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authorJens Axboe <jens.axboe@oracle.com>2008-01-29 14:53:40 +0100
committerJens Axboe <jens.axboe@oracle.com>2008-01-29 21:55:08 +0100
commit86db1e29772372155db08ff48a9ceb76e11a2ad1 (patch)
tree312f38eb3245873c476c50f816b85610fef9615a /block/blk-settings.c
parent8324aa91d1e11a1fc25f209687a0b2e6c2ed47d0 (diff)
downloadconfigs-86db1e29772372155db08ff48a9ceb76e11a2ad1.tar.gz
block: continue ll_rw_blk.c splitup
Adds files for barrier handling, rq execution, io context handling, mapping data to requests, and queue settings. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r--block/blk-settings.c402
1 files changed, 402 insertions, 0 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
new file mode 100644
index 00000000000..4df09a1b8f4
--- /dev/null
+++ b/block/blk-settings.c
@@ -0,0 +1,402 @@
+/*
+ * Functions related to setting various queue properties from drivers
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
+
+#include "blk.h"
+
+unsigned long blk_max_low_pfn, blk_max_pfn;
+EXPORT_SYMBOL(blk_max_low_pfn);
+EXPORT_SYMBOL(blk_max_pfn);
+
+/**
+ * blk_queue_prep_rq - set a prepare_request function for queue
+ * @q: queue
+ * @pfn: prepare_request function
+ *
+ * It's possible for a queue to register a prepare_request callback which
+ * is invoked before the request is handed to the request_fn. The goal of
+ * the function is to prepare a request for I/O, it can be used to build a
+ * cdb from the request data for instance.
+ *
+ */
+void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
+{
+ q->prep_rq_fn = pfn;
+}
+
+EXPORT_SYMBOL(blk_queue_prep_rq);
+
+/**
+ * blk_queue_merge_bvec - set a merge_bvec function for queue
+ * @q: queue
+ * @mbfn: merge_bvec_fn
+ *
+ * Usually queues have static limitations on the max sectors or segments that
+ * we can put in a request. Stacking drivers may have some settings that
+ * are dynamic, and thus we have to query the queue whether it is ok to
+ * add a new bio_vec to a bio at a given offset or not. If the block device
+ * has such limitations, it needs to register a merge_bvec_fn to control
+ * the size of bio's sent to it. Note that a block device *must* allow a
+ * single page to be added to an empty bio. The block device driver may want
+ * to use the bio_split() function to deal with these bio's. By default
+ * no merge_bvec_fn is defined for a queue, and only the fixed limits are
+ * honored.
+ */
+void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
+{
+ q->merge_bvec_fn = mbfn;
+}
+
+EXPORT_SYMBOL(blk_queue_merge_bvec);
+
+void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
+{
+ q->softirq_done_fn = fn;
+}
+
+EXPORT_SYMBOL(blk_queue_softirq_done);
+
+/**
+ * blk_queue_make_request - define an alternate make_request function for a device
+ * @q: the request queue for the device to be affected
+ * @mfn: the alternate make_request function
+ *
+ * Description:
+ * The normal way for &struct bios to be passed to a device
+ * driver is for them to be collected into requests on a request
+ * queue, and then to allow the device driver to select requests
+ * off that queue when it is ready. This works well for many block
+ * devices. However some block devices (typically virtual devices
+ * such as md or lvm) do not benefit from the processing on the
+ * request queue, and are served best by having the requests passed
+ * directly to them. This can be achieved by providing a function
+ * to blk_queue_make_request().
+ *
+ * Caveat:
+ * The driver that does this *must* be able to deal appropriately
+ * with buffers in "highmemory". This can be accomplished by either calling
+ * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
+ * blk_queue_bounce() to create a buffer in normal memory.
+ **/
+void blk_queue_make_request(struct request_queue * q, make_request_fn * mfn)
+{
+ /*
+ * set defaults
+ */
+ q->nr_requests = BLKDEV_MAX_RQ;
+ blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
+ blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
+ q->make_request_fn = mfn;
+ q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
+ q->backing_dev_info.state = 0;
+ q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
+ blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
+ blk_queue_hardsect_size(q, 512);
+ blk_queue_dma_alignment(q, 511);
+ blk_queue_congestion_threshold(q);
+ q->nr_batching = BLK_BATCH_REQ;
+
+ q->unplug_thresh = 4; /* hmm */
+ q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
+ if (q->unplug_delay == 0)
+ q->unplug_delay = 1;
+
+ INIT_WORK(&q->unplug_work, blk_unplug_work);
+
+ q->unplug_timer.function = blk_unplug_timeout;
+ q->unplug_timer.data = (unsigned long)q;
+
+ /*
+ * by default assume old behaviour and bounce for any highmem page
+ */
+ blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
+}
+
+EXPORT_SYMBOL(blk_queue_make_request);
+
+/**
+ * blk_queue_bounce_limit - set bounce buffer limit for queue
+ * @q: the request queue for the device
+ * @dma_addr: bus address limit
+ *
+ * Description:
+ * Different hardware can have different requirements as to what pages
+ * it can do I/O directly to. A low level driver can call
+ * blk_queue_bounce_limit to have lower memory pages allocated as bounce
+ * buffers for doing I/O to pages residing above @page.
