ext4: enable quota enforcement based on mount options

When quota information is stored in quota files, we enable only quota
accounting on mount and enforcement is enabled only in response to
Q_QUOTAON quotactl. To make ext4 behavior consistent with XFS, we add a
possibility to enable quota enforcement on mount by specifying
corresponding quota mount option (usrquota, grpquota, prjquota).

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ea31931..0c2bf44 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1117,9 +1117,15 @@
 #define EXT4_MOUNT_POSIX_ACL		0x08000	/* POSIX Access Control Lists */
 #define EXT4_MOUNT_NO_AUTO_DA_ALLOC	0x10000	/* No auto delalloc mapping */
 #define EXT4_MOUNT_BARRIER		0x20000 /* Use block barriers */
-#define EXT4_MOUNT_QUOTA		0x80000 /* Some quota option set */
-#define EXT4_MOUNT_USRQUOTA		0x100000 /* "old" user quota */
-#define EXT4_MOUNT_GRPQUOTA		0x200000 /* "old" group quota */
+#define EXT4_MOUNT_QUOTA		0x40000 /* Some quota option set */
+#define EXT4_MOUNT_USRQUOTA		0x80000 /* "old" user quota,
+						 * enable enforcement for hidden
+						 * quota files */
+#define EXT4_MOUNT_GRPQUOTA		0x100000 /* "old" group quota, enable
+						  * enforcement for hidden quota
+						  * files */
+#define EXT4_MOUNT_PRJQUOTA		0x200000 /* Enable project quota
+						  * enforcement */
 #define EXT4_MOUNT_DIOREAD_NOLOCK	0x400000 /* Enable support for dio read nolocking */
 #define EXT4_MOUNT_JOURNAL_CHECKSUM	0x800000 /* Journal checksums */
 #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT	0x1000000 /* Journal Async Commit */