3 files changed, 258 insertions, 1 deletions

diff --git a/fs/quota/Makefile b/fs/quota/Makefile
index 5f9e9e276af0..c66c37cdaa39 100644
--- a/fs/quota/Makefile
+++ b/fs/quota/Makefile
@@ -2,6 +2,6 @@ obj-$(CONFIG_QUOTA)		+= dquot.o
 obj-$(CONFIG_QFMT_V1)           += quota_v1.o
 obj-$(CONFIG_QFMT_V2)           += quota_v2.o
 obj-$(CONFIG_QUOTA_TREE)        += quota_tree.o
-obj-$(CONFIG_QUOTACTL)          += quota.o
+obj-$(CONFIG_QUOTACTL)          += quota.o kqid.o
 obj-$(CONFIG_QUOTACTL_COMPAT)   += compat.o
 obj-$(CONFIG_QUOTA_NETLINK_INTERFACE)   += netlink.o
diff --git a/fs/quota/kqid.c b/fs/quota/kqid.c
new file mode 100644
index 000000000000..2f97b0e2c501
--- /dev/null
+++ b/fs/quota/kqid.c
@@ -0,0 +1,132 @@
+#include <linux/fs.h>
+#include <linux/quota.h>
+#include <linux/export.h>
+
+/**
+ *      qid_eq - Test to see if to kquid values are the same
+ *      @left: A qid value
+ *      @right: Another quid value
+ *
+ *      Return true if the two qid values are equal and false otherwise.
+ */
+bool qid_eq(struct kqid left, struct kqid right)
+{
+        if (left.type != right.type)
+                return false;
+        switch(left.type) {
+        case USRQUOTA:
+                return uid_eq(left.uid, right.uid);
+        case GRPQUOTA:
+                return gid_eq(left.gid, right.gid);
+        case PRJQUOTA:
+                return projid_eq(left.projid, right.projid);
+        default:
+                BUG();
+        }
+}
+EXPORT_SYMBOL(qid_eq);
+
+/**
+ *      qid_lt - Test to see if one qid value is less than another
+ *      @left: The possibly lesser qid value
+ *      @right: The possibly greater qid value
+ *
+ *      Return true if left is less than right and false otherwise.
+ */
+bool qid_lt(struct kqid left, struct kqid right)
+{
+        if (left.type < right.type)
+                return true;
+        if (left.type > right.type)
+                return false;
+        switch (left.type) {
+        case USRQUOTA:
+                return uid_lt(left.uid, right.uid);
+        case GRPQUOTA:
+                return gid_lt(left.gid, right.gid);
+        case PRJQUOTA:
+                return projid_lt(left.projid, right.projid);
+        default:
+                BUG();
+        }
+}
+EXPORT_SYMBOL(qid_lt);
+
+/**
+ *      from_kqid - Create a qid from a kqid user-namespace pair.
+ *      @targ: The user namespace we want a qid in.
+ *      @kuid: The kernel internal quota identifier to start with.
+ *
+ *      Map @kqid into the user-namespace specified by @targ and
+ *      return the resulting qid.
+ *
+ *      There is always a mapping into the initial user_namespace.
+ *
+ *      If @kqid has no mapping in @targ (qid_t)-1 is returned.
+ */
+qid_t from_kqid(struct user_namespace *targ, struct kqid kqid)
+{
+        switch (kqid.type) {
+        case USRQUOTA:
+                return from_kuid(targ, kqid.uid);
+        case GRPQUOTA:
+                return from_kgid(targ, kqid.gid);
+        case PRJQUOTA:
+                return from_kprojid(targ, kqid.projid);
+        default:
+                BUG();
+        }
+}
+EXPORT_SYMBOL(from_kqid);
+
+/**
+ *      from_kqid_munged - Create a qid from a kqid user-namespace pair.
+ *      @targ: The user namespace we want a qid in.
+ *      @kqid: The kernel internal quota identifier to start with.
+ *
+ *      Map @kqid into the user-namespace specified by @targ and
+ *      return the resulting qid.
+ *
+ *      There is always a mapping into the initial user_namespace.
+ *
+ *      Unlike from_kqid from_kqid_munged never fails and always
+ *      returns a valid projid.  This makes from_kqid_munged
+ *      appropriate for use in places where failing to provide
+ *      a qid_t is not a good option.
+ *
+ *      If @kqid has no mapping in @targ the kqid.type specific
+ *      overflow identifier is returned.
+ */
+qid_t from_kqid_munged(struct user_namespace *targ, struct kqid kqid)
+{
+        switch (kqid.type) {
+        case USRQUOTA:
+                return from_kuid_munged(targ, kqid.uid);
+        case GRPQUOTA:
+                return from_kgid_munged(targ, kqid.gid);
+        case PRJQUOTA:
+                return from_kprojid_munged(targ, kqid.projid);
+        default:
+                BUG();
+        }
+}
+EXPORT_SYMBOL(from_kqid_munged);
+
+/**
+ *      qid_valid - Report if a valid value is stored in a kqid.
+ *      @qid: The kernel internal quota identifier to test.
+ */
+bool qid_valid(struct kqid qid)
+{
+        switch (qid.type) {
+        case USRQUOTA:
+                return uid_valid(qid.uid);
+        case GRPQUOTA:
+                return gid_valid(qid.gid);
+        case PRJQUOTA:
+                return projid_valid(qid.projid);
+        default:
+                BUG();
+        }
+}
+EXPORT_SYMBOL(qid_valid);
diff --git a/include/linux/quota.h b/include/linux/quota.h
index 524ede8a160a..00ac8d846c14 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -181,10 +181,135 @@ enum {
 #include <linux/dqblk_v2.h>
 
