Fixed MTP to work with TWRP

include/linux/res_counter.h

@@ -0,0 +1,223 @@
+#ifndef __RES_COUNTER_H__
+#define __RES_COUNTER_H__
+
+/*
+ * Resource Counters
+ * Contain common data types and routines for resource accounting
+ *
+ * Copyright 2007 OpenVZ SWsoft Inc
+ *
+ * Author: Pavel Emelianov <xemul@openvz.org>
+ *
+ * See Documentation/cgroups/resource_counter.txt for more
+ * info about what this counter is.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+
+/*
+ * The core object. the cgroup that wishes to account for some
+ * resource may include this counter into its structures and use
+ * the helpers described beyond
+ */
+
+struct res_counter {
+	/*
+	 * the current resource consumption level
+	 */
+	unsigned long long usage;
+	/*
+	 * the maximal value of the usage from the counter creation
+	 */
+	unsigned long long max_usage;
+	/*
+	 * the limit that usage cannot exceed
+	 */
+	unsigned long long limit;
+	/*
+	 * the limit that usage can be exceed
+	 */
+	unsigned long long soft_limit;
+	/*
+	 * the number of unsuccessful attempts to consume the resource
+	 */
+	unsigned long long failcnt;
+	/*
+	 * the lock to protect all of the above.
+	 * the routines below consider this to be IRQ-safe
+	 */
+	spinlock_t lock;
+	/*
+	 * Parent counter, used for hierarchial resource accounting
+	 */
+	struct res_counter *parent;
+};
+
+#define RES_COUNTER_MAX ULLONG_MAX
+
+/**
+ * Helpers to interact with userspace
+ * res_counter_read_u64() - returns the value of the specified member.
+ * res_counter_read/_write - put/get the specified fields from the
+ * res_counter struct to/from the user
+ *
+ * @counter:     the counter in question
+ * @member:  the field to work with (see RES_xxx below)
+ * @buf:     the buffer to opeate on,...
+ * @nbytes:  its size...
+ * @pos:     and the offset.
+ */
+
+u64 res_counter_read_u64(struct res_counter *counter, int member);
+
+ssize_t res_counter_read(struct res_counter *counter, int member,
+		const char __user *buf, size_t nbytes, loff_t *pos,
+		int (*read_strategy)(unsigned long long val, char *s));
+
+int res_counter_memparse_write_strategy(const char *buf,
+					unsigned long long *res);
+
+/*
+ * the field descriptors. one for each member of res_counter
+ */
+
+enum {
+	RES_USAGE,
+	RES_MAX_USAGE,
+	RES_LIMIT,
+	RES_FAILCNT,
+	RES_SOFT_LIMIT,
+};
+
+/*
+ * helpers for accounting
+ */
+
+void res_counter_init(struct res_counter *counter, struct res_counter *parent);
+
+/*
+ * charge - try to consume more resource.
+ *
+ * @counter: the counter
+ * @val: the amount of the resource. each controller defines its own
+ *       units, e.g. numbers, bytes, Kbytes, etc
+ *
+ * returns 0 on success and <0 if the counter->usage will exceed the
+ * counter->limit
+ *
+ * charge_nofail works the same, except that it charges the resource
+ * counter unconditionally, and returns < 0 if the after the current
+ * charge we are over limit.
+ */
+
+int __must_check res_counter_charge(struct res_counter *counter,
+		unsigned long val, struct res_counter **limit_fail_at);
+int res_counter_charge_nofail(struct res_counter *counter,
+		unsigned long val, struct res_counter **limit_fail_at);
+
+/*
+ * uncharge - tell that some portion of the resource is released
+ *
+ * @counter: the counter
+ * @val: the amount of the resource
+ *
+ * these calls check for usage underflow and show a warning on the console
+ *
+ * returns the total charges still present in @counter.
+ */
+
+u64 res_counter_uncharge(struct res_counter *counter, unsigned long val);
+
+u64 res_counter_uncharge_until(struct res_counter *counter,
+			       struct res_counter *top,
+			       unsigned long val);
+/**
+ * res_counter_margin - calculate chargeable space of a counter
+ * @cnt: the counter
+ *
+ * Returns the difference between the hard limit and the current usage
+ * of resource counter @cnt.
+ */
+static inline unsigned long long res_counter_margin(struct res_counter *cnt)
+{
+	unsigned long long margin;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	if (cnt->limit > cnt->usage)
+		margin = cnt->limit - cnt->usage;
+	else
+		margin = 0;
+	spin_unlock_irqrestore(&cnt->lock, flags);
+	return margin;
+}
+
+/**
+ * Get the difference between the usage and the soft limit
+ * @cnt: The counter
+ *
+ * Returns 0 if usage is less than or equal to soft limit
+ * The difference between usage and soft limit, otherwise.
+ */
+static inline unsigned long long
+res_counter_soft_limit_excess(struct res_counter *cnt)
+{
+	unsigned long long excess;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	if (cnt->usage <= cnt->soft_limit)
+		excess = 0;
+	else
+		excess = cnt->usage - cnt->soft_limit;
+	spin_unlock_irqrestore(&cnt->lock, flags);
+	return excess;
+}
+
+static inline void res_counter_reset_max(struct res_counter *cnt)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	cnt->max_usage = cnt->usage;
+	spin_unlock_irqrestore(&cnt->lock, flags);
+}
+
+static inline void res_counter_reset_failcnt(struct res_counter *cnt)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	cnt->failcnt = 0;
+	spin_unlock_irqrestore(&cnt->lock, flags);
+}
+
+static inline int res_counter_set_limit(struct res_counter *cnt,
+		unsigned long long limit)
+{
+	unsigned long flags;
+	int ret = -EBUSY;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	if (cnt->usage <= limit) {
+		cnt->limit = limit;
+		ret = 0;
+	}
+	spin_unlock_irqrestore(&cnt->lock, flags);
+	return ret;
+}
+
+static inline int
+res_counter_set_soft_limit(struct res_counter *cnt,
+				unsigned long long soft_limit)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&cnt->lock, flags);
+	cnt->soft_limit = soft_limit;
+	spin_unlock_irqrestore(&cnt->lock, flags);
+	return 0;
+}
+
+#endif