| /* |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| * Copyright (C) 1994, Karl Keyte: Added support for disk statistics |
| * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE |
| * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> |
| * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> - July2000 |
| * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 |
| */ |
| |
| /* |
| * This handles all read/write requests to block devices |
| */ |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/backing-dev.h> |
| #include <linux/bio.h> |
| #include <linux/blkdev.h> |
| #include <linux/highmem.h> |
| #include <linux/mm.h> |
| #include <linux/kernel_stat.h> |
| #include <linux/string.h> |
| #include <linux/init.h> |
| #include <linux/bootmem.h> /* for max_pfn/max_low_pfn */ |
| #include <linux/completion.h> |
| #include <linux/slab.h> |
| #include <linux/swap.h> |
| #include <linux/writeback.h> |
| #include <linux/interrupt.h> |
| #include <linux/cpu.h> |
| #include <linux/blktrace_api.h> |
| |
| /* |
| * for max sense size |
| */ |
| #include <scsi/scsi_cmnd.h> |
| |
| static void blk_unplug_work(void *data); |
| static void blk_unplug_timeout(unsigned long data); |
| static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io); |
| static void init_request_from_bio(struct request *req, struct bio *bio); |
| static int __make_request(request_queue_t *q, struct bio *bio); |
| static struct io_context *current_io_context(gfp_t gfp_flags, int node); |
| |
| /* |
| * For the allocated request tables |
| */ |
| static kmem_cache_t *request_cachep; |
| |
| /* |
| * For queue allocation |
| */ |
| static kmem_cache_t *requestq_cachep; |
| |
| /* |
| * For io context allocations |
| */ |
| static kmem_cache_t *iocontext_cachep; |
| |
| /* |
| * Controlling structure to kblockd |
| */ |
| static struct workqueue_struct *kblockd_workqueue; |
| |
| unsigned long blk_max_low_pfn, blk_max_pfn; |
| |
| EXPORT_SYMBOL(blk_max_low_pfn); |
| EXPORT_SYMBOL(blk_max_pfn); |
| |
| static DEFINE_PER_CPU(struct list_head, blk_cpu_done); |
| |
| /* Amount of time in which a process may batch requests */ |
| #define BLK_BATCH_TIME (HZ/50UL) |
| |
| /* Number of requests a "batching" process may submit */ |
| #define BLK_BATCH_REQ 32 |
| |
| /* |
| * Return the threshold (number of used requests) at which the queue is |
| * considered to be congested. It include a little hysteresis to keep the |
| * context switch rate down. |
| */ |
| static inline int queue_congestion_on_threshold(struct request_queue *q) |
| { |
| return q->nr_congestion_on; |
| } |
| |
| /* |
| * The threshold at which a queue is considered to be uncongested |
| */ |
| static inline int queue_congestion_off_threshold(struct request_queue *q) |
| { |
| return q->nr_congestion_off; |
| } |
| |
| static void blk_queue_congestion_threshold(struct request_queue *q) |
| { |
| int nr; |
| |
| nr = q->nr_requests - (q->nr_requests / 8) + 1; |
| if (nr > q->nr_requests) |
| nr = q->nr_requests; |
| q->nr_congestion_on = nr; |
| |
| nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; |
| if (nr < 1) |
| nr = 1; |
| q->nr_congestion_off = nr; |
| } |
| |
| /** |
| * blk_get_backing_dev_info - get the address of a queue's backing_dev_info |
| * @bdev: device |
| * |
| * Locates the passed device's request queue and returns the address of its |
| * backing_dev_info |
| * |
| * Will return NULL if the request queue cannot be located. |
| */ |
| struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) |
| { |
| struct backing_dev_info *ret = NULL; |
| request_queue_t *q = bdev_get_queue(bdev); |
| |
| if (q) |
| ret = &q->backing_dev_info; |
| return ret; |
| } |
| EXPORT_SYMBOL(blk_get_backing_dev_info); |
| |
| void blk_queue_activity_fn(request_queue_t *q, activity_fn *fn, void *data) |
| { |
| q->activity_fn = fn; |
| q->activity_data = data; |
| } |
| EXPORT_SYMBOL(blk_queue_activity_fn); |
| |
| /** |
| * blk_queue_prep_rq - set a prepare_request function for queue |
| * @q: queue |
| * @pfn: prepare_request function |
| * |
| * It's possible for a queue to register a prepare_request callback which |
| * is invoked before the request is handed to the request_fn. The goal of |
| * the function is to prepare a request for I/O, it can be used to build a |
| * cdb from the request data for instance. |
| * |
| */ |
| void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn) |
| { |
| q->prep_rq_fn = pfn; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_prep_rq); |
| |
| /** |
| * blk_queue_merge_bvec - set a merge_bvec function for queue |
| * @q: queue |
| * @mbfn: merge_bvec_fn |
| * |
| * Usually queues have static limitations on the max sectors or segments that |
| * we can put in a request. Stacking drivers may have some settings that |
| * are dynamic, and thus we have to query the queue whether it is ok to |
| * add a new bio_vec to a bio at a given offset or not. If the block device |
| * has such limitations, it needs to register a merge_bvec_fn to control |
| * the size of bio's sent to it. Note that a block device *must* allow a |
| * single page to be added to an empty bio. The block device driver may want |
| * to use the bio_split() function to deal with these bio's. By default |
| * no merge_bvec_fn is defined for a queue, and only the fixed limits are |
| * honored. |
| */ |
| void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn) |
| { |
| q->merge_bvec_fn = mbfn; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_merge_bvec); |
| |
| void blk_queue_softirq_done(request_queue_t *q, softirq_done_fn *fn) |
| { |
| q->softirq_done_fn = fn; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_softirq_done); |
| |
| /** |
| * blk_queue_make_request - define an alternate make_request function for a device |
| * @q: the request queue for the device to be affected |
| * @mfn: the alternate make_request function |
| * |
| * Description: |
| * The normal way for &struct bios to be passed to a device |
| * driver is for them to be collected into requests on a request |
| * queue, and then to allow the device driver to select requests |
| * off that queue when it is ready. This works well for many block |
| * devices. However some block devices (typically virtual devices |
| * such as md or lvm) do not benefit from the processing on the |
| * request queue, and are served best by having the requests passed |
| * directly to them. This can be achieved by providing a function |
| * to blk_queue_make_request(). |
| * |
| * Caveat: |
| * The driver that does this *must* be able to deal appropriately |
| * with buffers in "highmemory". This can be accomplished by either calling |
| * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling |
| * blk_queue_bounce() to create a buffer in normal memory. |
| **/ |
| void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn) |
| { |
| /* |
| * set defaults |
| */ |
| q->nr_requests = BLKDEV_MAX_RQ; |
| blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); |
| blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); |
| q->make_request_fn = mfn; |
| q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; |
| q->backing_dev_info.state = 0; |
| q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; |
| blk_queue_max_sectors(q, SAFE_MAX_SECTORS); |
| blk_queue_hardsect_size(q, 512); |
| blk_queue_dma_alignment(q, 511); |
| blk_queue_congestion_threshold(q); |
| q->nr_batching = BLK_BATCH_REQ; |
| |
| q->unplug_thresh = 4; /* hmm */ |
| q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ |
| if (q->unplug_delay == 0) |
| q->unplug_delay = 1; |
| |
| INIT_WORK(&q->unplug_work, blk_unplug_work, q); |
| |
| q->unplug_timer.function = blk_unplug_timeout; |
| q->unplug_timer.data = (unsigned long)q; |
| |
| /* |
| * by default assume old behaviour and bounce for any highmem page |
| */ |
| blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); |
| |
| blk_queue_activity_fn(q, NULL, NULL); |
| } |
| |
| EXPORT_SYMBOL(blk_queue_make_request); |
| |
| static void rq_init(request_queue_t *q, struct request *rq) |
| { |
| INIT_LIST_HEAD(&rq->queuelist); |
| INIT_LIST_HEAD(&rq->donelist); |
| |
| rq->errors = 0; |
| rq->bio = rq->biotail = NULL; |
| INIT_HLIST_NODE(&rq->hash); |
| RB_CLEAR_NODE(&rq->rb_node); |
| rq->ioprio = 0; |
| rq->buffer = NULL; |
| rq->ref_count = 1; |
| rq->q = q; |
| rq->special = NULL; |
| rq->data_len = 0; |
| rq->data = NULL; |
| rq->nr_phys_segments = 0; |
| rq->sense = NULL; |
| rq->end_io = NULL; |
| rq->end_io_data = NULL; |
| rq->completion_data = NULL; |
| } |
| |
| /** |
| * blk_queue_ordered - does this queue support ordered writes |
| * @q: the request queue |
| * @ordered: one of QUEUE_ORDERED_* |
| * @prepare_flush_fn: rq setup helper for cache flush ordered writes |
| * |
| * Description: |
| * For journalled file systems, doing ordered writes on a commit |
| * block instead of explicitly doing wait_on_buffer (which is bad |
| * for performance) can be a big win. Block drivers supporting this |
| * feature should call this function and indicate so. |
| * |
| **/ |
| int blk_queue_ordered(request_queue_t *q, unsigned ordered, |
| prepare_flush_fn *prepare_flush_fn) |
| { |
| if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) && |
| prepare_flush_fn == NULL) { |
| printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n"); |
| return -EINVAL; |
| } |
| |
| if (ordered != QUEUE_ORDERED_NONE && |
| ordered != QUEUE_ORDERED_DRAIN && |
| ordered != QUEUE_ORDERED_DRAIN_FLUSH && |
| ordered != QUEUE_ORDERED_DRAIN_FUA && |
| ordered != QUEUE_ORDERED_TAG && |
| ordered != QUEUE_ORDERED_TAG_FLUSH && |
| ordered != QUEUE_ORDERED_TAG_FUA) { |
| printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered); |
| return -EINVAL; |
| } |
| |
| q->ordered = ordered; |
| q->next_ordered = ordered; |
| q->prepare_flush_fn = prepare_flush_fn; |
| |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_ordered); |
| |
| /** |
| * blk_queue_issue_flush_fn - set function for issuing a flush |
| * @q: the request queue |
| * @iff: the function to be called issuing the flush |
| * |
| * Description: |
| * If a driver supports issuing a flush command, the support is notified |
| * to the block layer by defining it through this call. |
| * |
| **/ |
| void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff) |
| { |
| q->issue_flush_fn = iff; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_issue_flush_fn); |
| |
| /* |
| * Cache flushing for ordered writes handling |
| */ |
| inline unsigned blk_ordered_cur_seq(request_queue_t *q) |
| { |
| if (!q->ordseq) |
| return 0; |
| return 1 << ffz(q->ordseq); |
| } |
| |
| unsigned blk_ordered_req_seq(struct request *rq) |
| { |
| request_queue_t *q = rq->q; |
| |
| BUG_ON(q->ordseq == 0); |
| |
| if (rq == &q->pre_flush_rq) |
| return QUEUE_ORDSEQ_PREFLUSH; |
| if (rq == &q->bar_rq) |
| return QUEUE_ORDSEQ_BAR; |
| if (rq == &q->post_flush_rq) |
| return QUEUE_ORDSEQ_POSTFLUSH; |
| |
| if ((rq->cmd_flags & REQ_ORDERED_COLOR) == |
| (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR)) |
| return QUEUE_ORDSEQ_DRAIN; |
| else |
| return QUEUE_ORDSEQ_DONE; |
| } |
| |
| void blk_ordered_complete_seq(request_queue_t *q, unsigned seq, int error) |
| { |
| struct request *rq; |
