mm: shrinker: use min() to improve shrinker_debugfs_scan_write()

Use the min() macro to simplify the shrinker_debugfs_scan_write() function
and improve its readability.

Link: https://lkml.kernel.org/r/20240820042254.99115-2-thorsten.blum@toblux.comSigned-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/shrinker_debug.c

@@ -114,7 +114,7 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file,
 	int nid;
 	char kbuf[72];
 
-	read_len = size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1);
+	read_len = min(size, sizeof(kbuf) - 1);
 	if (copy_from_user(kbuf, buf, read_len))
 		return -EFAULT;
 	kbuf[read_len] = '\0';