diff options
author | Jens Axboe <jaxboe@fusionio.com> | 2010-04-16 15:13:15 -0400 |
---|---|---|
committer | Jens Axboe <jaxboe@fusionio.com> | 2011-03-10 02:45:54 -0500 |
commit | a488e74976bf0a9bccecdd094378394942dacef1 (patch) | |
tree | 94b69a2dd1e7126b83e311dc7c85def32ecde6dd /drivers | |
parent | 0a41e90bb7c931fd53d73ea770f5b251af6c91ce (diff) |
scsi: convert to blk_delay_queue()
It was always abuse to reuse the plugging infrastructure for this,
convert it to the (new) real API for delaying queueing a bit. A
default delay of 3 msec is defined, to match the previous
behaviour.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/scsi/scsi_lib.c | 44 |
1 files changed, 19 insertions, 25 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 9045c52abd25..5a0ae7a944ce 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c | |||
@@ -67,6 +67,13 @@ static struct scsi_host_sg_pool scsi_sg_pools[] = { | |||
67 | 67 | ||
68 | struct kmem_cache *scsi_sdb_cache; | 68 | struct kmem_cache *scsi_sdb_cache; |
69 | 69 | ||
70 | /* | ||
71 | * When to reinvoke queueing after a resource shortage. It's 3 msecs to | ||
72 | * not change behaviour from the previous unplug mechanism, experimentation | ||
73 | * may prove this needs changing. | ||
74 | */ | ||
75 | #define SCSI_QUEUE_DELAY 3 | ||
76 | |||
70 | static void scsi_run_queue(struct request_queue *q); | 77 | static void scsi_run_queue(struct request_queue *q); |
71 | 78 | ||
72 | /* | 79 | /* |
@@ -149,14 +156,7 @@ static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy) | |||
149 | /* | 156 | /* |
150 | * Requeue this command. It will go before all other commands | 157 | * Requeue this command. It will go before all other commands |
151 | * that are already in the queue. | 158 | * that are already in the queue. |
152 | * | 159 | */ |
153 | * NOTE: there is magic here about the way the queue is plugged if | ||
154 | * we have no outstanding commands. | ||
155 | * | ||
156 | * Although we *don't* plug the queue, we call the request | ||
157 | * function. The SCSI request function detects the blocked condition | ||
158 | * and plugs the queue appropriately. | ||
159 | */ | ||
160 | spin_lock_irqsave(q->queue_lock, flags); | 160 | spin_lock_irqsave(q->queue_lock, flags); |
161 | blk_requeue_request(q, cmd->request); | 161 | blk_requeue_request(q, cmd->request); |
162 | spin_unlock_irqrestore(q->queue_lock, flags); | 162 | spin_unlock_irqrestore(q->queue_lock, flags); |
@@ -1194,11 +1194,11 @@ int scsi_prep_return(struct request_queue *q, struct request *req, int ret) | |||
1194 | case BLKPREP_DEFER: | 1194 | case BLKPREP_DEFER: |
1195 | /* | 1195 | /* |
1196 | * If we defer, the blk_peek_request() returns NULL, but the | 1196 | * If we defer, the blk_peek_request() returns NULL, but the |
1197 | * queue must be restarted, so we plug here if no returning | 1197 | * queue must be restarted, so we schedule a callback to happen |
1198 | * command will automatically do that. | 1198 | * shortly. |
1199 | */ | 1199 | */ |
1200 | if (sdev->device_busy == 0) | 1200 | if (sdev->device_busy == 0) |
1201 | blk_plug_device(q); | 1201 | blk_delay_queue(q, SCSI_QUEUE_DELAY); |
1202 | break; | 1202 | break; |
1203 | default: | 1203 | default: |
1204 | req->cmd_flags |= REQ_DONTPREP; | 1204 | req->cmd_flags |= REQ_DONTPREP; |
@@ -1237,7 +1237,7 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, | |||
1237 | sdev_printk(KERN_INFO, sdev, | 1237 | sdev_printk(KERN_INFO, sdev, |
1238 | "unblocking device at zero depth\n")); | 1238 | "unblocking device at zero depth\n")); |
1239 | } else { | 1239 | } else { |
1240 | blk_plug_device(q); | 1240 | blk_delay_queue(q, SCSI_QUEUE_DELAY); |
1241 | return 0; | 1241 | return 0; |
1242 | } | 1242 | } |
1243 | } | 1243 | } |
@@ -1467,7 +1467,7 @@ static void scsi_request_fn(struct request_queue *q) | |||
1467 | * the host is no longer able to accept any more requests. | 1467 | * the host is no longer able to accept any more requests. |
1468 | */ | 1468 | */ |
1469 | shost = sdev->host; | 1469 | shost = sdev->host; |
1470 | while (!blk_queue_plugged(q)) { | 1470 | for (;;) { |
1471 | int rtn; | 1471 | int rtn; |
1472 | /* | 1472 | /* |
1473 | * get next queueable request. We do this early to make sure | 1473 | * get next queueable request. We do this early to make sure |
@@ -1546,15 +1546,8 @@ static void scsi_request_fn(struct request_queue *q) | |||
1546 | */ | 1546 | */ |
1547 | rtn = scsi_dispatch_cmd(cmd); | 1547 | rtn = scsi_dispatch_cmd(cmd); |
1548 | spin_lock_irq(q->queue_lock); | 1548 | spin_lock_irq(q->queue_lock); |
1549 | if(rtn) { | 1549 | if (rtn) |
1550 | /* we're refusing the command; because of | 1550 | goto out_delay; |
1551 | * the way locks get dropped, we need to | ||
1552 | * check here if plugging is required */ | ||
1553 | if(sdev->device_busy == 0) | ||
1554 | blk_plug_device(q); | ||
1555 | |||
1556 | break; | ||
1557 | } | ||
1558 | } | 1551 | } |
1559 | 1552 | ||
1560 | goto out; | 1553 | goto out; |
@@ -1573,9 +1566,10 @@ static void scsi_request_fn(struct request_queue *q) | |||
1573 | spin_lock_irq(q->queue_lock); | 1566 | spin_lock_irq(q->queue_lock); |
1574 | blk_requeue_request(q, req); | 1567 | blk_requeue_request(q, req); |
1575 | sdev->device_busy--; | 1568 | sdev->device_busy--; |
1576 | if(sdev->device_busy == 0) | 1569 | out_delay: |
1577 | blk_plug_device(q); | 1570 | if (sdev->device_busy == 0) |
1578 | out: | 1571 | blk_delay_queue(q, SCSI_QUEUE_DELAY); |
1572 | out: | ||
1579 | /* must be careful here...if we trigger the ->remove() function | 1573 | /* must be careful here...if we trigger the ->remove() function |
1580 | * we cannot be holding the q lock */ | 1574 | * we cannot be holding the q lock */ |
1581 | spin_unlock_irq(q->queue_lock); | 1575 | spin_unlock_irq(q->queue_lock); |