| int uptodate; |
| |
| if (error && !q->orderr) |
| q->orderr = error; |
| |
| BUG_ON(q->ordseq & seq); |
| q->ordseq |= seq; |
| |
| if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) |
| return; |
| |
| /* |
| * Okay, sequence complete. |
| */ |
| rq = q->orig_bar_rq; |
| uptodate = q->orderr ? q->orderr : 1; |
| |
| q->ordseq = 0; |
| |
| end_that_request_first(rq, uptodate, rq->hard_nr_sectors); |
| end_that_request_last(rq, uptodate); |
| } |
| |
| static void pre_flush_end_io(struct request *rq, int error) |
| { |
| elv_completed_request(rq->q, rq); |
| blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error); |
| } |
| |
| static void bar_end_io(struct request *rq, int error) |
| { |
| elv_completed_request(rq->q, rq); |
| blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error); |
| } |
| |
| static void post_flush_end_io(struct request *rq, int error) |
| { |
| elv_completed_request(rq->q, rq); |
| blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error); |
| } |
| |
| static void queue_flush(request_queue_t *q, unsigned which) |
| { |
| struct request *rq; |
| rq_end_io_fn *end_io; |
| |
| if (which == QUEUE_ORDERED_PREFLUSH) { |
| rq = &q->pre_flush_rq; |
| end_io = pre_flush_end_io; |
| } else { |
| rq = &q->post_flush_rq; |
| end_io = post_flush_end_io; |
| } |
| |
| rq->cmd_flags = REQ_HARDBARRIER; |
| rq_init(q, rq); |
| rq->elevator_private = NULL; |
| rq->elevator_private2 = NULL; |
| rq->rq_disk = q->bar_rq.rq_disk; |
| rq->end_io = end_io; |
| q->prepare_flush_fn(q, rq); |
| |
| elv_insert(q, rq, ELEVATOR_INSERT_FRONT); |
| } |
| |
| static inline struct request *start_ordered(request_queue_t *q, |
| struct request *rq) |
| { |
| q->bi_size = 0; |
| q->orderr = 0; |
| q->ordered = q->next_ordered; |
| q->ordseq |= QUEUE_ORDSEQ_STARTED; |
| |
| /* |
| * Prep proxy barrier request. |
| */ |
| blkdev_dequeue_request(rq); |
| q->orig_bar_rq = rq; |
| rq = &q->bar_rq; |
| rq->cmd_flags = 0; |
| rq_init(q, rq); |
| if (bio_data_dir(q->orig_bar_rq->bio) == WRITE) |
| rq->cmd_flags |= REQ_RW; |
| rq->cmd_flags |= q->ordered & QUEUE_ORDERED_FUA ? REQ_FUA : 0; |
| rq->elevator_private = NULL; |
| rq->elevator_private2 = NULL; |
| init_request_from_bio(rq, q->orig_bar_rq->bio); |
| rq->end_io = bar_end_io; |
| |
| /* |
| * Queue ordered sequence. As we stack them at the head, we |
| * need to queue in reverse order. Note that we rely on that |
| * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs |
| * request gets inbetween ordered sequence. |
| */ |
| if (q->ordered & QUEUE_ORDERED_POSTFLUSH) |
| queue_flush(q, QUEUE_ORDERED_POSTFLUSH); |
| else |
| q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH; |
| |
| elv_insert(q, rq, ELEVATOR_INSERT_FRONT); |
| |
| if (q->ordered & QUEUE_ORDERED_PREFLUSH) { |
| queue_flush(q, QUEUE_ORDERED_PREFLUSH); |
| rq = &q->pre_flush_rq; |
| } else |
| q->ordseq |= QUEUE_ORDSEQ_PREFLUSH; |
| |
| if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0) |
| q->ordseq |= QUEUE_ORDSEQ_DRAIN; |
| else |
| rq = NULL; |
| |
| return rq; |
| } |
| |
| int blk_do_ordered(request_queue_t *q, struct request **rqp) |
| { |
| struct request *rq = *rqp; |
| int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq); |
| |
| if (!q->ordseq) { |
| if (!is_barrier) |
| return 1; |
| |
| if (q->next_ordered != QUEUE_ORDERED_NONE) { |
| *rqp = start_ordered(q, rq); |
| return 1; |
| } else { |
| /* |
| * This can happen when the queue switches to |
| * ORDERED_NONE while this request is on it. |
| */ |
| blkdev_dequeue_request(rq); |
| end_that_request_first(rq, -EOPNOTSUPP, |
| rq->hard_nr_sectors); |
| end_that_request_last(rq, -EOPNOTSUPP); |
| *rqp = NULL; |
| return 0; |
| } |
| } |
| |
| /* |
| * Ordered sequence in progress |
| */ |
| |
| /* Special requests are not subject to ordering rules. */ |
| if (!blk_fs_request(rq) && |
| rq != &q->pre_flush_rq && rq != &q->post_flush_rq) |
| return 1; |
| |
| if (q->ordered & QUEUE_ORDERED_TAG) { |
| /* Ordered by tag. Blocking the next barrier is enough. */ |
| if (is_barrier && rq != &q->bar_rq) |
| *rqp = NULL; |
| } else { |
| /* Ordered by draining. Wait for turn. */ |
| WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q)); |
| if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q)) |
| *rqp = NULL; |
| } |
| |
| return 1; |
| } |
| |
| static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error) |
| { |
| request_queue_t *q = bio->bi_private; |
| struct bio_vec *bvec; |
| int i; |
| |
| /* |
| * This is dry run, restore bio_sector and size. We'll finish |
| * this request again with the original bi_end_io after an |
| * error occurs or post flush is complete. |
| */ |
| q->bi_size += bytes; |
| |
| if (bio->bi_size) |
| return 1; |
| |
| /* Rewind bvec's */ |
| bio->bi_idx = 0; |
| bio_for_each_segment(bvec, bio, i) { |
| bvec->bv_len += bvec->bv_offset; |
| bvec->bv_offset = 0; |
| } |
| |
| /* Reset bio */ |
| set_bit(BIO_UPTODATE, &bio->bi_flags); |
| bio->bi_size = q->bi_size; |
| bio->bi_sector -= (q->bi_size >> 9); |
| q->bi_size = 0; |
| |
| return 0; |
| } |
| |
| static int ordered_bio_endio(struct request *rq, struct bio *bio, |
| unsigned int nbytes, int error) |
| { |
| request_queue_t *q = rq->q; |
| bio_end_io_t *endio; |
| void *private; |
| |
| if (&q->bar_rq != rq) |
| return 0; |
| |
| /* |
| * Okay, this is the barrier request in progress, dry finish it. |
| */ |
| if (error && !q->orderr) |
| q->orderr = error; |
| |
| endio = bio->bi_end_io; |
| private = bio->bi_private; |
| bio->bi_end_io = flush_dry_bio_endio; |
| bio->bi_private = q; |
| |
| bio_endio(bio, nbytes, error); |
| |
| bio->bi_end_io = endio; |
| bio->bi_private = private; |
| |
| return 1; |
| } |
| |
| /** |
| * blk_queue_bounce_limit - set bounce buffer limit for queue |
| * @q: the request queue for the device |
| * @dma_addr: bus address limit |
| * |
| * Description: |
| * Different hardware can have different requirements as to what pages |
| * it can do I/O directly to. A low level driver can call |
| * blk_queue_bounce_limit to have lower memory pages allocated as bounce |
| * buffers for doing I/O to pages residing above @page. |
| **/ |
| void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr) |
| { |
| unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; |
| int dma = 0; |
| |
| q->bounce_gfp = GFP_NOIO; |
| #if BITS_PER_LONG == 64 |
| /* Assume anything <= 4GB can be handled by IOMMU. |
| Actually some IOMMUs can handle everything, but I don't |
| know of a way to test this here. */ |
| if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) |
| dma = 1; |
| q->bounce_pfn = max_low_pfn; |
| #else |
| if (bounce_pfn < blk_max_low_pfn) |
| dma = 1; |
| q->bounce_pfn = bounce_pfn; |
| #endif |
| if (dma) { |
| init_emergency_isa_pool(); |
| q->bounce_gfp = GFP_NOIO | GFP_DMA; |
| q->bounce_pfn = bounce_pfn; |
| } |
| } |
| |
| EXPORT_SYMBOL(blk_queue_bounce_limit); |
| |
| /** |
| * blk_queue_max_sectors - set max sectors for a request for this queue |
| * @q: the request queue for the device |
| * @max_sectors: max sectors in the usual 512b unit |
| * |
| * Description: |
| * Enables a low level driver to set an upper limit on the size of |
| * received requests. |
| **/ |
| void blk_queue_max_sectors(request_queue_t *q, unsigned int max_sectors) |
| { |
| if ((max_sectors << 9) < PAGE_CACHE_SIZE) { |
| max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); |
| printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors); |
| } |
| |
| if (BLK_DEF_MAX_SECTORS > max_sectors) |
| q->max_hw_sectors = q->max_sectors = max_sectors; |
| else { |
| q->max_sectors = BLK_DEF_MAX_SECTORS; |
| q->max_hw_sectors = max_sectors; |
| } |
| } |
| |
| EXPORT_SYMBOL(blk_queue_max_sectors); |
| |
| /** |
| * blk_queue_max_phys_segments - set max phys segments for a request for this queue |
| * @q: the request queue for the device |
| * @max_segments: max number of segments |
| * |
| * Description: |
| * Enables a low level driver to set an upper limit on the number of |
| * physical data segments in a request. This would be the largest sized |
| * scatter list the driver could handle. |
| **/ |
| void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments) |
| { |
| if (!max_segments) { |
| max_segments = 1; |
| printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); |
| } |
| |
| q->max_phys_segments = max_segments; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_max_phys_segments); |
| |
| /** |
| * blk_queue_max_hw_segments - set max hw segments for a request for this queue |
| * @q: the request queue for the device |
| * @max_segments: max number of segments |
| * |
| * Description: |
| * Enables a low level driver to set an upper limit on the number of |
| * hw data segments in a request. This would be the largest number of |
| * address/length pairs the host adapter can actually give as once |
| * to the device. |
| **/ |
| void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments) |
| { |
| if (!max_segments) { |
| max_segments = 1; |
| printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); |
| } |
| |
| q->max_hw_segments = max_segments; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_max_hw_segments); |
| |
| /** |
| * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg |
| * @q: the request queue for the device |
| * @max_size: max size of segment in bytes |
| * |
| * Description: |
| * Enables a low level driver to set an upper limit on the size of a |
| * coalesced segment |
| **/ |
| void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size) |
| { |
| if (max_size < PAGE_CACHE_SIZE) { |
| max_size = PAGE_CACHE_SIZE; |
| printk("%s: set to minimum %d\n", __FUNCTION__, max_size); |
| } |
| |
| q->max_segment_size = max_size; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_max_segment_size); |
| |
| /** |
| * blk_queue_hardsect_size - set hardware sector size for the queue |
| * @q: the request queue for the device |
| * @size: the hardware sector size, in bytes |
| * |
| * Description: |
| * This should typically be set to the lowest possible sector size |
| * that the hardware can operate on (possible without reverting to |
| * even internal read-modify-write operations). Usually the default |
| * of 512 covers most hardware. |
| **/ |
| void blk_queue_hardsect_size(request_queue_t *q, unsigned short size) |
| { |
| q->hardsect_size = size; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_hardsect_size); |
| |
| /* |
| * Returns the minimum that is _not_ zero, unless both are zero. |
| */ |
| #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) |
| |
| /** |
| * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers |
| * @t: the stacking driver (top) |
| * @b: the underlying device (bottom) |
| **/ |
| void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b) |
| { |
| /* zero is "infinity" */ |
| t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors); |
| t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors); |
| |
| t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments); |
| t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments); |
| t->max_segment_size = min(t->max_segment_size,b->max_segment_size); |
| t->hardsect_size = max(t->hardsect_size,b->hardsect_size); |
