Release 4.7 drivers/md/dm-stripe.c

Directory: drivers/md
/*
 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
 *
 * This file is released under the GPL.
 */

#include "dm.h"
#include <linux/device-mapper.h>

#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>
#include <linux/log2.h>


#define DM_MSG_PREFIX "striped"

#define DM_IO_ERROR_THRESHOLD 15


struct stripe {
	
struct dm_dev *dev;
	
sector_t physical_start;

	
atomic_t error_count;
};


struct stripe_c {
	
uint32_t stripes;
	
int stripes_shift;

	/* The size of this target / num. stripes */
	
sector_t stripe_width;

	
uint32_t chunk_size;
	
int chunk_size_shift;

	/* Needed for handling events */
	
struct dm_target *ti;

	/* Work struct used for triggering events*/
	
struct work_struct trigger_event;

	
struct stripe stripe[0];
};

/*
 * An event is triggered whenever a drive
 * drops out of a stripe volume.
 */


static void trigger_event(struct work_struct *work)
{
	struct stripe_c *sc = container_of(work, struct stripe_c,
					   trigger_event);
	dm_table_event(sc->ti->table);
}

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tejun heo tejun heo 1 2.86% 1 50.00%
Total 35 100.00% 2 100.00%



static inline struct stripe_c *alloc_context(unsigned int stripes)
{
	size_t len;

	if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
			     stripes))
		return NULL;

	len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);

	return kmalloc(len, GFP_KERNEL);
}

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alan cox alan cox 62 96.88% 1 33.33%
mikulas patocka mikulas patocka 1 1.56% 1 33.33%
joe thornber joe thornber 1 1.56% 1 33.33%
Total 64 100.00% 3 100.00%

/*
 * Parse a single <dev> <sector> pair
 */


static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
		      unsigned int stripe, char **argv)
{
	unsigned long long start;
	char dummy;
	int ret;

	if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
		return -EINVAL;

	ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
			    &sc->stripe[stripe].dev);
	if (ret)
		return ret;

	sc->stripe[stripe].physical_start = start;

	return 0;
}

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alan cox alan cox 89 80.91% 1 20.00%
vivek goyal vivek goyal 10 9.09% 1 20.00%
mikulas patocka mikulas patocka 7 6.36% 1 20.00%
andrew morton andrew morton 3 2.73% 1 20.00%
joe thornber joe thornber 1 0.91% 1 20.00%
Total 110 100.00% 5 100.00%

/*
 * Construct a striped mapping.
 * <number of stripes> <chunk size> [<dev_path> <offset>]+
 */


static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
	struct stripe_c *sc;
	sector_t width, tmp_len;
	uint32_t stripes;
	uint32_t chunk_size;
	int r;
	unsigned int i;

	if (argc < 2) {
		ti->error = "Not enough arguments";
		return -EINVAL;
	}

	if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
		ti->error = "Invalid stripe count";
		return -EINVAL;
	}

	if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
		ti->error = "Invalid chunk_size";
		return -EINVAL;
	}

	width = ti->len;
	if (sector_div(width, stripes)) {
		ti->error = "Target length not divisible by "
		    "number of stripes";
		return -EINVAL;
	}

	tmp_len = width;
	if (sector_div(tmp_len, chunk_size)) {
		ti->error = "Target length not divisible by "
		    "chunk size";
		return -EINVAL;
	}

	/*
         * Do we have enough arguments for that many stripes ?
         */
	if (argc != (2 + 2 * stripes)) {
		ti->error = "Not enough destinations "
			"specified";
		return -EINVAL;
	}

	sc = alloc_context(stripes);
	if (!sc) {
		ti->error = "Memory allocation for striped context "
		    "failed";
		return -ENOMEM;
	}

	INIT_WORK(&sc->trigger_event, trigger_event);

	/* Set pointer to dm target; used in trigger_event */
	sc->ti = ti;
	sc->stripes = stripes;
	sc->stripe_width = width;

	if (stripes & (stripes - 1))
		sc->stripes_shift = -1;
	else
		sc->stripes_shift = __ffs(stripes);

	r = dm_set_target_max_io_len(ti, chunk_size);
	if (r) {
		kfree(sc);
		return r;
	}

	ti->num_flush_bios = stripes;
	ti->num_discard_bios = stripes;
	ti->num_write_same_bios = stripes;

	sc->chunk_size = chunk_size;
	if (chunk_size & (chunk_size - 1))
		sc->chunk_size_shift = -1;
	else
		sc->chunk_size_shift = __ffs(chunk_size);