 #include <linux/atomic.h>
+#include <linux/uidgid.h>
+#include <linux/projid.h>
+
+#undef USRQUOTA
+#undef GRPQUOTA
+enum quota_type {
+        USRQUOTA = 0,           /* element used for user quotas */
+        GRPQUOTA = 1,           /* element used for group quotas */
+        PRJQUOTA = 2,           /* element used for project quotas */
+};
 
 typedef __kernel_uid32_t qid_t; /* Type in which we store ids in memory */
 typedef long long qsize_t;      /* Type in which we store sizes */
 
+struct kqid {                   /* Type in which we store the quota identifier */
+        union {
+                kuid_t uid;
+                kgid_t gid;
+                kprojid_t projid;
+        };
+        enum quota_type type;  /* USRQUOTA (uid) or GRPQUOTA (gid) or PRJQUOTA (projid) */
+};
+
+extern bool qid_eq(struct kqid left, struct kqid right);
+extern bool qid_lt(struct kqid left, struct kqid right);
+extern qid_t from_kqid(struct user_namespace *to, struct kqid qid);
+extern qid_t from_kqid_munged(struct user_namespace *to, struct kqid qid);
+extern bool qid_valid(struct kqid qid);
+
+/**
+ *      make_kqid - Map a user-namespace, type, qid tuple into a kqid.
+ *      @from: User namespace that the qid is in
+ *      @type: The type of quota
+ *      @qid: Quota identifier
+ *
+ *      Maps a user-namespace, type qid tuple into a kernel internal
+ *      kqid, and returns that kqid.
+ *
+ *      When there is no mapping defined for the user-namespace, type,
+ *      qid tuple an invalid kqid is returned.  Callers are expected to
+ *      test for and handle handle invalid kqids being returned.
+ *      Invalid kqids may be tested for using qid_valid().
+ */
+static inline struct kqid make_kqid(struct user_namespace *from,
+                                    enum quota_type type, qid_t qid)
+{
+        struct kqid kqid;
+
+        kqid.type = type;
+        switch (type) {
+        case USRQUOTA:
+                kqid.uid = make_kuid(from, qid);
+                break;
+        case GRPQUOTA:
+                kqid.gid = make_kgid(from, qid);
+                break;
+        case PRJQUOTA:
+                kqid.projid = make_kprojid(from, qid);
+                break;
+        default:
+                BUG();
+        }
+        return kqid;
+}
+
+/**
+ *      make_kqid_invalid - Explicitly make an invalid kqid
+ *      @type: The type of quota identifier
+ *
+ *      Returns an invalid kqid with the specified type.
+ */
+static inline struct kqid make_kqid_invalid(enum quota_type type)
+{
+        struct kqid kqid;
+
+        kqid.type = type;
+        switch (type) {
+        case USRQUOTA:
+                kqid.uid = INVALID_UID;
+                break;
+        case GRPQUOTA:
+                kqid.gid = INVALID_GID;
+                break;
+        case PRJQUOTA:
+                kqid.projid = INVALID_PROJID;
+                break;
+        default:
+                BUG();
+        }
+        return kqid;
+}
+
+/**
+ *      make_kqid_uid - Make a kqid from a kuid
+ *      @uid: The kuid to make the quota identifier from
+ */
+static inline struct kqid make_kqid_uid(kuid_t uid)
+{
+        struct kqid kqid;
+        kqid.type = USRQUOTA;
+        kqid.uid = uid;
+        return kqid;
+}
+
+/**
+ *      make_kqid_gid - Make a kqid from a kgid
+ *      @gid: The kgid to make the quota identifier from
+ */
+static inline struct kqid make_kqid_gid(kgid_t gid)
+{
+        struct kqid kqid;
+        kqid.type = GRPQUOTA;
+        kqid.gid = gid;
+        return kqid;
+}
+
+/**
+ *      make_kqid_projid - Make a kqid from a projid
+ *      @projid: The kprojid to make the quota identifier from
+ */
+static inline struct kqid make_kqid_projid(kprojid_t projid)
+{
+        struct kqid kqid;
+        kqid.type = PRJQUOTA;
+        kqid.projid = projid;
+        return kqid;
+}
+
+
 extern spinlock_t dq_data_lock;
 
 /* Maximal numbers of writes for quota operation (insert/delete/update)