| if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) |
| clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags); |
| } |
| |
| EXPORT_SYMBOL(blk_queue_stack_limits); |
| |
| /** |
| * blk_queue_segment_boundary - set boundary rules for segment merging |
| * @q: the request queue for the device |
| * @mask: the memory boundary mask |
| **/ |
| void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask) |
| { |
| if (mask < PAGE_CACHE_SIZE - 1) { |
| mask = PAGE_CACHE_SIZE - 1; |
| printk("%s: set to minimum %lx\n", __FUNCTION__, mask); |
| } |
| |
| q->seg_boundary_mask = mask; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_segment_boundary); |
| |
| /** |
| * blk_queue_dma_alignment - set dma length and memory alignment |
| * @q: the request queue for the device |
| * @mask: alignment mask |
| * |
| * description: |
| * set required memory and length aligment for direct dma transactions. |
| * this is used when buiding direct io requests for the queue. |
| * |
| **/ |
| void blk_queue_dma_alignment(request_queue_t *q, int mask) |
| { |
| q->dma_alignment = mask; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_dma_alignment); |
| |
| /** |
| * blk_queue_find_tag - find a request by its tag and queue |
| * @q: The request queue for the device |
| * @tag: The tag of the request |
| * |
| * Notes: |
| * Should be used when a device returns a tag and you want to match |
| * it with a request. |
| * |
| * no locks need be held. |
| **/ |
| struct request *blk_queue_find_tag(request_queue_t *q, int tag) |
| { |
| return blk_map_queue_find_tag(q->queue_tags, 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 |
| * |
| * Notes: |
| * blk_cleanup_queue() will take care of calling this function, if tagging |
| * has been used. So there's no need to call this directly. |
| **/ |
| static void __blk_queue_free_tags(request_queue_t *q) |
| { |
| struct blk_queue_tag *bqt = q->queue_tags; |
| |
| if (!bqt) |
| return; |
| |
| __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 |
| * |
| * Notes: |
| * This is used to disabled tagged queuing to a device, yet leave |
| * queue in function. |
| **/ |
| void blk_queue_free_tags(request_queue_t *q) |
| { |
| clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); |
| } |
| |
| EXPORT_SYMBOL(blk_queue_free_tags); |
| |
| static int |
| init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth) |
| { |
| struct request **tag_index; |
| unsigned long *tag_map; |
| int nr_ulongs; |
| |
| if (q && depth > q->nr_requests * 2) { |
| depth = q->nr_requests * 2; |
| printk(KERN_ERR "%s: adjusted depth to %d\n", |
| __FUNCTION__, depth); |
| } |
| |
| tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC); |
| if (!tag_index) |
| goto fail; |
| |
| nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG; |
| tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC); |
| if (!tag_map) |
| goto fail; |
| |
| tags->real_max_depth = depth; |
| tags->max_depth = depth; |
| tags->tag_index = tag_index; |
| tags->tag_map = tag_map; |
| |
| return 0; |
| fail: |
| kfree(tag_index); |
| 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 |
| * @depth: the maximum queue depth supported |
| * @tags: the tag to use |
| **/ |
| int blk_queue_init_tags(request_queue_t *q, int depth, |
| struct blk_queue_tag *tags) |
| { |
| int rc; |
| |
| BUG_ON(tags && q->queue_tags && tags != q->queue_tags); |
| |
| if (!tags && !q->queue_tags) { |
| tags = __blk_queue_init_tags(q, depth); |
| |
| if (!tags) |
| goto fail; |
| } else if (q->queue_tags) { |
| if ((rc = blk_queue_resize_tags(q, depth))) |
| return rc; |
| set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); |
| return 0; |
| } else |
| atomic_inc(&tags->refcnt); |
| |
| /* |
| * assign it, all done |
| */ |
| q->queue_tags = tags; |
| q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); |
| return 0; |
| fail: |
| kfree(tags); |
| return -ENOMEM; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_init_tags); |
| |
| /** |
| * blk_queue_resize_tags - change the queueing depth |
| * @q: the request queue for the device |
| * @new_depth: the new max command queueing depth |
| * |
| * Notes: |
| * Must be called with the queue lock held. |
| **/ |
| int blk_queue_resize_tags(request_queue_t *q, int new_depth) |
| { |
| struct blk_queue_tag *bqt = q->queue_tags; |
| struct request **tag_index; |
| unsigned long *tag_map; |
| int max_depth, nr_ulongs; |
| |
| if (!bqt) |
| return -ENXIO; |
| |
| /* |
| * if we already have large enough real_max_depth. just |
| * adjust max_depth. *NOTE* as requests with tag value |
| * between new_depth and real_max_depth can be in-flight, tag |
| * map can not be shrunk blindly here. |
| */ |
| if (new_depth <= bqt->real_max_depth) { |
| bqt->max_depth = 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 |
| */ |
| tag_index = bqt->tag_index; |
| tag_map = bqt->tag_map; |
| max_depth = bqt->real_max_depth; |
| |
| if (init_tag_map(q, bqt, new_depth)) |
| return -ENOMEM; |
| |
| memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *)); |
| nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG; |
| memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long)); |
| |
| kfree(tag_index); |
| kfree(tag_map); |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_resize_tags); |
| |
| /** |
| * blk_queue_end_tag - end tag operations for a request |
| * @q: the request queue for the device |
| * @rq: the request that has completed |
| * |
| * Description: |
| * Typically called when end_that_request_first() returns 0, meaning |
| * all transfers have been done for a request. It's important to call |
| * this function before end_that_request_last(), as that will put the |
| * request back on the free list thus corrupting the internal tag list. |
| * |
| * Notes: |
| * queue lock must be held. |
| **/ |
| void blk_queue_end_tag(request_queue_t *q, struct request *rq) |
| { |
| struct blk_queue_tag *bqt = q->queue_tags; |
| int tag = rq->tag; |
| |
| BUG_ON(tag == -1); |
| |
| if (unlikely(tag >= bqt->real_max_depth)) |
| /* |
| * This can happen after tag depth has been reduced. |
| * FIXME: how about a warning or info message here? |
| */ |
| return; |
| |
| if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) { |
| printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", |
| __FUNCTION__, tag); |
| return; |
| } |
| |
| list_del_init(&rq->queuelist); |
| rq->cmd_flags &= ~REQ_QUEUED; |
| rq->tag = -1; |
| |
| if (unlikely(bqt->tag_index[tag] == NULL)) |
| printk(KERN_ERR "%s: tag %d is missing\n", |
| __FUNCTION__, tag); |
| |
| bqt->tag_index[tag] = NULL; |
| bqt->busy--; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_end_tag); |
| |
| /** |
| * blk_queue_start_tag - find a free tag and assign it |
| * @q: the request queue for the device |
| * @rq: the block request that needs tagging |
| * |
| * Description: |
| * This can either be used as a stand-alone helper, or possibly be |
| * assigned as the queue &prep_rq_fn (in which case &struct request |
| * automagically gets a tag assigned). Note that this function |
| * assumes that any type of request can be queued! if this is not |
| * true for your device, you must check the request type before |
| * calling this function. The request will also be removed from |
| * the request queue, so it's the drivers responsibility to readd |
| * it if it should need to be restarted for some reason. |
| * |
| * Notes: |
| * queue lock must be held. |
| **/ |
| int blk_queue_start_tag(request_queue_t *q, struct request *rq) |
| { |
| struct blk_queue_tag *bqt = q->queue_tags; |
| int tag; |
| |
| if (unlikely((rq->cmd_flags & REQ_QUEUED))) { |
| printk(KERN_ERR |
| "%s: request %p for device [%s] already tagged %d", |
| __FUNCTION__, rq, |
| rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag); |
| BUG(); |
| } |
| |
| /* |
| * Protect against shared tag maps, as we may not have exclusive |
| * access to the tag map. |
| */ |
| do { |
| tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); |
| if (tag >= bqt->max_depth) |
| return 1; |
| |
| } while (test_and_set_bit(tag, bqt->tag_map)); |
| |
| rq->cmd_flags |= REQ_QUEUED; |
| rq->tag = tag; |
| bqt->tag_index[tag] = rq; |
| blkdev_dequeue_request(rq); |
| list_add(&rq->queuelist, &bqt->busy_list); |
| bqt->busy++; |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(blk_queue_start_tag); |
| |
| /** |
| * blk_queue_invalidate_tags - invalidate all pending tags |
| * @q: the request queue for the device |
| * |
| * Description: |
| * Hardware conditions may dictate a need to stop all pending requests. |
| * In this case, we will safely clear the block side of the tag queue and |
| * readd all requests to the request queue in the right order. |
| * |
| * Notes: |
| * queue lock must be held. |
| **/ |
| void blk_queue_invalidate_tags(request_queue_t *q) |
| { |
| struct blk_queue_tag *bqt = q->queue_tags; |
| struct list_head *tmp, *n; |
| struct request *rq; |
| |
| list_for_each_safe(tmp, n, &bqt->busy_list) { |
| rq = list_entry_rq(tmp); |
| |
| if (rq->tag == -1) { |
| printk(KERN_ERR |
| "%s: bad tag found on list\n", __FUNCTION__); |
| list_del_init(&rq->queuelist); |
| rq->cmd_flags &= ~REQ_QUEUED; |
| } else |
| blk_queue_end_tag(q, rq); |
| |
| rq->cmd_flags &= ~REQ_STARTED; |
| __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); |
| } |
| } |
| |
| EXPORT_SYMBOL(blk_queue_invalidate_tags); |
| |
| void blk_dump_rq_flags(struct request *rq, char *msg) |
| { |
| int bit; |
| |
| printk("%s: dev %s: type=%x, flags=%x\n", msg, |
| rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, |
| rq->cmd_flags); |
| |
| printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector, |
| rq->nr_sectors, |
| rq->current_nr_sectors); |
| printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len); |
| |
| if (blk_pc_request(rq)) { |
| printk("cdb: "); |
| for (bit = 0; bit < sizeof(rq->cmd); bit++) |
| printk("%02x ", rq->cmd[bit]); |
| printk("\n"); |
| } |
| } |
| |
| EXPORT_SYMBOL(blk_dump_rq_flags); |
| |
| void blk_recount_segments(request_queue_t *q, struct bio *bio) |
| { |
| struct bio_vec *bv, *bvprv = NULL; |
| int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster; |
| int high, highprv = 1; |
| |
| if (unlikely(!bio->bi_io_vec)) |
| return; |
| |
| cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); |
| hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0; |
| bio_for_each_segment(bv, bio, i) { |
| /* |
| * the trick here is making sure that a high page is never |
| * considered part of another segment, since that might |
| * change with the bounce page. |
| */ |
| high = page_to_pfn(bv->bv_page) >= q->bounce_pfn; |
| if (high || highprv) |
| goto new_hw_segment; |
| if (cluster) { |
| if (seg_size + bv->bv_len > q->max_segment_size) |
| goto new_segment; |
| if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) |
| goto new_segment; |
| if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) |
| goto new_segment; |
| if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) |
| goto new_hw_segment; |
| |
| seg_size += bv->bv_len; |
| hw_seg_size += bv->bv_len; |
| bvprv = bv; |
| continue; |
| } |
| new_segment: |
| if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) && |
