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-rw-r--r--fs/btrfs/extent-tree.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 171312d51799..07204bf601ed 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4227,6 +4227,24 @@ out:
space_info->chunk_alloc = 0;
spin_unlock(&space_info->lock);
mutex_unlock(&fs_info->chunk_mutex);
+ /*
+ * When we allocate a new chunk we reserve space in the chunk block
+ * reserve to make sure we can COW nodes/leafs in the chunk tree or
+ * add new nodes/leafs to it if we end up needing to do it when
+ * inserting the chunk item and updating device items as part of the
+ * second phase of chunk allocation, performed by
+ * btrfs_finish_chunk_alloc(). So make sure we don't accumulate a
+ * large number of new block groups to create in our transaction
+ * handle's new_bgs list to avoid exhausting the chunk block reserve
+ * in extreme cases - like having a single transaction create many new
+ * block groups when starting to write out the free space caches of all
+ * the block groups that were made dirty during the lifetime of the
+ * transaction.
+ */
+ if (trans->chunk_bytes_reserved >= (2 * 1024 * 1024ull)) {
+ btrfs_create_pending_block_groups(trans, trans->root);
+ btrfs_trans_release_chunk_metadata(trans);
+ }
return ret;
}