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00d61e3e8c
Looking a bit closer into this regression the reason this can't be right is that dma_addr common default is BLK_BOUNCE_HIGH and most machines have less than 4G. So if you do: if (b_pfn <= (min_t(u64, 0xffffffff, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) dma = 1 that will translate to: if (BLK_BOUNCE_HIGH <= BLK_BOUNCE_HIGH) dma = 1 So for 99% of hardware this will trigger unnecessary GFP_DMA allocations and isa pooling operations. Also note how the 32bit code still does b_pfn < blk_max_low_pfn. I guess this is what you were looking after. I didn't verify but as far as I can tell, this will stop the regression with isa dma operations at boot for 99% of blkdev/memory combinations out there and I guess this fixes the setups with >4G of ram and 32bit pci cards as well (this also retains symmetry with the 32bit code). Signed-off-by: Andrea Arcangeli <andrea@qumranet.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
415 lines
13 KiB
C
415 lines
13 KiB
C
/*
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* Functions related to setting various queue properties from drivers
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
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#include "blk.h"
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unsigned long blk_max_low_pfn;
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EXPORT_SYMBOL(blk_max_low_pfn);
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unsigned long blk_max_pfn;
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EXPORT_SYMBOL(blk_max_pfn);
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/**
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* blk_queue_prep_rq - set a prepare_request function for queue
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* @q: queue
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* @pfn: prepare_request function
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*
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* It's possible for a queue to register a prepare_request callback which
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* is invoked before the request is handed to the request_fn. The goal of
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* the function is to prepare a request for I/O, it can be used to build a
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* cdb from the request data for instance.
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*
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*/
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void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
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{
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q->prep_rq_fn = pfn;
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}
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EXPORT_SYMBOL(blk_queue_prep_rq);
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/**
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* blk_queue_merge_bvec - set a merge_bvec function for queue
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* @q: queue
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* @mbfn: merge_bvec_fn
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*
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* Usually queues have static limitations on the max sectors or segments that
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* we can put in a request. Stacking drivers may have some settings that
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* are dynamic, and thus we have to query the queue whether it is ok to
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* add a new bio_vec to a bio at a given offset or not. If the block device
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* has such limitations, it needs to register a merge_bvec_fn to control
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* the size of bio's sent to it. Note that a block device *must* allow a
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* single page to be added to an empty bio. The block device driver may want
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* to use the bio_split() function to deal with these bio's. By default
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* no merge_bvec_fn is defined for a queue, and only the fixed limits are
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* honored.
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*/
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void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
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{
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q->merge_bvec_fn = mbfn;
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}
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EXPORT_SYMBOL(blk_queue_merge_bvec);
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void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
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{
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q->softirq_done_fn = fn;
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}
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EXPORT_SYMBOL(blk_queue_softirq_done);
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/**
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* blk_queue_make_request - define an alternate make_request function for a device
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* @q: the request queue for the device to be affected
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* @mfn: the alternate make_request function
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*
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* Description:
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* The normal way for &struct bios to be passed to a device
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* driver is for them to be collected into requests on a request
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* queue, and then to allow the device driver to select requests
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* off that queue when it is ready. This works well for many block
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* devices. However some block devices (typically virtual devices
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* such as md or lvm) do not benefit from the processing on the
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* request queue, and are served best by having the requests passed
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* directly to them. This can be achieved by providing a function
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* to blk_queue_make_request().
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*
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* Caveat:
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* The driver that does this *must* be able to deal appropriately
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* with buffers in "highmemory". This can be accomplished by either calling
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* __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
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* blk_queue_bounce() to create a buffer in normal memory.
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**/
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void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
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{
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/*
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* set defaults
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*/
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q->nr_requests = BLKDEV_MAX_RQ;
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blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
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blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
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q->make_request_fn = mfn;
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q->backing_dev_info.ra_pages =
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(VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
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q->backing_dev_info.state = 0;
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q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
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blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
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blk_queue_hardsect_size(q, 512);
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blk_queue_dma_alignment(q, 511);
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blk_queue_congestion_threshold(q);
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q->nr_batching = BLK_BATCH_REQ;
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q->unplug_thresh = 4; /* hmm */
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q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
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if (q->unplug_delay == 0)
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q->unplug_delay = 1;
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INIT_WORK(&q->unplug_work, blk_unplug_work);
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q->unplug_timer.function = blk_unplug_timeout;
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q->unplug_timer.data = (unsigned long)q;
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/*
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* by default assume old behaviour and bounce for any highmem page
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*/
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blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
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}
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EXPORT_SYMBOL(blk_queue_make_request);
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/**
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* blk_queue_bounce_limit - set bounce buffer limit for queue
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* @q: the request queue for the device
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* @dma_addr: bus address limit
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*
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* Description:
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* Different hardware can have different requirements as to what pages
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* it can do I/O directly to. A low level driver can call
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* blk_queue_bounce_limit to have lower memory pages allocated as bounce
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* buffers for doing I/O to pages residing above @page.