| !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) { |
| hw_seg_size += bv->bv_len; |
| } else { |
| new_hw_segment: |
| if (hw_seg_size > bio->bi_hw_front_size) |
| bio->bi_hw_front_size = hw_seg_size; |
| hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len; |
| nr_hw_segs++; |
| } |
| |
| nr_phys_segs++; |
| bvprv = bv; |
| seg_size = bv->bv_len; |
| highprv = high; |
| } |
| if (hw_seg_size > bio->bi_hw_back_size) |
| bio->bi_hw_back_size = hw_seg_size; |
| if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size) |
| bio->bi_hw_front_size = hw_seg_size; |
| bio->bi_phys_segments = nr_phys_segs; |
| bio->bi_hw_segments = nr_hw_segs; |
| bio->bi_flags |= (1 << BIO_SEG_VALID); |
| } |
| |
| |
| static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio, |
| struct bio *nxt) |
| { |
| if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) |
| return 0; |
| |
| if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) |
| return 0; |
| if (bio->bi_size + nxt->bi_size > q->max_segment_size) |
| return 0; |
| |
| /* |
| * bio and nxt are contigous in memory, check if the queue allows |
| * these two to be merged into one |
| */ |
| if (BIO_SEG_BOUNDARY(q, bio, nxt)) |
| return 1; |
| |
| return 0; |
| } |
| |
| static int blk_hw_contig_segment(request_queue_t *q, struct bio *bio, |
| struct bio *nxt) |
| { |
| if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) |
| blk_recount_segments(q, bio); |
| if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID))) |
| blk_recount_segments(q, nxt); |
| if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) || |
| BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size)) |
| return 0; |
| if (bio->bi_size + nxt->bi_size > q->max_segment_size) |
| return 0; |
| |
| return 1; |
| } |
| |
| /* |
| * map a request to scatterlist, return number of sg entries setup. Caller |
| * must make sure sg can hold rq->nr_phys_segments entries |
| */ |
| int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg) |
| { |
| struct bio_vec *bvec, *bvprv; |
| struct bio *bio; |
| int nsegs, i, cluster; |
| |
| nsegs = 0; |
| cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); |
| |
| /* |
| * for each bio in rq |
| */ |
| bvprv = NULL; |
| rq_for_each_bio(bio, rq) { |
| /* |
| * for each segment in bio |
| */ |
| bio_for_each_segment(bvec, bio, i) { |
| int nbytes = bvec->bv_len; |
| |
| if (bvprv && cluster) { |
| if (sg[nsegs - 1].length + nbytes > q->max_segment_size) |
| goto new_segment; |
| |
| if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) |
| goto new_segment; |
| if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) |
| goto new_segment; |
| |
| sg[nsegs - 1].length += nbytes; |
| } else { |
| new_segment: |
| memset(&sg[nsegs],0,sizeof(struct scatterlist)); |
| sg[nsegs].page = bvec->bv_page; |
| sg[nsegs].length = nbytes; |
| sg[nsegs].offset = bvec->bv_offset; |
| |
| nsegs++; |
| } |
| bvprv = bvec; |
| } /* segments in bio */ |
| } /* bios in rq */ |
| |
| return nsegs; |
| } |
| |
| EXPORT_SYMBOL(blk_rq_map_sg); |
| |
| /* |
| * the standard queue merge functions, can be overridden with device |
| * specific ones if so desired |
| */ |
| |
| static inline int ll_new_mergeable(request_queue_t *q, |
| struct request *req, |
| struct bio *bio) |
| { |
| int nr_phys_segs = bio_phys_segments(q, bio); |
| |
| if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { |
| req->cmd_flags |= REQ_NOMERGE; |
| if (req == q->last_merge) |
| q->last_merge = NULL; |
| return 0; |
| } |
| |
| /* |
| * A hw segment is just getting larger, bump just the phys |
| * counter. |
| */ |
| req->nr_phys_segments += nr_phys_segs; |
| return 1; |
| } |
| |
| static inline int ll_new_hw_segment(request_queue_t *q, |
| struct request *req, |
| struct bio *bio) |
| { |
| int nr_hw_segs = bio_hw_segments(q, bio); |
| int nr_phys_segs = bio_phys_segments(q, bio); |
| |
| if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments |
| || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { |
| req->cmd_flags |= REQ_NOMERGE; |
| if (req == q->last_merge) |
| q->last_merge = NULL; |
| return 0; |
| } |
| |
| /* |
| * This will form the start of a new hw segment. Bump both |
| * counters. |
| */ |
| req->nr_hw_segments += nr_hw_segs; |
| req->nr_phys_segments += nr_phys_segs; |
| return 1; |
| } |
| |
| static int ll_back_merge_fn(request_queue_t *q, struct request *req, |
| struct bio *bio) |
| { |
| unsigned short max_sectors; |
| int len; |
| |
| if (unlikely(blk_pc_request(req))) |
| max_sectors = q->max_hw_sectors; |
| else |
| max_sectors = q->max_sectors; |
| |
| if (req->nr_sectors + bio_sectors(bio) > max_sectors) { |
| req->cmd_flags |= REQ_NOMERGE; |
| if (req == q->last_merge) |
| q->last_merge = NULL; |
| return 0; |
| } |
| if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID))) |
| blk_recount_segments(q, req->biotail); |
| if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) |
| blk_recount_segments(q, bio); |
| len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size; |
| if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) && |
| !BIOVEC_VIRT_OVERSIZE(len)) { |
| int mergeable = ll_new_mergeable(q, req, bio); |
| |
| if (mergeable) { |
| if (req->nr_hw_segments == 1) |
| req->bio->bi_hw_front_size = len; |
| if (bio->bi_hw_segments == 1) |
| bio->bi_hw_back_size = len; |
| } |
| return mergeable; |
| } |
| |
| return ll_new_hw_segment(q, req, bio); |
| } |
| |
| static int ll_front_merge_fn(request_queue_t *q, struct request *req, |
| struct bio *bio) |
| { |
| unsigned short max_sectors; |
| int len; |
| |
| if (unlikely(blk_pc_request(req))) |
| max_sectors = q->max_hw_sectors; |
| else |
| max_sectors = q->max_sectors; |
| |
| |
| if (req->nr_sectors + bio_sectors(bio) > max_sectors) { |
| req->cmd_flags |= REQ_NOMERGE; |
| if (req == q->last_merge) |
| q->last_merge = NULL; |
| return 0; |
| } |
| len = bio->bi_hw_back_size + req->bio->bi_hw_front_size; |
| if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) |
| blk_recount_segments(q, bio); |
| if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID))) |
| blk_recount_segments(q, req->bio); |
| if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) && |
| !BIOVEC_VIRT_OVERSIZE(len)) { |
| int mergeable = ll_new_mergeable(q, req, bio); |
| |
| if (mergeable) { |
| if (bio->bi_hw_segments == 1) |
| bio->bi_hw_front_size = len; |
| if (req->nr_hw_segments == 1) |
| req->biotail->bi_hw_back_size = len; |
| } |
| return mergeable; |
| } |
| |
| return ll_new_hw_segment(q, req, bio); |
| } |
| |
| static int ll_merge_requests_fn(request_queue_t *q, struct request *req, |
| struct request *next) |
| { |
| int total_phys_segments; |
| int total_hw_segments; |
| |
| /* |
| * First check if the either of the requests are re-queued |
| * requests. Can't merge them if they are. |
| */ |
| if (req->special || next->special) |
| return 0; |
| |
| /* |
| * Will it become too large? |
| */ |
| if ((req->nr_sectors + next->nr_sectors) > q->max_sectors) |
| return 0; |
| |
| total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; |
| if (blk_phys_contig_segment(q, req->biotail, next->bio)) |
| total_phys_segments--; |
| |
| if (total_phys_segments > q->max_phys_segments) |
| return 0; |
| |
| total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; |
| if (blk_hw_contig_segment(q, req->biotail, next->bio)) { |
| int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size; |
| /* |
| * propagate the combined length to the end of the requests |
| */ |
| if (req->nr_hw_segments == 1) |
| req->bio->bi_hw_front_size = len; |
| if (next->nr_hw_segments == 1) |
| next->biotail->bi_hw_back_size = len; |
| total_hw_segments--; |
| } |
| |
| if (total_hw_segments > q->max_hw_segments) |
| return 0; |
| |
| /* Merge is OK... */ |
| req->nr_phys_segments = total_phys_segments; |
| req->nr_hw_segments = total_hw_segments; |
| return 1; |
| } |
| |
| /* |
| * "plug" the device if there are no outstanding requests: this will |
| * force the transfer to start only after we have put all the requests |
| * on the list. |
| * |
| * This is called with interrupts off and no requests on the queue and |
| * with the queue lock held. |
| */ |
| void blk_plug_device(request_queue_t *q) |
| { |
| WARN_ON(!irqs_disabled()); |
| |
| /* |
| * don't plug a stopped queue, it must be paired with blk_start_queue() |
| * which will restart the queueing |
| */ |
| if (blk_queue_stopped(q)) |
| return; |
| |
| if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) { |
| mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); |
| blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG); |
| } |
| } |
| |
| EXPORT_SYMBOL(blk_plug_device); |
| |
| /* |
| * remove the queue from the plugged list, if present. called with |
| * queue lock held and interrupts disabled. |
| */ |
| int blk_remove_plug(request_queue_t *q) |
| { |
| WARN_ON(!irqs_disabled()); |
| |
| if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) |
| return 0; |
| |
| del_timer(&q->unplug_timer); |
| return 1; |
| } |
| |
| EXPORT_SYMBOL(blk_remove_plug); |
| |
| /* |
| * remove the plug and let it rip.. |
| */ |
| void __generic_unplug_device(request_queue_t *q) |
| { |
| if (unlikely(blk_queue_stopped(q))) |
| return; |
| |
| if (!blk_remove_plug(q)) |
| return; |
| |
| q->request_fn(q); |
| } |
| EXPORT_SYMBOL(__generic_unplug_device); |
| |
| /** |
| * generic_unplug_device - fire a request queue |
| * @q: The &request_queue_t in question |
| * |
| * Description: |
| * Linux uses plugging to build bigger requests queues before letting |
| * the device have at them. If a queue is plugged, the I/O scheduler |
| * is still adding and merging requests on the queue. Once the queue |
| * gets unplugged, the request_fn defined for the queue is invoked and |
| * transfers started. |
| **/ |
| void generic_unplug_device(request_queue_t *q) |
| { |
| spin_lock_irq(q->queue_lock); |
| __generic_unplug_device(q); |
| spin_unlock_irq(q->queue_lock); |
| } |
| EXPORT_SYMBOL(generic_unplug_device); |
| |
| static void blk_backing_dev_unplug(struct backing_dev_info *bdi, |
| struct page *page) |
| { |
| request_queue_t *q = bdi->unplug_io_data; |
| |
| /* |
| * devices don't necessarily have an ->unplug_fn defined |
| */ |
| if (q->unplug_fn) { |
| blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, |
| q->rq.count[READ] + q->rq.count[WRITE]); |
| |
| q->unplug_fn(q); |
| } |
| } |
| |
| static void blk_unplug_work(void *data) |
| { |
| request_queue_t *q = data; |
| |
| blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, |
| q->rq.count[READ] + q->rq.count[WRITE]); |
| |
| q->unplug_fn(q); |
| } |
| |
| static void blk_unplug_timeout(unsigned long data) |
| { |
| request_queue_t *q = (request_queue_t *)data; |
| |
| blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL, |
| q->rq.count[READ] + q->rq.count[WRITE]); |
| |
| kblockd_schedule_work(&q->unplug_work); |
| } |
| |
| /** |
| * blk_start_queue - restart a previously stopped queue |
| * @q: The &request_queue_t in question |
| * |
| * Description: |
| * blk_start_queue() will clear the stop flag on the queue, and call |
| * the request_fn for the queue if it was in a stopped state when |
| * entered. Also see blk_stop_queue(). Queue lock must be held. |
