Memory controller improve user interface

Change the interface to use bytes instead of pages.  Page sizes can vary
across platforms and configurations.  A new strategy routine has been added
to the resource counters infrastructure to format the data as desired.

Suggested by David Rientjes, Andrew Morton and Herbert Poetzl

Tested on a UML setup with the config for memory control enabled.

[kamezawa.hiroyu@jp.fujitsu.com: possible race fix in res_counter]
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 25 insertions, 11 deletions

diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 722c484b068..16cbec2d5d6 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -16,7 +16,7 @@
 void res_counter_init(struct res_counter *counter)
 {
         spin_lock_init(&counter->lock);
-        counter->limit = (unsigned long)LONG_MAX;
+        counter->limit = (unsigned long long)LLONG_MAX;
 }
 
 int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
@@ -59,8 +59,8 @@ void res_counter_uncharge(struct res_counter *counter, unsigned long val)
 }
 
 
-static inline unsigned long *res_counter_member(struct res_counter *counter,
-                                                int member)
+static inline unsigned long long *
+res_counter_member(struct res_counter *counter, int member)
 {
         switch (member) {
         case RES_USAGE:
@@ -76,24 +76,30 @@ static inline unsigned long *res_counter_member(struct res_counter *counter,
 }
 
 ssize_t res_counter_read(struct res_counter *counter, int member,
-                const char __user *userbuf, size_t nbytes, loff_t *pos)
+                const char __user *userbuf, size_t nbytes, loff_t *pos,
+                int (*read_strategy)(unsigned long long val, char *st_buf))
 {
-        unsigned long *val;
+        unsigned long long *val;
         char buf[64], *s;
 
         s = buf;
         val = res_counter_member(counter, member);
-        s += sprintf(s, "%lu\n", *val);
+        if (read_strategy)
+                s += read_strategy(*val, s);
+        else
+                s += sprintf(s, "%llu\n", *val);
         return simple_read_from_buffer((void __user *)userbuf, nbytes,
                         pos, buf, s - buf);
 }
 
 ssize_t res_counter_write(struct res_counter *counter, int member,
-                const char __user *userbuf, size_t nbytes, loff_t *pos)
+                const char __user *userbuf, size_t nbytes, loff_t *pos,
+                int (*write_strategy)(char *st_buf, unsigned long long *val))
 {
         int ret;
         char *buf, *end;
-        unsigned long tmp, *val;
+        unsigned long flags;
+        unsigned long long tmp, *val;
 
         buf = kmalloc(nbytes + 1, GFP_KERNEL);
         ret = -ENOMEM;
@@ -106,12 +112,20 @@ ssize_t res_counter_write(struct res_counter *counter, int member,
                 goto out_free;
 
         ret = -EINVAL;
-        tmp = simple_strtoul(buf, &end, 10);
-        if (*end != '\0')
-                goto out_free;
 
+        if (write_strategy) {
+                if (write_strategy(buf, &tmp)) {
+                        goto out_free;
+                }
+        } else {
+                tmp = simple_strtoull(buf, &end, 10);
+                if (*end != '\0')
+                        goto out_free;
+        }
+        spin_lock_irqsave(&counter->lock, flags);
         val = res_counter_member(counter, member);
         *val = tmp;
+        spin_unlock_irqrestore(&counter->lock, flags);
         ret = nbytes;
 out_free:
         kfree(buf);