btrfs: do not BUG_ON() when freeing tree block after error
When freeing a tree block, at btrfs_free_tree_block(), if we fail to create a delayed reference we don't deal with the error and just do a BUG_ON(). The error most likely to happen is -ENOMEM, and we have a comment mentioning that only -ENOMEM can happen, but that is not true, because in case qgroups are enabled any error returned from btrfs_qgroup_trace_extent_post() (can be -EUCLEAN or anything returned from btrfs_search_slot() for example) can be propagated back to btrfs_free_tree_block(). So stop doing a BUG_ON() and return the error to the callers and make them abort the transaction to prevent leaking space. Syzbot was triggering this, likely due to memory allocation failure injection. Reported-by: syzbot+a306f914b4d01b3958fe@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/000000000000fcba1e05e998263c@google.com/ Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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b751915765
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bb3868033a
@ -620,10 +620,16 @@ int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
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atomic_inc(&cow->refs);
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rcu_assign_pointer(root->node, cow);
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btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
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parent_start, last_ref);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
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parent_start, last_ref);
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free_extent_buffer(buf);
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add_root_to_dirty_list(root);
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if (ret < 0) {
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btrfs_tree_unlock(cow);
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free_extent_buffer(cow);
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btrfs_abort_transaction(trans, ret);
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return ret;
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}
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} else {
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WARN_ON(trans->transid != btrfs_header_generation(parent));
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ret = btrfs_tree_mod_log_insert_key(parent, parent_slot,
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@ -648,8 +654,14 @@ int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
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return ret;
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}
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}
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btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
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parent_start, last_ref);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
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parent_start, last_ref);
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if (ret < 0) {
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btrfs_tree_unlock(cow);
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free_extent_buffer(cow);
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btrfs_abort_transaction(trans, ret);
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return ret;
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}
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}
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if (unlock_orig)
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btrfs_tree_unlock(buf);
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@ -983,9 +995,13 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
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free_extent_buffer(mid);
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root_sub_used_bytes(root);
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btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
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/* once for the root ptr */
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free_extent_buffer_stale(mid);
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if (ret < 0) {
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btrfs_abort_transaction(trans, ret);
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goto out;
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}
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return 0;
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}
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if (btrfs_header_nritems(mid) >
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@ -1053,10 +1069,14 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
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goto out;
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}
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root_sub_used_bytes(root);
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btrfs_free_tree_block(trans, btrfs_root_id(root), right,
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0, 1);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(root),
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right, 0, 1);
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free_extent_buffer_stale(right);
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right = NULL;
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if (ret < 0) {
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btrfs_abort_transaction(trans, ret);
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goto out;
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}
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} else {
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struct btrfs_disk_key right_key;
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btrfs_node_key(right, &right_key, 0);
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@ -1111,9 +1131,13 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
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goto out;
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}
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root_sub_used_bytes(root);
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btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
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free_extent_buffer_stale(mid);
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mid = NULL;
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if (ret < 0) {
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btrfs_abort_transaction(trans, ret);
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goto out;
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}
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} else {
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/* update the parent key to reflect our changes */
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struct btrfs_disk_key mid_key;
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@ -2878,7 +2902,11 @@ static noinline int insert_new_root(struct btrfs_trans_handle *trans,
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old = root->node;
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ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
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if (ret < 0) {
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btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
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int ret2;
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ret2 = btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
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if (ret2 < 0)
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btrfs_abort_transaction(trans, ret2);
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btrfs_tree_unlock(c);
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free_extent_buffer(c);
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return ret;
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@ -4447,9 +4475,12 @@ static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
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root_sub_used_bytes(root);
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atomic_inc(&leaf->refs);
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btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
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free_extent_buffer_stale(leaf);
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return 0;
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if (ret < 0)
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btrfs_abort_transaction(trans, ret);
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return ret;
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}
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/*
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* delete the item at the leaf level in path. If that empties
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@ -3419,10 +3419,10 @@ out_delayed_unlock:
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return 0;
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}
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void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
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u64 root_id,
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struct extent_buffer *buf,
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u64 parent, int last_ref)
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int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
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u64 root_id,
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struct extent_buffer *buf,
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u64 parent, int last_ref)
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{
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struct btrfs_fs_info *fs_info = trans->fs_info;
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struct btrfs_block_group *bg;
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@ -3449,11 +3449,12 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
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btrfs_init_tree_ref(&generic_ref, btrfs_header_level(buf), 0, false);
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btrfs_ref_tree_mod(fs_info, &generic_ref);
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ret = btrfs_add_delayed_tree_ref(trans, &generic_ref, NULL);
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BUG_ON(ret); /* -ENOMEM */
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if (ret < 0)
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return ret;
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}
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if (!last_ref)
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return;
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return 0;
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if (btrfs_header_generation(buf) != trans->transid)
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goto out;
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@ -3510,6 +3511,7 @@ out:
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* matter anymore.
