diff options
Diffstat (limited to 'kernel/block/blk-settings.c')
| -rw-r--r-- | kernel/block/blk-settings.c | 861 |
1 files changed, 861 insertions, 0 deletions
diff --git a/kernel/block/blk-settings.c b/kernel/block/blk-settings.c new file mode 100644 index 000000000..12600bfff --- /dev/null +++ b/kernel/block/blk-settings.c @@ -0,0 +1,861 @@ +/* + * 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 <linux/gcd.h> +#include <linux/lcm.h> +#include <linux/jiffies.h> +#include <linux/gfp.h> + +#include "blk.h" + +unsigned long blk_max_low_pfn; +EXPORT_SYMBOL(blk_max_low_pfn); + +unsigned long 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_unprep_rq - set an unprepare_request function for queue + * @q: queue + * @ufn: unprepare_request function + * + * It's possible for a queue to register an unprepare_request callback + * which is invoked before the request is finally completed. The goal + * of the function is to deallocate any data that was allocated in the + * prepare_request callback. + * + */ +void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn) +{ + q->unprep_rq_fn = ufn; +} +EXPORT_SYMBOL(blk_queue_unprep_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); + +void blk_queue_rq_timeout(struct request_queue *q, unsigned int timeout) +{ + q->rq_timeout = timeout; +} +EXPORT_SYMBOL_GPL(blk_queue_rq_timeout); + +void blk_queue_rq_timed_out(struct request_queue *q, rq_timed_out_fn *fn) +{ + q->rq_timed_out_fn = fn; +} +EXPORT_SYMBOL_GPL(blk_queue_rq_timed_out); + +void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn) +{ + q->lld_busy_fn = fn; +} +EXPORT_SYMBOL_GPL(blk_queue_lld_busy); + +/** + * blk_set_default_limits - reset limits to default values + * @lim: the queue_limits structure to reset + * + * Description: + * Returns a queue_limit struct to its default state. + */ +void blk_set_default_limits(struct queue_limits *lim) +{ + lim->max_segments = BLK_MAX_SEGMENTS; + lim->max_integrity_segments = 0; + lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; + lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; + lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS; + lim->chunk_sectors = 0; + lim->max_write_same_sectors = 0; + lim->max_discard_sectors = 0; + lim->discard_granularity = 0; + lim->discard_alignment = 0; + lim->discard_misaligned = 0; + lim->discard_zeroes_data = 0; + lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; + lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT); + lim->alignment_offset = 0; + lim->io_opt = 0; + lim->misaligned = 0; + lim->cluster = 1; +} +EXPORT_SYMBOL(blk_set_default_limits); + +/** + * blk_set_stacking_limits - set default limits for stacking devices + * @lim: the queue_limits structure to reset + * + * Description: + * Returns a queue_limit struct to its default state. Should be used + * by stacking drivers like DM that have no internal limits. + */ +void blk_set_stacking_limits(struct queue_limits *lim) +{ + blk_set_default_limits(lim); + + /* Inherit limits from component devices */ + lim->discard_zeroes_data = 1; + lim->max_segments = USHRT_MAX; + lim->max_hw_sectors = UINT_MAX; + lim->max_segment_size = UINT_MAX; + lim->max_sectors = UINT_MAX; + lim->max_write_same_sectors = UINT_MAX; +} +EXPORT_SYMBOL(blk_set_stacking_limits); + +/** + * 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; + + q->make_request_fn = mfn; + blk_queue_dma_alignment(q, 511); + blk_queue_congestion_threshold(q); + q->nr_batching = BLK_BATCH_REQ; + + blk_set_default_limits(&q->limits); + + /* + * 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 + * @max_addr: the maximum address the device can handle + * + * 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 @max_addr. + **/ +void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr) +{ + unsigned long b_pfn = max_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 (b_pfn < (min_t(u64, 0xffffffffUL, BLK_BOUNCE_HIGH) >> PAGE_SHIFT)) + dma = 1; + q->limits.bounce_pfn = max(max_low_pfn, b_pfn); +#else + if (b_pfn < blk_max_low_pfn) + dma = 1; + q->limits.bounce_pfn = b_pfn; +#endif + if (dma) { + init_emergency_isa_pool(); + q->bounce_gfp = GFP_NOIO | GFP_DMA; + q->limits.bounce_pfn = b_pfn; + } +} +EXPORT_SYMBOL(blk_queue_bounce_limit); + +/** + * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request + * @limits: the queue limits + * @max_hw_sectors: max hardware sectors in the usual 