	/*
         * Get the stripe destinations.
         */
	for (i = 0; i < stripes; i++) {
		argv += 2;

		r = get_stripe(ti, sc, i, argv);
		if (r < 0) {
			ti->error = "Couldn't parse stripe destination";
			while (i--)
				dm_put_device(ti, sc->stripe[i].dev);
			kfree(sc);
			return r;
		}
		atomic_set(&(sc->stripe[i].error_count), 0);
	}

	ti->private = sc;

	return 0;
}

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alan cox alan cox 224 49.12% 1 4.17%
mikulas patocka mikulas patocka 64 14.04% 6 25.00%
joe thornber joe thornber 41 8.99% 3 12.50%
mike snitzer mike snitzer 40 8.77% 4 16.67%
brian wood brian wood 33 7.24% 1 4.17%
kevin corry kevin corry 15 3.29% 1 4.17%
ma jianpeng ma jianpeng 13 2.85% 1 4.17%
alasdair kergon alasdair kergon 10 2.19% 2 8.33%
pavitra kumar pavitra kumar 7 1.54% 1 4.17%
andrew morton andrew morton 6 1.32% 2 8.33%
nikanth karthikesan nikanth karthikesan 2 0.44% 1 4.17%
tejun heo tejun heo 1 0.22% 1 4.17%
Total 456 100.00% 24 100.00%



static void stripe_dtr(struct dm_target *ti)
{
	unsigned int i;
	struct stripe_c *sc = (struct stripe_c *) ti->private;

	for (i = 0; i < sc->stripes; i++)
		dm_put_device(ti, sc->stripe[i].dev);

	flush_work(&sc->trigger_event);
	kfree(sc);
}

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alan cox alan cox 63 88.73% 1 25.00%
tejun heo tejun heo 5 7.04% 2 50.00%
brian wood brian wood 3 4.23% 1 25.00%
Total 71 100.00% 4 100.00%



static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
			      uint32_t *stripe, sector_t *result)
{
	sector_t chunk = dm_target_offset(sc->ti, sector);
	sector_t chunk_offset;

	if (sc->chunk_size_shift < 0)
		chunk_offset = sector_div(chunk, sc->chunk_size);
	else {
		chunk_offset = chunk & (sc->chunk_size - 1);
		chunk >>= sc->chunk_size_shift;
	}

	if (sc->stripes_shift < 0)
		*stripe = sector_div(chunk, sc->stripes);
	else {
		*stripe = chunk & (sc->stripes - 1);
		chunk >>= sc->stripes_shift;
	}

	if (sc->chunk_size_shift < 0)
		chunk *= sc->chunk_size;
	else
		chunk <<= sc->chunk_size_shift;

	*result = chunk + chunk_offset;
}

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mikulas patocka mikulas patocka 136 92.52% 4 80.00%
mike snitzer mike snitzer 11 7.48% 1 20.00%
Total 147 100.00% 5 100.00%



static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
				    uint32_t target_stripe, sector_t *result)
{
	uint32_t stripe;

	stripe_map_sector(sc, sector, &stripe, result);
	if (stripe == target_stripe)
		return;

	/* round down */
	sector = *result;
	if (sc->chunk_size_shift < 0)
		*result -= sector_div(sector, sc->chunk_size);
	else
		*result = sector & ~(sector_t)(sc->chunk_size - 1);

	if (target_stripe < stripe)
		*result += sc->chunk_size;		/* next chunk */
}

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mikulas patocka mikulas patocka 87 86.14% 2 66.67%
mike snitzer mike snitzer 14 13.86% 1 33.33%
Total 101 100.00% 3 100.00%



static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
			    uint32_t target_stripe)
{
	sector_t begin, end;

	stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
				target_stripe, &begin);
	stripe_map_range_sector(sc, bio_end_sector(bio),
				target_stripe, &end);
	if (begin < end) {
		bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
		bio->bi_iter.bi_sector = begin +
			sc->stripe[target_stripe].physical_start;
		bio->bi_iter.bi_size = to_bytes(end - begin);
		return DM_MAPIO_REMAPPED;
	} else {
		/* The range doesn't map to the target stripe */
		bio_endio(bio);
		return DM_MAPIO_SUBMITTED;
	}
}

