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[PATCH] helper function for retrieving scsi_cmd given host based block layer tag

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This was necessitated by the need for a function to get back
to a scsi_cmnd, when an hba the posts its (corresponding) completion
interrupt with a block layer tag as its reference.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: David Somayajulu <david.somayajulu@qlogic.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
David C Somayajulu 2006-10-04 08:27:25 +02:00 committed by Jens Axboe
parent 4a61f17378
commit f583f4924d
3 changed files with 29 additions and 6 deletions
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7
block/ll_rw_blk.c
View File

@ -840,12 +840,7 @@ EXPORT_SYMBOL(blk_queue_dma_alignment);
**/
struct request *blk_queue_find_tag(request_queue_t *q, int tag)
{
struct blk_queue_tag *bqt = q->queue_tags;
if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
return NULL;
return bqt->tag_index[tag];
return blk_map_queue_find_tag(q->queue_tags, tag);
}
EXPORT_SYMBOL(blk_queue_find_tag);

8
include/linux/blkdev.h
View File

@ -769,6 +769,14 @@ extern struct blk_queue_tag *blk_init_tags(int);
extern void blk_free_tags(struct blk_queue_tag *);
extern void blk_congestion_end(int rw);
static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
int tag)
{
if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
return NULL;
return bqt->tag_index[tag];
}
extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
extern int blkdev_issue_flush(struct block_device *, sector_t *);

20
include/scsi/scsi_tcq.h
View File

@ -144,5 +144,25 @@ static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
return shost->bqt ? 0 : -ENOMEM;
}
/**
* scsi_host_find_tag - find the tagged command by host
* @shost: pointer to scsi_host
* @tag: tag of the scsi_cmnd
*
* Notes:
* Only works with tags allocated by the generic blk layer.
**/
static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost,
int tag)
{
struct request *req;
if (tag != SCSI_NO_TAG) {
req = blk_map_queue_find_tag(shost->bqt, tag);
return req ? (struct scsi_cmnd *)req->special : NULL;
}
return NULL;
}
#endif /* CONFIG_BLOCK */
#endif /* _SCSI_SCSI_TCQ_H */