Btrfs: don't do async reclaim during log replay

Trying to reproduce a log enospc bug I hit a panic in the async reclaim code
during log replay.  This is because we use fs_info->fs_root as our root for
shrinking and such.  Technically we can use whatever root we want, but let's
just not allow async reclaim while we're doing log replay.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 28a27d5f02d3..44d04979f071 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4513,7 +4513,13 @@ again:
                 space_info->flush = 1;
         } else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
                 used += orig_bytes;
-                if (need_do_async_reclaim(space_info, root->fs_info, used) &&
+                /*
+                 * We will do the space reservation dance during log replay,
+                 * which means we won't have fs_info->fs_root set, so don't do
+                 * the async reclaim as we will panic.
+                 */
+                if (!root->fs_info->log_root_recovering &&
+                    need_do_async_reclaim(space_info, root->fs_info, used) &&
                     !work_busy(&root->fs_info->async_reclaim_work))
                         queue_work(system_unbound_wq,
                                    &root->fs_info->async_reclaim_work);