linux/block/blk-settings.c

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/*
* 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 cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#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);
block: add lld busy state exporting interface This patch adds an new interface, blk_lld_busy(), to check lld's busy state from the block layer. blk_lld_busy() calls down into low-level drivers for the checking if the drivers set q->lld_busy_fn() using blk_queue_lld_busy(). This resolves a performance problem on request stacking devices below. Some drivers like scsi mid layer stop dispatching request when they detect busy state on its low-level device like host/target/device. It allows other requests to stay in the I/O scheduler's queue for a chance of merging. Request stacking drivers like request-based dm should follow the same logic. However, there is no generic interface for the stacked device to check if the underlying device(s) are busy. If the request stacking driver dispatches and submits requests to the busy underlying device, the requests will stay in the underlying device's queue without a chance of merging. This causes performance problem on burst I/O load. With this patch, busy state of the underlying device is exported via q->lld_busy_fn(). So the request stacking driver can check it and stop dispatching requests if busy. The underlying device driver must return the busy state appropriately: 1: when the device driver can't process requests immediately. 0: when the device driver can process requests immediately, including abnormal situations where the device driver needs to kill all requests. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-10-01 14:12:15 +00:00
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. Can be used by
* stacking drivers like DM that stage table swaps and reuse an
* existing device queue.
*/
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 = BLK_DEF_MAX_SECTORS;
lim->max_hw_sectors = INT_MAX;
lim->max_discard_sectors = 0;
lim->discard_granularity = 0;
lim->discard_alignment = 0;
lim->discard_misaligned = 0;
lim->discard_zeroes_data = -1;
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_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;
block: fix setting of max_segment_size and seg_boundary mask Fix setting of max_segment_size and seg_boundary mask for stacked md/dm devices. When stacking devices (LVM over MD over SCSI) some of the request queue parameters are not set up correctly in some cases by default, namely max_segment_size and and seg_boundary mask. If you create MD device over SCSI, these attributes are zeroed. Problem become when there is over this mapping next device-mapper mapping - queue attributes are set in DM this way: request_queue max_segment_size seg_boundary_mask SCSI 65536 0xffffffff MD RAID1 0 0 LVM 65536 -1 (64bit) Unfortunately bio_add_page (resp. bio_phys_segments) calculates number of physical segments according to these parameters. During the generic_make_request() is segment cout recalculated and can increase bio->bi_phys_segments count over the allowed limit. (After bio_clone() in stack operation.) Thi is specially problem in CCISS driver, where it produce OOPS here BUG_ON(creq->nr_phys_segments > MAXSGENTRIES); (MAXSEGENTRIES is 31 by default.) Sometimes even this command is enough to cause oops: dd iflag=direct if=/dev/<vg>/<lv> of=/dev/null bs=128000 count=10 This command generates bios with 250 sectors, allocated in 32 4k-pages (last page uses only 1024 bytes). For LVM layer, it allocates bio with 31 segments (still OK for CCISS), unfortunatelly on lower layer it is recalculated to 32 segments and this violates CCISS restriction and triggers BUG_ON(). The patch tries to fix it by: * initializing attributes above in queue request constructor blk_queue_make_request() * make sure that blk_queue_stack_limits() inherits setting (DM uses its own function to set the limits because it blk_queue_stack_limits() was introduced later. It should probably switch to use generic stack limit function too.) * sets the default seg_boundary value in one place (blkdev.h) * use this mask as default in DM (instead of -1, which differs in 64bit) Bugs related to this: https://bugzilla.redhat.com/show_bug.cgi?id=471639 http://bugzilla.kernel.org/show_bug.cgi?id=8672 Signed-off-by: Milan Broz <mbroz@redhat.com> Reviewed-by: Alasdair G Kergon <agk@redhat.com> Cc: Neil Brown <neilb@suse.de> Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Cc: Tejun Heo <htejun@gmail.com> Cc: Mike Miller <mike.miller@hp.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-12-03 11:55:08 +00:00
q->make_request_fn = mfn;
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 = msecs_to_jiffies(3); /* 3 milliseconds */
if (q->unplug_delay == 0)
q->unplug_delay = 1;
q->unplug_timer.function = blk_unplug_timeout;
q->unplug_timer.data = (unsigned long)q;
blk_set_default_limits(&q->limits);
blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS);
/*
* If the caller didn't supply a lock, fall back to our embedded
* per-queue locks
*/
if (!q->queue_lock)
q->queue_lock = &q->__queue_lock;
/*
* 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_mask: 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 @dma_mask.
**/
void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask)
{
unsigned long b_pfn = dma_mask >> 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_hw_sectors = max_hw_sectors;
limits->max_sectors = min_t(unsigned int, max_hw_sectors,
BLK_DEF_MAX_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_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_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->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) - 1)) {
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(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;
}
/* Find lowest common alignment_offset */
t->alignment_offset = lcm(t->alignment_offset, alignment)
& (max(t->physical_block_size, t->io_min) - 1);
/* 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) - 1))
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(t->discard_alignment, alignment) &
(t->discard_granularity - 1);
}
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);
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);