[PATCH v3 1/2] ubifs: prefer kstrtobool_from_user() over custom helper

[Dmitry Antipov]

Adjust 'dfs_file_write()' and 'dfs_global_file_write()' to prefer generic
'kstrtobool_from_user()' over an ad-hoc 'interpret_user_input()' helper,
thus making the latter not needed anymore.

Reviewed-by: Zhihao Cheng <chengzhihao1 at huawei.com>
Signed-off-by: Dmitry Antipov <dmantipov at yandex.ru>
---
v3: bump version to match the series
v2: add Reviewed-by: and bump version to match the series
---
 fs/ubifs/debug.c | 44 ++++++++++----------------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 160c16aa7b6e..252cf82012cf 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -2732,39 +2732,14 @@ static ssize_t dfs_file_read(struct file *file, char __user *u, size_t count,
 	return provide_user_output(val, u, count, ppos);
 }
 
-/**
- * interpret_user_input - interpret user debugfs file input.
- * @u: user-provided buffer with the input
- * @count: buffer size
- *
- * This is a helper function which interpret user input to a boolean UBIFS
- * debugfs file. Returns %0 or %1 in case of success and a negative error code
- * in case of failure.
- */
-static int interpret_user_input(const char __user *u, size_t count)
-{
-	size_t buf_size;
-	char buf[8];
-
-	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
-	if (copy_from_user(buf, u, buf_size))
-		return -EFAULT;
-
-	if (buf[0] == '1')
-		return 1;
-	else if (buf[0] == '0')
-		return 0;
-
-	return -EINVAL;
-}
-
 static ssize_t dfs_file_write(struct file *file, const char __user *u,
 			      size_t count, loff_t *ppos)
 {
 	struct ubifs_info *c = file->private_data;
 	struct ubifs_debug_info *d = c->dbg;
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
 	if (file->f_path.dentry == d->dfs_dump_lprops) {
 		ubifs_dump_lprops(c);
@@ -2781,9 +2756,9 @@ static ssize_t dfs_file_write(struct file *file, const char __user *u,
 		return count;
 	}
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == d->dfs_chk_gen)
 		d->chk_gen = val;
@@ -2926,11 +2901,12 @@ static ssize_t dfs_global_file_write(struct file *file, const char __user *u,
 				     size_t count, loff_t *ppos)
 {
 	struct dentry *dent = file->f_path.dentry;
-	int val;
+	bool val;
+	int ret;
 
-	val = interpret_user_input(u, count);
-	if (val < 0)
-		return val;
+	ret = kstrtobool_from_user(u, count, &val);
+	if (unlikely(ret))
+		return ret;
 
 	if (dent == dfs_chk_gen)
 		ubifs_dbg.chk_gen = val;
-- 
2.53.0