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 2A5417E for ; Wed, 2 Nov 2022 03:10:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39325C433C1; Wed, 2 Nov 2022 03:10:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667358649; bh=xA4mQAal6pHW63JAX1mvRsr/9zyhRBSvZ1pHZWWLQtU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L4DuSDxKDX38GaFXR3PKBRQz/ywMWI0kUE6mtr8sgjdPzZEDLM24WtsBuN/HOUdjn pZTCFZgo1A6viaYwEMg6TouwvWD9hdqDQRlTBBsPDR2pQBV08R9+r7Ox47I/Ps382d kEUa5vMPvkrCq5lTc6jC5mXRcGb/xM+7L1wzaWAg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Kuai , Bart Van Assche Subject: [PATCH 5.15 127/132] scsi: sd: Revert "scsi: sd: Remove a local variable" Date: Wed, 2 Nov 2022 03:33:53 +0100 Message-Id: <20221102022103.008409308@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221102022059.593236470@linuxfoundation.org> References: <20221102022059.593236470@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Yu Kuai This reverts commit 84f7a9de0602704bbec774a6c7f7c8c4994bee9c. Because it introduces a problem that rq->__data_len is set to the wrong value. before the patch: 1) nr_bytes = rq->__data_len 2) rq->__data_len = sdp->sector_size 3) scsi_init_io() 4) rq->__data_len = nr_bytes after the patch: 1) rq->__data_len = sdp->sector_size 2) scsi_init_io() 3) rq->__data_len = rq->__data_len -> __data_len is wrong It will cause that io can only complete one segment each time, and the io will requeue in scsi_io_completion_action(), which will cause severe performance degradation. Scsi write same is removed in commit e383e16e84e9 ("scsi: sd: Remove WRITE_SAME support") from mainline, hence this patch is only needed for stable kernels. Fixes: 84f7a9de0602 ("scsi: sd: Remove a local variable") Signed-off-by: Yu Kuai Reviewed-by: Bart Van Assche Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/sd.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1072,6 +1072,7 @@ static blk_status_t sd_setup_write_same_ struct bio *bio = rq->bio; u64 lba = sectors_to_logical(sdp, blk_rq_pos(rq)); u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq)); + unsigned int nr_bytes = blk_rq_bytes(rq); blk_status_t ret; if (sdkp->device->no_write_same) @@ -1108,7 +1109,7 @@ static blk_status_t sd_setup_write_same_ */ rq->__data_len = sdp->sector_size; ret = scsi_alloc_sgtables(cmd); - rq->__data_len = blk_rq_bytes(rq); + rq->__data_len = nr_bytes; return ret; }