Btrfs: fix the skipped transaction commit during the file sync

We may abort the wait earlier if ->last_trans_log_full_commit was set to
the current transaction id, at this case, we need commit the current
transaction instead of the log sub-transaction. But the current code
didn't tell the caller to do it (return 0, not -EAGAIN). Fix it.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>

1 files changed, 16 insertions, 10 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 5a4e10b9ac3e..8a03b39648be 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2364,6 +2364,7 @@ static int wait_log_commit(struct btrfs_trans_handle *trans,
 {
         DEFINE_WAIT(wait);
         int index = transid % 2;
+        int ret = 0;
 
         /*
          * we only allow two pending log transactions at a time,
@@ -2371,21 +2372,26 @@ static int wait_log_commit(struct btrfs_trans_handle *trans,
          * current transaction, we're done
          */
         do {
+                if (ACCESS_ONCE(root->fs_info->last_trans_log_full_commit) ==
+                    trans->transid) {
+                        ret = -EAGAIN;
+                        break;
+                }
+
                 prepare_to_wait(&root->log_commit_wait[index],
                                 &wait, TASK_UNINTERRUPTIBLE);
                 mutex_unlock(&root->log_mutex);
 
-                if (ACCESS_ONCE(root->fs_info->last_trans_log_full_commit) !=
-                    trans->transid && root->log_transid < transid + 2 &&
+                if (root->log_transid < transid + 2 &&
                     atomic_read(&root->log_commit[index]))
                         schedule();
 
                 finish_wait(&root->log_commit_wait[index], &wait);
                 mutex_lock(&root->log_mutex);
-        } while (ACCESS_ONCE(root->fs_info->last_trans_log_full_commit) !=
-                 trans->transid && root->log_transid < transid + 2 &&
+        } while (root->log_transid < transid + 2 &&
                  atomic_read(&root->log_commit[index]));
-        return 0;
+
+        return ret;
 }
 
 static void wait_for_writer(struct btrfs_trans_handle *trans,
@@ -2433,15 +2439,16 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
         log_transid = root->log_transid;
         index1 = root->log_transid % 2;
         if (atomic_read(&root->log_commit[index1])) {
-                wait_log_commit(trans, root, root->log_transid);
+                ret = wait_log_commit(trans, root, root->log_transid);
                 mutex_unlock(&root->log_mutex);
-                return 0;
+                return ret;
         }
         atomic_set(&root->log_commit[index1], 1);
 
         /* wait for previous tree log sync to complete */
         if (atomic_read(&root->log_commit[(index1 + 1) % 2]))
                 wait_log_commit(trans, root, root->log_transid - 1);
+
         while (1) {
                 int batch = atomic_read(&root->log_batch);
                 /* when we're on an ssd, just kick the log commit out */
@@ -2529,11 +2536,10 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
         if (atomic_read(&log_root_tree->log_commit[index2])) {
                 blk_finish_plug(&plug);
                 btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
-                wait_log_commit(trans, log_root_tree,
-                                log_root_tree->log_transid);
+                ret = wait_log_commit(trans, log_root_tree,
+                                      log_root_tree->log_transid);
                 btrfs_free_logged_extents(log, log_transid);
                 mutex_unlock(&log_root_tree->log_mutex);
-                ret = 0;
                 goto out;
         }
         atomic_set(&log_root_tree->log_commit[index2], 1);