xen: make sysfs files behave as their names suggest

1: make "target_kb" only accept and produce a memory size in kilobytes.
2: add a second "target" file which produces output in bytes, and will accept
   memparse input (scaled bytes)

This fixes the rather irritating problem that writing the same value
read back into target_kb would end up shrinking the domain by a factor
of 1024, with generally bad results.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stable Kernel <stable@kernel.org>
Cc: "dan.magenheimer@oracle.com" <dan.magenheimer@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 32 insertions, 1 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 2ba8f95516a0..efa4b363ce72 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -498,7 +498,7 @@ static ssize_t store_target_kb(struct sys_device *dev,
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        target_bytes = memparse(buf, &endchar);
+        target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
 
         balloon_set_new_target(target_bytes >> PAGE_SHIFT);
 
@@ -508,8 +508,39 @@ static ssize_t store_target_kb(struct sys_device *dev,
 static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR,
                    show_target_kb, store_target_kb);
 
+
+static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr,
+                              char *buf)
+{
+        return sprintf(buf, "%llu\n",
+                       (u64)balloon_stats.target_pages << PAGE_SHIFT);
+}
+
+static ssize_t store_target(struct sys_device *dev,
+                            struct sysdev_attribute *attr,
+                            const char *buf,
+                            size_t count)
+{
+        char *endchar;
+        unsigned long long target_bytes;
+
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+
+        target_bytes = memparse(buf, &endchar);
+
+        balloon_set_new_target(target_bytes >> PAGE_SHIFT);
+
+        return count;
+}
+
+static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR,
+                   show_target, store_target);
+
+
 static struct sysdev_attribute *balloon_attrs[] = {
         &attr_target_kb,
+        &attr_target,
 };
 
 static struct attribute *balloon_info_attrs[] = {