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 <jba...@fb.com>
---
V1->V2: use fs_info->log_root_recovering instead, didn't notice this existed
before.

 fs/btrfs/extent-tree.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 28a27d5..44d0497 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);
-- 
1.8.3.1

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