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>

1 files changed, 17 insertions, 26 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 9314adeba946..2e65e8e73844 100644
--- 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;