| **/ |
| void blk_start_queue(request_queue_t *q) |
| { |
| WARN_ON(!irqs_disabled()); |
| |
| clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); |
| |
| /* |
| * one level of recursion is ok and is much faster than kicking |
| * the unplug handling |
| */ |
| if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { |
| q->request_fn(q); |
| clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); |
| } else { |
| blk_plug_device(q); |
| kblockd_schedule_work(&q->unplug_work); |
| } |
| } |
| |
| EXPORT_SYMBOL(blk_start_queue); |
| |
| /** |
| * blk_stop_queue - stop a queue |
| * @q: The &request_queue_t in question |
| * |
| * Description: |
| * The Linux block layer assumes that a block driver will consume all |
| * entries on the request queue when the request_fn strategy is called. |
| * Often this will not happen, because of hardware limitations (queue |
| * depth settings). If a device driver gets a 'queue full' response, |
| * or if it simply chooses not to queue more I/O at one point, it can |
| * call this function to prevent the request_fn from being called until |
| * the driver has signalled it's ready to go again. This happens by calling |
| * blk_start_queue() to restart queue operations. Queue lock must be held. |
| **/ |
| void blk_stop_queue(request_queue_t *q) |
| { |
| blk_remove_plug(q); |
| set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); |
| } |
| EXPORT_SYMBOL(blk_stop_queue); |
| |
| /** |
| * blk_sync_queue - cancel any pending callbacks on a queue |
| * @q: the queue |
| * |
| * Description: |
| * The block layer may perform asynchronous callback activity |
| * on a queue, such as calling the unplug function after a timeout. |
| * A block device may call blk_sync_queue to ensure that any |
| * such activity is cancelled, thus allowing it to release resources |
| * the the callbacks might use. The caller must already have made sure |
| * that its ->make_request_fn will not re-add plugging prior to calling |
| * this function. |
| * |
| */ |
| void blk_sync_queue(struct request_queue *q) |
| { |
| del_timer_sync(&q->unplug_timer); |
| kblockd_flush(); |
| } |
| EXPORT_SYMBOL(blk_sync_queue); |
| |
| /** |
| * blk_run_queue - run a single device queue |
| * @q: The queue to run |
| */ |
| void blk_run_queue(struct request_queue *q) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| blk_remove_plug(q); |
| |
| /* |
| * Only recurse once to avoid overrunning the stack, let the unplug |
| * handling reinvoke the handler shortly if we already got there. |
| */ |
| if (!elv_queue_empty(q)) { |
| if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { |
| q->request_fn(q); |
| clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); |
| } else { |
| blk_plug_device(q); |
| kblockd_schedule_work(&q->unplug_work); |
| } |
| } |
| |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| EXPORT_SYMBOL(blk_run_queue); |
| |
| /** |
| * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed |
| * @kobj: the kobj belonging of the request queue to be released |
| * |
| * Description: |
| * blk_cleanup_queue is the pair to blk_init_queue() or |
| * blk_queue_make_request(). It should be called when a request queue is |
| * being released; typically when a block device is being de-registered. |
| * Currently, its primary task it to free all the &struct request |
| * structures that were allocated to the queue and the queue itself. |
| * |
| * Caveat: |
| * Hopefully the low level driver will have finished any |
| * outstanding requests first... |
| **/ |
| static void blk_release_queue(struct kobject *kobj) |
| { |
| request_queue_t *q = container_of(kobj, struct request_queue, kobj); |
| struct request_list *rl = &q->rq; |
| |
| blk_sync_queue(q); |
| |
| if (rl->rq_pool) |
| mempool_destroy(rl->rq_pool); |
| |
| if (q->queue_tags) |
| __blk_queue_free_tags(q); |
| |
| blk_trace_shutdown(q); |
| |
| kmem_cache_free(requestq_cachep, q); |
| } |
| |
| void blk_put_queue(request_queue_t *q) |
| { |
| kobject_put(&q->kobj); |
| } |
| EXPORT_SYMBOL(blk_put_queue); |
| |
| void blk_cleanup_queue(request_queue_t * q) |
| { |
| mutex_lock(&q->sysfs_lock); |
| set_bit(QUEUE_FLAG_DEAD, &q->queue_flags); |
| mutex_unlock(&q->sysfs_lock); |
| |
| if (q->elevator) |
| elevator_exit(q->elevator); |
| |
| blk_put_queue(q); |
| } |
| |
| EXPORT_SYMBOL(blk_cleanup_queue); |
| |
| static int blk_init_free_list(request_queue_t *q) |
| { |
| struct request_list *rl = &q->rq; |
| |
| rl->count[READ] = rl->count[WRITE] = 0; |
| rl->starved[READ] = rl->starved[WRITE] = 0; |
| rl->elvpriv = 0; |
| init_waitqueue_head(&rl->wait[READ]); |
| init_waitqueue_head(&rl->wait[WRITE]); |
| |
| rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
| mempool_free_slab, request_cachep, q->node); |
| |
| if (!rl->rq_pool) |
| return -ENOMEM; |
| |
| return 0; |
| } |
| |
| request_queue_t *blk_alloc_queue(gfp_t gfp_mask) |
| { |
| return blk_alloc_queue_node(gfp_mask, -1); |
| } |
| EXPORT_SYMBOL(blk_alloc_queue); |
| |
| static struct kobj_type queue_ktype; |
| |
| request_queue_t *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) |
| { |
| request_queue_t *q; |
| |
| q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id); |
| if (!q) |
| return NULL; |
| |
| memset(q, 0, sizeof(*q)); |
| init_timer(&q->unplug_timer); |
| |
| snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue"); |
| q->kobj.ktype = &queue_ktype; |
| kobject_init(&q->kobj); |
| |
| q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; |
| q->backing_dev_info.unplug_io_data = q; |
| |
| mutex_init(&q->sysfs_lock); |
| |
| return q; |
| } |
| EXPORT_SYMBOL(blk_alloc_queue_node); |
| |
| /** |
| * blk_init_queue - prepare a request queue for use with a block device |
| * @rfn: The function to be called to process requests that have been |
| * placed on the queue. |
| * @lock: Request queue spin lock |
| * |
| * Description: |
| * If a block device wishes to use the standard request handling procedures, |
| * which sorts requests and coalesces adjacent requests, then it must |
| * call blk_init_queue(). The function @rfn will be called when there |
| * are requests on the queue that need to be processed. If the device |
| * supports plugging, then @rfn may not be called immediately when requests |
| * are available on the queue, but may be called at some time later instead. |
| * Plugged queues are generally unplugged when a buffer belonging to one |
| * of the requests on the queue is needed, or due to memory pressure. |
| * |
| * @rfn is not required, or even expected, to remove all requests off the |
| * queue, but only as many as it can handle at a time. If it does leave |
| * requests on the queue, it is responsible for arranging that the requests |
| * get dealt with eventually. |
| * |
| * The queue spin lock must be held while manipulating the requests on the |
| * request queue; this lock will be taken also from interrupt context, so irq |
| * disabling is needed for it. |
| * |
| * Function returns a pointer to the initialized request queue, or NULL if |
| * it didn't succeed. |
| * |
| * Note: |
| * blk_init_queue() must be paired with a blk_cleanup_queue() call |
| * when the block device is deactivated (such as at module unload). |
| **/ |
| |
| request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
| { |
| return blk_init_queue_node(rfn, lock, -1); |
| } |
| EXPORT_SYMBOL(blk_init_queue); |
| |
| request_queue_t * |
| blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) |
| { |
| request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id); |
| |
| if (!q) |
| return NULL; |
| |
| q->node = node_id; |
| if (blk_init_free_list(q)) { |
| kmem_cache_free(requestq_cachep, q); |
| return NULL; |
| } |
| |
| /* |
| * if caller didn't supply a lock, they get per-queue locking with |
| * our embedded lock |
| */ |
| if (!lock) { |
| spin_lock_init(&q->__queue_lock); |
| lock = &q->__queue_lock; |
| } |
| |
| q->request_fn = rfn; |
| q->back_merge_fn = ll_back_merge_fn; |
| q->front_merge_fn = ll_front_merge_fn; |
| q->merge_requests_fn = ll_merge_requests_fn; |
| q->prep_rq_fn = NULL; |
| q->unplug_fn = generic_unplug_device; |
| q->queue_flags = (1 << QUEUE_FLAG_CLUSTER); |
| q->queue_lock = lock; |
| |
| blk_queue_segment_boundary(q, 0xffffffff); |
| |
| blk_queue_make_request(q, __make_request); |
| blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE); |
| |
| blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); |
| blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); |
| |
| /* |
| * all done |
| */ |
| if (!elevator_init(q, NULL)) { |
| blk_queue_congestion_threshold(q); |
| return q; |
| } |
| |
| blk_put_queue(q); |
| return NULL; |
| } |
| EXPORT_SYMBOL(blk_init_queue_node); |
| |
| int blk_get_queue(request_queue_t *q) |
| { |
| if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { |
| kobject_get(&q->kobj); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| EXPORT_SYMBOL(blk_get_queue); |
| |
| static inline void blk_free_request(request_queue_t *q, struct request *rq) |
| { |
| if (rq->cmd_flags & REQ_ELVPRIV) |
| elv_put_request(q, rq); |
| mempool_free(rq, q->rq.rq_pool); |
| } |
| |
| static struct request * |
| blk_alloc_request(request_queue_t *q, int rw, int priv, gfp_t gfp_mask) |
| { |
| struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); |
| |
| if (!rq) |
| return NULL; |
| |
| /* |
| * first three bits are identical in rq->cmd_flags and bio->bi_rw, |
| * see bio.h and blkdev.h |
| */ |
| rq->cmd_flags = rw | REQ_ALLOCED; |
| |
| if (priv) { |
| if (unlikely(elv_set_request(q, rq, gfp_mask))) { |
| mempool_free(rq, q->rq.rq_pool); |
| return NULL; |
| } |
| rq->cmd_flags |= REQ_ELVPRIV; |
| } |
| |
| return rq; |
| } |
| |
| /* |
| * ioc_batching returns true if the ioc is a valid batching request and |
| * should be given priority access to a request. |
| */ |
| static inline int ioc_batching(request_queue_t *q, struct io_context *ioc) |
| { |
| if (!ioc) |
| return 0; |
| |
| /* |
| * Make sure the process is able to allocate at least 1 request |
| * even if the batch times out, otherwise we could theoretically |
| * lose wakeups. |
| */ |
| return ioc->nr_batch_requests == q->nr_batching || |
| (ioc->nr_batch_requests > 0 |
| && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); |
| } |
| |
| /* |
| * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This |
| * will cause the process to be a "batcher" on all queues in the system. This |
| * is the behaviour we want though - once it gets a wakeup it should be given |
| * a nice run. |
| */ |
| static void ioc_set_batching(request_queue_t *q, struct io_context *ioc) |
| { |
| if (!ioc || ioc_batching(q, ioc)) |
| return; |
| |
| ioc->nr_batch_requests = q->nr_batching; |
| ioc->last_waited = jiffies; |
| } |
| |
| static void __freed_request(request_queue_t *q, int rw) |
| { |
| struct request_list *rl = &q->rq; |
| |
| if (rl->count[rw] < queue_congestion_off_threshold(q)) |
| blk_clear_queue_congested(q, rw); |
| |
| if (rl->count[rw] + 1 <= q->nr_requests) { |
| if (waitqueue_active(&rl->wait[rw])) |
| wake_up(&rl->wait[rw]); |
| |
| blk_clear_queue_full(q, rw); |
| } |
| } |
| |
| /* |
| * A request has just been released. Account for it, update the full and |
