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[SCSI] block: add support for shared tag maps

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The current block queue implementation already contains most of the
machinery for shared tag maps.  The only remaining pieces are a way to
allocate and destroy a tag map independently of the queues (so that
the maps can be managed on the life cycle of the overseeing entity)

Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
James Bottomley 2006-08-30 15:48:45 -04:00 committed by James Bottomley
parent f19eaa7f53
commit 492dfb4896
2 changed files with 90 additions and 21 deletions
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109
block/ll_rw_blk.c
View file

@ -847,6 +847,35 @@ struct request *blk_queue_find_tag(request_queue_t *q, int tag)
EXPORT_SYMBOL(blk_queue_find_tag);
/**
* __blk_free_tags - release a given set of tag maintenance info
* @bqt: the tag map to free
*
* Tries to free the specified @bqt@. Returns true if it was
* actually freed and false if there are still references using it
*/
static int __blk_free_tags(struct blk_queue_tag *bqt)
{
int retval;
retval = atomic_dec_and_test(&bqt->refcnt);
if (retval) {
BUG_ON(bqt->busy);
BUG_ON(!list_empty(&bqt->busy_list));
kfree(bqt->tag_index);
bqt->tag_index = NULL;
kfree(bqt->tag_map);
bqt->tag_map = NULL;
kfree(bqt);
}
return retval;
}
/**
* __blk_queue_free_tags - release tag maintenance info
* @q: the request queue for the device
@ -862,23 +891,28 @@ static void __blk_queue_free_tags(request_queue_t *q)
if (!bqt)
return;
if (atomic_dec_and_test(&bqt->refcnt)) {
BUG_ON(bqt->busy);
BUG_ON(!list_empty(&bqt->busy_list));
kfree(bqt->tag_index);
bqt->tag_index = NULL;
kfree(bqt->tag_map);
bqt->tag_map = NULL;
kfree(bqt);
}
__blk_free_tags(bqt);
q->queue_tags = NULL;
q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED);
}
/**
* blk_free_tags - release a given set of tag maintenance info
* @bqt: the tag map to free
*
* For externally managed @bqt@ frees the map. Callers of this
* function must guarantee to have released all the queues that
* might have been using this tag map.
*/
void blk_free_tags(struct blk_queue_tag *bqt)
{
if (unlikely(!__blk_free_tags(bqt)))
BUG();
}
EXPORT_SYMBOL(blk_free_tags);
/**
* blk_queue_free_tags - release tag maintenance info
* @q: the request queue for the device
@ -901,7 +935,7 @@ init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth)
unsigned long *tag_map;
int nr_ulongs;
if (depth > q->nr_requests * 2) {
if (q && depth > q->nr_requests * 2) {
depth = q->nr_requests * 2;
printk(KERN_ERR "%s: adjusted depth to %d\n",
__FUNCTION__, depth);
@ -927,6 +961,38 @@ fail:
return -ENOMEM;
}
static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q,
int depth)
{
struct blk_queue_tag *tags;
tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
if (!tags)
goto fail;
if (init_tag_map(q, tags, depth))
goto fail;
INIT_LIST_HEAD(&tags->busy_list);
tags->busy = 0;
atomic_set(&tags->refcnt, 1);
return tags;
fail:
kfree(tags);
return NULL;
}
/**
* blk_init_tags - initialize the tag info for an external tag map
* @depth: the maximum queue depth supported
* @tags: the tag to use
**/
struct blk_queue_tag *blk_init_tags(int depth)
{
return __blk_queue_init_tags(NULL, depth);
}
EXPORT_SYMBOL(blk_init_tags);
/**
* blk_queue_init_tags - initialize the queue tag info
* @q: the request queue for the device
@ -941,16 +1007,10 @@ int blk_queue_init_tags(request_queue_t *q, int depth,
BUG_ON(tags && q->queue_tags && tags != q->queue_tags);
if (!tags && !q->queue_tags) {
tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
tags = __blk_queue_init_tags(q, depth);
if (!tags)
goto fail;
if (init_tag_map(q, tags, depth))
goto fail;
INIT_LIST_HEAD(&tags->busy_list);
tags->busy = 0;
atomic_set(&tags->refcnt, 1);
} else if (q->queue_tags) {
if ((rc = blk_queue_resize_tags(q, depth)))
return rc;
@ -1001,6 +1061,13 @@ int blk_queue_resize_tags(request_queue_t *q, int new_depth)
return 0;
}
/*
* Currently cannot replace a shared tag map with a new
* one, so error out if this is the case
*/
if (atomic_read(&bqt->refcnt) != 1)
return -EBUSY;
/*
* save the old state info, so we can copy it back
*/

2
include/linux/blkdev.h
View file

@ -746,6 +746,8 @@ extern void blk_queue_free_tags(request_queue_t *);
extern int blk_queue_resize_tags(request_queue_t *, int);
extern void blk_queue_invalidate_tags(request_queue_t *);
extern long blk_congestion_wait(int rw, long timeout);
extern struct blk_queue_tag *blk_init_tags(int);
extern void blk_free_tags(struct blk_queue_tag *);
extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
extern int blkdev_issue_flush(struct block_device *, sector_t *);