From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E9679415F13; Tue, 21 Jul 2026 21:45:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670320; cv=none; b=rNdBErmhUf80Q2EbsFMDe2IrQdkuLqOrwtCjNUNfAJ208B9ZEaeOHE22np+CbEVbhNPHaHtYtuzsGXjE1J97D7wqaGQOMTIfnrq4QPuawtJKsIcWrVGNKh3XZ5zzF1Ne3L5z5BzrUya6xq3LtjGqhRxpGPWw/unkoD41GiZzFBw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670320; c=relaxed/simple; bh=XFeSrvC7C/iPRpD42XF0u7XrsxPmo/5edho8GDwXdd8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Kyz+i/goTe/MxDq5RrHZFyJVrdMZUcbArCV0chx6u8FLtKNiiF/CwecmNO2BOPwPv6v7ocKXZBKy2dnmATdK5857bIsJce6qSPh4N5OCM7owD+BuGdE4SfIzbT6NwZZz6VNGnKUpBx9Qo1TQ66bRXqtSzMU+MFAdkgjjJWeb7HE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=k3amEAfE; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="k3amEAfE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A6AB1F000E9; Tue, 21 Jul 2026 21:45:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784670319; bh=HpqTllSnJWg3oYQK9x8k7MzfsF9EMEaC0SkKvWFiwoY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=k3amEAfEmTAsS5Irr3Sr8v6olF2ZtFqMPWVHGizk2cPDgQu/g7OparTRNJec3APcl 18+xvI+96VZE8FHTCdnPoChluVyAkutI9n6I/hBpucbHaKWG8QXb5/Gbuuv1ATcpLA sKE9jzCN2NicEBFUPE46ZQQw5sBri3ruDuf/q2DM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mikulas Patocka Subject: [PATCH 6.1 0845/1067] dm-bufio: fix wrong count calculation in dm_bufio_issue_discard Date: Tue, 21 Jul 2026 17:24:06 +0200 Message-ID: <20260721152443.453089536@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152424.521567757@linuxfoundation.org> References: <20260721152424.521567757@linuxfoundation.org> User-Agent: quilt/0.69 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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit 422f1d4f141eaa3a6e4199ceec86cc6b9bf26570 upstream. block_to_sector converts a block number to a sector number and adds c->start to the result. It is inappropriate to use this function for converting the number of blocks to a number to sectors because c->start would be incorrectly added to the result. Luckily, the only target that uses dm_bufio_issue_discard is dm-ebs, which sets c->start to 0, so this bug is latent. Signed-off-by: Mikulas Patocka Assisted-by: Claude:claude-opus-4-6 Fixes: 6fbeb0048e6b ("dm bufio: implement discard") Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm-bufio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1395,7 +1395,9 @@ int dm_bufio_issue_discard(struct dm_buf struct dm_io_region io_reg = { .bdev = c->bdev, .sector = block_to_sector(c, block), - .count = block_to_sector(c, count), + .count = likely(c->sectors_per_block_bits >= 0) ? + count << c->sectors_per_block_bits : + count * (c->block_size >> SECTOR_SHIFT), }; BUG_ON(dm_bufio_in_request());