diff options
author | Jeff Garzik <jgarzik@pobox.com> | 2005-06-30 00:49:18 -0400 |
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committer | Jeff Garzik <jgarzik@pobox.com> | 2005-06-30 00:49:18 -0400 |
commit | 0c168775709faa74c1b87f1e61046e0c51ade7f3 (patch) | |
tree | c40fd8818c64c5d7d1d90afab0bd6ffd94505526 /drivers/block | |
parent | 9bd481f85940726bf66aae5cd03c5b912ad0ae4c (diff) | |
parent | 9b4311eedb17fa88f02e4876cd6aa9a08e383cd6 (diff) |
Merge upstream 2.6.13-rc1-git1 into 'ieee80211' branch of netdev-2.6.
Diffstat (limited to 'drivers/block')
-rw-r--r-- | drivers/block/cciss.c | 1 | ||||
-rw-r--r-- | drivers/block/ll_rw_blk.c | 151 |
2 files changed, 71 insertions, 81 deletions
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c index 653512b77570..3e9fb6e4a52a 100644 --- a/drivers/block/cciss.c +++ b/drivers/block/cciss.c @@ -786,7 +786,6 @@ static int cciss_ioctl(struct inode *inode, struct file *filep, case CCISS_GETLUNINFO: { LogvolInfo_struct luninfo; - int i; luninfo.LunID = drv->LunID; luninfo.num_opens = drv->usage_count; diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c index 234fdcfbdf01..692a5fced76e 100644 --- a/drivers/block/ll_rw_blk.c +++ b/drivers/block/ll_rw_blk.c @@ -1867,19 +1867,20 @@ static void freed_request(request_queue_t *q, int rw) #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) /* - * Get a free request, queue_lock must not be held + * Get a free request, queue_lock must be held. + * Returns NULL on failure, with queue_lock held. + * Returns !NULL on success, with queue_lock *not held*. */ static struct request *get_request(request_queue_t *q, int rw, struct bio *bio, int gfp_mask) { struct request *rq = NULL; struct request_list *rl = &q->rq; - struct io_context *ioc = get_io_context(gfp_mask); + struct io_context *ioc = current_io_context(GFP_ATOMIC); if (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags))) goto out; - spin_lock_irq(q->queue_lock); if (rl->count[rw]+1 >= q->nr_requests) { /* * The queue will fill after this allocation, so set it as @@ -1907,11 +1908,18 @@ static struct request *get_request(request_queue_t *q, int rw, struct bio *bio, * The queue is full and the allocating process is not a * "batcher", and not exempted by the IO scheduler */ - spin_unlock_irq(q->queue_lock); goto out; } get_rq: + /* + * Only allow batching queuers to allocate up to 50% over the defined + * limit of requests, otherwise we could have thousands of requests + * allocated with any setting of ->nr_requests + */ + if (rl->count[rw] >= (3 * q->nr_requests / 2)) + goto out; + rl->count[rw]++; rl->starved[rw] = 0; if (rl->count[rw] >= queue_congestion_on_threshold(q)) @@ -1941,7 +1949,6 @@ rq_starved: if (unlikely(rl->count[rw] == 0)) rl->starved[rw] = 1; - spin_unlock_irq(q->queue_lock); goto out; } @@ -1951,21 +1958,23 @@ rq_starved: rq_init(q, rq); rq->rl = rl; out: - put_io_context(ioc); return rq; } /* * No available requests for this queue, unplug the device and wait for some * requests to become available. + * + * Called with q->queue_lock held, and returns with it unlocked. */ static struct request *get_request_wait(request_queue_t *q, int rw, struct bio *bio) { - DEFINE_WAIT(wait); struct request *rq; - do { + rq = get_request(q, rw, bio, GFP_NOIO); + while (!rq) { + DEFINE_WAIT(wait); struct request_list *rl = &q->rq; prepare_to_wait_exclusive(&rl->wait[rw], &wait, @@ -1976,7 +1985,8 @@ static struct request *get_request_wait(request_queue_t *q, int rw, if (!rq) { struct io_context *ioc; - generic_unplug_device(q); + __generic_unplug_device(q); + spin_unlock_irq(q->queue_lock); io_schedule(); /* @@ -1985,12 +1995,13 @@ static struct request *get_request_wait(request_queue_t *q, int rw, * up to a big batch of them for a small period time. * See ioc_batching, ioc_set_batching */ - ioc = get_io_context(GFP_NOIO); + ioc = current_io_context(GFP_NOIO); ioc_set_batching(q, ioc); - put_io_context(ioc); + + spin_lock_irq(q->queue_lock); } finish_wait(&rl->wait[rw], &wait); - } while (!rq); + } return rq; } @@ -2001,14 +2012,18 @@ struct request *blk_get_request(request_queue_t *q, int rw, int gfp_mask) BUG_ON(rw != READ && rw != WRITE); - if (gfp_mask & __GFP_WAIT) + spin_lock_irq(q->queue_lock); + if (gfp_mask & __GFP_WAIT) { rq = get_request_wait(q, rw, NULL); - else + } else { rq = get_request(q, rw, NULL, gfp_mask); + if (!rq) + spin_unlock_irq(q->queue_lock); + } + /* q->queue_lock is unlocked at this point */ return rq; } - EXPORT_SYMBOL(blk_get_request); /** @@ -2512,7 +2527,7 @@ EXPORT_SYMBOL(blk_attempt_remerge); static int __make_request(request_queue_t *q, struct bio *bio) { - struct request *req, *freereq = NULL; + struct request *req; int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync; unsigned short prio; sector_t sector; @@ -2540,14 +2555,9 @@ static int __make_request(request_queue_t *q, struct bio *bio) goto end_io; } -again: spin_lock_irq(q->queue_lock); - if (elv_queue_empty(q)) { - blk_plug_device(q); - goto get_rq; - } - if (barrier) + if (unlikely(barrier) || elv_queue_empty(q)) goto get_rq; el_ret = elv_merge(q, &req, bio); @@ -2592,40 +2602,24 @@ again: elv_merged_request(q, req); goto out; - /* - * elevator says don't/can't merge. get new request - */ - case ELEVATOR_NO_MERGE: - break; - + /* ELV_NO_MERGE: elevator says don't/can't merge. */ default: - printk("elevator returned crap (%d)\n", el_ret); - BUG(); + ; } +get_rq: /* - * Grab a free request from the freelist - if that is empty, check - * if we are doing read ahead and abort instead of blocking for - * a free slot. + * Grab a free request. This is might sleep but can not fail. + * Returns with the queue unlocked. + */ + req = get_request_wait(q, rw, bio); + + /* + * After dropping the lock and possibly sleeping here, our request + * may now be mergeable after it had proven unmergeable (above). + * We don't worry about that case for efficiency. It won't happen + * often, and the elevators are able to handle it. */ -get_rq: - if (freereq) { - req = freereq; - freereq = NULL; - } else { - spin_unlock_irq(q->queue_lock); - if ((freereq = get_request(q, rw, bio, GFP_ATOMIC)) == NULL) { - /* - * READA bit set - */ - err = -EWOULDBLOCK; - if (bio_rw_ahead(bio)) - goto end_io; - - freereq = get_request_wait(q, rw, bio); - } - goto again; - } req->flags |= REQ_CMD; @@ -2654,10 +2648,11 @@ get_rq: req->rq_disk = bio->bi_bdev->bd_disk; req->start_time = jiffies; + spin_lock_irq(q->queue_lock); + if (elv_queue_empty(q)) + blk_plug_device(q); add_request(q, req); out: - if (freereq) - __blk_put_request(q, freereq); if (sync) __generic_unplug_device(q); @@ -3284,24 +3279,20 @@ void exit_io_context(void) /* * If the current task has no IO context then create one and initialise it. - * If it does have a context, take a ref on it. + * Otherwise, return its existing IO context. * - * This is always called in the context of the task which submitted the I/O. - * But weird things happen, so we disable local interrupts to ensure exclusive - * access to *current. + * This returned IO context doesn't have a specifically elevated refcount, + * but since the current task itself holds a reference, the context can be + * used in general code, so long as it stays within `current` context. */ -struct io_context *get_io_context(int gfp_flags) +struct io_context *current_io_context(int gfp_flags) { struct task_struct *tsk = current; - unsigned long flags; struct io_context *ret; - local_irq_save(flags); ret = tsk->io_context; - if (ret) - goto out; - - local_irq_restore(flags); + if (likely(ret)) + return ret; ret = kmem_cache_alloc(iocontext_cachep, gfp_flags); if (ret) { @@ -3312,25 +3303,25 @@ struct io_context *get_io_context(int gfp_flags) ret->nr_batch_requests = 0; /* because this is 0 */ ret->aic = NULL; ret->cic = NULL; + tsk->io_context = ret; + } - local_irq_save(flags); - - /* - * very unlikely, someone raced with us in setting up the task - * io context. free new context and just grab a reference. - */ - if (!tsk->io_context) - tsk->io_context = ret; - else { - kmem_cache_free(iocontext_cachep, ret); - ret = tsk->io_context; - } + return ret; +} +EXPORT_SYMBOL(current_io_context); -out: +/* + * If the current task has no IO context then create one and initialise it. + * If it does have a context, take a ref on it. + * + * This is always called in the context of the task which submitted the I/O. + */ +struct io_context *get_io_context(int gfp_flags) +{ + struct io_context *ret; + ret = current_io_context(gfp_flags); + if (likely(ret)) atomic_inc(&ret->refcount); - local_irq_restore(flags); - } - return ret; } EXPORT_SYMBOL(get_io_context); |