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 B91041552FD; Tue, 10 Sep 2024 10:45:19 +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=1725965119; cv=none; b=RTFSmJ82g6qP9OAve0/8BeEQgillGXupm2M5AOGBi4hy1WRTwRZw2Dnr/3PkoAm2A2yUpXSAxbgh8Kj2WV/tVwYITWvDiq83/YdASMi7dBbglqYVvUq761VS9GjlknqOvGf103l9kXfjbijQHqsGWNCl8w9D3UOU1Mec6vMlVs0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725965119; c=relaxed/simple; bh=AuprMJEdAoAV/TK+xXJ5MyVrCVHE0dxzhpkOUTEQz/g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Pz7nO4FCxffENfZNMxwOtA9Ubgz5+wQl9fY3eUO5ZJcSX7HVfe5DiCq7IJohdQISrN8sBojQTNKwATUdpnJjAdYj6Qjkhz8OAoZtI4rCu0M404ZF6wtFydmKEVsLU/WXAcEpcXCFZWvucinWmGd9ccRRU2mizIDl2DUpvU4t5eM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0Je8at2V; 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="0Je8at2V" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 390E2C4CECD; Tue, 10 Sep 2024 10:45:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725965119; bh=AuprMJEdAoAV/TK+xXJ5MyVrCVHE0dxzhpkOUTEQz/g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0Je8at2VMTQvGLG0v+yFTFfNRjPkHAbCfbABQTPlgnbiarwcWv8dGshvXBDEh/B2k bmq+BjD87guGtpu488EIzNj3nOhO9s+hoVtE+NjlhxlcxJCgU5trR4FlLQfhBDxNd2 YEfi6KF7RJWrtdkF+FEnQYi6rum4kHYdhM+A/ehI= 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 5.10 143/186] btrfs: clean up our handling of refs == 0 in snapshot delete Date: Tue, 10 Sep 2024 11:33:58 +0200 Message-ID: <20240910092600.494368276@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910092554.645718780@linuxfoundation.org> References: <20240910092554.645718780@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 5.10-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 22fee61bb51a..afa1eccd5e2d 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4806,7 +4806,15 @@ 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) @@ -4873,7 +4881,11 @@ 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) { @@ -5006,8 +5018,9 @@ 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; @@ -5209,7 +5222,12 @@ 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