@@ -1996,6 +1996,7 @@ void btrfs_put_root(struct btrfs_root *root)
if (refcount_dec_and_test(&root->refs)) {
WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
+ WARN_ON(test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state));
if (root->anon_dev)
free_anon_bdev(root->anon_dev);
btrfs_drew_lock_destroy(&root->snapshot_lock);
@@ -1936,6 +1936,8 @@ void merge_reloc_roots(struct reloc_control *rc)
root->reloc_root = NULL;
btrfs_put_root(reloc_root);
}
+ clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE,
+ &root->state);
btrfs_put_root(root);
}
[BUG] There are several reported runaway balance, that balance is flooding the kernel with "Found X extents" where the X never changes. [CAUSE] Commit d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") introduced BTRFS_ROOT_DEAD_RELOC_TREE bit to indicate that one subvolume has finished its tree blocks swap with its reloc tree. However if balance is canceled or hits ENOSPC halfway, we didn't clear the BTRFS_ROOT_DEAD_RELOC_TREE bit, leaving that bit hanging forever until unmount. Any subvolume root with that bit, would cause backref cache to skip this tree block, as it has finished its tree block swap. This would cause all tree blocks of that root be ignored by balance, leading to runaway balance. [FIX] Fix the problem by also clearing the BTRFS_ROOT_DEAD_RELOC_TREE bit for the original subvolume of orphan reloc root. Furthermore to avoid such damn bug to bother anybody anymore, add unmount time check to detect and warn about this bit. Fixes: d2311e698578 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots") Signed-off-by: Qu Wenruo <wqu@suse.com> --- fs/btrfs/disk-io.c | 1 + fs/btrfs/relocation.c | 2 ++ 2 files changed, 3 insertions(+)