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 CCFF01922C4; Tue, 10 Sep 2024 10:33:13 +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=1725964393; cv=none; b=SD/Big3P/ww4VTdGxmOuLJTecR3ePX1ZTI1CZP4YHZYOBQctKZ/s/gL0MSeXlNvVjn9HVevM8H+e7bbmM49TwRK1Kza+16WIhABdMs0wXdsKzgTw+FO0Z8r/R5y4CeuLiho6AbQjDgy0nHckTw0VWUwav8fjGcsAxqkWhO3SPhQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725964393; c=relaxed/simple; bh=vQ2V3lKVBDFQmO0IS+u03pV3tTvtfvfBmSmKd0lMwag=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lBgK4u3oFmV05djWL5dh5Z8gJiV2FUnHVGxaDpjWaz4RUM1IicpVY2ceyXV+bGWVEZ6Xu9h/IyFZMJS7xHriIPeK4dBui6mGXczKak6D0xniV5TajCAl+wp+pulc0Jv2sBxic0yetUC7SdsyAnTOtiY6K9VKcntZ6SR45eOxip8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hrXzr2WD; 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="hrXzr2WD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54959C4CEC6; Tue, 10 Sep 2024 10:33:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1725964393; bh=vQ2V3lKVBDFQmO0IS+u03pV3tTvtfvfBmSmKd0lMwag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hrXzr2WDZvEn9FRKTKKqKqY7Nwt8rwG4Y1k2iR5OYtyjXYA70R0R6UPp0iVWOzl7j 0eDDaOcq1AIC0z+KtJKzpu374GdnaJMUzQWLUjCty6Aw2cGW5bZP+4Xnftfx86Ig5Y fGteVFZAGGE0JwKK6sMODLslZ0FRBj+5vA16ABLQ= 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 6.6 167/269] btrfs: clean up our handling of refs == 0 in snapshot delete Date: Tue, 10 Sep 2024 11:32:34 +0200 Message-ID: <20240910092614.110587867@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240910092608.225137854@linuxfoundation.org> References: <20240910092608.225137854@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 6.6-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 2d39481fb3ce..72851adc1fee 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5085,7 +5085,15 @@ 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) @@ -5152,7 +5160,11 @@ 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) { @@ -5286,8 +5298,9 @@ 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; @@ -5487,7 +5500,12 @@ 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