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>

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 5a4e10b9ac3e9e12ff5b4a0675b1796fdfd4c81f..8a03b39648be080302ed1e352c3b01d2b517667e 100644 (file)
--- 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);