| * congestion status, wake up any waiters. Called under q->queue_lock. |
| */ |
| static void freed_request(request_queue_t *q, int rw, int priv) |
| { |
| struct request_list *rl = &q->rq; |
| |
| rl->count[rw]--; |
| if (priv) |
| rl->elvpriv--; |
| |
| __freed_request(q, rw); |
| |
| if (unlikely(rl->starved[rw ^ 1])) |
| __freed_request(q, rw ^ 1); |
| } |
| |
| #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) |
| /* |
| * 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, |
| gfp_t gfp_mask) |
| { |
| struct request *rq = NULL; |
| struct request_list *rl = &q->rq; |
| struct io_context *ioc = NULL; |
| int may_queue, priv; |
| |
| may_queue = elv_may_queue(q, rw); |
| if (may_queue == ELV_MQUEUE_NO) |
| goto rq_starved; |
| |
| if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) { |
| if (rl->count[rw]+1 >= q->nr_requests) { |
| ioc = current_io_context(GFP_ATOMIC, q->node); |
| /* |
| * The queue will fill after this allocation, so set |
| * it as full, and mark this process as "batching". |
| * This process will be allowed to complete a batch of |
| * requests, others will be blocked. |
| */ |
| if (!blk_queue_full(q, rw)) { |
| ioc_set_batching(q, ioc); |
| blk_set_queue_full(q, rw); |
| } else { |
| if (may_queue != ELV_MQUEUE_MUST |
| && !ioc_batching(q, ioc)) { |
| /* |
| * The queue is full and the allocating |
| * process is not a "batcher", and not |
| * exempted by the IO scheduler |
| */ |
| goto out; |
| } |
| } |
| } |
| blk_set_queue_congested(q, rw); |
| } |
| |
| /* |
| * 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; |
| |
| priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); |
| if (priv) |
| rl->elvpriv++; |
| |
| spin_unlock_irq(q->queue_lock); |
| |
| rq = blk_alloc_request(q, rw, priv, gfp_mask); |
| if (unlikely(!rq)) { |
| /* |
| * Allocation failed presumably due to memory. Undo anything |
| * we might have messed up. |
| * |
| * Allocating task should really be put onto the front of the |
| * wait queue, but this is pretty rare. |
| */ |
| spin_lock_irq(q->queue_lock); |
| freed_request(q, rw, priv); |
| |
| /* |
| * in the very unlikely event that allocation failed and no |
| * requests for this direction was pending, mark us starved |
| * so that freeing of a request in the other direction will |
| * notice us. another possible fix would be to split the |
| * rq mempool into READ and WRITE |
| */ |
| rq_starved: |
| if (unlikely(rl->count[rw] == 0)) |
| rl->starved[rw] = 1; |
| |
| goto out; |
| } |
| |
| /* |
| * ioc may be NULL here, and ioc_batching will be false. That's |
| * OK, if the queue is under the request limit then requests need |
| * not count toward the nr_batch_requests limit. There will always |
| * be some limit enforced by BLK_BATCH_TIME. |
| */ |
| if (ioc_batching(q, ioc)) |
| ioc->nr_batch_requests--; |
| |
| rq_init(q, rq); |
| |
| blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ); |
| out: |
| 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) |
| { |
| struct request *rq; |
| |
| 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, |
| TASK_UNINTERRUPTIBLE); |
| |
| rq = get_request(q, rw, bio, GFP_NOIO); |
| |
| if (!rq) { |
| struct io_context *ioc; |
| |
| blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ); |
| |
| __generic_unplug_device(q); |
| spin_unlock_irq(q->queue_lock); |
| io_schedule(); |
| |
| /* |
| * After sleeping, we become a "batching" process and |
| * will be able to allocate at least one request, and |
| * up to a big batch of them for a small period time. |
| * See ioc_batching, ioc_set_batching |
| */ |
| ioc = current_io_context(GFP_NOIO, q->node); |
| ioc_set_batching(q, ioc); |
| |
| spin_lock_irq(q->queue_lock); |
| } |
| finish_wait(&rl->wait[rw], &wait); |
| } |
| |
| return rq; |
| } |
| |
| struct request *blk_get_request(request_queue_t *q, int rw, gfp_t gfp_mask) |
| { |
| struct request *rq; |
| |
| BUG_ON(rw != READ && rw != WRITE); |
| |
| spin_lock_irq(q->queue_lock); |
| if (gfp_mask & __GFP_WAIT) { |
| rq = get_request_wait(q, rw, NULL); |
| } 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); |
| |
| /** |
| * blk_start_queueing - initiate dispatch of requests to device |
| * @q: request queue to kick into gear |
| * |
| * This is basically a helper to remove the need to know whether a queue |
| * is plugged or not if someone just wants to initiate dispatch of requests |
| * for this queue. |
| * |
| * The queue lock must be held with interrupts disabled. |
| */ |
| void blk_start_queueing(request_queue_t *q) |
| { |
| if (!blk_queue_plugged(q)) |
| q->request_fn(q); |
| else |
| __generic_unplug_device(q); |
| } |
| EXPORT_SYMBOL(blk_start_queueing); |
| |
| /** |
| * blk_requeue_request - put a request back on queue |
| * @q: request queue where request should be inserted |
| * @rq: request to be inserted |
| * |
| * Description: |
| * Drivers often keep queueing requests until the hardware cannot accept |
| * more, when that condition happens we need to put the request back |
| * on the queue. Must be called with queue lock held. |
| */ |
| void blk_requeue_request(request_queue_t *q, struct request *rq) |
| { |
| blk_add_trace_rq(q, rq, BLK_TA_REQUEUE); |
| |
| if (blk_rq_tagged(rq)) |
| blk_queue_end_tag(q, rq); |
| |
| elv_requeue_request(q, rq); |
| } |
| |
| EXPORT_SYMBOL(blk_requeue_request); |
| |
| /** |
| * blk_insert_request - insert a special request in to a request queue |
| * @q: request queue where request should be inserted |
| * @rq: request to be inserted |
| * @at_head: insert request at head or tail of queue |
| * @data: private data |
| * |
| * Description: |
| * Many block devices need to execute commands asynchronously, so they don't |
| * block the whole kernel from preemption during request execution. This is |
| * accomplished normally by inserting aritficial requests tagged as |
| * REQ_SPECIAL in to the corresponding request queue, and letting them be |
| * scheduled for actual execution by the request queue. |
| * |
| * We have the option of inserting the head or the tail of the queue. |
| * Typically we use the tail for new ioctls and so forth. We use the head |
| * of the queue for things like a QUEUE_FULL message from a device, or a |
| * host that is unable to accept a particular command. |
| */ |
| void blk_insert_request(request_queue_t *q, struct request *rq, |
| int at_head, void *data) |
| { |
| int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
| unsigned long flags; |
| |
| /* |
| * tell I/O scheduler that this isn't a regular read/write (ie it |
| * must not attempt merges on this) and that it acts as a soft |
| * barrier |
| */ |
| rq->cmd_type = REQ_TYPE_SPECIAL; |
| rq->cmd_flags |= REQ_SOFTBARRIER; |
| |
| rq->special = data; |
| |
| spin_lock_irqsave(q->queue_lock, flags); |
| |
| /* |
| * If command is tagged, release the tag |
| */ |
| if (blk_rq_tagged(rq)) |
| blk_queue_end_tag(q, rq); |
| |
| drive_stat_acct(rq, rq->nr_sectors, 1); |
| __elv_add_request(q, rq, where, 0); |
| blk_start_queueing(q); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| |
| EXPORT_SYMBOL(blk_insert_request); |
| |
| /** |
| * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage |
| * @q: request queue where request should be inserted |
| * @rq: request structure to fill |
| * @ubuf: the user buffer |
| * @len: length of user data |
| * |
| * Description: |
| * Data will be mapped directly for zero copy io, if possible. Otherwise |
| * a kernel bounce buffer is used. |
| * |
| * A matching blk_rq_unmap_user() must be issued at the end of io, while |
| * still in process context. |
| * |
| * Note: The mapped bio may need to be bounced through blk_queue_bounce() |
| * before being submitted to the device, as pages mapped may be out of |
| * reach. It's the callers responsibility to make sure this happens. The |
| * original bio must be passed back in to blk_rq_unmap_user() for proper |
| * unmapping. |
| */ |
| int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf, |
| unsigned int len) |
| { |
| unsigned long uaddr; |
| struct bio *bio; |
| int reading; |
| |
| if (len > (q->max_hw_sectors << 9)) |
| return -EINVAL; |
| if (!len || !ubuf) |
| return -EINVAL; |
| |
| reading = rq_data_dir(rq) == READ; |
| |
| /* |
| * if alignment requirement is satisfied, map in user pages for |
| * direct dma. else, set up kernel bounce buffers |
| */ |
| uaddr = (unsigned long) ubuf; |
| if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q))) |
| bio = bio_map_user(q, NULL, uaddr, len, reading); |
| else |
| bio = bio_copy_user(q, uaddr, len, reading); |
| |
| if (!IS_ERR(bio)) { |
| rq->bio = rq->biotail = bio; |
| blk_rq_bio_prep(q, rq, bio); |
| |
| rq->buffer = rq->data = NULL; |
| rq->data_len = len; |
| return 0; |
| } |
| |
| /* |
| * bio is the err-ptr |
| */ |
| return PTR_ERR(bio); |
| } |
| |
| EXPORT_SYMBOL(blk_rq_map_user); |
| |
| /** |
| * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage |
| * @q: request queue where request should be inserted |
| * @rq: request to map data to |
| * @iov: pointer to the iovec |
| * @iov_count: number of elements in the iovec |
| * |
| * Description: |
| * Data will be mapped directly for zero copy io, if possible. Otherwise |
| * a kernel bounce buffer is used. |
| * |
| * A matching blk_rq_unmap_user() must be issued at the end of io, while |
| * still in process context. |
| * |
| * Note: The mapped bio may need to be bounced through blk_queue_bounce() |
| * before being submitted to the device, as pages mapped may be out of |
| * reach. It's the callers responsibility to make sure this happens. The |
| * original bio must be passed back in to blk_rq_unmap_user() for proper |
| * unmapping. |
| */ |
| int blk_rq_map_user_iov(request_queue_t *q, struct request *rq, |
| struct sg_iovec *iov, int iov_count) |
| { |
| struct bio *bio; |
| |
| if (!iov || iov_count <= 0) |
| return -EINVAL; |
| |
| /* we don't allow misaligned data like bio_map_user() does. If the |
| * user is using sg, they're expected to know the alignment constraints |
| * and respect them accordingly */ |
| bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ); |
| if (IS_ERR(bio)) |
| return PTR_ERR(bio); |
| |
| rq->bio = rq->biotail = bio; |
| blk_rq_bio_prep(q, rq, bio); |
| rq->buffer = rq->data = NULL; |
| rq->data_len = bio->bi_size; |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(blk_rq_map_user_iov); |
| |
| /** |
| * blk_rq_unmap_user - unmap a request with user data |
| * @bio: bio to be unmapped |
| * @ulen: length of user buffer |
| * |
| * Description: |
| * Unmap a bio previously mapped by blk_rq_map_user(). |
| */ |
| int blk_rq_unmap_user(struct bio *bio, unsigned int ulen) |
| { |
| int ret = 0; |
| |
| if (bio) { |
| if (bio_flagged(bio, BIO_USER_MAPPED)) |
| bio_unmap_user(bio); |
| else |
| ret = bio_uncopy_user(bio); |
| } |
| |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(blk_rq_unmap_user); |
| |
| /** |
| * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage |
| * @q: request queue where request should be inserted |
| * @rq: request to fill |
| * @kbuf: the kernel buffer |
| * @len: length of user data |
| * @gfp_mask: memory allocation flags |
| */ |
| int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf, |
