btrfs: Remove useless condition in start_log_trans()

Dan Carpenter <dan.carpenter@oracle.com> reported a smatch warning
for start_log_trans():
 fs/btrfs/tree-log.c:178 start_log_trans()
 warn: we tested 'root->log_root' before and it was 'false'

 fs/btrfs/tree-log.c
 147          if (root->log_root) {
 We test "root->log_root" here.
 ...

Reason:
 Condition of:
 fs/btrfs/tree-log.c:178: if (!root->log_root) {
 is not necessary after commit: 7237f1833

 It caused a smatch warning, and no functionally error.

Fix:
 Deleting above condition will make smatch shut up,
 but a better way is to do cleanup for start_log_trans()
 to remove duplicated code and make code more readable.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 9314ade..2e65e8e 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -140,55 +140,46 @@ static int start_log_trans(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root,
                           struct btrfs_log_ctx *ctx)
 {
-       int index;
-       int ret;
+       int ret = 0;
 
        mutex_lock(&root->log_mutex);
+
        if (root->log_root) {
                if (btrfs_need_log_full_commit(root->fs_info, trans)) {
                        ret = -EAGAIN;
                        goto out;
                }
+
                if (!root->log_start_pid) {
-                       root->log_start_pid = current->pid;
                        clear_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
+                       root->log_start_pid = current->pid;
                } else if (root->log_start_pid != current->pid) {
                        set_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
                }
+       } else {
+               mutex_lock(&root->fs_info->tree_log_mutex);
+               if (!root->fs_info->log_root_tree)
+                       ret = btrfs_init_log_root_tree(trans, root->fs_info);
+               mutex_unlock(&root->fs_info->tree_log_mutex);
+               if (ret)
+                       goto out;
 
-               atomic_inc(&root->log_batch);
-               atomic_inc(&root->log_writers);
-               if (ctx) {
-                       index = root->log_transid % 2;
-                       list_add_tail(&ctx->list, &root->log_ctxs[index]);
-                       ctx->log_transid = root->log_transid;
-               }
-               mutex_unlock(&root->log_mutex);
-               return 0;
-       }
-
-       ret = 0;
-       mutex_lock(&root->fs_info->tree_log_mutex);
-       if (!root->fs_info->log_root_tree)
-               ret = btrfs_init_log_root_tree(trans, root->fs_info);
-       mutex_unlock(&root->fs_info->tree_log_mutex);
-       if (ret)
-               goto out;
-
-       if (!root->log_root) {
                ret = btrfs_add_log_tree(trans, root);
                if (ret)
                        goto out;
+
+               clear_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
+               root->log_start_pid = current->pid;
        }
-       clear_bit(BTRFS_ROOT_MULTI_LOG_TASKS, &root->state);
-       root->log_start_pid = current->pid;
+
        atomic_inc(&root->log_batch);
        atomic_inc(&root->log_writers);
        if (ctx) {
-               index = root->log_transid % 2;
+               int index = root->log_transid % 2;
                list_add_tail(&ctx->list, &root->log_ctxs[index]);
                ctx->log_transid = root->log_transid;
        }
+
 out:
        mutex_unlock(&root->log_mutex);
        return ret;