84 lines
2.8 KiB
Diff
84 lines
2.8 KiB
Diff
From: Venkatesh Srinivas <venkateshs@google.com>
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Date: Sun, 6 Jul 2014 16:39:27 +0200
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Subject: virtio-scsi: Implement change_queue_depth for virtscsi targets
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Origin: https://git.kernel.org/linus/761f1193f299873236dbc21277864d70cb7ba8a3
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change_queue_depth allows changing per-target queue depth via sysfs.
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It also allows the SCSI midlayer to ramp down the number of concurrent
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inflight requests in response to a SCSI BUSY status response and allows
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the midlayer to ramp the count back up to the device maximum when the
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BUSY condition has resolved.
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Signed-off-by: Venkatesh Srinivas <venkateshs@google.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Christoph Hellwig <hch@lst.de>
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[bwh: Backported to 3.16: adjust context]
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---
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drivers/scsi/virtio_scsi.c | 33 +++++++++++++++++++++++++++++++++
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1 file changed, 33 insertions(+)
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--- a/drivers/scsi/virtio_scsi.c
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+++ b/drivers/scsi/virtio_scsi.c
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@@ -27,6 +27,7 @@
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#include <scsi/scsi_host.h>
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#include <scsi/scsi_device.h>
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#include <scsi/scsi_cmnd.h>
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+#include <scsi/scsi_tcq.h>
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#define VIRTIO_SCSI_MEMPOOL_SZ 64
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#define VIRTIO_SCSI_EVENT_LEN 8
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@@ -641,6 +642,36 @@ static int virtscsi_device_reset(struct
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return virtscsi_tmf(vscsi, cmd);
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}
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+/**
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+ * virtscsi_change_queue_depth() - Change a virtscsi target's queue depth
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+ * @sdev: Virtscsi target whose queue depth to change
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+ * @qdepth: New queue depth
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+ * @reason: Reason for the queue depth change.
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+ */
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+static int virtscsi_change_queue_depth(struct scsi_device *sdev,
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+ int qdepth,
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+ int reason)
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+{
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+ struct Scsi_Host *shost = sdev->host;
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+ int max_depth = shost->cmd_per_lun;
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+
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+ switch (reason) {
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+ case SCSI_QDEPTH_QFULL: /* Drop qdepth in response to BUSY state */
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+ scsi_track_queue_full(sdev, qdepth);
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+ break;
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+ case SCSI_QDEPTH_RAMP_UP: /* Raise qdepth after BUSY state resolved */
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+ case SCSI_QDEPTH_DEFAULT: /* Manual change via sysfs */
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+ scsi_adjust_queue_depth(sdev,
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+ scsi_get_tag_type(sdev),
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+ min(max_depth, qdepth));
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+ break;
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+ default:
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+ return -EOPNOTSUPP;
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+ }
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+
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+ return sdev->queue_depth;
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+}
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+
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static int virtscsi_abort(struct scsi_cmnd *sc)
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{
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struct virtio_scsi *vscsi = shost_priv(sc->device->host);
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@@ -693,6 +724,7 @@ static struct scsi_host_template virtscs
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.this_id = -1,
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.cmd_size = sizeof(struct virtio_scsi_cmd),
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.queuecommand = virtscsi_queuecommand_single,
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+ .change_queue_depth = virtscsi_change_queue_depth,
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.eh_abort_handler = virtscsi_abort,
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.eh_device_reset_handler = virtscsi_device_reset,
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@@ -710,6 +742,7 @@ static struct scsi_host_template virtscs
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.this_id = -1,
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.cmd_size = sizeof(struct virtio_scsi_cmd),
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.queuecommand = virtscsi_queuecommand_multi,
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+ .change_queue_depth = virtscsi_change_queue_depth,
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.eh_abort_handler = virtscsi_abort,
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.eh_device_reset_handler = virtscsi_device_reset,
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