[SCSI] add shared tag map helpers
This patch adds support for sharing tag maps at the host level (i.e. either every queue [LUN] has its own tag map or there's a single one for the entire host). This formulation is primarily intended to help single issue queue hardware, like the aic7xxx Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
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@ -265,6 +265,9 @@ static void scsi_host_dev_release(struct device *dev)
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destroy_workqueue(shost->work_q);
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scsi_destroy_command_freelist(shost);
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if (shost->bqt)
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blk_free_tags(shost->bqt);
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kfree(shost->shost_data);
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if (parent)
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@ -16,6 +16,7 @@ struct scsi_target;
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struct Scsi_Host;
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struct scsi_host_cmd_pool;
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struct scsi_transport_template;
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struct blk_queue_tags;
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/*
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@ -465,6 +466,12 @@ struct Scsi_Host {
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struct scsi_host_template *hostt;
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struct scsi_transport_template *transportt;
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/*
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* area to keep a shared tag map (if needed, will be
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* NULL if not)
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*/
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struct blk_queue_tag *bqt;
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/*
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* The following two fields are protected with host_lock;
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* however, eh routines can safely access during eh processing
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@ -4,6 +4,7 @@
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#include <linux/blkdev.h>
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#include <scsi/scsi_cmnd.h>
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#include <scsi/scsi_device.h>
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#include <scsi/scsi_host.h>
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#define MSG_SIMPLE_TAG 0x20
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@ -66,7 +67,8 @@ static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth)
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return;
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if (!blk_queue_tagged(sdev->request_queue))
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blk_queue_init_tags(sdev->request_queue, depth, NULL);
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blk_queue_init_tags(sdev->request_queue, depth,
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sdev->host->bqt);
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scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
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}
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@ -131,4 +133,14 @@ static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag)
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return sdev->current_cmnd;
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}
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/**
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* scsi_init_shared_tag_map - create a shared tag map
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* @shost: the host to share the tag map among all devices
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* @depth: the total depth of the map
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*/
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static inline void scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
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{
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shost->bqt = blk_init_tags(depth);
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}
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#endif /* _SCSI_SCSI_TCQ_H */
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