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| author |   Venkatesh Srinivas <venkateshs@google.com> | 2014-07-06 16:39:27 +0200 |
|---|---|---|
| committer |   Christoph Hellwig <hch@lst.de> | 2014-07-25 17:17:00 -0400 |
| commit | 761f1193f299873236dbc21277864d70cb7ba8a3 (patch) | |
| tree | a01e870c27f8512c58b51f340572f5b02e8d162a /drivers/scsi/virtio_scsi.c | |
| parent | virtio-scsi: replace target spinlock with seqcount (diff) | |
| download | linux-dev-761f1193f299873236dbc21277864d70cb7ba8a3.tar.xz linux-dev-761f1193f299873236dbc21277864d70cb7ba8a3.zip | |
virtio-scsi: Implement change_queue_depth for virtscsi targets
change_queue_depth allows changing per-target queue depth via sysfs.
It also allows the SCSI midlayer to ramp down the number of concurrent
inflight requests in response to a SCSI BUSY status response and allows
the midlayer to ramp the count back up to the device maximum when the
BUSY condition has resolved.
Signed-off-by: Venkatesh Srinivas <venkateshs@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'drivers/scsi/virtio_scsi.c')
| -rw-r--r-- | drivers/scsi/virtio_scsi.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index cdce502c3c46..eee1bc0b506e 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -27,6 +27,7 @@ #include <scsi/scsi_host.h> #include <scsi/scsi_device.h> #include <scsi/scsi_cmnd.h> +#include <scsi/scsi_tcq.h> #include <linux/seqlock.h> #define VIRTIO_SCSI_MEMPOOL_SZ 64 @@ -654,6 +655,36 @@ static int virtscsi_device_reset(struct scsi_cmnd *sc) return virtscsi_tmf(vscsi, cmd); } +/** + * virtscsi_change_queue_depth() - Change a virtscsi target's queue depth + * @sdev: Virtscsi target whose queue depth to change + * @qdepth: New queue depth + * @reason: Reason for the queue depth change. + */ +static int virtscsi_change_queue_depth(struct scsi_device *sdev, + int qdepth, + int reason) +{ + struct Scsi_Host *shost = sdev->host; + int max_depth = shost->cmd_per_lun; + + switch (reason) { + case SCSI_QDEPTH_QFULL: /* Drop qdepth in response to BUSY state */ + scsi_track_queue_full(sdev, qdepth); + break; + case SCSI_QDEPTH_RAMP_UP: /* Raise qdepth after BUSY state resolved */ + case SCSI_QDEPTH_DEFAULT: /* Manual change via sysfs */ + scsi_adjust_queue_depth(sdev, + scsi_get_tag_type(sdev), + min(max_depth, qdepth)); + break; + default: + return -EOPNOTSUPP; + } + + return sdev->queue_depth; +} + static int virtscsi_abort(struct scsi_cmnd *sc) { struct virtio_scsi *vscsi = shost_priv(sc->device->host); @@ -709,6 +740,7 @@ static struct scsi_host_template virtscsi_host_template_single = { .this_id = -1, .cmd_size = sizeof(struct virtio_scsi_cmd), .queuecommand = virtscsi_queuecommand_single, + .change_queue_depth = virtscsi_change_queue_depth, .eh_abort_handler = virtscsi_abort, .eh_device_reset_handler = virtscsi_device_reset, @@ -726,6 +758,7 @@ static struct scsi_host_template virtscsi_host_template_multi = { .this_id = -1, .cmd_size = sizeof(struct virtio_scsi_cmd), .queuecommand = virtscsi_queuecommand_multi, + .change_queue_depth = virtscsi_change_queue_depth, .eh_abort_handler = virtscsi_abort, .eh_device_reset_handler = virtscsi_device_reset, |