[RFC PATCH v1 1/4] cgroup quota: add disk space parse strategy to res_counter

[Jeff Liu <jeff.liu@oracle.com>]

Introduce a new disk space parse strategy routine for cgroup quota supports.
disk_space_parse() is simply copied from mmparse() with Petabytes and Terabytes parse.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
---
 include/linux/res_counter.h |    3 ++
 kernel/res_counter.c        |   58 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 0 deletions(-)

diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index c9d625c..f8ce315 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -79,6 +79,9 @@ typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
 int res_counter_memparse_write_strategy(const char *buf,
 					unsigned long long *res);
 
+int res_counter_diskspace_parse_write_strategy(const char *buf,
+					       unsigned long long *res);
+
 int res_counter_write(struct res_counter *counter, int member,
 		      const char *buffer, write_strategy_fn write_strategy);
 
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 34683ef..42c1623 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -145,6 +145,64 @@ u64 res_counter_read_u64(struct res_counter *counter, int member)
 }
 #endif
 
+/*
+ * Copy from memparse(), add terabytes, petabytes parse support.
+ */
+unsigned long long disk_space_parse(const char *ptr, char **retptr)
+{
+	char *endptr; /* local pointer to end of parsed string */
+	unsigned long long ret = kstrtoull(ptr, &endptr, 0);
+
+	switch (*endptr) {
+	case 'P':
+	case 'p':
+		ret <<= 10;
+	case 'T':
+	case 't':
+		ret <<= 10;
+	case 'G':
+	case 'g':
+		ret <<= 10;
+	case 'M':
+	case 'm':
+		ret <<= 10;
+	case 'K':
+	case 'k':
+		ret <<= 10;
+		endptr++;
+	default:
+		break;
+	}
+
+	if (retptr)
+		*retptr = endptr;
+
+	return ret;
+}
+
+int res_counter_diskspace_parse_write_strategy(const char *buf,
+					       unsigned long long *res)
+{
+	char *end;
+
+	/* return RESOURCE_MAX(unlimited) if "-1" is specified */
+	if (*buf == '-') {
+		*res = kstrtoull(buf + 1, &end, 10);
+		if (*res != 1 || *end != '\0')
+			return -EINVAL;
+		*res = RESOURCE_MAX;
+		return 0;
+	}
+
+	/* FIXME - make memparse() take const char* args */
+	*res = disk_space_parse((char *)buf, &end);
+	if (*end != '\0')
+		return -EINVAL;
+
+	/* FIXME - need to return *res as block aligned? */
+	return 0;
+}
+
 int res_counter_memparse_write_strategy(const char *buf,
 					unsigned long long *res)
 {
-- 
1.7.9