| unsigned int len, gfp_t gfp_mask) |
| { |
| struct bio *bio; |
| |
| if (len > (q->max_hw_sectors << 9)) |
| return -EINVAL; |
| if (!len || !kbuf) |
| return -EINVAL; |
| |
| bio = bio_map_kern(q, kbuf, len, gfp_mask); |
| if (IS_ERR(bio)) |
| return PTR_ERR(bio); |
| |
| if (rq_data_dir(rq) == WRITE) |
| bio->bi_rw |= (1 << BIO_RW); |
| |
| rq->bio = rq->biotail = bio; |
| blk_rq_bio_prep(q, rq, bio); |
| |
| rq->buffer = rq->data = NULL; |
| rq->data_len = len; |
| return 0; |
| } |
| |
| EXPORT_SYMBOL(blk_rq_map_kern); |
| |
| /** |
| * blk_execute_rq_nowait - insert a request into queue for execution |
| * @q: queue to insert the request in |
| * @bd_disk: matching gendisk |
| * @rq: request to insert |
| * @at_head: insert request at head or tail of queue |
| * @done: I/O completion handler |
| * |
| * Description: |
| * Insert a fully prepared request at the back of the io scheduler queue |
| * for execution. Don't wait for completion. |
| */ |
| void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk, |
| struct request *rq, int at_head, |
| rq_end_io_fn *done) |
| { |
| int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
| |
| rq->rq_disk = bd_disk; |
| rq->cmd_flags |= REQ_NOMERGE; |
| rq->end_io = done; |
| WARN_ON(irqs_disabled()); |
| spin_lock_irq(q->queue_lock); |
| __elv_add_request(q, rq, where, 1); |
| __generic_unplug_device(q); |
| spin_unlock_irq(q->queue_lock); |
| } |
| EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); |
| |
| /** |
| * blk_execute_rq - insert a request into queue for execution |
| * @q: queue to insert the request in |
| * @bd_disk: matching gendisk |
| * @rq: request to insert |
| * @at_head: insert request at head or tail of queue |
| * |
| * Description: |
| * Insert a fully prepared request at the back of the io scheduler queue |
| * for execution and wait for completion. |
| */ |
| int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk, |
| struct request *rq, int at_head) |
| { |
| DECLARE_COMPLETION_ONSTACK(wait); |
| char sense[SCSI_SENSE_BUFFERSIZE]; |
| int err = 0; |
| |
| /* |
| * we need an extra reference to the request, so we can look at |
| * it after io completion |
| */ |
| rq->ref_count++; |
| |
| if (!rq->sense) { |
| memset(sense, 0, sizeof(sense)); |
| rq->sense = sense; |
| rq->sense_len = 0; |
| } |
| |
| rq->end_io_data = &wait; |
| blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); |
| wait_for_completion(&wait); |
| |
| if (rq->errors) |
| err = -EIO; |
| |
| return err; |
| } |
| |
| EXPORT_SYMBOL(blk_execute_rq); |
| |
| /** |
| * blkdev_issue_flush - queue a flush |
| * @bdev: blockdev to issue flush for |
| * @error_sector: error sector |
| * |
| * Description: |
| * Issue a flush for the block device in question. Caller can supply |
| * room for storing the error offset in case of a flush error, if they |
| * wish to. Caller must run wait_for_completion() on its own. |
| */ |
| int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector) |
| { |
| request_queue_t *q; |
| |
| if (bdev->bd_disk == NULL) |
| return -ENXIO; |
| |
| q = bdev_get_queue(bdev); |
| if (!q) |
| return -ENXIO; |
| if (!q->issue_flush_fn) |
| return -EOPNOTSUPP; |
| |
| return q->issue_flush_fn(q, bdev->bd_disk, error_sector); |
| } |
| |
| EXPORT_SYMBOL(blkdev_issue_flush); |
| |
| static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io) |
| { |
| int rw = rq_data_dir(rq); |
| |
| if (!blk_fs_request(rq) || !rq->rq_disk) |
| return; |
| |
| if (!new_io) { |
| __disk_stat_inc(rq->rq_disk, merges[rw]); |
| } else { |
| disk_round_stats(rq->rq_disk); |
| rq->rq_disk->in_flight++; |
| } |
| } |
| |
| /* |
| * add-request adds a request to the linked list. |
| * queue lock is held and interrupts disabled, as we muck with the |
| * request queue list. |
| */ |
| static inline void add_request(request_queue_t * q, struct request * req) |
| { |
| drive_stat_acct(req, req->nr_sectors, 1); |
| |
| if (q->activity_fn) |
| q->activity_fn(q->activity_data, rq_data_dir(req)); |
| |
| /* |
| * elevator indicated where it wants this request to be |
| * inserted at elevator_merge time |
| */ |
| __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); |
| } |
| |
| /* |
| * disk_round_stats() - Round off the performance stats on a struct |
| * disk_stats. |
| * |
| * The average IO queue length and utilisation statistics are maintained |
| * by observing the current state of the queue length and the amount of |
| * time it has been in this state for. |
| * |
| * Normally, that accounting is done on IO completion, but that can result |
| * in more than a second's worth of IO being accounted for within any one |
| * second, leading to >100% utilisation. To deal with that, we call this |
| * function to do a round-off before returning the results when reading |
| * /proc/diskstats. This accounts immediately for all queue usage up to |
| * the current jiffies and restarts the counters again. |
| */ |
| void disk_round_stats(struct gendisk *disk) |
| { |
| unsigned long now = jiffies; |
| |
| if (now == disk->stamp) |
| return; |
| |
| if (disk->in_flight) { |
| __disk_stat_add(disk, time_in_queue, |
| disk->in_flight * (now - disk->stamp)); |
| __disk_stat_add(disk, io_ticks, (now - disk->stamp)); |
| } |
| disk->stamp = now; |
| } |
| |
| EXPORT_SYMBOL_GPL(disk_round_stats); |
| |
| /* |
| * queue lock must be held |
| */ |
| void __blk_put_request(request_queue_t *q, struct request *req) |
| { |
| if (unlikely(!q)) |
| return; |
| if (unlikely(--req->ref_count)) |
| return; |
| |
| elv_completed_request(q, req); |
| |
| /* |
| * Request may not have originated from ll_rw_blk. if not, |
| * it didn't come out of our reserved rq pools |
| */ |
| if (req->cmd_flags & REQ_ALLOCED) { |
| int rw = rq_data_dir(req); |
| int priv = req->cmd_flags & REQ_ELVPRIV; |
| |
| BUG_ON(!list_empty(&req->queuelist)); |
| BUG_ON(!hlist_unhashed(&req->hash)); |
| |
| blk_free_request(q, req); |
| freed_request(q, rw, priv); |
| } |
| } |
| |
| EXPORT_SYMBOL_GPL(__blk_put_request); |
| |
| void blk_put_request(struct request *req) |
| { |
| unsigned long flags; |
| request_queue_t *q = req->q; |
| |
| /* |
| * Gee, IDE calls in w/ NULL q. Fix IDE and remove the |
| * following if (q) test. |
| */ |
| if (q) { |
| spin_lock_irqsave(q->queue_lock, flags); |
| __blk_put_request(q, req); |
| spin_unlock_irqrestore(q->queue_lock, flags); |
| } |
| } |
| |
| EXPORT_SYMBOL(blk_put_request); |
| |
| /** |
| * blk_end_sync_rq - executes a completion event on a request |
| * @rq: request to complete |
| * @error: end io status of the request |
| */ |
| void blk_end_sync_rq(struct request *rq, int error) |
| { |
| struct completion *waiting = rq->end_io_data; |
| |
| rq->end_io_data = NULL; |
| __blk_put_request(rq->q, rq); |
| |
| /* |
| * complete last, if this is a stack request the process (and thus |
| * the rq pointer) could be invalid right after this complete() |
| */ |
| complete(waiting); |
| } |
| EXPORT_SYMBOL(blk_end_sync_rq); |
| |
| /* |
| * Has to be called with the request spinlock acquired |
| */ |
| static int attempt_merge(request_queue_t *q, struct request *req, |
| struct request *next) |
| { |
| if (!rq_mergeable(req) || !rq_mergeable(next)) |
| return 0; |
| |
| /* |
| * not contiguous |
| */ |
| if (req->sector + req->nr_sectors != next->sector) |
| return 0; |
| |
| if (rq_data_dir(req) != rq_data_dir(next) |
| || req->rq_disk != next->rq_disk |
| || next->special) |
| return 0; |
| |
| /* |
| * If we are allowed to merge, then append bio list |
| * from next to rq and release next. merge_requests_fn |
| * will have updated segment counts, update sector |
| * counts here. |
| */ |
| if (!q->merge_requests_fn(q, req, next)) |
| return 0; |
| |
| /* |
| * At this point we have either done a back merge |
| * or front merge. We need the smaller start_time of |
| * the merged requests to be the current request |
| * for accounting purposes. |
| */ |
| if (time_after(req->start_time, next->start_time)) |
| req->start_time = next->start_time; |
| |
| req->biotail->bi_next = next->bio; |
| req->biotail = next->biotail; |
| |
| req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors; |
| |
| elv_merge_requests(q, req, next); |
| |
| if (req->rq_disk) { |
| disk_round_stats(req->rq_disk); |
| req->rq_disk->in_flight--; |
| } |
| |
| req->ioprio = ioprio_best(req->ioprio, next->ioprio); |
| |
| __blk_put_request(q, next); |
| return 1; |
| } |
| |
| static inline int attempt_back_merge(request_queue_t *q, struct request *rq) |
| { |
| struct request *next = elv_latter_request(q, rq); |
| |
| if (next) |
| return attempt_merge(q, rq, next); |
| |
| return 0; |
| } |
| |
| static inline int attempt_front_merge(request_queue_t *q, struct request *rq) |
| { |
| struct request *prev = elv_former_request(q, rq); |
| |
| if (prev) |
| return attempt_merge(q, prev, rq); |
| |
| return 0; |
| } |
| |
| static void init_request_from_bio(struct request *req, struct bio *bio) |
| { |
| req->cmd_type = REQ_TYPE_FS; |
| |
| /* |
| * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST) |
| */ |
| if (bio_rw_ahead(bio) || bio_failfast(bio)) |
| req->cmd_flags |= REQ_FAILFAST; |
| |
| /* |
| * REQ_BARRIER implies no merging, but lets make it explicit |
| */ |
| if (unlikely(bio_barrier(bio))) |
| req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE); |
| |
| if (bio_sync(bio)) |
| req->cmd_flags |= REQ_RW_SYNC; |
| if (bio_rw_meta(bio)) |
| req->cmd_flags |= REQ_RW_META; |
| |
| req->errors = 0; |
| req->hard_sector = req->sector = bio->bi_sector; |
| req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio); |
| req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio); |
| req->nr_phys_segments = bio_phys_segments(req->q, bio); |
| req->nr_hw_segments = bio_hw_segments(req->q, bio); |
| req->buffer = bio_data(bio); /* see ->buffer comment above */ |
| req->bio = req->biotail = bio; |
| req->ioprio = bio_prio(bio); |
| req->rq_disk = bio->bi_bdev->bd_disk; |
| req->start_time = jiffies; |
| } |
| |
| static int __make_request(request_queue_t *q, struct bio *bio) |
| { |
| struct request *req; |
| int el_ret, nr_sectors, barrier, err; |
| const unsigned short prio = bio_prio(bio); |
| const int sync = bio_sync(bio); |
| |
| nr_sectors = bio_sectors(bio); |
| |
| /* |
| * low level driver can indicate that it wants pages above a |
| * certain limit bounced to low memory (ie for highmem, or even |
| * ISA dma in theory) |
| */ |
| blk_queue_bounce(q, &bio); |
| |
| barrier = bio_barrier(bio); |
| if (unlikely(barrier) && (q->next_ordered == QUEUE_ORDERED_NONE)) { |
| err = -EOPNOTSUPP; |
| goto end_io; |
| } |
| |
| spin_lock_irq(q->queue_lock); |
| |
| if (unlikely(barrier) || elv_queue_empty(q)) |
| goto get_rq; |
| |
| el_ret = elv_merge(q, &req, bio); |
| switch (el_ret) { |
| case ELEVATOR_BACK_MERGE: |
| BUG_ON(!rq_mergeable(req)); |
| |
| if (!q->back_merge_fn(q, req, bio)) |
| break; |
| |
| blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE); |
| |
| req->biotail->bi_next = bio; |
| req->biotail = bio; |
| req->nr_sectors = req->hard_nr_sectors += nr_sectors; |
| req->ioprio = ioprio_best(req->ioprio, prio); |
| drive_stat_acct(req, nr_sectors, 0); |
| if (!attempt_back_merge(q, req)) |
