/* * linux/drivers/block/ll_rw_blk.c * * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 1994, Karl Keyte: Added support for disk statistics * Elevator latency, (C) 2000 Andrea Arcangeli SuSE * Queue request tables / lock, selectable elevator, Jens Axboe * kernel-doc documentation started by NeilBrown - July2000 * bio rewrite, highmem i/o, etc, Jens Axboe - may 2001 */ /* * This handles all read/write requests to block devices */ #include #include #include #include #include #include #include #include #include #include #include #include /* for max_pfn/max_low_pfn */ #include #include #include #include #include /* * for max sense size */ #include 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); /* * 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; static wait_queue_head_t congestion_wqh[2] = { __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) }; /* * 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); /* 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; } /* * A queue has just exitted congestion. Note this in the global counter of * congested queues, and wake up anyone who was waiting for requests to be * put back. */ static void clear_queue_congested(request_queue_t *q, int rw) { enum bdi_state bit; wait_queue_head_t *wqh = &congestion_wqh[rw]; bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; clear_bit(bit, &q->backing_dev_info.state); smp_mb__after_clear_bit(); if (waitqueue_active(wqh)) wake_up(wqh); } /* * A queue has just entered congestion. Flag that in the queue's VM-visible * state flags and increment the global gounter of congested queues. */ static void set_queue_congested(request_queue_t *q, int rw) { enum bdi_state bit; bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; set_bit(bit, &q->backing_dev_info.state); } /** * 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); /** * 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, 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 inline void rq_init(request_queue_t *q, struct request *rq) { INIT_LIST_HEAD(&rq->queuelist); rq->errors = 0; rq->rq_status = RQ_ACTIVE; rq->bio = rq->biotail = NULL; rq->ioprio = 0; rq->buffer = NULL; rq->ref_count = 1; rq->q = q; rq->waiting = NULL; 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; } /** * blk_queue_ordered - does this queue support ordered writes * @q: the request queue * @flag: see below * * 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. * **/ void blk_queue_ordered(request_queue_t *q, int flag) { switch (flag) { case QUEUE_ORDERED_NONE: if (q->flush_rq) kmem_cache_free(request_cachep, q->flush_rq); q->flush_rq = NULL; q->ordered = flag; break; case QUEUE_ORDERED_TAG: q->ordered = flag; break; case QUEUE_ORDERED_FLUSH: q->ordered = flag; if (!q->flush_rq) q->flush_rq = kmem_cache_alloc(request_cachep, GFP_KERNEL); break; default: printk("blk_queue_ordered: bad value %d\n", flag); break; } } 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 */ static void blk_pre_flush_end_io(struct request *flush_rq) { struct request *rq = flush_rq->end_io_data; request_queue_t *q = rq->q; elv_completed_request(q, flush_rq); rq->flags |= REQ_BAR_PREFLUSH; if (!flush_rq->errors) elv_requeue_request(q, rq); else { q->end_flush_fn(q, flush_rq); clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); q->request_fn(q); } } static void blk_post_flush_end_io(struct request *flush_rq) { struct request *rq = flush_rq->end_io_data; request_queue_t *q = rq->q; elv_completed_request(q, flush_rq); rq->flags |= REQ_BAR_POSTFLUSH; q->end_flush_fn(q, flush_rq); clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); q->request_fn(q); } struct request *blk_start_pre_flush(request_queue_t *q, struct request *rq) { struct request *flush_rq = q->flush_rq; BUG_ON(!blk_barrier_rq(rq)); if (test_and_set_bit(QUEUE_FLAG_FLUSH, &q->queue_flags)) return NULL; rq_init(q, flush_rq); flush_rq->elevator_private = NULL; flush_rq->flags = REQ_BAR_FLUSH; flush_rq->rq_disk = rq->rq_disk; flush_rq->rl = NULL; /* * prepare_flush returns 0 if no flush is needed, just mark both * pre and post flush as done in that case */ if (!q->prepare_flush_fn(q, flush_rq)) { rq->flags |= REQ_BAR_PREFLUSH | REQ_BAR_POSTFLUSH; clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); return rq; } /* * some drivers dequeue requests right away, some only after io * completion. make sure the request is dequeued. */ if (!list_empty(&rq->queuelist)) blkdev_dequeue_request(rq); flush_rq->end_io_data = rq; flush_rq->end_io = blk_pre_flush_end_io; __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0); return flush_rq; } static void blk_start_post_flush(request_queue_t *q, struct request *rq) { struct request *flush_rq = q->flush_rq; BUG_ON(!blk_barrier_rq(rq)); rq_init(q, flush_rq); flush_rq->elevator_private = NULL; flush_rq->flags = REQ_BAR_FLUSH; flush_rq->rq_disk = rq->rq_disk; flush_rq->rl = NULL; if (q->prepare_flush_fn(q, flush_rq)) { flush_rq->end_io_data = rq; flush_rq->end_io = blk_post_flush_end_io; __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0); q->request_fn(q); } } static inline int blk_check_end_barrier(request_queue_t *q, struct request *rq, int sectors) { if (sectors > rq->nr_sectors) sectors = rq->nr_sectors; rq->nr_sectors -= sectors; return rq->nr_sectors; } static int __blk_complete_barrier_rq(request_queue_t *q, struct request *rq, int sectors, int queue_locked) { if (q->ordered != QUEUE_ORDERED_FLUSH) return 0; if (!blk_fs_request(rq) || !blk_barrier_rq(rq)) return 0; if (blk_barrier_postflush(rq)) return 0; if (!blk_check_end_barrier(q, rq, sectors)) { unsigned long flags = 0; if (!queue_locked) spin_lock_irqsave(q->queue_lock, flags); blk_start_post_flush(q, rq); if (!queue_locked) spin_unlock_irqrestore(q->queue_lock, flags); } return 1; } /** * blk_complete_barrier_rq - complete possible barrier request * @q: the request queue for the device * @rq: the request * @sectors: number of sectors to complete * * Description: * Used in driver end_io handling to determine whether to postpone * completion of a barrier request until a post flush has been done. This * is the unlocked variant, used if the caller doesn't already hold the * queue lock. **/ int blk_complete_barrier_rq(request_queue_t *q, struct request *rq, int sectors) { return __blk_complete_barrier_rq(q, rq, sectors, 0); } EXPORT_SYMBOL(blk_complete_barrier_rq); /** * blk_complete_barrier_rq_locked - complete possible barrier request * @q: the request queue for the device * @rq: the request * @sectors: number of sectors to complete * * Description: * See blk_complete_barrier_rq(). This variant must be used if the caller * holds the queue lock. **/ int blk_complete_barrier_rq_locked(request_queue_t *q, struct request *rq, int sectors) { return __blk_complete_barrier_rq(q, rq, sectors, 1); } EXPORT_SYMBOL(blk_complete_barrier_rq_locked); /** * 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. By default * the block layer sets this to the highest numbered "low" memory page. **/ void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr) { unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; /* * set appropriate bounce gfp mask -- unfortunately we don't have a * full 4GB zone, so we have to resort to low memory for any bounces. * ISA has its own < 16MB zone. */ if (bounce_pfn < blk_max_low_pfn) { BUG_ON(dma_addr < BLK_BOUNCE_ISA); init_emergency_isa_pool(); q->bounce_gfp = GFP_NOIO | GFP_DMA; } else q->bounce_gfp = GFP_NOIO; 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 short 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); } q->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 = t->max_hw_sectors = min_not_zero(t->max_sectors,b->max_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); } 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) { struct blk_queue_tag *bqt = q->queue_tags; if (unlikely(bqt == NULL || tag >= bqt->real_max_depth)) return NULL; return bqt->tag_index[tag]; } EXPORT_SYMBOL(blk_queue_find_tag); /** * __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; if (atomic_dec_and_test(&bqt->refcnt)) { BUG_ON(bqt->busy); BUG_ON(!list_empty(&bqt->busy_list)); kfree(bqt->tag_index); bqt->tag_index = NULL; kfree(bqt->tag_map); bqt->tag_map = NULL; kfree(bqt); } q->queue_tags = NULL; q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED); } /** * 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 (depth > q->nr_requests * 2) { depth = q->nr_requests * 2; printk(KERN_ERR "%s: adjusted depth to %d\n", __FUNCTION__, depth); } tag_index = kmalloc(depth * sizeof(struct request *), GFP_ATOMIC); if (!tag_index) goto fail; nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG; tag_map = kmalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC); if (!tag_map) goto fail; memset(tag_index, 0, depth * sizeof(struct request *)); memset(tag_map, 0, nr_ulongs * sizeof(unsigned long)); 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; } /** * 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 = 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); } 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; } /* * 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->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->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(); } tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); if (tag >= bqt->max_depth) return 1; __set_bit(tag, bqt->tag_map); rq->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->flags &= ~REQ_QUEUED; } else blk_queue_end_tag(q, rq); rq->flags &= ~REQ_STARTED; __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); } } EXPORT_SYMBOL(blk_queue_invalidate_tags); static char *rq_flags[] = { "REQ_RW", "REQ_FAILFAST", "REQ_SORTED", "REQ_SOFTBARRIER", "REQ_HARDBARRIER", "REQ_CMD", "REQ_NOMERGE", "REQ_STARTED", "REQ_DONTPREP", "REQ_QUEUED", "REQ_ELVPRIV", "REQ_PC", "REQ_BLOCK_PC", "REQ_SENSE", "REQ_FAILED", "REQ_QUIET", "REQ_SPECIAL", "REQ_DRIVE_CMD", "REQ_DRIVE_TASK", "REQ_DRIVE_TASKFILE", "REQ_PREEMPT", "REQ_PM_SUSPEND", "REQ_PM_RESUME", "REQ_PM_SHUTDOWN", }; void blk_dump_rq_flags(struct request *rq, char *msg) { int bit; printk("%s: dev %s: flags = ", msg, rq->rq_disk ? rq->rq_disk->disk_name : "?"); bit = 0; do { if (rq->flags & (1 << bit)) printk("%s ", rq_flags[bit]); bit++; } while (bit < __REQ_NR_BITS); 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 (rq->flags & (REQ_BLOCK_PC | REQ_PC)) { 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->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->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) { int len; if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) { req->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) { int len; if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) { req->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 (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) return; if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); } 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(test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))) 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) q->unplug_fn(q); } static void blk_unplug_work(void *data) { request_queue_t *q = data; q->unplug_fn(q); } static void blk_unplug_timeout(unsigned long data) { request_queue_t *q = (request_queue_t *)data; 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) { 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); if (!elv_queue_empty(q)) q->request_fn(q); 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 * @q: 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... **/ void blk_cleanup_queue(request_queue_t * q) { struct request_list *rl = &q->rq; if (!atomic_dec_and_test(&q->refcnt)) return; if (q->elevator) elevator_exit(q->elevator); blk_sync_queue(q); if (rl->rq_pool) mempool_destroy(rl->rq_pool); if (q->queue_tags) __blk_queue_free_tags(q); blk_queue_ordered(q, QUEUE_ORDERED_NONE); kmem_cache_free(requestq_cachep, 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; } static int __make_request(request_queue_t *, struct bio *); request_queue_t *blk_alloc_queue(int gfp_mask) { return blk_alloc_queue_node(gfp_mask, -1); } EXPORT_SYMBOL(blk_alloc_queue); request_queue_t *blk_alloc_queue_node(int 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); atomic_set(&q->refcnt, 1); q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; q->backing_dev_info.unplug_io_data = q; 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. * * 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)) goto out_init; /* * 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_cleanup_queue(q); out_init: