vfs: Add general support to enforce project quota limits

This patch adds support for a new quota type PRJQUOTA for project quota
enforcement. Also a new method get_projid() is added into dquot_operations
structure.
Signed-off-by: Li Xi <lixi@ddn.com>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/dquot.c

@@ -1163,8 +1163,8 @@ static int need_print_warning(struct dquot_warn *warn)
 			return uid_eq(current_fsuid(), warn->w_dq_id.uid);
 		case GRPQUOTA:
 			return in_group_p(warn->w_dq_id.gid);
-		case PRJQUOTA:	/* Never taken... Just make gcc happy */
-			return 0;
+		case PRJQUOTA:
+			return 1;
 	}
 	return 0;
 }
@@ -1405,6 +1405,9 @@ static void __dquot_initialize(struct inode *inode, int type)
 	/* First get references to structures we might need. */
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 		struct kqid qid;
+		kprojid_t projid;
+		int rc;
+
 		got[cnt] = NULL;
 		if (type != -1 && cnt != type)
 			continue;
@@ -1415,6 +1418,10 @@ static void __dquot_initialize(struct inode *inode, int type)
 		 */
 		if (dquots[cnt])
 			continue;
+
+		if (!sb_has_quota_active(sb, cnt))
+			continue;
+
 		init_needed = 1;
 
 		switch (cnt) {
@@ -1424,6 +1431,12 @@ static void __dquot_initialize(struct inode *inode, int type)
 		case GRPQUOTA:
 			qid = make_kqid_gid(inode->i_gid);
 			break;
+		case PRJQUOTA:
+			rc = inode->i_sb->dq_op->get_projid(inode, &projid);
+			if (rc)
+				continue;
+			qid = make_kqid_projid(projid);
+			break;
 		}
 		got[cnt] = dqget(sb, qid);
 	}
@@ -2176,7 +2189,8 @@ static int vfs_load_quota_inode(struct inode *inode, int type, int format_id,
 		error = -EROFS;
 		goto out_fmt;
 	}
-	if (!sb->s_op->quota_write || !sb->s_op->quota_read) {
+	if (!sb->s_op->quota_write || !sb->s_op->quota_read ||
+	    (type == PRJQUOTA && sb->dq_op->get_projid == NULL)) {
 		error = -EINVAL;
 		goto out_fmt;
 	}

fs/quota/quotaio_v2.h

@@ -13,12 +13,14 @@
  */
 #define V2_INITQMAGICS {\
 	0xd9c01f11,	/* USRQUOTA */\
-	0xd9c01927	/* GRPQUOTA */\
+	0xd9c01927,	/* GRPQUOTA */\
+	0xd9c03f14,	/* PRJQUOTA */\
 }
 
 #define V2_INITQVERSIONS {\
 	1,		/* USRQUOTA */\
-	1		/* GRPQUOTA */\
+	1,		/* GRPQUOTA */\
+	1,		/* PRJQUOTA */\
 }
 
 /* First generic header */

include/linux/quota.h

@@ -50,6 +50,7 @@
 
 #undef USRQUOTA
 #undef GRPQUOTA
+#undef PRJQUOTA
 enum quota_type {
 	USRQUOTA = 0,		/* element used for user quotas */
 	GRPQUOTA = 1,		/* element used for group quotas */
@@ -319,6 +320,7 @@ struct dquot_operations {
 	/* get reserved quota for delayed alloc, value returned is managed by
 	 * quota code only */
 	qsize_t *(*get_reserved_space) (struct inode *);
+	int (*get_projid) (struct inode *, kprojid_t *);/* Get project ID */
 };
 
 struct path;

include/uapi/linux/quota.h

@@ -36,11 +36,12 @@
 #include <linux/errno.h>
 #include <linux/types.h>
 
-#define __DQUOT_VERSION__	"dquot_6.5.2"
+#define __DQUOT_VERSION__	"dquot_6.6.0"
 
-#define MAXQUOTAS 2
+#define MAXQUOTAS 3
 #define USRQUOTA  0		/* element used for user quotas */
 #define GRPQUOTA  1		/* element used for group quotas */
+#define PRJQUOTA  2		/* element used for project quotas */
 
 /*
  * Definitions for the default names of the quotas files.
@@ -48,6 +49,7 @@
 #define INITQFNAMES { \
 	"user",    /* USRQUOTA */ \
 	"group",   /* GRPQUOTA */ \
+	"project", /* PRJQUOTA */ \
 	"undefined", \
 };