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*/
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clear_bit(EXTENT_BUFFER_CORRUPT, &buf->bflags);
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return 0;
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}
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/* Can return -ENOMEM */
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@ -5754,7 +5756,7 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
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struct walk_control *wc)
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{
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struct btrfs_fs_info *fs_info = root->fs_info;
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int ret;
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int ret = 0;
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int level = wc->level;
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struct extent_buffer *eb = path->nodes[level];
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u64 parent = 0;
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@ -5849,12 +5851,14 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans,
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goto owner_mismatch;
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}
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btrfs_free_tree_block(trans, btrfs_root_id(root), eb, parent,
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wc->refs[level] == 1);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(root), eb, parent,
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wc->refs[level] == 1);
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if (ret < 0)
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btrfs_abort_transaction(trans, ret);
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out:
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wc->refs[level] = 0;
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wc->flags[level] = 0;
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return 0;
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return ret;
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owner_mismatch:
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btrfs_err_rl(fs_info, "unexpected tree owner, have %llu expect %llu",
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@ -127,10 +127,10 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
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u64 empty_size,
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u64 reloc_src_root,
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enum btrfs_lock_nesting nest);
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void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
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u64 root_id,
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struct extent_buffer *buf,
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u64 parent, int last_ref);
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int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
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u64 root_id,
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struct extent_buffer *buf,
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u64 parent, int last_ref);
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int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, u64 owner,
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u64 offset, u64 ram_bytes,
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@ -1300,10 +1300,14 @@ int btrfs_delete_free_space_tree(struct btrfs_fs_info *fs_info)
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btrfs_tree_lock(free_space_root->node);
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btrfs_clear_buffer_dirty(trans, free_space_root->node);
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btrfs_tree_unlock(free_space_root->node);
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btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
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free_space_root->node, 0, 1);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(free_space_root),
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free_space_root->node, 0, 1);
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btrfs_put_root(free_space_root);
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if (ret < 0) {
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btrfs_abort_transaction(trans, ret);
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btrfs_end_transaction(trans);
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return ret;
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}
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return btrfs_commit_transaction(trans);
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}
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@ -714,6 +714,8 @@ static noinline int create_subvol(struct mnt_idmap *idmap,
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ret = btrfs_insert_root(trans, fs_info->tree_root, &key,
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root_item);
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if (ret) {
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int ret2;
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/*
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* Since we don't abort the transaction in this case, free the
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* tree block so that we don't leak space and leave the
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@ -724,7 +726,9 @@ static noinline int create_subvol(struct mnt_idmap *idmap,
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btrfs_tree_lock(leaf);
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btrfs_clear_buffer_dirty(trans, leaf);
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btrfs_tree_unlock(leaf);
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btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
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ret2 = btrfs_free_tree_block(trans, objectid, leaf, 0, 1);
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if (ret2 < 0)
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btrfs_abort_transaction(trans, ret2);
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free_extent_buffer(leaf);
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goto out;
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}
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@ -1441,9 +1441,11 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
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btrfs_tree_lock(quota_root->node);
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btrfs_clear_buffer_dirty(trans, quota_root->node);
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btrfs_tree_unlock(quota_root->node);
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btrfs_free_tree_block(trans, btrfs_root_id(quota_root),
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quota_root->node, 0, 1);
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ret = btrfs_free_tree_block(trans, btrfs_root_id(quota_root),
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quota_root->node, 0, 1);
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if (ret < 0)
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btrfs_abort_transaction(trans, ret);
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out:
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btrfs_put_root(quota_root);
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