diff options
Diffstat (limited to 'block/ll_rw_blk.c')
| -rw-r--r-- | block/ll_rw_blk.c | 3612 |
1 files changed, 3612 insertions, 0 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c new file mode 100644 index 00000000000..5f52e30b43f --- /dev/null +++ b/block/ll_rw_blk.c @@ -0,0 +1,3612 @@ +/* + * 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 <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/config.h> +#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/blkdev.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); + +/* + * 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(gfp_t gfp_mask) +{ + return blk_alloc_queue_node(gfp_mask, -1); +} +EXPORT_SYMBOL(blk_alloc_queue); + +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); + 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, 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->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, + gfp_t 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_ELVSWITCH, &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, 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_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, gfp_t 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 (!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; +} + +/* + * 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; + 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; + 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); + } + + 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; + 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; + const int rw = rq_data_dir(req); + + __disk_stat_inc(disk, ios[rw]); + __disk_stat_add(disk, ticks[rw], duration); + 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(gfp_t 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(gfp_t 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); + } +} |