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Commit f583f492 authored by David C Somayajulu's avatar David C Somayajulu Committed by Jens Axboe
Browse files

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



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: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarDavid Somayajulu <david.somayajulu@qlogic.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 4a61f173

block/ll_rw_blk.c

+1 −6
Original line number Diff line number Diff line
@@ -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);

include/linux/blkdev.h

+8 −0
Original line number Diff line number Diff line
@@ -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 *);

include/scsi/scsi_tcq.h

+20 −0
Original line number Diff line number Diff line
@@ -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 */