kmem_cache_free(requestq_cachep, 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))) { atomic_inc(&q->refcnt); return 0; } return 1; } EXPORT_SYMBOL(blk_get_queue); static inline void blk_free_request(request_queue_t *q, struct request *rq) { if (rq->flags & REQ_ELVPRIV) elv_put_request(q, rq); mempool_free(rq, q->rq.rq_pool); } static inline struct request * blk_alloc_request(request_queue_t *q, int rw, struct bio *bio, int priv, int gfp_mask) { struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); if (!rq) return NULL; /* * first three bits are identical in rq->flags and bio->bi_rw, * see bio.h and blkdev.h */ rq->flags = rw; if (priv) { if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) { mempool_free(rq, q->rq.rq_pool); return NULL; } rq->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)) 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, int gfp_mask) { struct request *rq = NULL; struct request_list *rl = &q->rq; struct io_context *ioc = current_io_context(GFP_ATOMIC); int priv; if (rl->count[rw]+1 >= q->nr_requests) { /* * 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); } } switch (elv_may_queue(q, rw, bio)) { case ELV_MQUEUE_NO: goto rq_starved; case ELV_MQUEUE_MAY: break; case ELV_MQUEUE_MUST: goto get_rq; } if (blk_queue_full(q, rw) && !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; } get_rq: /* * Only allow batching queuers to allocate up to 50% over the defined * limit of requests, otherwise we could have thousands of requests * allocated with any setting of ->nr_requests */ if (rl->count[rw] >= (3 * q->nr_requests / 2)) goto out; rl->count[rw]++; rl->starved[rw] = 0; if (rl->count[rw] >= queue_congestion_on_threshold(q)) set_queue_congested(q, rw); priv = !test_bit(QUEUE_FLAG_BYPASS, &q->queue_flags); if (priv) rl->elvpriv++; spin_unlock_irq(q->queue_lock); rq = blk_alloc_request(q, rw, bio, priv, gfp_mask); if (!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; } if (ioc_batching(q, ioc)) ioc->nr_batch_requests--; rq_init(q, rq); rq->rl = rl; 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; __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); 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, int 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_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) { 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->flags |= REQ_SPECIAL | 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); if (blk_queue_plugged(q)) __generic_unplug_device(q); else q->request_fn(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_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, unsigned int gfp_mask) { struct bio *bio; if (len > (q->max_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, void (*done)(struct request *)) { int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; rq->rq_disk = bd_disk; rq->flags |= REQ_NOMERGE; rq->end_io = done; elv_add_request(q, rq, where, 1); generic_unplug_device(q); } /** * 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(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->waiting = &wait; blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); wait_for_completion(&wait); rq->waiting = NULL; 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 (rw == READ) { __disk_stat_add(rq->rq_disk, read_sectors, nr_sectors); if (!new_io) __disk_stat_inc(rq->rq_disk, read_merges); } else if (rw == WRITE) { __disk_stat_add(rq->rq_disk, write_sectors, nr_sectors); if (!new_io) __disk_stat_inc(rq->rq_disk, write_merges); } if (new_io) { 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; } /* * queue lock must be held */ static void __blk_put_request(request_queue_t *q, struct request *req) { struct request_list *rl = req->rl; if (unlikely(!q)) return; if (unlikely(--req->ref_count)) return; elv_completed_request(q, req); req->rq_status = RQ_INACTIVE; req->rl = NULL; /* * Request may not have originated from ll_rw_blk. if not, * it didn't come out of our reserved rq pools */ if (rl) { int rw = rq_data_dir(req); int priv = req->flags & REQ_ELVPRIV; BUG_ON(!list_empty(&req->queuelist)); blk_free_request(q, req); freed_request(q, rw, priv); } } 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 */ void blk_end_sync_rq(struct request *rq) { struct completion *waiting = rq->waiting; rq->waiting = 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); /** * blk_congestion_wait - wait for a queue to become uncongested * @rw: READ or WRITE * @timeout: timeout in jiffies * * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion. * If no queues are congested then just wait for the next request to be * returned. */ long blk_congestion_wait(int rw, long timeout) { long ret; DEFINE_WAIT(wait); wait_queue_head_t *wqh = &congestion_wqh[rw]; prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); ret = io_schedule_timeout(timeout); finish_wait(wqh, &wait); return ret; } EXPORT_SYMBOL(blk_congestion_wait); /* * 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 contigious */ 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->waiting || 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; } /** * blk_attempt_remerge - attempt to remerge active head with next request * @q: The &request_queue_t belonging to the device * @rq: The head request (usually) * * Description: * For head-active devices, the queue can easily be unplugged so quickly * that proper merging is not done on the front request. This may hurt * performance greatly for some devices. The block layer cannot safely * do merging on that first request for these queues, but the driver can * call this function and make it happen any way. Only the driver knows * when it is safe to do so. **/ void blk_attempt_remerge(request_queue_t *q, struct request *rq) { unsigned long flags; spin_lock_irqsave(q->queue_lock, flags); attempt_back_merge(q, rq); spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL(blk_attempt_remerge); static int __make_request(request_queue_t *q, struct bio *bio) { struct request *req; int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync; unsigned short prio; sector_t sector; sector = bio->bi_sector; nr_sectors = bio_sectors(bio); cur_nr_sectors = bio_cur_sectors(bio); prio = bio_prio(bio); rw = bio_data_dir(bio); sync = bio_sync(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); spin_lock_prefetch(q->queue_lock); barrier = bio_barrier(bio); if (unlikely(barrier) && (q->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; 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); goto out; case ELEVATOR_FRONT_MERGE: BUG_ON(!rq_mergeable(req)); if (!q->front_merge_fn(q, req, bio)) break; 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 = cur_nr_sectors; req->hard_cur_sectors = cur_nr_sectors; req->sector = req->hard_sector = 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); 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, rw, bio); /* * After dropping the lock and possibly sleeping here, our request * may now be mergeable after it had proven unmergeable (above). * We don't worry about that case for efficiency. It won't happen * often, and the elevators are able to handle it. */ req->flags |= REQ_CMD; /* * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST) */ if (bio_rw_ahead(bio) || bio_failfast(bio)) req->flags |= REQ_FAILFAST; /* * REQ_BARRIER implies no merging, but lets make it explicit */ if (unlikely(barrier)) req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE); req->errors = 0; req->hard_sector = req->sector = sector; req->hard_nr_sectors = req->nr_sectors = nr_sectors; req->current_nr_sectors = req->hard_cur_sectors = cur_nr_sectors; req->nr_phys_segments = bio_phys_segments(q, bio); req->nr_hw_segments = bio_hw_segments(q, bio); req->buffer = bio_data(bio); /* see ->buffer comment above */ req->waiting = NULL; req->bio = req->biotail = bio; req->ioprio = prio; req->rq_disk = bio->bi_bdev->bd_disk; req->start_time = jiffies; spin_lock_irq(q->queue_lock); if (elv_queue_empty(q)) blk_plug_device(q); add_request(q, req); out: if (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; switch (bio_data_dir(bio)) { case READ: p->read_sectors += bio_sectors(bio); p->reads++; break; case WRITE: p->write_sectors += bio_sectors(bio); p->writes++; break; } 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; int ret, nr_sectors = bio_sectors(bio); 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. */ 