From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 23AD81885A6; Tue, 10 Sep 2024 09:39:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725961184; cv=none; b=CLLkNhZI9fGGlN3oDJqXliCU02jtBAgvNgcBpK2Lxf2Q934SEx5rgotekaoALzLDkzrnGKwaWcyas1jdtdb63zvtoGgZotRO0WcyAALvSd9uuEqqzuvAaUY3rFNBIGVHoP9SArHoNHRoAaVx3LVb1eWyyfvw+/t0qpLCE/fNkwA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725961184; c=relaxed/simple; bh=n7QNquyuN/JDlGCMcSL8DD6Au31ILUM6hEFXxl5LXhY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CGskcvDJm1xfo9v5iwh+7s9U9BbCgXU25OC0BHqYgA83+ObKhrsFJfNKAWK3lxA1WIosi//8bG5LBDNwvndv8ridHd1Su1K1AUkX5oSb3xyQluJTLKnMCd9HhYUiWDlLf7FRuM9fpb3oCc5Ws70jGriSQ5Vm83ebVxmch4Puv/o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fbI1Jt7R; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fbI1Jt7R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D233C4CED0; Tue, 10 Sep 2024 09:39:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725961184; bh=n7QNquyuN/JDlGCMcSL8DD6Au31ILUM6hEFXxl5LXhY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fbI1Jt7RkFi/0hXsLYby6BO7avIBz5ql0ZgtWHUp238rPb1sGxumGkbCLswdn/nWh wHUmlNAXLFp1pVJvKN4L+3WJhyhGBIGyLHyD63M0oUpnWKljKgpiVbM7aEmnvR2mV3 g7nJNOCYSwyvlEl1Y38XG3emivvCfSvtWUU6r6xg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josef Bacik , David Sterba , Sasha Levin Subject: [PATCH 4.19 64/96] btrfs: clean up our handling of refs == 0 in snapshot delete Date: Tue, 10 Sep 2024 11:32:06 +0200 Message-ID: <20240910092544.339127034@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910092541.383432924@linuxfoundation.org> References: <20240910092541.383432924@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josef Bacik [ Upstream commit b8ccef048354074a548f108e51d0557d6adfd3a3 ] In reada we BUG_ON(refs == 0), which could be unkind since we aren't holding a lock on the extent leaf and thus could get a transient incorrect answer. In walk_down_proc we also BUG_ON(refs == 0), which could happen if we have extent tree corruption. Change that to return -EUCLEAN. In do_walk_down() we catch this case and handle it correctly, however we return -EIO, which -EUCLEAN is a more appropriate error code. Finally in walk_up_proc we have the same BUG_ON(refs == 0), so convert that to proper error handling. Also adjust the error message so we can actually do something with the information. Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/extent-tree.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 635d51c8098d..6b8ece5175ef 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -8409,7 +8409,15 @@ static noinline void reada_walk_down(struct btrfs_trans_handle *trans, /* We don't care about errors in readahead. */ if (ret < 0) continue; - BUG_ON(refs == 0); + + /* + * This could be racey, it's conceivable that we raced and end + * up with a bogus refs count, if that's the case just skip, if + * we are actually corrupt we will notice when we look up + * everything again with our locks. + */ + if (refs == 0) + continue; if (wc->stage == DROP_REFERENCE) { if (refs == 1) @@ -8476,7 +8484,11 @@ static noinline int walk_down_proc(struct btrfs_trans_handle *trans, BUG_ON(ret == -ENOMEM); if (ret) return ret; - BUG_ON(wc->refs[level] == 0); + if (unlikely(wc->refs[level] == 0)) { + btrfs_err(fs_info, "bytenr %llu has 0 references, expect > 0", + eb->start); + return -EUCLEAN; + } } if (wc->stage == DROP_REFERENCE) { @@ -8584,8 +8596,9 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans, goto out_unlock; if (unlikely(wc->refs[level - 1] == 0)) { - btrfs_err(fs_info, "Missing references."); - ret = -EIO; + btrfs_err(fs_info, "bytenr %llu has 0 references, expect > 0", + bytenr); + ret = -EUCLEAN; goto out_unlock; } *lookup_info = 0; @@ -8753,7 +8766,12 @@ static noinline int walk_up_proc(struct btrfs_trans_handle *trans, path->locks[level] = 0; return ret; } - BUG_ON(wc->refs[level] == 0); + if (unlikely(wc->refs[level] == 0)) { + btrfs_tree_unlock_rw(eb, path->locks[level]); + btrfs_err(fs_info, "bytenr %llu has 0 references, expect > 0", + eb->start); + return -EUCLEAN; + } if (wc->refs[level] == 1) { btrfs_tree_unlock_rw(eb, path->locks[level]); path->locks[level] = 0; -- 2.43.0