512b unit + * + * Description: + * Enables a low level driver to set a hard upper limit, + * max_hw_sectors, on the size of requests. max_hw_sectors is set by + * the device driver based upon the combined capabilities of I/O + * controller and storage device. + * + * max_sectors is a soft limit imposed by the block layer for + * filesystem type requests. This value can be overridden on a + * per-device basis in /sys/block/<device>/queue/max_sectors_kb. + * The soft limit can not exceed max_hw_sectors. + **/ +void blk_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors) +{ + if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) { + max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9); + printk(KERN_INFO "%s: set to minimum %d\n", + __func__, max_hw_sectors); + } + + limits->max_sectors = limits->max_hw_sectors = max_hw_sectors; +} +EXPORT_SYMBOL(blk_limits_max_hw_sectors); + +/** + * blk_queue_max_hw_sectors - set max sectors for a request for this queue + * @q: the request queue for the device + * @max_hw_sectors: max hardware sectors in the usual 512b unit + * + * Description: + * See description for blk_limits_max_hw_sectors(). + **/ +void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) +{ + blk_limits_max_hw_sectors(&q->limits, max_hw_sectors); +} +EXPORT_SYMBOL(blk_queue_max_hw_sectors); + +/** + * blk_queue_chunk_sectors - set size of the chunk for this queue + * @q: the request queue for the device + * @chunk_sectors: chunk sectors in the usual 512b unit + * + * Description: + * If a driver doesn't want IOs to cross a given chunk size, it can set + * this limit and prevent merging across chunks. Note that the chunk size + * must currently be a power-of-2 in sectors. Also note that the block + * layer must accept a page worth of data at any offset. So if the + * crossing of chunks is a hard limitation in the driver, it must still be + * prepared to split single page bios. + **/ +void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors) +{ + BUG_ON(!is_power_of_2(chunk_sectors)); + q->limits.chunk_sectors = chunk_sectors; +} +EXPORT_SYMBOL(blk_queue_chunk_sectors); + +/** + * blk_queue_max_discard_sectors - set max sectors for a single discard + * @q: the request queue for the device + * @max_discard_sectors: maximum number of sectors to discard + **/ +void blk_queue_max_discard_sectors(struct request_queue *q, + unsigned int max_discard_sectors) +{ + q->limits.max_discard_sectors = max_discard_sectors; +} +EXPORT_SYMBOL(blk_queue_max_discard_sectors); + +/** + * blk_queue_max_write_same_sectors - set max sectors for a single write same + * @q: the request queue for the device + * @max_write_same_sectors: maximum number of sectors to write per command + **/ +void blk_queue_max_write_same_sectors(struct request_queue *q, + unsigned int max_write_same_sectors) +{ + q->limits.max_write_same_sectors = max_write_same_sectors; +} +EXPORT_SYMBOL(blk_queue_max_write_same_sectors); + +/** + * blk_queue_max_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. + **/ +void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments) +{ + if (!max_segments) { + max_segments = 1; + printk(KERN_INFO "%s: set to minimum %d\n", + __func__, max_segments); + } + + q->limits.max_segments = max_segments; +} +EXPORT_SYMBOL(blk_queue_max_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(KERN_INFO "%s: set to minimum %d\n", + __func__, max_size); + } + + q->limits.max_segment_size = max_size; +} +EXPORT_SYMBOL(blk_queue_max_segment_size); + +/** + * blk_queue_logical_block_size - set logical block size for the queue + * @q: the request queue for the device + * @size: the logical block size, in bytes + * + * Description: + * This should be set to the lowest possible block size that the + * storage device can address. The default of 512 covers most + * hardware. + **/ +void blk_queue_logical_block_size(struct request_queue *q, unsigned short size) +{ + q->limits.logical_block_size = size; + + if (q->limits.physical_block_size < size) + q->limits.physical_block_size = size; + + if (q->limits.io_min < q->limits.physical_block_size) + q->limits.io_min = q->limits.physical_block_size; +} +EXPORT_SYMBOL(blk_queue_logical_block_size); + +/** + * blk_queue_physical_block_size - set physical block size for the queue + * @q: the request queue for the device + * @size: the physical block size, in bytes + * + * Description: + * This should be set to the lowest possible sector size that the + * hardware can operate on without reverting to read-modify-write + * operations. + */ +void blk_queue_physical_block_size(struct request_queue *q, unsigned int size) +{ + q->limits.physical_block_size = size; + + if (q->limits.physical_block_size < q->limits.logical_block_size) + q->limits.physical_block_size = q->limits.logical_block_size; + + if (q->limits.io_min < q->limits.physical_block_size) + q->limits.io_min = q->limits.physical_block_size; +} +EXPORT_SYMBOL(blk_queue_physical_block_size); + +/** + * blk_queue_alignment_offset - set physical block alignment offset + * @q: the request queue for the device + * @offset: alignment offset in bytes + * + * Description: + * Some devices are naturally misaligned to compensate for things like + * the legacy DOS partition table 63-sector offset. Low-level drivers + * should call this function for devices whose first sector is not + * naturally aligned. + */ +void blk_queue_alignment_offset(struct request_queue *q, unsigned int offset) +{ + q->limits.alignment_offset = + offset & (q->limits.physical_block_size - 1); + q->limits.misaligned = 0; +} +EXPORT_SYMBOL(blk_queue_alignment_offset); + +/** + * blk_limits_io_min - set minimum request size for a device + * @limits: the queue limits + * @min: smallest I/O size in bytes + * + * Description: + * Some devices have an internal block size bigger than the reported + * hardware sector size. This function can be used to signal the + * smallest I/O the device can perform without incurring a performance + * penalty. + */ +void blk_limits_io_min(struct queue_limits *limits, unsigned int min) +{ + limits->io_min = min; + + if (limits->io_min < limits->logical_block_size) + limits->io_min = limits->logical_block_size; + + if (limits->io_min < limits->physical_block_size) + limits->io_min = limits->physical_block_size; +} +EXPORT_SYMBOL(blk_limits_io_min); + +/** + * blk_queue_io_min - set minimum request size for the queue + * @q: the request queue for the device + * @min: smallest I/O size in bytes + * + * Description: + * Storage devices may report a granularity or preferred minimum I/O + * size which is the smallest request the device can perform without + * incurring a performance penalty. For disk drives this is often the + * physical block size. For RAID arrays it is often the stripe chunk + * size. A properly aligned multiple of minimum_io_size is the + * preferred request size for workloads where a high number of I/O + * operations is desired. + */ +void blk_queue_io_min(struct request_queue *q, unsigned int min) +{ + blk_limits_io_min(&q->limits, min); +} +EXPORT_SYMBOL(blk_queue_io_min); + +/** + * blk_limits_io_opt - set optimal request size for a device + * @limits: the queue limits + * @opt: smallest I/O size in bytes + * + * Description: + * Storage devices may report an optimal I/O size, which is the + * device's preferred unit for sustained I/O. This is rarely reported + * for disk drives. For RAID arrays it is usually the stripe width or + * the internal track size. A properly aligned multiple of + * optimal_io_size is the preferred request size for workloads where + * sustained throughput is desired. + */ +void blk_limits_io_opt(struct queue_limits *limits, unsigned int opt) +{ + limits->io_opt = opt; +} +EXPORT_SYMBOL(blk_limits_io_opt); + +/** + * blk_queue_io_opt - set optimal request size for the queue + * @q: the request queue for the device + * @opt: optimal request size in bytes + * + * Description: + * Storage devices may report an optimal I/O size, which is the + * device's preferred unit for sustained I/O. This is rarely reported + * for disk drives. For RAID arrays it is usually the stripe width or + * the internal track size. A properly aligned multiple of + * optimal_io_size is the preferred request size for workloads where + * sustained throughput is desired. + */ +void blk_queue_io_opt(struct request_queue *q, unsigned int opt) +{ + blk_limits_io_opt(&q->limits, opt); +} +EXPORT_SYMBOL(blk_queue_io_opt); + +/** + * 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) +{ + blk_stack_limits(&t->limits, &b->limits, 0); +} +EXPORT_SYMBOL(blk_queue_stack_limits); + +/** + * blk_stack_limits - adjust queue_limits for stacked devices + * @t: the stacking driver limits (top device) + * @b: the underlying queue limits (bottom, component