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); 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) mod_page_state(pgpgout, count); else mod_page_state(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; /* * 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->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); } 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; 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' */ if (unlikely(nr_bytes <= 0)) break; } } /* * completely done */ if (!req->bio) return 0; /* * if the request wasn't completed, update state */ if (bio_nbytes) { bio_endio(bio, bio_nbytes, error); bio->bi_idx += next_idx; bio_iovec(bio)->bv_offset += nr_bytes; bio_iovec(bio)->bv_len -= nr_bytes; } blk_recalc_rq_sectors(req, total_bytes >> 9); blk_recalc_rq_segments(req); return 1; } /** * end_that_request_first - end I/O on a request * @req: the request being processed * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error * @nr_sectors: number of sectors to end I/O on * * Description: * Ends I/O on a number of sectors attached to @req, and sets it up * for the next range of segments (if any) in the cluster. * * Return: * 0 - we are done with this request, call end_that_request_last() * 1 - still buffers pending for this request **/ int end_that_request_first(struct request *req, int uptodate, int nr_sectors) { return __end_that_request_first(req, uptodate, nr_sectors << 9); } EXPORT_SYMBOL(end_that_request_first); /** * end_that_request_chunk - end I/O on a request * @req: the request being processed * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error * @nr_bytes: number of bytes to complete * * Description: * Ends I/O on a number of bytes attached to @req, and sets it up * for the next range of segments (if any). Like end_that_request_first(), * but deals with bytes instead of sectors. * * Return: * 0 - we are done with this request, call end_that_request_last() * 1 - still buffers pending for this request **/ int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes) { return __end_that_request_first(req, uptodate, nr_bytes); } EXPORT_SYMBOL(end_that_request_chunk); /* * queue lock must be held */ void end_that_request_last(struct request *req) { struct gendisk *disk = req->rq_disk; if (unlikely(laptop_mode) && blk_fs_request(req)) laptop_io_completion(); if (disk && blk_fs_request(req)) { unsigned long duration = jiffies - req->start_time; switch (rq_data_dir(req)) { case WRITE: __disk_stat_inc(disk, writes); __disk_stat_add(disk, write_ticks, duration); break; case READ: __disk_stat_inc(disk, reads); __disk_stat_add(disk, read_ticks, duration); break; } disk_round_stats(disk); disk->in_flight--; } if (req->end_io) req->end_io(req); else __blk_put_request(req->q, req); } EXPORT_SYMBOL(end_that_request_last); void end_request(struct request *req, int uptodate) { if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) { add_disk_randomness(req->rq_disk); blkdev_dequeue_request(req); end_that_request_last(req); } } EXPORT_SYMBOL(end_request); void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio) { /* first three bits are identical in rq->flags and bio->bi_rw */ rq->flags |= (bio->bi_rw & 7); rq->nr_phys_segments = bio_phys_segments(q, bio); rq->nr_hw_segments = bio_hw_segments(q, bio); rq->current_nr_sectors = bio_cur_sectors(bio); rq->hard_cur_sectors = rq->current_nr_sectors; rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio); rq->buffer = bio_data(bio); rq->bio = rq->biotail = bio; } EXPORT_SYMBOL(blk_rq_bio_prep); int kblockd_schedule_work(struct work_struct *work) { return queue_work(kblockd_workqueue, work); } EXPORT_SYMBOL(kblockd_schedule_work); void kblockd_flush(void) { flush_workqueue(kblockd_workqueue); } EXPORT_SYMBOL(kblockd_flush); int __init blk_dev_init(void) { kblockd_workqueue = create_workqueue("kblockd"); if (!kblockd_workqueue) panic("Failed to create kblockd\n"); request_cachep = kmem_cache_create("blkdev_requests", sizeof(struct request), 0, SLAB_PANIC, NULL, NULL); requestq_cachep = kmem_cache_create("blkdev_queue", sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL); iocontext_cachep = kmem_cache_create("blkdev_ioc", sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL); blk_max_low_pfn = max_low_pfn; blk_max_pfn = max_pfn; return 0; } /* * IO Context helper functions */ void put_io_context(struct io_context *ioc) { if (ioc == NULL) return; BUG_ON(atomic_read(&ioc->refcount) == 0); if (atomic_dec_and_test(&ioc->refcount)) { if (ioc->aic && ioc->aic->dtor) ioc->aic->dtor(ioc->aic); if (ioc->cic && ioc->cic->dtor) ioc->cic->dtor(ioc->cic); kmem_cache_free(iocontext_cachep, ioc); } } EXPORT_SYMBOL(put_io_context); /* Called by the exitting task */ void exit_io_context(void) { unsigned long flags; struct io_context *ioc; local_irq_save(flags); task_lock(current); ioc = current->io_context; current->io_context = NULL; ioc->task = NULL; task_unlock(current); local_irq_restore(flags); if (ioc->aic && ioc->aic->exit) ioc->aic->exit(ioc->aic); if (ioc->cic && ioc->cic->exit) ioc->cic->exit(ioc->cic); put_io_context(ioc); } /* * If the current task has no IO context then create one and initialise it. * Otherwise, return its existing IO context. * * This returned IO context doesn't have a specifically elevated refcount, * but since the current task itself holds a reference, the context can be * used in general code, so long as it stays within `current` context. */ struct io_context *current_io_context(int gfp_flags) { struct task_struct *tsk = current; struct io_context *ret; ret = tsk->io_context; if (likely(ret)) return ret; ret = kmem_cache_alloc(iocontext_cachep, gfp_flags); if (ret) { atomic_set(&ret->refcount, 1); ret->task = current; ret->set_ioprio = NULL; ret->last_waited = jiffies; /* doesn't matter... */ ret->nr_batch_requests = 0; /* because this is 0 */ ret->aic = NULL; ret->cic = NULL; tsk->io_context = ret; } return ret; } EXPORT_SYMBOL(current_io_context); /* * If the current task has no IO context then create one and initialise it. * If it does have a context, take a ref on it. * * This is always called in the context of the task which submitted the I/O. */ struct io_context *get_io_context(int gfp_flags) { struct io_context *ret; ret = current_io_context(gfp_flags); if (likely(ret)) atomic_inc(&ret->refcount); return ret; } EXPORT_SYMBOL(get_io_context); void copy_io_context(struct io_context **pdst, struct io_context **psrc) { struct io_context *src = *psrc; struct io_context *dst = *pdst; if (src) { BUG_ON(atomic_read(&src->refcount) == 0); atomic_inc(&src->refcount); put_io_context(dst); *pdst = src; } } EXPORT_SYMBOL(copy_io_context); void swap_io_context(struct io_context **ioc1, struct io_context **ioc2) { struct io_context *temp; temp = *ioc1; *ioc1 = *ioc2; *ioc2 = temp; } EXPORT_SYMBOL(swap_io_context); /* * sysfs parts below */ struct queue_sysfs_entry { struct attribute attr; ssize_t (*show)(struct request_queue *, char *); ssize_t (*store)(struct request_queue *, const char *, size_t); }; static ssize_t queue_var_show(unsigned int var, char *page) { return sprintf(page, "%d\n", var); } static ssize_t queue_var_store(unsigned long *var, const char *page, size_t count) { char *p = (char *) page; *var = simple_strtoul(p, &p, 10); return count; } static ssize_t queue_requests_show(struct request_queue *q, char *page) { return queue_var_show(q->nr_requests, (page)); } static ssize_t queue_requests_store(struct request_queue *q, const char *page, size_t count) { struct request_list *rl = &q->rq; int ret = queue_var_store(&q->nr_requests, page, count); if (q->nr_requests < BLKDEV_MIN_RQ) q->nr_requests = BLKDEV_MIN_RQ; blk_queue_congestion_threshold(q); if (rl->count[READ] >= queue_congestion_on_threshold(q)) set_queue_congested(q, READ); else if (rl->count[READ] < queue_congestion_off_threshold(q)) clear_queue_congested(q, READ); if (rl->count[WRITE] >= queue_congestion_on_threshold(q)) set_queue_congested(q, WRITE); else if (rl->count[WRITE] < queue_congestion_off_threshold(q)) clear_queue_congested(q, WRITE); if (rl->count[READ] >= q->nr_requests) { blk_set_queue_full(q, READ); } else if (rl->count[READ]+1 <= q->nr_requests) { blk_clear_queue_full(q, READ); wake_up(&rl->wait[READ]); } if (rl->count[WRITE] >= q->nr_requests) { blk_set_queue_full(q, WRITE); } else if (rl->count[WRITE]+1 <= q->nr_requests) { blk_clear_queue_full(q, WRITE); wake_up(&rl->wait[WRITE]); } return