+ **/
+void blk_queue_bounce_limit(struct request_queue *q, u64 dma_addr)
+{
+ unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT;
+ int dma = 0;
+
+ q->bounce_gfp = GFP_NOIO;
+#if BITS_PER_LONG == 64
+ /* Assume anything <= 4GB can be handled by IOMMU.
+ Actually some IOMMUs can handle everything, but I don't
+ know of a way to test this here. */
+ if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
+ dma = 1;
+ q->bounce_pfn = max_low_pfn;
+#else
+ if (bounce_pfn < blk_max_low_pfn)
+ dma = 1;
+ q->bounce_pfn = bounce_pfn;
+#endif
+ if (dma) {
+ init_emergency_isa_pool();
+ q->bounce_gfp = GFP_NOIO | GFP_DMA;
+ q->bounce_pfn = bounce_pfn;
+ }
+}
+
+EXPORT_SYMBOL(blk_queue_bounce_limit);
+
+/**
+ * blk_queue_max_sectors - set max sectors for a request for this queue
+ * @q: the request queue for the device
+ * @max_sectors: max sectors in the usual 512b unit
+ *
+ * Description:
+ * Enables a low level driver to set an upper limit on the size of
+ * received requests.
+ **/
+void blk_queue_max_sectors(struct request_queue *q, unsigned int max_sectors)
+{
+ if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
+ max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
+ printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors);
+ }
+
+ if (BLK_DEF_MAX_SECTORS > max_sectors)
+ q->max_hw_sectors = q->max_sectors = max_sectors;
+ else {
+ q->max_sectors = BLK_DEF_MAX_SECTORS;
+ q->max_hw_sectors = max_sectors;
+ }
+}
+
+EXPORT_SYMBOL(blk_queue_max_sectors);
+
+/**
+ * blk_queue_max_phys_segments - set max phys segments for a request for this queue
+ * @q: the request queue for the device
+ * @max_segments: max number of segments
+ *
+ * Description:
+ * Enables a low level driver to set an upper limit on the number of
+ * physical data segments in a request. This would be the largest sized
+ * scatter list the driver could handle.
+ **/
+void blk_queue_max_phys_segments(struct request_queue *q,
+ unsigned short max_segments)
+{
+ if (!max_segments) {
+ max_segments = 1;
+ printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
+ }
+
+ q->max_phys_segments = max_segments;
+}
+
+EXPORT_SYMBOL(blk_queue_max_phys_segments);
+
+/**
+ * blk_queue_max_hw_segments - set max hw segments for a request for this queue
+ * @q: the request queue for the device
+ * @max_segments: max number of segments
+ *
+ * Description:
+ * Enables a low level driver to set an upper limit on the number of
+ * hw data segments in a request. This would be the largest number of
+ * address/length pairs the host adapter can actually give as once
+ * to the device.
+ **/
+void blk_queue_max_hw_segments(struct request_queue *q,
+ unsigned short max_segments)
+{
+ if (!max_segments) {
+ max_segments = 1;
+ printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
+ }
+
+ q->max_hw_segments = max_segments;
+}
+
+EXPORT_SYMBOL(blk_queue_max_hw_segments);
+
+/**
+ * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
+ * @q: the request queue for the device
+ * @max_size: max size of segment in bytes
+ *
+ * Description:
+ * Enables a low level driver to set an upper limit on the size of a
+ * coalesced segment
+ **/
+void blk_queue_max_segment_size(struct request_queue *q, unsigned int max_size)
+{
+ if (max_size < PAGE_CACHE_SIZE) {
+ max_size = PAGE_CACHE_SIZE;
+ printk("%s: set to minimum %d\n", __FUNCTION__, max_size);
+ }
+
+ q->max_segment_size = max_size;
+}
+
+EXPORT_SYMBOL(blk_queue_max_segment_size);
+
+/**
+ * blk_queue_hardsect_size - set hardware sector size for the queue
+ * @q: the request queue for the device
+ * @size: the hardware sector size, in bytes
+ *
+ * Description:
+ * This should typically be set to the lowest possible sector size
+ * that the hardware can operate on (possible without reverting to
+ * even internal read-modify-write operations). Usually the default
+ * of 512 covers most hardware.
