From a168ee84c90b39ece357da127ab388f2f64db19c Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 29 Jan 2008 14:49:21 +0100 Subject: block: first step of splitting ll_rw_blk, rename it Then we retain history in blk-core.c Signed-off-by: Jens Axboe --- block/ll_rw_blk.c | 4457 ----------------------------------------------------- 1 file changed, 4457 deletions(-) delete mode 100644 block/ll_rw_blk.c (limited to 'block/ll_rw_blk.c') diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c deleted file mode 100644 index 1932a56f5e4..00000000000 --- a/block/ll_rw_blk.c +++ /dev/null @@ -1,4457 +0,0 @@ -/* - * Copyright (C) 1991, 1992 Linus Torvalds - * Copyright (C) 1994, Karl Keyte: Added support for disk statistics - * Elevator latency, (C) 2000 Andrea Arcangeli SuSE - * Queue request tables / lock, selectable elevator, Jens Axboe - * kernel-doc documentation started by NeilBrown - July2000 - * bio rewrite, highmem i/o, etc, Jens Axboe - may 2001 - */ - -/* - * This handles all read/write requests to block devices - */ -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include /* for max_pfn/max_low_pfn */ -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -/* - * for max sense size - */ -#include - -static void blk_unplug_work(struct work_struct *work); -static void blk_unplug_timeout(unsigned long data); -static void drive_stat_acct(struct request *rq, int new_io); -static void init_request_from_bio(struct request *req, struct bio *bio); -static int __make_request(struct request_queue *q, struct bio *bio); -static struct io_context *current_io_context(gfp_t gfp_flags, int node); -static void blk_recalc_rq_segments(struct request *rq); -static void blk_rq_bio_prep(struct request_queue *q, struct request *rq, - struct bio *bio); - -/* - * For the allocated request tables - */ -static struct kmem_cache *request_cachep; - -/* - * For queue allocation - */ -static struct kmem_cache *requestq_cachep; - -/* - * For io context allocations - */ -static struct kmem_cache *iocontext_cachep; - -/* - * Controlling structure to kblockd - */ -static struct workqueue_struct *kblockd_workqueue; - -unsigned long blk_max_low_pfn, blk_max_pfn; - -EXPORT_SYMBOL(blk_max_low_pfn); -EXPORT_SYMBOL(blk_max_pfn); - -static DEFINE_PER_CPU(struct list_head, blk_cpu_done); - -/* Amount of time in which a process may batch requests */ -#define BLK_BATCH_TIME (HZ/50UL) - -/* Number of requests a "batching" process may submit */ -#define BLK_BATCH_REQ 32 - -/* - * Return the threshold (number of used requests) at which the queue is - * considered to be congested. It include a little hysteresis to keep the - * context switch rate down. - */ -static inline int queue_congestion_on_threshold(struct request_queue *q) -{ - return q->nr_congestion_on; -} - -/* - * The threshold at which a queue is considered to be uncongested - */ -static inline int queue_congestion_off_threshold(struct request_queue *q) -{ - return q->nr_congestion_off; -} - -static void blk_queue_congestion_threshold(struct request_queue *q) -{ - int nr; - - nr = q->nr_requests - (q->nr_requests / 8) + 1; - if (nr > q->nr_requests) - nr = q->nr_requests; - q->nr_congestion_on = nr; - - nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; - if (nr < 1) - nr = 1; - q->nr_congestion_off = nr; -} - -/** - * blk_get_backing_dev_info - get the address of a queue's backing_dev_info - * @bdev: device - * - * Locates the passed device's request queue and returns the address of its - * backing_dev_info - * - * Will return NULL if the request queue cannot be located. - */ -struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) -{ - struct backing_dev_info *ret = NULL; - struct request_queue *q = bdev_get_queue(bdev); - - if (q) - ret = &q->backing_dev_info; - return ret; -} -EXPORT_SYMBOL(blk_get_backing_dev_info); - -/** - * 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(struct request_queue *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(struct request_queue *q, merge_bvec_fn *mbfn) -{ - q->merge_bvec_fn = mbfn; -} - -EXPORT_SYMBOL(blk_queue_merge_bvec); - -void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn) -{ - q->softirq_done_fn = fn; -} - -EXPORT_SYMBOL(blk_queue_softirq_done); - -/** - * blk_queue_make_request - define an alternate make_request function for a device - * @q: the request queue for the device to be affected - * @mfn: the alternate make_request function - * - * Description: - * The normal way for &struct bios to be passed to a device - * driver is for them to be collected into requests on a request - * queue, and then to allow the device driver to select requests - * off that queue when it is ready. This works well for many block - * devices. However some block devices (typically virtual devices - * such as md or lvm) do not benefit from the processing on the - * request queue, and are served best by having the requests passed - * directly to them. This can be achieved by providing a function - * to blk_queue_make_request(). - * - * Caveat: - * The driver that does this *must* be able to deal appropriately - * with buffers in "highmemory". This can be accomplished by either calling - * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling - * blk_queue_bounce() to create a buffer in normal memory. - **/ -void blk_queue_make_request(struct request_queue * q, make_request_fn * mfn) -{ - /* - * set defaults - */ - q->nr_requests = BLKDEV_MAX_RQ; - blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); - blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); - q->make_request_fn = mfn; - q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; - q->backing_dev_info.state = 0; - q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; - blk_queue_max_sectors(q, SAFE_MAX_SECTORS); - blk_queue_hardsect_size(q, 512); - blk_queue_dma_alignment(q, 511); - blk_queue_congestion_threshold(q); - q->nr_batching = BLK_BATCH_REQ; - - q->unplug_thresh = 4; /* hmm */ - q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ - if (q->unplug_delay == 0) - q->unplug_delay = 