ret; } static ssize_t queue_ra_show(struct request_queue *q, char *page) { int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); return queue_var_show(ra_kb, (page)); } static ssize_t queue_ra_store(struct request_queue *q, const char *page, size_t count) { unsigned long ra_kb; ssize_t ret = queue_var_store(&ra_kb, page, count); spin_lock_irq(q->queue_lock); if (ra_kb > (q->max_sectors >> 1)) ra_kb = (q->max_sectors >> 1); q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10); spin_unlock_irq(q->queue_lock); return ret; } static ssize_t queue_max_sectors_show(struct request_queue *q, char *page) { int max_sectors_kb = q->max_sectors >> 1; return queue_var_show(max_sectors_kb, (page)); } static ssize_t queue_max_sectors_store(struct request_queue *q, const char *page, size_t count) { unsigned long max_sectors_kb, max_hw_sectors_kb = q->max_hw_sectors >> 1, page_kb = 1 << (PAGE_CACHE_SHIFT - 10); ssize_t ret = queue_var_store(&max_sectors_kb, page, count); int ra_kb; if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb) return -EINVAL; /* * Take the queue lock to update the readahead and max_sectors * values synchronously: */ spin_lock_irq(q->queue_lock); /* * Trim readahead window as well, if necessary: */ ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); if (ra_kb > max_sectors_kb) q->backing_dev_info.ra_pages = max_sectors_kb >> (PAGE_CACHE_SHIFT - 10); q->max_sectors = max_sectors_kb << 1; spin_unlock_irq(q->queue_lock); return ret; } static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page) { int max_hw_sectors_kb = q->max_hw_sectors >> 1; return queue_var_show(max_hw_sectors_kb, (page)); } static struct queue_sysfs_entry queue_requests_entry = { .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR }, .show = queue_requests_show, .store = queue_requests_store, }; static struct queue_sysfs_entry queue_ra_entry = { .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR }, .show = queue_ra_show, .store = queue_ra_store, }; static struct queue_sysfs_entry queue_max_sectors_entry = { .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR }, .show = queue_max_sectors_show, .store = queue_max_sectors_store, }; static struct queue_sysfs_entry queue_max_hw_sectors_entry = { .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO }, .show = queue_max_hw_sectors_show, }; static struct queue_sysfs_entry queue_iosched_entry = { .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR }, .show = elv_iosched_show, .store = elv_iosched_store, }; static struct attribute *default_attrs[] = { &queue_requests_entry.attr, &queue_ra_entry.attr, &queue_max_hw_sectors_entry.attr, &queue_max_sectors_entry.attr, &queue_iosched_entry.attr, NULL, }; #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr) static ssize_t queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page) { struct queue_sysfs_entry *entry = to_queue(attr); struct request_queue *q; q = container_of(kobj, struct request_queue, kobj); if (!entry->show) return -EIO; return entry->show(q, page); } static ssize_t queue_attr_store(struct kobject *kobj, struct attribute *attr, const char *page, size_t length) { struct queue_sysfs_entry *entry = to_queue(attr); struct request_queue *q; q = container_of(kobj, struct request_queue, kobj); if (!entry->store) return -EIO; return entry->store(q, page, length); } static struct sysfs_ops queue_sysfs_ops = { .show = queue_attr_show, .store = queue_attr_store, }; static struct kobj_type queue_ktype = { .sysfs_ops = &queue_sysfs_ops, .default_attrs = default_attrs, }; int blk_register_queue(struct gendisk *disk) { int ret; request_queue_t *q = disk->queue; if (!q || !q->request_fn) return -ENXIO; q->kobj.parent = kobject_get(&disk->kobj); if (!q->kobj.parent) return -EBUSY; snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue"); q->kobj.ktype = &queue_ktype; ret = kobject_register(&q->kobj); if (ret < 0) return ret; ret = elv_register_queue(q); if (ret) { kobject_unregister(&q->kobj); return ret; } return 0; } void blk_unregister_queue(struct gendisk *disk) { request_queue_t *q = disk->queue; if (q && q->request_fn) { elv_unregister_queue(q); kobject_unregister(&q->kobj); kobject_put(&disk->kobj); } }