[PATCH V2 1/2] Btrfs: cleanup duplicated division functions

[Miao Xie <miaox@cn.fujitsu.com>]

div_factor{_fine} has been implemented for two times, cleanup it.
And I move them into a independent file named math.h because they are
common math functions.

Because those functions are mostly used on the hot path, and we are sure
the parameters are right in the most cases, we don't add complex checks
for the parameters. But in the other place, we must check and make sure
the parameters are right. So besides the code cleanup, this patch also
add a check for the usage of the space balance, it is the only place that
we need add check to make sure the parameters of div_factor{_fine} are
right till now.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
---
Changelog v1 -> v2:
- add missing check
---
 fs/btrfs/extent-tree.c |   19 +------------------
 fs/btrfs/ioctl.c       |   18 ++++++++++++++++++
 fs/btrfs/math.h        |   44 ++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.c     |   23 +----------------------
 4 files changed, 64 insertions(+), 40 deletions(-)
 create mode 100644 fs/btrfs/math.h

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a010234..5f6bae1 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -33,6 +33,7 @@
 #include "volumes.h"
 #include "locking.h"
 #include "free-space-cache.h"
+#include "math.h"
 
 #undef SCRAMBLE_DELAYED_REFS
 
@@ -648,24 +649,6 @@ void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
 	rcu_read_unlock();
 }
 
-static u64 div_factor(u64 num, int factor)
-{
-	if (factor == 10)
-		return num;
-	num *= factor;
-	do_div(num, 10);
-	return num;
-}
-
-static u64 div_factor_fine(u64 num, int factor)
-{
-	if (factor == 100)
-		return num;
-	num *= factor;
-	do_div(num, 100);
-	return num;
-}
-
 u64 btrfs_find_block_group(struct btrfs_root *root,
 			   u64 search_start, u64 search_hint, int owner)
 {
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9384a2a..d8d53f7 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3335,6 +3335,24 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
 
 			goto do_balance;
 		}
+
+		if ((bargs->data.flags & BTRFS_BALANCE_ARGS_USAGE) &&
+		    (bargs->data.usage < 0 || bargs->data.usage > 100)) {
+			ret = -EINVAL;
+			goto out_bargs;
+		}
+
+		if ((bargs->meta.flags & BTRFS_BALANCE_ARGS_USAGE) &&
+		    (bargs->meta.usage < 0 || bargs->meta.usage > 100)) {
+			ret = -EINVAL;
+			goto out_bargs;
+		}
+
+		if ((bargs->sys.flags & BTRFS_BALANCE_ARGS_USAGE) &&
+		    (bargs->sys.usage < 0 || bargs->sys.usage > 100)) {
+			ret = -EINVAL;
+			goto out_bargs;
+		}
 	} else {
 		bargs = NULL;
 	}
diff --git a/fs/btrfs/math.h b/fs/btrfs/math.h
new file mode 100644
index 0000000..b7816ce
--- /dev/null
+++ b/fs/btrfs/math.h
@@ -0,0 +1,44 @@
+
+/*
+ * Copyright (C) 2012 Fujitsu.  All rights reserved.
+ * Written by Miao Xie <miaox@cn.fujitsu.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#ifndef __BTRFS_MATH_H
+#define __BTRFS_MATH_H
+
+#include <asm/div64.h>
+
+static inline u64 div_factor(u64 num, int factor)
+{
+	if (factor == 10)
+		return num;
+	num *= factor;
+	do_div(num, 10);
+	return num;
+}
+
+static inline u64 div_factor_fine(u64 num, int factor)
+{
+	if (factor == 100)
+		return num;
+	num *= factor;
+	do_div(num, 100);
+	return num;
+}
+
+#endif
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 3f4e70e..2558fc0 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -25,7 +25,6 @@
 #include <linux/capability.h>
 #include <linux/ratelimit.h>
 #include <linux/kthread.h>
-#include <asm/div64.h>
 #include "compat.h"
 #include "ctree.h"
 #include "extent_map.h"
@@ -36,6 +35,7 @@
 #include "async-thread.h"
 #include "check-integrity.h"
 #include "rcu-string.h"
+#include "math.h"
 
 static int init_first_rw_device(struct btrfs_trans_handle *trans,
 				struct btrfs_root *root,
@@ -2325,18 +2325,6 @@ static int chunk_profiles_filter(u64 chunk_type,
 	return 1;
 }
 
-static u64 div_factor_fine(u64 num, int factor)
-{
-	if (factor <= 0)
-		return 0;
-	if (factor >= 100)
-		return num;
-
-	num *= factor;
-	do_div(num, 100);
-	return num;
-}
-
 static int chunk_usage_filter(struct btrfs_fs_info *fs_info, u64 chunk_offset,
 			      struct btrfs_balance_args *bargs)
 {
@@ -2501,15 +2489,6 @@ static int should_balance_chunk(struct btrfs_root *root,
 	return 1;
 }
 
-static u64 div_factor(u64 num, int factor)
-{
-	if (factor == 10)
-		return num;
-	num *= factor;
-	do_div(num, 10);
-	return num;
-}
-
 static int __btrfs_balance(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_balance_control *bctl = fs_info->balance_ctl;
-- 
1.7.6.5