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 C549C18CC11; Tue, 10 Sep 2024 10:03:08 +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=1725962588; cv=none; b=GFI19q0UZiqnujhsj7fVfzwW4wvzBX2PgytMhfW1YbohDXGeK+MqXuYc0MqXYnJDOtTT7nYDZeBalrbFhVxRinw+NbRIOCPu0wI37Lu1OuR+VmACYSqAnSFXFJ1iCVBtft/bNEPzSd43it1eH1Hr58o0IDZdlQgevvno4MRmsec= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725962588; c=relaxed/simple; bh=PXF2UyoIoNrAVdnhr/h6Glv4twhjnz4bNtqBcbif/EE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=V5wLW0NL2bMWesp6iwHL/Z0K1JYDCtIVQUdbm/5nHXRObYZidyUSEoNyF6p1htmp+pwdXgkzsgrWGEmbMga37NkinMhEZsrxj42XGimYofU/rihamMzcfm/nPXmHGujS9pyB7lLXFofQ0/D9jq4lgJDh2SviFu8hCCWqJ90Zyvs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SFZCpqWZ; 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="SFZCpqWZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48C65C4CEC6; Tue, 10 Sep 2024 10:03:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725962588; bh=PXF2UyoIoNrAVdnhr/h6Glv4twhjnz4bNtqBcbif/EE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SFZCpqWZtRr90P+vg0fuWR+y4CcbeELX+D052fBP56c3a57/Klwk8COHsbVjVRBbY FB+8AzjiNXzBAc4e0++AD5kHL2+NtggLzRuX22yYlKR1LnGLlI62y9He9oXAGnator 0UBFTIseu9Lg2d7Hse9tvT/0OX5KzOx1vtUJJ1wU= 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 5.4 084/121] btrfs: clean up our handling of refs == 0 in snapshot delete Date: Tue, 10 Sep 2024 11:32:39 +0200 Message-ID: <20240910092549.888257023@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910092545.737864202@linuxfoundation.org> References: <20240910092545.737864202@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 5.4-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 202e6b6e2add..7e5ac187463e 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4684,7 +4684,15 @@ 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) @@ -4751,7 +4759,11 @@ 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) { @@ -4885,8 +4897,9 @@ 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; @@ -5088,7 +5101,12 @@ 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