btrfs: Fix busyloop in transaction_kthread()

When a filesystem got aborted due do error, transaction_kthread() will
busyloop.  Fix it by going to sleep in that case as well. Maybe we should
just stop transaction_kthread() when filesystem is aborted but that would be
more complex.

Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 16a0cada26c2..438993e3d832 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1640,8 +1640,10 @@ static int transaction_kthread(void *arg)
         u64 transid;
         unsigned long now;
         unsigned long delay;
+        bool cannot_commit;
 
         do {
+                cannot_commit = false;
                 delay = HZ * 30;
                 vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
                 mutex_lock(&root->fs_info->transaction_kthread_mutex);
@@ -1665,8 +1667,10 @@ static int transaction_kthread(void *arg)
 
                 /* If the file system is aborted, this will always fail. */
                 trans = btrfs_join_transaction(root);
-                if (IS_ERR(trans))
+                if (IS_ERR(trans)) {
+                        cannot_commit = true;
                         goto sleep;
+                }
                 if (transid == trans->transid) {
                         btrfs_commit_transaction(trans, root);
                 } else {
@@ -1679,7 +1683,8 @@ sleep:
                 if (!try_to_freeze()) {
                         set_current_state(TASK_INTERRUPTIBLE);
                         if (!kthread_should_stop() &&
-                            !btrfs_transaction_blocked(root->fs_info))
+                            (!btrfs_transaction_blocked(root->fs_info) ||
+                             cannot_commit))
                                 schedule_timeout(delay);
                         __set_current_state(TASK_RUNNING);
                 }