+ **/
+void blk_queue_hardsect_size(struct request_queue *q, unsigned short size)
+{
+ q->hardsect_size = size;
+}
+
+EXPORT_SYMBOL(blk_queue_hardsect_size);
+
+/*
+ * Returns the minimum that is _not_ zero, unless both are zero.
+ */
+#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
+
+/**
+ * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
+ * @t: the stacking driver (top)
+ * @b: the underlying device (bottom)
+ **/
+void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
+{
+ /* zero is "infinity" */
+ t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors);
+ t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors);
+
+ t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
+ t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
+ t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
+ t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
+ if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
+ clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
+}
+
+EXPORT_SYMBOL(blk_queue_stack_limits);
+
+/**
+ * blk_queue_dma_drain - Set up a drain buffer for excess dma.
+ *
+ * @q: the request queue for the device
+ * @buf: physically contiguous buffer
+ * @size: size of the buffer in bytes
+ *
+ * Some devices have excess DMA problems and can't simply discard (or
+ * zero fill) the unwanted piece of the transfer. They have to have a
+ * real area of memory to transfer it into. The use case for this is
+ * ATAPI devices in DMA mode. If the packet command causes a transfer
+ * bigger than the transfer size some HBAs will lock up if there
+ * aren't DMA elements to contain the excess transfer. What this API
+ * does is adjust the queue so that the buf is always appended
+ * silently to the scatterlist.
+ *
+ * Note: This routine adjusts max_hw_segments to make room for
+ * appending the drain buffer. If you call
+ * blk_queue_max_hw_segments() or blk_queue_max_phys_segments() after
+ * calling this routine, you must set the limit to one fewer than your
+ * device can support otherwise there won't be room for the drain
+ * buffer.
+ */
+int blk_queue_dma_drain(struct request_queue *q, void *buf,
+ unsigned int size)
+{
+ if (q->max_hw_segments < 2 || q->max_phys_segments < 2)
+ return -EINVAL;
+ /* make room for appending the drain */
+ --q->max_hw_segments;
+ --q->max_phys_segments;
+ q->dma_drain_buffer = buf;
+ q->dma_drain_size = size;
+
+ return 0;
+}
+
+EXPORT_SYMBOL_GPL(blk_queue_dma_drain);
+
+/**
+ * blk_queue_segment_boundary - set boundary rules for segment merging
+ * @q: the request queue for the device
+ * @mask: the memory boundary mask
+ **/
+void blk_queue_segment_boundary(struct request_queue *q, unsigned long mask)
+{
+ if (mask < PAGE_CACHE_SIZE - 1) {
+ mask = PAGE_CACHE_SIZE - 1;
+ printk("%s: set to minimum %lx\n", __FUNCTION__, mask);
+ }
+
+ q->seg_boundary_mask = mask;
+}
+
+EXPORT_SYMBOL(blk_queue_segment_boundary);
+
+/**
+ * blk_queue_dma_alignment - set dma length and memory alignment
+ * @q: the request queue for the device
+ * @mask: alignment mask
+ *
+ * description:
+ * set required memory and length aligment for direct dma transactions.
+ * this is used when buiding direct io requests for the queue.
+ *
+ **/
+void blk_queue_dma_alignment(struct request_queue *q, int mask)
+{
+ q->dma_alignment = mask;
+}
+
+EXPORT_SYMBOL(blk_queue_dma_alignment);
+
+/**
+ * blk_queue_update_dma_alignment - update dma length and memory alignment
+ * @q: the request queue for the device
+ * @mask: alignment mask
+ *
+ * description:
+ * update required memory and length aligment for direct dma transactions.
+ * If the requested alignment is larger than the current alignment, then
+ * the current queue alignment is updated to the new value, otherwise it
+ * is left alone. The design of this is to allow multiple objects
+ * (driver, device, transport etc) to set their respective
+ * alignments without having them interfere.
+ *
+ **/
+void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
+{
+ BUG_ON(mask > PAGE_SIZE);
+
+ if (mask > q->dma_alignment)
+ q->dma_alignment = mask;
+}
+
+EXPORT_SYMBOL(blk_queue_update_dma_alignment);
+
+int __init blk_settings_init(void)
+{
+ blk_max_low_pfn = max_low_pfn - 1;
+ blk_max_pfn = max_pfn - 1;
+ return 0;
+}
+subsys_initcall(blk_settings_init);