| elv_merged_request(q, req, el_ret); |
| goto out; |
| |
| case ELEVATOR_FRONT_MERGE: |
| BUG_ON(!rq_mergeable(req)); |
| |
| if (!q->front_merge_fn(q, req, bio)) |
| break; |
| |
| blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE); |
| |
| bio->bi_next = req->bio; |
| req->bio = bio; |
| |
| /* |
| * may not be valid. if the low level driver said |
| * it didn't need a bounce buffer then it better |
| * not touch req->buffer either... |
| */ |
| req->buffer = bio_data(bio); |
| req->current_nr_sectors = bio_cur_sectors(bio); |
| req->hard_cur_sectors = req->current_nr_sectors; |
| req->sector = req->hard_sector = bio->bi_sector; |
| req->nr_sectors = req->hard_nr_sectors += nr_sectors; |
| req->ioprio = ioprio_best(req->ioprio, prio); |
| drive_stat_acct(req, nr_sectors, 0); |
| if (!attempt_front_merge(q, req)) |
| elv_merged_request(q, req, el_ret); |
| goto out; |
| |
| /* ELV_NO_MERGE: elevator says don't/can't merge. */ |
| default: |
| ; |
| } |
| |
| get_rq: |
| /* |
| * Grab a free request. This is might sleep but can not fail. |
| * Returns with the queue unlocked. |
| */ |
| req = get_request_wait(q, bio_data_dir(bio), 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. |
| */ |
| init_request_from_bio(req, bio); |
| |
| spin_lock_irq(q->queue_lock); |
| if (elv_queue_empty(q)) |
| blk_plug_device(q); |
| add_request(q, req); |
| out: |
| if (sync) |
| __generic_unplug_device(q); |
| |
| spin_unlock_irq(q->queue_lock); |
| return 0; |
| |
| end_io: |
| bio_endio(bio, nr_sectors << 9, err); |
| return 0; |
| } |
| |
| /* |
| * If bio->bi_dev is a partition, remap the location |
| */ |
| static inline void blk_partition_remap(struct bio *bio) |
| { |
| struct block_device *bdev = bio->bi_bdev; |
| |
| if (bdev != bdev->bd_contains) { |
| struct hd_struct *p = bdev->bd_part; |
| const int rw = bio_data_dir(bio); |
| |
| p->sectors[rw] += bio_sectors(bio); |
| p->ios[rw]++; |
| |
| bio->bi_sector += p->start_sect; |
| bio->bi_bdev = bdev->bd_contains; |
| } |
| } |
| |
| static void handle_bad_sector(struct bio *bio) |
| { |
| char b[BDEVNAME_SIZE]; |
| |
| printk(KERN_INFO "attempt to access beyond end of device\n"); |
| printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", |
| bdevname(bio->bi_bdev, b), |
| bio->bi_rw, |
| (unsigned long long)bio->bi_sector + bio_sectors(bio), |
| (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); |
| |
| set_bit(BIO_EOF, &bio->bi_flags); |
| } |
| |
| /** |
| * generic_make_request: hand a buffer to its device driver for I/O |
| * @bio: The bio describing the location in memory and on the device. |
| * |
| * generic_make_request() is used to make I/O requests of block |
| * devices. It is passed a &struct bio, which describes the I/O that needs |
| * to be done. |
| * |
| * generic_make_request() does not return any status. The |
| * success/failure status of the request, along with notification of |
| * completion, is delivered asynchronously through the bio->bi_end_io |
| * function described (one day) else where. |
| * |
| * The caller of generic_make_request must make sure that bi_io_vec |
| * are set to describe the memory buffer, and that bi_dev and bi_sector are |
| * set to describe the device address, and the |
| * bi_end_io and optionally bi_private are set to describe how |
| * completion notification should be signaled. |
| * |
| * generic_make_request and the drivers it calls may use bi_next if this |
| * bio happens to be merged with someone else, and may change bi_dev and |
| * bi_sector for remaps as it sees fit. So the values of these fields |
| * should NOT be depended on after the call to generic_make_request. |
| */ |
| void generic_make_request(struct bio *bio) |
| { |
| request_queue_t *q; |
| sector_t maxsector; |
| sector_t old_sector; |
| int ret, nr_sectors = bio_sectors(bio); |
| dev_t old_dev; |
| |
| might_sleep(); |
| /* Test device or partition size, when known. */ |
| maxsector = bio->bi_bdev->bd_inode->i_size >> 9; |
| if (maxsector) { |
| sector_t sector = bio->bi_sector; |
| |
| if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { |
| /* |
| * This may well happen - the kernel calls bread() |
| * without checking the size of the device, e.g., when |
| * mounting a device. |
| */ |
| handle_bad_sector(bio); |
| goto end_io; |
| } |
| } |
| |
| /* |
| * Resolve the mapping until finished. (drivers are |
| * still free to implement/resolve their own stacking |
| * by explicitly returning 0) |
| * |
| * NOTE: we don't repeat the blk_size check for each new device. |
| * Stacking drivers are expected to know what they are doing. |
| */ |
| old_sector = -1; |
| old_dev = 0; |
| do { |
| char b[BDEVNAME_SIZE]; |
| |
| q = bdev_get_queue(bio->bi_bdev); |
| if (!q) { |
| printk(KERN_ERR |
| "generic_make_request: Trying to access " |
| "nonexistent block-device %s (%Lu)\n", |
| bdevname(bio->bi_bdev, b), |
| (long long) bio->bi_sector); |
| end_io: |
| bio_endio(bio, bio->bi_size, -EIO); |
| break; |
| } |
| |
| if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) { |
| printk("bio too big device %s (%u > %u)\n", |
| bdevname(bio->bi_bdev, b), |
| bio_sectors(bio), |
| q->max_hw_sectors); |
| goto end_io; |
| } |
| |
| if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) |
| goto end_io; |
| |
| /* |
| * If this device has partitions, remap block n |
| * of partition p to block n+start(p) of the disk. |
| */ |
| blk_partition_remap(bio); |
| |
| if (old_sector != -1) |
| blk_add_trace_remap(q, bio, old_dev, bio->bi_sector, |
| old_sector); |
| |
| blk_add_trace_bio(q, bio, BLK_TA_QUEUE); |
| |
| old_sector = bio->bi_sector; |
| old_dev = bio->bi_bdev->bd_dev; |
| |
| maxsector = bio->bi_bdev->bd_inode->i_size >> 9; |
| if (maxsector) { |
| sector_t sector = bio->bi_sector; |
| |
| if (maxsector < nr_sectors || |
| maxsector - nr_sectors < sector) { |
| /* |
| * This may well happen - partitions are not |
| * checked to make sure they are within the size |
| * of the whole device. |
| */ |
| handle_bad_sector(bio); |
| goto end_io; |
| } |
| } |
| |
| ret = q->make_request_fn(q, bio); |
| } while (ret); |
| } |
| |
| EXPORT_SYMBOL(generic_make_request); |
| |
| /** |
| * submit_bio: submit a bio to the block device layer for I/O |
| * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) |
| * @bio: The &struct bio which describes the I/O |
| * |
| * submit_bio() is very similar in purpose to generic_make_request(), and |
| * uses that function to do most of the work. Both are fairly rough |
| * interfaces, @bio must be presetup and ready for I/O. |
| * |
| */ |
| void submit_bio(int rw, struct bio *bio) |
| { |
| int count = bio_sectors(bio); |
| |
| BIO_BUG_ON(!bio->bi_size); |
| BIO_BUG_ON(!bio->bi_io_vec); |
| bio->bi_rw |= rw; |
| if (rw & WRITE) |
| count_vm_events(PGPGOUT, count); |
| else |
| count_vm_events(PGPGIN, count); |
| |
| if (unlikely(block_dump)) { |
| char b[BDEVNAME_SIZE]; |
| printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n", |
| current->comm, current->pid, |
| (rw & WRITE) ? "WRITE" : "READ", |
| (unsigned long long)bio->bi_sector, |
| bdevname(bio->bi_bdev,b)); |
| } |
| |
| generic_make_request(bio); |
| } |
| |
| EXPORT_SYMBOL(submit_bio); |
| |
| static void blk_recalc_rq_segments(struct request *rq) |
| { |
| struct bio *bio, *prevbio = NULL; |
| int nr_phys_segs, nr_hw_segs; |
| unsigned int phys_size, hw_size; |
| request_queue_t *q = rq->q; |
| |
| if (!rq->bio) |
| return; |
| |
| phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; |
| rq_for_each_bio(bio, rq) { |
| /* Force bio hw/phys segs to be recalculated. */ |
| bio->bi_flags &= ~(1 << BIO_SEG_VALID); |
| |
| nr_phys_segs += bio_phys_segments(q, bio); |
| nr_hw_segs += bio_hw_segments(q, bio); |
| if (prevbio) { |
| int pseg = phys_size + prevbio->bi_size + bio->bi_size; |
| int hseg = hw_size + prevbio->bi_size + bio->bi_size; |
| |
| if (blk_phys_contig_segment(q, prevbio, bio) && |
| pseg <= q->max_segment_size) { |
| nr_phys_segs--; |
| phys_size += prevbio->bi_size + bio->bi_size; |
| } else |
| phys_size = 0; |
| |
| if (blk_hw_contig_segment(q, prevbio, bio) && |
| hseg <= q->max_segment_size) { |
| nr_hw_segs--; |
| hw_size += prevbio->bi_size + bio->bi_size; |
| } else |
| hw_size = 0; |
| } |
| prevbio = bio; |
| } |
| |
| rq->nr_phys_segments = nr_phys_segs; |
| rq->nr_hw_segments = nr_hw_segs; |
| } |
| |
| static void blk_recalc_rq_sectors(struct request *rq, int nsect) |
| { |
| if (blk_fs_request(rq)) { |
| rq->hard_sector += nsect; |
| rq->hard_nr_sectors -= nsect; |
| |
| /* |
| * Move the I/O submission pointers ahead if required. |
| */ |
| if ((rq->nr_sectors >= rq->hard_nr_sectors) && |
| (rq->sector <= rq->hard_sector)) { |
| rq->sector = rq->hard_sector; |
| rq->nr_sectors = rq->hard_nr_sectors; |
| rq->hard_cur_sectors = bio_cur_sectors(rq->bio); |
| rq->current_nr_sectors = rq->hard_cur_sectors; |
| rq->buffer = bio_data(rq->bio); |
| } |
| |
| /* |
| * if total number of sectors is less than the first segment |
| * size, something has gone terribly wrong |
| */ |
| if (rq->nr_sectors < rq->current_nr_sectors) { |
| printk("blk: request botched\n"); |
| rq->nr_sectors = rq->current_nr_sectors; |
| } |
| } |
| } |
| |
| static int __end_that_request_first(struct request *req, int uptodate, |
| int nr_bytes) |
| { |
| int total_bytes, bio_nbytes, error, next_idx = 0; |
| struct bio *bio; |
| |
| blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE); |
| |
| /* |
| * extend uptodate bool to allow < 0 value to be direct io error |
| */ |
| error = 0; |
| if (end_io_error(uptodate)) |
| error = !uptodate ? -EIO : uptodate; |
| |
| /* |
| * for a REQ_BLOCK_PC request, we want to carry any eventual |
| * sense key with us all the way through |
| */ |
| if (!blk_pc_request(req)) |
| req->errors = 0; |
| |
| if (!uptodate) { |
| if (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET)) |
| printk("end_request: I/O error, dev %s, sector %llu\n", |
| req->rq_disk ? req->rq_disk->disk_name : "?", |
| (unsigned long long)req->sector); |
| } |
| |
| if (blk_fs_request(req) && req->rq_disk) { |
| const int rw = rq_data_dir(req); |
| |
| disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9); |
| } |
| |
| total_bytes = bio_nbytes = 0; |
| while ((bio = req->bio) != NULL) { |
| int nbytes; |
| |
| if (nr_bytes >= bio->bi_size) { |
| req->bio = bio->bi_next; |
| nbytes = bio->bi_size; |
| if (!ordered_bio_endio(req, bio, nbytes, error)) |
| bio_endio(bio, nbytes, error); |
| next_idx = 0; |
| bio_nbytes = 0; |
| } else { |
| int idx = bio->bi_idx + next_idx; |
| |
| if (unlikely(bio->bi_idx >= bio->bi_vcnt)) { |
| blk_dump_rq_flags(req, "__end_that"); |
| printk("%s: bio idx %d >= vcnt %d\n", |
| __FUNCTION__, |
| bio->bi_idx, bio->bi_vcnt); |
| break; |
| } |
| |
| nbytes = bio_iovec_idx(bio, idx)->bv_len; |
| BIO_BUG_ON(nbytes > bio->bi_size); |
| |
| /* |
| * not a complete bvec done |
| */ |
| if (unlikely(nbytes > nr_bytes)) { |
| bio_nbytes += nr_bytes; |
| total_bytes += nr_bytes; |
| break; |
| } |
| |
| /* |
| * advance to the next vector |
| */ |
| next_idx++; |
| bio_nbytes += nbytes; |
| } |
| |
| total_bytes += nbytes; |
| nr_bytes -= nbytes; |
| |
| if ((bio = req->bio)) { |
| /* |
| * end more in this run, or just return 'not-done' |
|
|