linux-kernel - [PATCH 4.9 53/94] scsi: mpt3sas: Force request partial completion alignment

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Message-Id: <20170605153105.408662789@linuxfoundation.org>
Date:   Mon,  5 Jun 2017 18:17:29 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mauricio Faria De Oliveira <mauricfo@...ux.vnet.ibm.com>,
        "Guilherme G. Piccoli" <gpiccoli@...ux.vnet.ibm.com>,
        Ram Pai <linuxram@...ibm.com>,
        Sreekanth Reddy <Sreekanth.Reddy@...adcom.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.9 53/94] scsi: mpt3sas: Force request partial completion alignment

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ram Pai <linuxram@...ibm.com>

commit f2e767bb5d6ee0d988cb7d4e54b0b21175802b6b upstream.

The firmware or device, possibly under a heavy I/O load, can return on a
partial unaligned boundary. Scsi-ml expects these requests to be
completed on an alignment boundary. Scsi-ml blindly requeues the I/O
without checking the alignment boundary of the I/O request for the
remaining bytes. This leads to errors, since devices cannot perform
non-aligned read/write operations.

This patch fixes the issue in the driver. It aligns unaligned
completions of FS requests, by truncating them to the nearest alignment
boundary.

[mkp: simplified if statement]

Reported-by: Mauricio Faria De Oliveira <mauricfo@...ux.vnet.ibm.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@...ux.vnet.ibm.com>
Signed-off-by: Ram Pai <linuxram@...ibm.com>
Acked-by: Sreekanth Reddy <Sreekanth.Reddy@...adcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/scsi/mpt3sas/mpt3sas_scsih.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -4634,6 +4634,7 @@ _scsih_io_done(struct MPT3SAS_ADAPTER *i
 	struct MPT3SAS_DEVICE *sas_device_priv_data;
 	u32 response_code = 0;
 	unsigned long flags;
+	unsigned int sector_sz;

 	mpi_reply = mpt3sas_base_get_reply_virt_addr(ioc, reply);
 	scmd = _scsih_scsi_lookup_get_clear(ioc, smid);
@@ -4692,6 +4693,20 @@ _scsih_io_done(struct MPT3SAS_ADAPTER *i
 	}

 	xfer_cnt = le32_to_cpu(mpi_reply->TransferCount);
+
+	/* In case of bogus fw or device, we could end up having
+	 * unaligned partial completion. We can force alignment here,
+	 * then scsi-ml does not need to handle this misbehavior.
+	 */
+	sector_sz = scmd->device->sector_size;
+	if (unlikely(scmd->request->cmd_type == REQ_TYPE_FS && sector_sz &&
+		     xfer_cnt % sector_sz)) {
+		sdev_printk(KERN_INFO, scmd->device,
+		    "unaligned partial completion avoided (xfer_cnt=%u, sector_sz=%u)\n",
+			    xfer_cnt, sector_sz);
+		xfer_cnt = round_down(xfer_cnt, sector_sz);
+	}
+
 	scsi_set_resid(scmd, scsi_bufflen(scmd) - xfer_cnt);
 	if (ioc_status & MPI2_IOCSTATUS_FLAG_LOG_INFO_AVAILABLE)
 		log_info =  le32_to_cpu(mpi_reply->IOCLogInfo);