1 files changed, 9 insertions, 4 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index dcec3d3ea64f..219576c52d80 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -527,14 +527,18 @@ ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
                                 const void *from, size_t available)
 {
         loff_t pos = *ppos;
+        size_t ret;
+
         if (pos < 0)
                 return -EINVAL;
-        if (pos >= available)
+        if (pos >= available || !count)
                 return 0;
         if (count > available - pos)
                 count = available - pos;
-        if (copy_to_user(to, from + pos, count))
+        ret = copy_to_user(to, from + pos, count);
+        if (ret == count)
                 return -EFAULT;
+        count -= ret;
         *ppos = pos + count;
         return count;
 }
@@ -735,10 +739,11 @@ ssize_t simple_attr_write(struct file *file, const char __user *buf,
         if (copy_from_user(attr->set_buf, buf, size))
                 goto out;
 
-        ret = len; /* claim we got the whole input */
         attr->set_buf[size] = '\0';
         val = simple_strtol(attr->set_buf, NULL, 0);
-        attr->set(attr->data, val);
+        ret = attr->set(attr->data, val);
+        if (ret == 0)
+                ret = len; /* on success, claim we got the whole input */
 out:
         mutex_unlock(&attr->mutex);
         return ret;