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 3C64E192B8F; Tue, 10 Sep 2024 10:11:44 +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=1725963104; cv=none; b=Qpv+5l8n6/3pFFPP/j9dthZcVr5xx/j9qSECTMrLnVgCN4pHJCVexT7we5+CiY3wseyaC8/weicwrmu0t1nsoioKlLbiA/tY3aG4Eqvd+5H+OWjlvl2H43SIKhrTAvnXcfOjaNKOZ+V2d4C4SBJJseMSt3/UklzsQcB4h+omUx0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725963104; c=relaxed/simple; bh=53SFkpSINNX2GzazPliHP6H1fIthbmetxR+Y1ukjYj8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LQAFJ+1R6dnJhRtOgq4Oo7ByC4lwF6qrhRHBTrDbJKpeoEXTAQDaRMqwnToIyNEe3jm7PkRzMEjBrM4ry2Ec1jl/vpcRCC2T8ofxv8mA59r4nXK8cURWJUWEvvfZqi3X/ju4AElrwXdHgITK1zJ/cC0rhFRzcUBuIN9gptOn5fo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RO4LB3kf; 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="RO4LB3kf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B904C4CEC6; Tue, 10 Sep 2024 10:11:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725963104; bh=53SFkpSINNX2GzazPliHP6H1fIthbmetxR+Y1ukjYj8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RO4LB3kfpzzIvDw3QutpABmRoBWG0qaTfYdBJVLSSOUspPhY4XwHxzx5xG3uVsExx k4VRzRP30seRyyP3iTRfJggPgXddA37W5AuLg1lzhGQEW/bQJqMO6WBb33X16xu9X2 CRJo1Gm7XIefIwOCyuVdE8rL1Gcjz3WTxsWBQJjk= 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 6.1 110/192] btrfs: clean up our handling of refs == 0 in snapshot delete Date: Tue, 10 Sep 2024 11:32:14 +0200 Message-ID: <20240910092602.519149084@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910092557.876094467@linuxfoundation.org> References: <20240910092557.876094467@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-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 d6efdcf95991..0d97c8ee6b4f 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5141,7 +5141,15 @@ 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) @@ -5208,7 +5216,11 @@ 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) { @@ -5338,8 +5350,9 @@ 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; @@ -5540,7 +5553,12 @@ 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