1; - - INIT_WORK(&q->unplug_work, blk_unplug_work); - - q->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); -} - -EXPORT_SYMBOL(blk_queue_make_request); - -static void rq_init(struct request_queue *q, struct request *rq) -{ - INIT_LIST_HEAD(&rq->queuelist); - INIT_LIST_HEAD(&rq->donelist); - - rq->errors = 0; - rq->bio = rq->biotail = NULL; - INIT_HLIST_NODE(&rq->hash); - RB_CLEAR_NODE(&rq->rb_node); - rq->ioprio = 0; - rq->buffer = NULL; - rq->ref_count = 1; - rq->q = q; - rq->special = NULL; - rq->data_len = 0; - rq->data = NULL; - rq->nr_phys_segments = 0; - rq->sense = NULL; - rq->end_io = NULL; - rq->end_io_data = NULL; - rq->completion_data = NULL; - rq->next_rq = NULL; -} - -/** - * blk_queue_ordered - does this queue support ordered writes - * @q: the request queue - * @ordered: one of QUEUE_ORDERED_* - * @prepare_flush_fn: rq setup helper for cache flush ordered writes - * - * Description: - * For journalled file systems, doing ordered writes on a commit - * block instead of explicitly doing wait_on_buffer (which is bad - * for performance) can be a big win. Block drivers supporting this - * feature should call this function and indicate so. - * - **/ -int blk_queue_ordered(struct request_queue *q, unsigned ordered, - prepare_flush_fn *prepare_flush_fn) -{ - if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) && - prepare_flush_fn == NULL) { - printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n"); - return -EINVAL; - } - - if (ordered != QUEUE_ORDERED_NONE && - ordered != QUEUE_ORDERED_DRAIN && - ordered != QUEUE_ORDERED_DRAIN_FLUSH && - ordered != QUEUE_ORDERED_DRAIN_FUA && - ordered != QUEUE_ORDERED_TAG && - ordered != QUEUE_ORDERED_TAG_FLUSH && - ordered != QUEUE_ORDERED_TAG_FUA) { - printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered); - return -EINVAL; - } - - q->ordered = ordered; - q->next_ordered = ordered; - q->prepare_flush_fn = prepare_flush_fn; - - return 0; -} - -EXPORT_SYMBOL(blk_queue_ordered); - -/* - * Cache flushing for ordered writes handling - */ -inline unsigned blk_ordered_cur_seq(struct request_queue *q) -{ - if (!q->ordseq) - return 0; - return 1 << ffz(q->ordseq); -} - -unsigned blk_ordered_req_seq(struct request *rq) -{ - struct request_queue *q = rq->q; - - BUG_ON(q->ordseq == 0); - - if (rq == &q->pre_flush_rq) - return QUEUE_ORDSEQ_PREFLUSH; - if (rq == &q->bar_rq) - return QUEUE_ORDSEQ_BAR; - if (rq == &q->post_flush_rq) - return QUEUE_ORDSEQ_POSTFLUSH; - - /* - * !fs requests don't need to follow barrier ordering. Always - * put them at the front. This fixes the following deadlock. - * - * http://thread.gmane.org/gmane.linux.kernel/537473 - */ - if (!blk_fs_request(rq)) - return QUEUE_ORDSEQ_DRAIN; - - if ((rq->cmd_flags & REQ_ORDERED_COLOR) == - (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR)) - return QUEUE_ORDSEQ_DRAIN; - else - return QUEUE_ORDSEQ_DONE; -} - -void blk_ordered_complete_seq(struct request_queue *q, unsigned seq, int error) -{ - struct request *rq; - - if (error && !q->orderr) - q->orderr = error; - - BUG_ON(q->ordseq & seq); - q->ordseq |= seq; - - if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE) - return; - - /* - * Okay, sequence complete. - */ - q->ordseq = 0; - rq = q->orig_bar_rq; - - if (__blk_end_request(rq, q->orderr, blk_rq_bytes(rq))) - BUG(); -} - -static void pre_flush_end_io(struct request *rq, int error) -{ - elv_completed_request(rq->q, rq); - blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error); -} - -static void bar_end_io(struct request *rq, int error) -{ - elv_completed_request(rq->q, rq); - blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error); -} - -static void post_flush_end_io(struct request *rq, int error) -{ - elv_completed_request(rq->q, rq); - blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error); -} - -static void queue_flush(struct request_queue *q, unsigned which) -{ - struct request *rq; - rq_end_io_fn *end_io; - - if (which == QUEUE_ORDERED_PREFLUSH) { - rq = &q->pre_flush_rq; - end_io = pre_flush_end_io; - } else { - rq = &q->post_flush_rq; - end_io = post_flush_end_io; - } - - rq->cmd_flags = REQ_HARDBARRIER; - rq_init(q, rq); - rq->elevator_private = NULL; - rq->elevator_private2 = NULL; - rq->rq_disk = q->bar_rq.rq_disk; - rq->end_io = end_io; - q->prepare_flush_fn(q, rq); - - elv_insert(q, rq, ELEVATOR_INSERT_FRONT); -} - -static inline struct request *start_ordered(struct request_queue *q, - struct request *rq) -{ - q->orderr = 0; - q->ordered = q->next_ordered; - q->ordseq |= QUEUE_ORDSEQ_STARTED; - - /* - * Prep proxy barrier request. - */ - blkdev_dequeue_request(rq); - q->orig_bar_rq = rq; - rq = &q->bar_rq; - rq->cmd_flags = 0; - rq_init(q, rq); - if (bio_data_dir(q->orig_bar_rq->bio) == WRITE) - rq->cmd_flags |= REQ_RW; - if (q->ordered & QUEUE_ORDERED_FUA) - rq->cmd_flags |= REQ_FUA; - rq->elevator_private = NULL; - rq->elevator_private2 = NULL; - init_request_from_bio(rq, q->orig_bar_rq->bio); - rq->end_io = bar_end_io; - - /* - * Queue ordered sequence. As we stack them at the head, we - * need to queue in reverse order. Note that we rely on that - * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs - * request gets inbetween ordered sequence. If this request is - * an empty barrier, we don't need to do a postflush ever since - * there will be no data written between the pre and post flush. - * Hence a single flush will suffice. - */ - if ((q->ordered & QUEUE_ORDERED_POSTFLUSH) && !blk_empty_barrier(rq)) - queue_flush(q, QUEUE_ORDERED_POSTFLUSH); - else - q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH; - - elv_insert(q, rq, ELEVATOR_INSERT_FRONT); - - if (q->ordered & QUEUE_ORDERED_PREFLUSH) { - queue_flush(q, QUEUE_ORDERED_PREFLUSH); - rq = &q->pre_flush_rq; - } else - q->ordseq |= QUEUE_ORDSEQ_PREFLUSH; - - if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0) - q->ordseq |= QUEUE_ORDSEQ_DRAIN; - else - rq = NULL; - - return rq; -} - -int blk_do_ordered(struct request_queue *q, struct request **rqp) -{ - struct request *rq = *rqp; - const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq); - - if (!q->ordseq) { - if (!is_barrier) - return 1; - - if (q->next_ordered != QUEUE_ORDERED_NONE) { - *rqp = start_ordered(q, rq); - return 1; - } else { - /* - * This can happen when the queue switches to - * ORDERED_NONE while this request is on it. - */ - blkdev_dequeue_request(rq); - if (__blk_end_request(rq, -EOPNOTSUPP, - blk_rq_bytes(rq))) - BUG(); - *rqp = NULL; - return 0; - } - } - - /* - * Ordered sequence in progress - */ - - /* Special requests are not subject to ordering rules. */ - if (!blk_fs_request(rq) && - rq != &q->pre_flush_rq && rq != &q->post_flush_rq) - return 1; - - if (q->ordered & QUEUE_ORDERED_TAG) { - /* Ordered by tag. Blocking the next barrier is enough. */ - if (is_barrier && rq != &q->bar_rq) - *rqp = NULL; - } else { - /* Ordered by draining. Wait for turn. */ - WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q)); - if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q)) - *rqp = NULL; - } - - return 1; -} - -static void req_bio_endio(struct request *rq, struct bio *bio, - unsigned int nbytes, int error) -{ - struct request_queue *q = rq->q; - - if (&q->bar_rq != rq) { - if (error) - clear_bit(BIO_UPTODATE, &bio->bi_flags); - else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) - error = -EIO; - - if (unlikely(nbytes > bio->bi_size)) { - printk("%s: want %u bytes done, only %u left\n", - __FUNCTION__, nbytes, bio->bi_size); - nbytes = bio->bi_size; - } - - bio->bi_size -= nbytes; - bio->bi_sector += (nbytes >> 9); - if (bio->bi_size == 0) - bio_endio(bio, error); - } else { - - /* - * Okay, this is the barrier request in progress, just - * record the error; - */ - if (error && !q->orderr) - q->orderr = error; - } -} - -/** - * blk_queue_bounce_limit - set bounce buffer limit for queue - * @q: the request queue for the device - * @dma_addr: bus address limit - * - * Description: - * Different hardware can have different requirements as to what pages - * it can do I/O directly to. A low level driver can call - * blk_queue_bounce_limit to have lower memory pages allocated as bounce - * buffers for doing I/O to pages residing above @page. - **/ -void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr) -{ - unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; - int dma = 0; - - q->bounce_gfp = GFP_NOIO; -#if BITS_PER_LONG == 64 - /* Assume anything <= 4GB can be handled by IOMMU. - Actually some IOMMUs can handle everything, but I don't - know of a way to test this here. */ - if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) - dma = 1; - q->bounce_pfn = max_low_pfn; -#else - if (bounce_pfn < blk_max_low_pfn) - dma = 1; - q->bounce_pfn = bounce_pfn; -#endif - if (dma) { - init_emergency_isa_pool(); - q->bounce_gfp = GFP_NOIO | GFP_DMA; - q->bounce_pfn = bounce_pfn; - } -} - -EXPORT_SYMBOL(blk_queue_bounce_limit); - -/** - * blk_queue_max_sectors - set max sectors for a request for this queue - * @q: the request queue for the device - * @max_sectors: max sectors in the usual 512b unit - * - * Description: - * Enables a low level driver to set an upper limit on the size of - * received requests. - **/ -void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors) -{ - if ((max_sectors << 9) < PAGE_CACHE_SIZE) { - max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); - printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors); - } - - if (BLK_DEF_MAX_SECTORS > max_sectors) - q->max_hw_sectors = q->max_sectors = max_sectors; - else { - q->max_sectors = BLK_DEF_MAX_SECTORS; - q->max_hw_sectors = max_sectors; - } -} - -EXPORT_SYMBOL(blk_queue_max_sectors); - -/** - * blk_queue_max_phys_segments - set max phys segments for a request for this queue - * @q: the request queue for the device - * @max_segments: max number of segments - * - * Description: - * Enables a low level driver to set an upper limit on the number of - * physical data segments in a request. This would be the largest sized - * scatter list the driver could handle. - **/ -void blk_queue_max_phys_segments(struct request_queue *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(struct request_queue *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(struct request_queue *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(struct request_queue *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(struct request_queue *t, struct request_queue *b) -{ - /* zero is "infinity" */ - t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors); - t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors); - - t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments); - t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments); - t->max_segment_size = min(t->max_segment_size,b->max_segment_size); - t->hardsect_size = max(t->hardsect_size,b->hardsect_size); - if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) - clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags); -} - -EXPORT_SYMBOL(blk_queue_stack_limits); - -/** - * blk_queue_dma_drain - Set up a drain buffer for excess dma. - * - * @q: the request queue for the device - * @buf: physically contiguous buffer - * @size: size of the buffer in bytes - * - * Some devices have excess DMA problems and can't simply discard (or - * zero fill) the unwanted piece of the transfer. They have to have a - * real area of memory to transfer it into. The use case for this is - * ATAPI devices in DMA mode. If the packet command causes a transfer - * bigger than the transfer size some HBAs will lock up if there - * aren't DMA elements to contain the excess transfer. What this API - * does is adjust the queue so that the buf is always appended - * silently to the scatterlist. - * - * Note: This routine adjusts max_hw_segments to make room for - * appending the drain buffer. If you call - * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after - * calling this routine, you must set the limit to one fewer than your - * device can support otherwise there won't be room for the drain - * buffer. - */ -int blk_queue_dma_drain(struct request_queue *q, void *buf, - unsigned int size) -{ - if (q->max_hw_segments < 2 || q->max_phys_segments < 2) - return -EINVAL; - /* make room for appending the drain */ - --q->max_hw_segments; - --q->max_phys_segments; - q->dma_drain_buffer = buf; - q->dma_drain_size = size; - - return 0; -} - -EXPORT_SYMBOL_GPL(blk_queue_dma_drain); - -/** - * 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(struct request_queue *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(struct request_queue *q, int mask) -{ - q->dma_alignment = mask; -} - -EXPORT_SYMBOL(blk_queue_dma_alignment); - -/** - * blk_queue_update_dma_alignment - update dma length and memory alignment - * @q: the request queue for the device - * @mask: alignment mask - * - * description: - * update required memory and length aligment for direct dma transactions. - * If the requested alignment is larger than the current alignment, then - * the current queue alignment is updated to the new value, otherwise it - * is left alone. The design of this is to allow multiple objects - * (driver, device, transport etc) to set their respective - * alignments without having them interfere. - * - **/ -void blk_queue_update_dma_alignment(struct request_queue *q, int mask) -{ - BUG_ON(mask > PAGE_SIZE); - - if (mask > q->dma_alignment) - q->dma_alignment = mask; -} - -EXPORT_SYMBOL(blk_queue_update_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(struct request_queue *q, int tag) -{ - return blk_map_queue_find_tag(q->queue_tags, tag); -} - -EXPORT_SYMBOL(blk_queue_find_tag); - -/** - * __blk_free_tags - release a given set of tag maintenance info - * @bqt: the tag map to free - * - * Tries to free the specified @bqt@. Returns true if it was - * actually freed and false if there are still references using it - */ -static int __blk_free_tags(struct blk_queue_tag *bqt) -{ - int retval; - - retval = atomic_dec_and_test(&bqt->refcnt); - if (retval) { - BUG_ON(bqt->busy); - - kfree(bqt->tag_index); - bqt->tag_index = NULL; - - kfree(bqt->tag_map); - bqt->tag_map = NULL; - - kfree(bqt); - - } - - return retval; -} - -/** - * __blk_queue_free_tags - release tag maintenance info - * @q: the request queue for the device - * - * Notes: - * blk_cleanup_queue() will take care of calling this function, if tagging - * has been used. So there's no need to call this directly. - **/ -static void __blk_queue_free_tags(struct request_queue *q) -{ - struct blk_queue_tag *bqt = q->queue_tags; - - if (!bqt) - return; - - __blk_free_tags(bqt); - - q->queue_tags = NULL; - q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED); -} - - -/** - * blk_free_tags - release a given set of tag maintenance info - * @bqt: the tag map to free - * - * For externally managed @bqt@ frees the map. Callers of this - * function must guarantee to have released all the queues that - * might have been using this tag map. - */ -void blk_free_tags(struct blk_queue_tag *bqt) -{ - if (unlikely(!__blk_free_tags(bqt))) - BUG(); -} -EXPORT_SYMBOL(blk_free_tags); - -/** - * blk_queue_free_tags - release tag maintenance info - * @q: the request queue for the device - * - * Notes: - * This is used to disabled tagged queuing to a device, yet leave - * queue in function. - **/ -void blk_queue_free_tags(struct request_queue *q) -{ - clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); -} - -EXPORT_SYMBOL(blk_queue_free_tags); - -static int -init_tag_map(struct request_queue *q, struct blk_queue_tag *tags, int depth) -{ - struct request **tag_index; - unsigned long *tag_map; - int nr_ulongs; - - if (q && depth > q->nr_requests * 2) { - depth = q->nr_requests * 2; - printk(KERN_ERR "%s: adjusted depth to %d\n", - __FUNCTION__, depth); - } - - tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC); - if (!tag_index) - goto fail; - - nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG; - tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC); - if (!tag_map) - goto fail; - - tags->real_max_depth = depth; - tags->max_depth = depth; - tags->tag_index = tag_index; - tags->tag_map = tag_map; - - return 0; -fail: - kfree(tag_index); - return -ENOMEM; -} - -static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q, - int depth) -{ - struct blk_queue_tag *tags; - - tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC); - if (!tags) - goto fail; - - if (init_tag_map(q, tags, depth)) - goto fail; - - tags->busy = 0; - atomic_set(&tags->refcnt, 1); - return tags; -fail: - kfree(tags); - return NULL; -} - -/** - * blk_init_tags - initialize the tag info for an external tag map - * @depth: the maximum queue depth supported - * @tags: the tag to use - **/ -struct blk_queue_tag *blk_init_tags(int depth) -{ - return __blk_queue_init_tags(NULL, depth); -} -EXPORT_SYMBOL(blk_init_tags); - -/** - * blk_queue_init_tags - initialize the queue tag info - * @q: the request queue for the device - * @depth: the maximum queue depth supported - * @tags: the tag to use - **/ -int blk_queue_init_tags(struct request_queue *q, int depth, - struct blk_queue_tag *tags) -{ - int rc; - - BUG_ON(tags && q->queue_tags && tags != q->queue_tags); - - if (!tags && !q->queue_tags) { - tags = __blk_queue_init_tags(q, depth); - - if (!tags) - goto fail; - } else if (q->queue_tags) { - if ((rc = blk_queue_resize_tags(q, depth))) - return rc; - set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); - return 0; - } else - atomic_inc(&tags->refcnt); - - /* - * assign it, all done - */ - q->queue_tags = tags; - q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); - INIT_LIST_HEAD(&q->tag_busy_list); - 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(struct request_queue *q, int new_depth) -{ - struct blk_queue_tag *bqt = q->queue_tags; - struct request **tag_index; - unsigned long *tag_map; - int max_depth, nr_ulongs; - - if (!bqt) - return -ENXIO; - - /* - * if we already have large enough real_max_depth. just - * adjust max_depth. *NOTE* as requests with tag value - * between new_depth and real_max_depth can be in-flight, tag - * map can not be shrunk blindly here. - */ - if (new_depth <= bqt->real_max_depth) { - bqt->max_depth = new_depth; - return 0; - } - - /* - * Currently cannot replace a shared tag map with a new - * one, so error out if this is the case - */ - if (atomic_read(&bqt->refcnt) != 1) - return -EBUSY; - - /* - * save the old state info, so