT4_MAXQUOTAS 2
+#define EXT4_MAXQUOTAS 3
 
 /*
  * fourth extended-fs super-block data in memory