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**/
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void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr)
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{
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unsigned long b_pfn = dma_addr >> PAGE_SHIFT;
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int dma = 0;
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q->bounce_gfp = GFP_NOIO;
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#if BITS_PER_LONG == 64
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/* Assume anything <= 4GB can be handled by IOMMU.
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Actually some IOMMUs can handle everything, but I don't
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know of a way to test this here. */
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if (b_pfn < (min_t(u64, 0x100000000UL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
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dma = 1;
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q->bounce_pfn = max_low_pfn;
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#else
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if (b_pfn < blk_max_low_pfn)
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dma = 1;
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q->bounce_pfn = b_pfn;
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#endif
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if (dma) {
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init_emergency_isa_pool();
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q->bounce_gfp = GFP_NOIO | GFP_DMA;
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q->bounce_pfn = b_pfn;
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}
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}
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EXPORT_SYMBOL(blk_queue_bounce_limit);
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/**
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* blk_queue_max_sectors - set max sectors for a request for this queue
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* @q: the request queue for the device
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* @max_sectors: max sectors in the usual 512b unit
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*
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* Description:
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* Enables a low level driver to set an upper limit on the size of
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* received requests.
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**/
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void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors)
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{
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if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
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max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
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printk(KERN_INFO "%s: set to minimum %d\n", __FUNCTION__,
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max_sectors);
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}
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if (BLK_DEF_MAX_SECTORS > max_sectors)
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q->max_hw_sectors = q->max_sectors = max_sectors;
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else {
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q->max_sectors = BLK_DEF_MAX_SECTORS;
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q->max_hw_sectors = max_sectors;
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}
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}
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EXPORT_SYMBOL(blk_queue_max_sectors);
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/**
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* blk_queue_max_phys_segments - set max phys segments for a request for this queue
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* @q: the request queue for the device
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* @max_segments: max number of segments
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*
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* Description:
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* Enables a low level driver to set an upper limit on the number of
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* physical data segments in a request. This would be the largest sized
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* scatter list the driver could handle.
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**/
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void blk_queue_max_phys_segments(struct request_queue *q,
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unsigned short max_segments)
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{
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if (!max_segments) {
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max_segments = 1;
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printk(KERN_INFO "%s: set to minimum %d\n", __FUNCTION__,
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max_segments);
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}
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q->max_phys_segments = max_segments;
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}
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EXPORT_SYMBOL(blk_queue_max_phys_segments);
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/**
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* blk_queue_max_hw_segments - set max hw segments for a request for this queue
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* @q: the request queue for the device
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* @max_segments: max number of segments
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*
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* Description:
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* Enables a low level driver to set an upper limit on the number of
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* hw data segments in a request. This would be the largest number of
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* address/length pairs the host adapter can actually give as once
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* to the device.
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**/
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void blk_queue_max_hw_segments(struct request_queue *q,
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unsigned short max_segments)
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{
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if (!max_segments) {
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max_segments = 1;
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printk(KERN_INFO "%s: set to minimum %d\n", __FUNCTION__,
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max_segments);
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}
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q->max_hw_segments = max_segments;
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}
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EXPORT_SYMBOL(blk_queue_max_hw_segments);
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/**
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* blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
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* @q: the request queue for the device
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* @max_size: max size of segment in bytes
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*
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* Description:
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* Enables a low level driver to set an upper limit on the size of a
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* coalesced segment
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**/
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void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
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{
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if (max_size < PAGE_CACHE_SIZE) {
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max_size = PAGE_CACHE_SIZE;
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printk(KERN_INFO "%s: set to minimum %d\n", __FUNCTION__,
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max_size);
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}
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q->max_segment_size = max_size;
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}
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EXPORT_SYMBOL(blk_queue_max_segment_size);
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/**
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* blk_queue_hardsect_size - set hardware sector size for the queue
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* @q: the request queue for the device
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* @size: the hardware sector size, in bytes
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*
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* Description:
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* This should typically be set to the lowest possible sector size
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* that the hardware can operate on (possible without reverting to
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* even internal read-modify-write operations). Usually the default
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* of 512 covers most hardware.
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**/
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void blk_queue_hardsect_size(struct request_queue *q, unsigned short size)
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{
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q->hardsect_size = size;
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}
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EXPORT_SYMBOL(blk_queue_hardsect_size);
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/*
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* Returns the minimum that is _not_ zero, unless both are zero.
