kernel: trace: blktrace: remove redundent memcpy() in compat_blk_trace_setup()

do_blk_trace_setup() will fully initialize 'buts.name', so can remove
the related memcpy(). And also use BLKTRACE_BDEV_SIZE and ARRAY_SIZE
instead of hard code number '32'.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 2 insertions, 3 deletions

diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index a12f6ed91c84..afc1343df3c7 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -89,7 +89,7 @@ static inline int blk_trace_init_sysfs(struct device *dev)
 #ifdef CONFIG_COMPAT
 
 struct compat_blk_user_trace_setup {
-        char name[32];
+        char name[BLKTRACE_BDEV_SIZE];
         u16 act_mask;
         u32 buf_size;
         u32 buf_nr;
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 7f727b34280d..f785aef65799 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -579,13 +579,12 @@ static int compat_blk_trace_setup(struct request_queue *q, char *name,
                 .end_lba = cbuts.end_lba,
                 .pid = cbuts.pid,
         };
-        memcpy(&buts.name, &cbuts.name, 32);
 
         ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
         if (ret)
                 return ret;
 
-        if (copy_to_user(arg, &buts.name, 32)) {
+        if (copy_to_user(arg, &buts.name, ARRAY_SIZE(buts.name))) {
                 blk_trace_remove(q);
                 return -EFAULT;
         }