device) + * @start: first data sector within component device + * + * Description: + * This function is used by stacking drivers like MD and DM to ensure + * that all component devices have compatible block sizes and + * alignments. The stacking driver must provide a queue_limits + * struct (top) and then iteratively call the stacking function for + * all component (bottom) devices. The stacking function will + * attempt to combine the values and ensure proper alignment. + * + * Returns 0 if the top and bottom queue_limits are compatible. The + * top device's block sizes and alignment offsets may be adjusted to + * ensure alignment with the bottom device. If no compatible sizes + * and alignments exist, -1 is returned and the resulting top + * queue_limits will have the misaligned flag set to indicate that + * the alignment_offset is undefined. + */ +int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, + sector_t start) +{ + unsigned int top, bottom, alignment, ret = 0; + + 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_write_same_sectors = min(t->max_write_same_sectors, + b->max_write_same_sectors); + t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn); + + t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask, + b->seg_boundary_mask); + + t->max_segments = min_not_zero(t->max_segments, b->max_segments); + t->max_integrity_segments = min_not_zero(t->max_integrity_segments, + b->max_integrity_segments); + + t->max_segment_size = min_not_zero(t->max_segment_size, + b->max_segment_size); + + t->misaligned |= b->misaligned; + + alignment = queue_limit_alignment_offset(b, start); + + /* Bottom device has different alignment. Check that it is + * compatible with the current top alignment. + */ + if (t->alignment_offset != alignment) { + + top = max(t->physical_block_size, t->io_min) + + t->alignment_offset; + bottom = max(b->physical_block_size, b->io_min) + alignment; + + /* Verify that top and bottom intervals line up */ + if (max(top, bottom) % min(top, bottom)) { + t->misaligned = 1; + ret = -1; + } + } + + t->logical_block_size = max(t->logical_block_size, + b->logical_block_size); + + t->physical_block_size = max(t->physical_block_size, + b->physical_block_size); + + t->io_min = max(t->io_min, b->io_min); + t->io_opt = lcm_not_zero(t->io_opt, b->io_opt); + + t->cluster &= b->cluster; + t->discard_zeroes_data &= b->discard_zeroes_data; + + /* Physical block size a multiple of the logical block size? */ + if (t->physical_block_size & (t->logical_block_size - 1)) { + t->physical_block_size = t->logical_block_size; + t->misaligned = 1; + ret = -1; + } + + /* Minimum I/O a multiple of the physical block size? */ + if (t->io_min & (t->physical_block_size - 1)) { + t->io_min = t->physical_block_size; + t->misaligned = 1; + ret = -1; + } + + /* Optimal I/O a multiple of the physical block size? */ + if (t->io_opt & (t->physical_block_size - 1)) { + t->io_opt = 0; + t->misaligned = 1; + ret = -1; + } + + t->raid_partial_stripes_expensive = + max(t->raid_partial_stripes_expensive, + b->raid_partial_stripes_expensive); + + /* Find lowest common alignment_offset */ + t->alignment_offset = lcm_not_zero(t->alignment_offset, alignment) + % max(t->physical_block_size, t->io_min); + + /* Verify that new alignment_offset is on a logical block boundary */ + if (t->alignment_offset & (t->logical_block_size - 1)) { + t->misaligned = 1; + ret = -1; + } + + /* Discard alignment and granularity */ + if (b->discard_granularity) { + alignment = queue_limit_discard_alignment(b, start); + + if (t->discard_granularity != 0 && + t->discard_alignment != alignment) { + top = t->discard_granularity + t->discard_alignment; + bottom = b->discard_granularity + alignment; + + /* Verify that top and bottom intervals line up */ + if ((max(top, bottom) % min(top, bottom)) != 0) + t->discard_misaligned = 1; + } + + t->max_discard_sectors = min_not_zero(t->max_discard_sectors, + b->max_discard_sectors); + t->discard_granularity = max(t->discard_granularity, + b->discard_granularity); + t->discard_alignment = lcm_not_zero(t->discard_alignment, alignment) % + t->discard_granularity; + } + + return ret; +} +EXPORT_SYMBOL(blk_stack_limits); + +/** + * bdev_stack_limits - adjust queue limits for stacked drivers + * @t: the stacking driver limits (top device) + * @bdev: the component block_device (bottom) + * @start: first data sector within