+++ /dev/null
-/*
- * 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);
- }
-}
git.samba.org / sfrench / cifs-2.6.git / blobdiff