1 files changed, 402 insertions, 0 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
new file mode 100644
index 000000000000..4df09a1b8f43
--- /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);