we can copy it back - */ - tag_index = bqt->tag_index; - tag_map = bqt->tag_map; - max_depth = bqt->real_max_depth; - - if (init_tag_map(q, bqt, new_depth)) - return -ENOMEM; - - memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *)); - nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG; - memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long)); - - kfree(tag_index); - kfree(tag_map); - return 0; -} - -EXPORT_SYMBOL(blk_queue_resize_tags); - -/** - * blk_queue_end_tag - end tag operations for a request - * @q: the request queue for the device - * @rq: the request that has completed - * - * Description: - * Typically called when end_that_request_first() returns 0, meaning - * all transfers have been done for a request. It's important to call - * this function before end_that_request_last(), as that will put the - * request back on the free list thus corrupting the internal tag list. - * - * Notes: - * queue lock must be held. - **/ -void blk_queue_end_tag(struct request_queue *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; - - list_del_init(&rq->queuelist); - rq->cmd_flags &= ~REQ_QUEUED; - rq->tag = -1; - - if (unlikely(bqt->tag_index[tag] == NULL)) - printk(KERN_ERR "%s: tag %d is missing\n", - __FUNCTION__, tag); - - bqt->tag_index[tag] = NULL; - - if (unlikely(!test_bit(tag, bqt->tag_map))) { - printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n", - __FUNCTION__, tag); - return; - } - /* - * The tag_map bit acts as a lock for tag_index[bit], so we need - * unlock memory barrier semantics. - */ - clear_bit_unlock(tag, bqt->tag_map); - 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(struct request_queue *q, struct request *rq) -{ - struct blk_queue_tag *bqt = q->queue_tags; - int tag; - - if (unlikely((rq->cmd_flags & REQ_QUEUED))) { - printk(KERN_ERR - "%s: request %p for device [%s] already tagged %d", - __FUNCTION__, rq, - rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag); - BUG(); - } - - /* - * Protect against shared tag maps, as we may not have exclusive - * access to the tag map. - */ - do { - tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); - if (tag >= bqt->max_depth) - return 1; - - } while (test_and_set_bit_lock(tag, bqt->tag_map)); - /* - * We need lock ordering semantics given by test_and_set_bit_lock. - * See blk_queue_end_tag for details. - */ - - rq->cmd_flags |= REQ_QUEUED; - rq->tag = tag; - bqt->tag_index[tag] = rq; - blkdev_dequeue_request(rq); - list_add(&rq->queuelist, &q->tag_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(struct request_queue *q) -{ - struct list_head *tmp, *n; - - list_for_each_safe(tmp, n, &q->tag_busy_list) - blk_requeue_request(q, list_entry_rq(tmp)); -} - -EXPORT_SYMBOL(blk_queue_invalidate_tags); - -void blk_dump_rq_flags(struct request *rq, char *msg) -{ - int bit; - - printk("%s: dev %s: type=%x, flags=%x\n", msg, - rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, - rq->cmd_flags); - - printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector, - rq->nr_sectors, - rq->current_nr_sectors); - printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len); - - if (blk_pc_request(rq)) { - printk("cdb: "); - for (bit = 0; bit < sizeof(rq->cmd); bit++) - printk("%02x ", rq->cmd[bit]); - printk("\n"); - } -} - -EXPORT_SYMBOL(blk_dump_rq_flags); - -void blk_recount_segments(struct request_queue *q, struct bio *bio) -{ - struct request rq; - struct bio *nxt = bio->bi_next; - rq.q = q; - rq.bio = rq.biotail = bio; - bio->bi_next = NULL; - blk_recalc_rq_segments(&rq); - bio->bi_next = nxt; - bio->bi_phys_segments = rq.nr_phys_segments; - bio->bi_hw_segments = rq.nr_hw_segments; - bio->bi_flags |= (1 << BIO_SEG_VALID); -} -EXPORT_SYMBOL(blk_recount_segments); - -static void blk_recalc_rq_segments(struct request *rq) -{ - int nr_phys_segs; - int nr_hw_segs; - unsigned int phys_size; - unsigned int hw_size; - struct bio_vec *bv, *bvprv = NULL; - int seg_size; - int hw_seg_size; - int cluster; - struct req_iterator iter; - int high, highprv = 1; - struct request_queue *q = rq->q; - - if (!rq->bio) - return; - - cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); - hw_seg_size = seg_size = 0; - phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; - rq_for_each_segment(bv, rq, iter) { - /* - * 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 (nr_hw_segs == 1 && - hw_seg_size > rq->bio->bi_hw_front_size) - rq->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 (nr_hw_segs == 1 && - hw_seg_size > rq->bio->bi_hw_front_size) - rq->bio->bi_hw_front_size = hw_seg_size; - if (hw_seg_size > rq->biotail->bi_hw_back_size) - rq->biotail->bi_hw_back_size = hw_seg_size; - rq->nr_phys_segments = nr_phys_segs; - rq->nr_hw_segments = nr_hw_segs; -} - -static int blk_phys_contig_segment(struct request_queue *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(struct request_queue *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_back_size + nxt->bi_hw_front_size)) - return 0; - if (bio->bi_hw_back_size + nxt->bi_hw_front_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(struct request_queue *q, struct request *rq, - struct scatterlist *sglist) -{ - struct bio_vec *bvec, *bvprv; - struct req_iterator iter; - struct scatterlist *sg; - int nsegs, cluster; - - nsegs = 0; - cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); - - /* - * for each bio in rq - */ - bvprv = NULL; - sg = NULL; - rq_for_each_segment(bvec, rq, iter) { - int nbytes = bvec->bv_len; - - if (bvprv && cluster) { - if (sg->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->length += nbytes; - } else { -new_segment: - if (!sg) - sg = sglist; - else { - /* - * If the driver previously mapped a shorter - * list, we could see a termination bit - * prematurely unless it fully inits the sg - * table on each mapping. We KNOW that there - * must be more entries here or the driver - * would be buggy, so force clear the - * termination bit to avoid doing a full - * sg_init_table() in drivers for each command. - */ - sg->page_link &= ~0x02; - sg = sg_next(sg); - } - - sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset); - nsegs++; - } - bvprv = bvec; - } /* segments in rq */ - - if (q->dma_drain_size) { - sg->page_link &= ~0x02; - sg = sg_next(sg); - sg_set_page(sg, virt_to_page(q->dma_drain_buffer), - q->dma_drain_size, - ((unsigned long)q->dma_drain_buffer) & - (PAGE_SIZE - 1)); - nsegs++; - } - - if (sg) - sg_mark_end(sg); - - 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(struct request_queue *q, - struct request *req, - struct bio *bio) -{ - int nr_phys_segs = bio_phys_segments(q, bio); - - if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { - req->cmd_flags |= REQ_NOMERGE; - if (req == q->last_merge) - q->last_merge = NULL; - return 0; - } - - /* - * A hw segment is just getting larger, bump just the phys - * counter. - */ - req->nr_phys_segments += nr_phys_segs; - return 1; -} - -static inline int ll_new_hw_segment(struct request_queue *q, - struct request *req, - struct bio *bio) -{ - int nr_hw_segs = bio_hw_segments(q, bio); - int nr_phys_segs = bio_phys_segments(q, bio); - - if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments - || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { - req->cmd_flags |= REQ_NOMERGE; - if (req == q->last_merge) - q->last_merge = NULL; - return 0; - } - - /* - * This will form the start of a new hw segment. Bump both - * counters. - */ - req->nr_hw_segments += nr_hw_segs; - req->nr_phys_segments += nr_phys_segs; - return 1; -} - -static int ll_back_merge_fn(struct request_queue *q, struct request *req, - struct bio *bio) -{ - unsigned short max_sectors; - int len; - - if (unlikely(blk_pc_request(req))) - max_sectors = q->max_hw_sectors; - else - max_sectors = q->max_sectors; - - if (req->nr_sectors + bio_sectors(bio) > max_sectors) { - req->cmd_flags |= REQ_NOMERGE; - if (req == q->last_merge) - q->last_merge = NULL; - return 0; - } - if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID))) - blk_recount_segments(q, req->biotail); - if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) - blk_recount_segments(q, bio); - len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size; - if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) && - !BIOVEC_VIRT_OVERSIZE(len)) { - int mergeable = ll_new_mergeable(q, req, bio); - - if (mergeable) { - if (req->nr_hw_segments == 1) - req->bio->bi_hw_front_size = len; - if (bio->bi_hw_segments == 1) - bio->bi_hw_back_size = len; - } - return mergeable; - } - - return ll_new_hw_segment(q, req, bio); -} - -static int ll_front_merge_fn(struct request_queue *q, struct request *req, - struct bio *bio) -{ - unsigned short max_sectors; - int len; - - if (unlikely(blk_pc_request(req))) - max_sectors = q->max_hw_sectors; - else - max_sectors = q->max_sectors; - - - if (req->nr_sectors + bio_sectors(bio) > max_sectors) { - req->cmd_flags |= REQ_NOMERGE; - if (req == q->last_merge) - q->last_merge = NULL; - return 0; - } - len = bio->bi_hw_back_size + req->bio->bi_hw_front_size; - if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) - blk_recount_segments(q, bio); - if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID))) - blk_recount_segments(q, req->bio); - if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) && - !BIOVEC_VIRT_OVERSIZE(len)) { - int mergeable = ll_new_mergeable(q, req, bio); - - if (mergeable) { - if (bio->bi_hw_segments == 1) - bio->bi_hw_front_size = len; - if (req->nr_hw_segments == 1) - req->biotail->bi_hw_back_size = len; - } - return mergeable; - } - - return ll_new_hw_segment(q, req, bio); -} - -static int ll_merge_requests_fn(struct request_queue *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(struct request_queue *q) -{ - WARN_ON(!irqs_disabled()); - - /* - * don't plug a stopped queue, it must be paired with blk_start_queue() - * which will restart the queueing - */ - if (blk_queue_stopped(q)) - return; - - if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) { - mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); - blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG); - } -} - -EXPORT_SYMBOL(blk_plug_device); - -/* - * remove the queue from the plugged list, if present. called with - * queue lock held and interrupts disabled. - */ -int blk_remove_plug(struct request_queue *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(struct request_queue *q) -{ - if (unlikely(blk_queue_stopped(q))) - return; - - if (!blk_remove_plug(q)) - return; - - q->request_fn(q); -} -EXPORT_SYMBOL(__generic_unplug_device); - -/** - * generic_unplug_device - fire a request queue - * @q: The &struct request_queue 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(struct request_queue *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) -{ - struct request_queue *q = bdi->unplug_io_data; - - blk_unplug(q); -} - -static void blk_unplug_work(struct work_struct *work) -{ - struct request_queue *q = - container_of(work, struct request_queue, unplug_work); - - blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, - q->rq.count[READ] + q->rq.count[WRITE]); - - q->unplug_fn(q); -} - -static void blk_unplug_timeout(unsigned long data) -{ - struct request_queue *q = (struct request_queue *)data; - - blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL, - q->rq.count[READ] + q->rq.count[WRITE]); - - kblockd_schedule_work(&q->unplug_work); -} - -void blk_unplug(struct request_queue *q) -{ - /* - * devices don't necessarily have an ->unplug_fn defined - */ - if (q->unplug_fn) { - blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, - q->rq.count[READ] + q->rq.count[WRITE]); - - q->unplug_fn(q); - } -} -EXPORT_SYMBOL(blk_unplug); - -/** - * blk_start_queue - restart a previously stopped queue - * @q: The &struct request_queue 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(struct request_queue *q) -{ - WARN_ON(!irqs_disabled()); - - clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); - - /* - * one level of recursion is ok and is much faster than kicking - * the unplug handling - */ - if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { - q->request_fn(q); - clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); - } else { - blk_plug_device(q); - kblockd_schedule_work(&q->unplug_work); - } -} - -EXPORT_SYMBOL(blk_start_queue); - -/** - * blk_stop_queue - stop a queue - * @q: The &struct request_queue 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(struct request_queue *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 - * that 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_work(&q->unplug_work); -} -EXPORT_SYMBOL(blk_sync_queue); - -/** - * blk_run_queue - run a single device queue - * @q: The queue to run - */ -void blk_run_queue(struct request_queue *q) -{ - unsigned long flags; - - spin_lock_irqsave(q->queue_lock, flags); - blk_remove_plug(q); - - /* - * Only recurse once to avoid overrunning the stack, let the unplug - * handling reinvoke the handler shortly if we already got there. - */ - if (!elv_queue_empty(q)) { - if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { - q->request_fn(q); - clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); - } else { - blk_plug_device(q); - kblockd_schedule_work(&q->unplug_work); - } - } - - spin_unlock_irqrestore(q->queue_lock, flags); -} -EXPORT_SYMBOL(blk_run_queue); - -/** - * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed - * @kobj: the kobj belonging of the request queue to be released - * - * Description: - * blk_cleanup_queue is the pair to blk_init_queue() or - * blk_queue_make_request(). It should be called when a request queue is - * being released; typically when a block device is being de-registered. - * Currently, its primary task it to free all the &struct request - * structures that were allocated to the queue and the queue itself. - * - * Caveat: - * Hopefully the low level driver will have finished any - * outstanding requests first... - **/ -static void blk_release_queue(struct kobject *kobj) -{ - struct request_queue *q = - container_of(kobj, struct request_queue, kobj); - struct request_list *rl = &q->rq; - - blk_sync_queue(q); - - if (rl->rq_pool) - mempool_destroy(rl->rq_pool); - - if (q->queue_tags) - __blk_queue_free_tags(q); - - blk_trace_shutdown(q); - - bdi_destroy(&q->backing_dev_info); - kmem_cache_free(requestq_cachep, q); -} - -void blk_put_queue(struct request_queue *q) -{ - kobject_put(&q->kobj); -} -EXPORT_SYMBOL(blk_put_queue); - -void blk_cleanup_queue(struct request_queue * q) -{ - mutex_lock(&q->sysfs_lock); - set_bit(QUEUE_FLAG_DEAD, &q->queue_flags); - mutex_unlock(&q->sysfs_lock); - - if (q->elevator) - elevator_exit(q->elevator); - - blk_put_queue(q); -} - -EXPORT_SYMBOL(blk_cleanup_queue); - -static int blk_init_free_list(struct request_queue *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; -} - -struct request_queue *blk_alloc_queue(gfp_t gfp_mask) -{ - return blk_alloc_queue_node(gfp_mask, -1); -} -EXPORT_SYMBOL(blk_alloc_queue); - -static struct kobj_type queue_ktype; - -struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) -{ - struct request_queue *q; - int err; - - q = kmem_cache_alloc_node(requestq_cachep, - gfp_mask | __GFP_ZERO, node_id); - if (!q) - return NULL; - - q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; - q->backing_dev_info.unplug_io_data = q; - err = bdi_init(&q->backing_dev_info); - if (err) { - kmem_cache_free(requestq_cachep, q); - return NULL; - } - - init_timer(&q->unplug_timer); - - kobject_init(&q->kobj, &queue_ktype); - - mutex_init(&q->sysfs_lock); - - return q; -} -EXPORT_SYMBOL(blk_alloc_queue_node); - -/** - * blk_init_queue - prepare a request queue for use with a block device - * @rfn: The function to be called to process requests that have been - * placed on the queue. - * @lock: Request queue spin lock - * - * Description: - * If a block device wishes to use the standard request handling procedures, - * which sorts requests and coalesces adjacent requests, then it must - * call blk_init_queue(). The function @rfn will be called when there - * are requests on the queue that need to be processed. If the device - * supports plugging, then @rfn may not be called immediately when requests - * are available on the queue, but may be called at some time later instead. - * Plugged queues are generally unplugged when a buffer belonging to one - * of the requests on the queue is needed, or due to memory pressure. - * - * @rfn is not required, or even expected, to remove all requests off the - * queue, but only as many as it can handle at a time. If it does leave - * requests on the queue, it is responsible for arranging that the requests - * get dealt with eventually. - * - * The queue spin lock must be held while manipulating the requests on the - * request queue; this lock will be taken also from interrupt context, so irq - * disabling is needed for it. - * - * Function returns a pointer to the initialized request queue, or NULL if - * it didn't succeed. - * - * Note: - * blk_init_queue() must be paired with a blk_cleanup_queue() call - * when the block device is deactivated (such as at module unload). - **/ - -struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) -{ - return blk_init_queue_node(rfn, lock, -1); -} -EXPORT_SYMBOL(blk_init_queue); - -struct request_queue * -blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) -{ - struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id); - - if (!q) - return NULL; - - q->node = node_id; - if (blk_init_free_list(q)) { - kmem_cache_free(requestq_cachep, q); - return NULL; - } - - /* - * if caller didn't supply a lock, they get per-queue locking with - * our embedded lock - */ - if (!lock) { - spin_lock_init(&q->__queue_lock); - lock = &q->__queue_lock; - } - - q->request_fn = rfn; - q->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); - - q->sg_reserved_size = INT_MAX; - - /* - * all done - */ - if (!elevator_init(q, NULL)) { - blk_queue_congestion_threshold(q); - return q; - } - - blk_put_queue(q); - return NULL; -} -EXPORT_SYMBOL(blk_init_queue_node); - -int blk_get_queue(struct request_queue *q) -{ - if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { - kobject_get(&q->kobj); - return 0; - } - - return 1; -} - -EXPORT_SYMBOL(blk_get_queue); - -static inline void blk_free_request(struct request_queue *q, struct request *rq) -{ - if (rq->cmd_flags & REQ_ELVPRIV) - elv_put_request(q, rq); - mempool_free(rq, q->rq.rq_pool); -} - -static struct request * -blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask) -{ - struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); - - if (!rq) - return NULL; - - /* - * first three bits are identical in rq->cmd_flags and bio->bi_rw, - * see bio.h and blkdev.h - */ - rq->cmd_flags = rw | REQ_ALLOCED; - - if (priv) { - if (unlikely(elv_set_request(q, rq, gfp_mask))) { - mempool_free(rq, q->rq.rq_pool); - return NULL; - } - rq->cmd_flags |= REQ_ELVPRIV; - } - - return rq; -} - -/* - * ioc_batching returns true if the ioc is a valid batching request and - * should be given priority access to a request. - */ -static inline int ioc_batching(struct request_queue *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(struct request_queue *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(struct request_queue *q, int rw) -{ - struct request_list *rl = &q->rq; - - if (rl->count[rw] < queue_congestion_off_threshold(q)) - blk_clear_queue_congested(q, rw); - - if (rl->count[rw] + 1 <= q->nr_requests) { - if (waitqueue_active(&rl->wait[rw])) - wake_up(&rl->wait[rw]); - - blk_clear_queue_full(q, rw); - } -} - -/* - * A request has just been released. Account for it, update the full and - * congestion status, wake up any waiters. Called under q->queue_lock. - */ -static void freed_request(struct request_queue *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(struct request_queue *q, int rw_flags, - struct bio *bio, gfp_t gfp_mask) -{ - struct request *rq = NULL; - struct request_list *rl = &q->rq; - struct io_context *ioc = NULL; - const int rw = rw_flags & 0x01; - int may_queue, priv; - - may_queue = elv_may_queue(q, rw_flags); - if (may_queue == ELV_MQUEUE_NO) - goto rq_starved; - - if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) { - if (rl->count[rw]+1 >= q->nr_requests) { - ioc = current_io_context(GFP_ATOMIC, q->node); - /* - * The queue will fill after this allocation, so set - * it as full, and mark this process as "batching". - * This process will be allowed to complete a batch of - * requests, others will be blocked. - */ - if (!blk_queue_full(q, rw)) { - ioc_set_batching(q, ioc); - blk_set_queue_full(q, rw); - } else { - if (may_queue != ELV_MQUEUE_MUST - && !ioc_batching(q, ioc)) { - /* - * The queue is full and the allocating - * process is not a "batcher", and not - * exempted by the IO scheduler - */ - goto out; - } - } - } - blk_set_queue_congested(q, rw); - } - - /* - * Only allow batching queuers to allocate up to 50% over the defined - * limit of requests, otherwise we could have thousands of requests - * allocated with any setting of ->nr_requests - */ - if (rl->count[rw] >= (3 * q->nr_requests / 2)) - goto out; - - rl->count[rw]++; - rl->starved[rw] = 0; - - priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); - if (priv) - rl->elvpriv++; - - spin_unlock_irq(q->queue_lock); - - rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); - if (unlikely(!rq)) { - /* - * Allocation failed presumably due to memory. Undo anything - * we might have messed up. - * - * Allocating task should really be put onto the front of the - * wait queue, but this is pretty rare. - */ - spin_lock_irq(q->queue_lock); - freed_request(q, rw, priv); - - /* - * in the very unlikely event that allocation failed and no - * requests for this direction was pending, mark us starved - * so that freeing of a request in the other direction will - * notice us. another possible fix would be to split the - * rq mempool into READ and WRITE - */ -rq_starved: - if (unlikely(rl->count[rw] == 0)) - rl->starved[rw] = 1; - - goto out; - } - - /* - * ioc may be NULL here, and ioc_batching will be false. That's - * OK, if the queue is under the request limit then requests need - * not count toward the nr_batch_requests limit. There will always - * be some limit enforced by BLK_BATCH_TIME. - */ - if (ioc_batching(q, ioc)) - ioc->nr_batch_requests--; - - rq_init(q, rq); - - blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ); -out: - return rq; -} - -/* - * No available requests for this queue, unplug the device and wait for some - * requests to become available. - * - * Called with q->queue_lock held, and returns with it unlocked. - */ -static struct request *get_request_wait(struct request_queue *q, int rw_flags, - struct bio *bio) -{ - const int rw = rw_flags & 0x01; - struct request *rq; - - rq = get_request(q, rw_flags, 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_flags, bio, GFP_NOIO); - - if (!rq) { - struct io_context *ioc; - - blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ); - - __generic_unplug_device(q); - spin_unlock_irq(q->queue_lock); - io_schedule(); - - /* - * After sleeping, we become a "batching" process and - * will be able to allocate at least one request, and - * up to a big batch of them for a small period time. - * See ioc_batching, ioc_set_batching - */ - ioc = current_io_context(GFP_NOIO, q->node); - ioc_set_batching(q, ioc); - - spin_lock_irq(q->queue_lock); - } - finish_wait(&rl->wait[rw], &wait); - } - - return rq; -} - -struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) -{ - struct request *rq; - - BUG_ON(rw != READ && rw != WRITE); - - spin_lock_irq(q->queue_lock); - if (gfp_mask & __GFP_WAIT) { - rq = get_request_wait(q, rw, NULL); - } else { - rq = get_request(q, rw, NULL, gfp_mask); - if (!rq) - spin_unlock_irq(q->queue_lock); - } - /* q->queue_lock is unlocked at this point */ - - return rq; -} -EXPORT_SYMBOL(blk_get_request); - -/** - * blk_start_queueing - initiate dispatch of requests to device - * @q: request queue to kick into gear - * - * This is basically a helper to remove the need to know whether a queue - * is plugged or not if someone just wants to initiate dispatch of requests - * for this queue. - * - * The queue lock must be held with interrupts disabled. - */ -void blk_start_queueing(struct request_queue *q) -{ - if (!blk_queue_plugged(q)) - q->request_fn(q); - else - __generic_unplug_device(q); -} -EXPORT_SYMBOL(blk_start_queueing); - -/** - * blk_requeue_request - put a