component device + * + * Description: + * Merges queue limits for a top device and a block_device. Returns + * 0 if alignment didn't change. Returns -1 if adding the bottom + * device caused misalignment. + */ +int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev, + sector_t start) +{ + struct request_queue *bq = bdev_get_queue(bdev); + + start += get_start_sect(bdev); + + return blk_stack_limits(t, &bq->limits, start); +} +EXPORT_SYMBOL(bdev_stack_limits); + +/** + * disk_stack_limits - adjust queue limits for stacked drivers + * @disk: MD/DM gendisk (top) + * @bdev: the underlying block device (bottom) + * @offset: offset to beginning of data within component device + * + * Description: + * Merges the limits for a top level gendisk and a bottom level + * block_device. + */ +void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, + sector_t offset) +{ + struct request_queue *t = disk->queue; + + if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) { + char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE]; + + disk_name(disk, 0, top); + bdevname(bdev, bottom); + + printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n", + top, bottom); + } +} +EXPORT_SYMBOL(disk_stack_limits); + +/** + * blk_queue_dma_pad - set pad mask + * @q: the request queue for the device + * @mask: pad mask + * + * Set dma pad mask. + * + * Appending pad buffer to a request modifies the last entry of a + * scatter list such that it includes the pad buffer. + **/ +void blk_queue_dma_pad(struct request_queue *q, unsigned int mask) +{ + q->dma_pad_mask = mask; +} +EXPORT_SYMBOL(blk_queue_dma_pad); + +/** + * blk_queue_update_dma_pad - update pad mask + * @q: the request queue for the device + * @mask: pad mask + * + * Update dma pad mask. + * + * Appending pad buffer to a request modifies the last entry of a + * scatter list such that it includes the pad buffer. + **/ +void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) +{ + if (mask > q->dma_pad_mask) + q->dma_pad_mask = mask; +} +EXPORT_SYMBOL(blk_queue_update_dma_pad); + +/** + * blk_queue_dma_drain - Set up a drain buffer for excess dma. + * @q: the request queue for the device + * @dma_drain_needed: fn which returns non-zero if drain is necessary + * @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_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, + dma_drain_needed_fn *dma_drain_needed, + void *buf, unsigned int size) +{ + if (queue_max_segments(q) < 2) + return -EINVAL; + /* make room for appending the drain */ + blk_queue_max_segments(q, queue_max_segments(q) - 1); + q->dma_drain_needed = dma_drain_needed; + 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(KERN_INFO "%s: set to minimum %lx\n", + __func__, mask); + } + + q->limits.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 alignment for direct dma transactions. + * this is used when building 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 alignment for direct dma transactions. + * If the requested alignment is larger than the current alignment, then + * the current queue alignment is updated to the new value, otherwise it + * is left alone. The design of this is to allow multiple objects + * (driver, device, transport etc) to set their respective + * alignments without having them interfere. + * + **/ +void blk_queue_update_dma_alignment(struct request_queue *q, int mask) +{ + BUG_ON(mask > PAGE_SIZE); + + if (mask > q->dma_alignment) + q->dma_alignment = mask; +} +EXPORT_SYMBOL(blk_queue_update_dma_alignment); + +/** + * blk_queue_flush - configure queue's cache flush capability + * @q: the request queue for the device + * @flush: 0, REQ_FLUSH or REQ_FLUSH | REQ_FUA + * + * Tell block layer cache flush capability of @q. If it supports + * flushing, REQ_FLUSH should be set. If it supports bypassing + * write cache for individual writes, REQ_FUA should be set. + */ +void blk_queue_flush(struct request_queue *q, unsigned int flush) +{ + WARN_ON_ONCE(flush & ~(REQ_FLUSH | REQ_FUA)); + + if (WARN_ON_ONCE(!(flush & REQ_FLUSH) && (flush & REQ_FUA))) + flush &= ~REQ_FUA; + + q->flush_flags = flush & (REQ_FLUSH | REQ_FUA); +} +EXPORT_SYMBOL_GPL(blk_queue_flush); + +void blk_queue_flush_queueable(struct request_queue *q, bool queueable) +{ + q->flush_not_queueable = !queueable; +} +EXPORT_SYMBOL_GPL(blk_queue_flush_queueable); + +static 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); |