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>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 16a0cada26c22195dcadd477f7ca634209a13ab3..438993e3d832588666d79dff9f3e92e0538fc3c7 100644 (file)
--- 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);
                }