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*/
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#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
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/**
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* blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
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* @t: the stacking driver (top)
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* @b: the underlying device (bottom)
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**/
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void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
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{
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/* zero is "infinity" */
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t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
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t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
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t->max_phys_segments = min(t->max_phys_segments, b->max_phys_segments);
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t->max_hw_segments = min(t->max_hw_segments, b->max_hw_segments);
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t->max_segment_size = min(t->max_segment_size, b->max_segment_size);
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t->hardsect_size = max(t->hardsect_size, b->hardsect_size);
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if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
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clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
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}
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EXPORT_SYMBOL(blk_queue_stack_limits);
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/**
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* blk_queue_dma_pad - set pad mask
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* @q: the request queue for the device
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* @mask: pad mask
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*
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* Set pad mask. Direct IO requests are padded to the mask specified.
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*
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* Appending pad buffer to a request modifies ->data_len such that it
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* includes the pad buffer. The original requested data length can be
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* obtained using blk_rq_raw_data_len().
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**/
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void blk_queue_dma_pad(struct request_queue *q, unsigned int mask)
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{
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q->dma_pad_mask = mask;
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}
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EXPORT_SYMBOL(blk_queue_dma_pad);
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/**
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* blk_queue_dma_drain - Set up a drain buffer for excess dma.
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* @q: the request queue for the device
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* @dma_drain_needed: fn which returns non-zero if drain is necessary
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* @buf: physically contiguous buffer
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* @size: size of the buffer in bytes
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*
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* Some devices have excess DMA problems and can't simply discard (or
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* zero fill) the unwanted piece of the transfer. They have to have a
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* real area of memory to transfer it into. The use case for this is
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* ATAPI devices in DMA mode. If the packet command causes a transfer
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* bigger than the transfer size some HBAs will lock up if there
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* aren't DMA elements to contain the excess transfer. What this API
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* does is adjust the queue so that the buf is always appended
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* silently to the scatterlist.
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*
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* Note: This routine adjusts max_hw_segments to make room for
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* appending the drain buffer. If you call
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* blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
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* calling this routine, you must set the limit to one fewer than your
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* device can support otherwise there won't be room for the drain
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* buffer.
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*/
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int blk_queue_dma_drain(struct request_queue *q,
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dma_drain_needed_fn *dma_drain_needed,
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void *buf, unsigned int size)
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{
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if (q->max_hw_segments < 2 || q->max_phys_segments < 2)
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return -EINVAL;
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/* make room for appending the drain */
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--q->max_hw_segments;
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--q->max_phys_segments;
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q->dma_drain_needed = dma_drain_needed;
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q->dma_drain_buffer = buf;
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q->dma_drain_size = size;
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return 0;
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}
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EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
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/**
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* blk_queue_segment_boundary - set boundary rules for segment merging
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* @q: the request queue for the device
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* @mask: the memory boundary mask
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**/
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void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
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{
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if (mask < PAGE_CACHE_SIZE - 1) {
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mask = PAGE_CACHE_SIZE - 1;
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printk(KERN_INFO "%s: set to minimum %lx\n", __FUNCTION__,
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mask);
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}
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q->seg_boundary_mask = mask;
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}
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EXPORT_SYMBOL(blk_queue_segment_boundary);
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/**
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* blk_queue_dma_alignment - set dma length and memory alignment
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* @q: the request queue for the device
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* @mask: alignment mask
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*
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* description:
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* set required memory and length aligment for direct dma transactions.
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* this is used when buiding direct io requests for the queue.
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*
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**/
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void blk_queue_dma_alignment(struct request_queue *q, int mask)
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{
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q->dma_alignment = mask;
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}
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EXPORT_SYMBOL(blk_queue_dma_alignment);
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/**
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* blk_queue_update_dma_alignment - update dma length and memory alignment
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* @q: the request queue for the device
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* @mask: alignment mask
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*
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* description:
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* update required memory and length aligment for direct dma transactions.
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* If the requested alignment is larger than the current alignment, then
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* the current queue alignment is updated to the new value, otherwise it
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* is left alone. The design of this is to allow multiple objects
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* (driver, device, transport etc) to set their respective
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* alignments without having them interfere.
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*
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**/
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void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
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{
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BUG_ON(mask > PAGE_SIZE);
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if (mask > q->dma_alignment)
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q->dma_alignment = mask;
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}
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EXPORT_SYMBOL(blk_queue_update_dma_alignment);
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static int __init blk_settings_init(void)
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{
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blk_max_low_pfn = max_low_pfn - 1;
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blk_max_pfn = max_pfn - 1;
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return 0;
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}
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subsys_initcall(blk_settings_init);
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