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mikulas patocka mikulas patocka 115 93.50% 1 25.00%
kent overstreet kent overstreet 7 5.69% 2 50.00%
mike snitzer mike snitzer 1 0.81% 1 25.00%
Total 123 100.00% 4 100.00%



static int stripe_map(struct dm_target *ti, struct bio *bio)
{
	struct stripe_c *sc = ti->private;
	uint32_t stripe;
	unsigned target_bio_nr;

	if (bio->bi_rw & REQ_FLUSH) {
		target_bio_nr = dm_bio_get_target_bio_nr(bio);
		BUG_ON(target_bio_nr >= sc->stripes);
		bio->bi_bdev = sc->stripe[target_bio_nr].dev->bdev;
		return DM_MAPIO_REMAPPED;
	}
	if (unlikely(bio->bi_rw & REQ_DISCARD) ||
	    unlikely(bio->bi_rw & REQ_WRITE_SAME)) {
		target_bio_nr = dm_bio_get_target_bio_nr(bio);
		BUG_ON(target_bio_nr >= sc->stripes);
		return stripe_map_range(sc, bio, target_bio_nr);
	}

	stripe_map_sector(sc, bio->bi_iter.bi_sector,
			  &stripe, &bio->bi_iter.bi_sector);

	bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
	bio->bi_bdev = sc->stripe[stripe].dev->bdev;

	return DM_MAPIO_REMAPPED;
}

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mikulas patocka mikulas patocka 83 46.89% 4 30.77%
alan cox alan cox 54 30.51% 1 7.69%
mike snitzer mike snitzer 16 9.04% 2 15.38%
alasdair kergon alasdair kergon 11 6.21% 2 15.38%
kent overstreet kent overstreet 6 3.39% 1 7.69%
tejun heo tejun heo 4 2.26% 1 7.69%
kevin corry kevin corry 2 1.13% 1 7.69%
kiyoshi ueda kiyoshi ueda 1 0.56% 1 7.69%
Total 177 100.00% 13 100.00%

/*
 * Stripe status:
 *
 * INFO
 * #stripes [stripe_name <stripe_name>] [group word count]
 * [error count 'A|D' <error count 'A|D'>]
 *
 * TABLE
 * #stripes [stripe chunk size]
 * [stripe_name physical_start <stripe_name physical_start>]
 *
 */



static void stripe_status(struct dm_target *ti, status_type_t type,
			  unsigned status_flags, char *result, unsigned maxlen)
{
	struct stripe_c *sc = (struct stripe_c *) ti->private;
	char buffer[sc->stripes + 1];
	unsigned int sz = 0;
	unsigned int i;

	switch (type) {
	case STATUSTYPE_INFO:
		DMEMIT("%d ", sc->stripes);
		for (i = 0; i < sc->stripes; i++)  {
			DMEMIT("%s ", sc->stripe[i].dev->name);
			buffer[i] = atomic_read(&(sc->stripe[i].error_count)) ?
				'D' : 'A';
		}
		buffer[i] = '\0';
		DMEMIT("1 %s", buffer);
		break;

	case STATUSTYPE_TABLE:
		DMEMIT("%d %llu", sc->stripes,
			(unsigned long long)sc->chunk_size);
		for (i = 0; i < sc->stripes; i++)
			DMEMIT(" %s %llu", sc->stripe[i].dev->name,
			    (unsigned long long)sc->stripe[i].physical_start);
		break;
	}
}

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brian wood brian wood 85 39.53% 1 9.09%
andrew morton andrew morton 16 7.44% 2 18.18%
kevin corry kevin corry 11 5.12% 1 9.09%
alasdair kergon alasdair kergon 4 1.86% 2 18.18%
joe thornber joe thornber 2 0.93% 1 9.09%
lars marowsky-bree lars marowsky-bree 2 0.93% 1 9.09%
mikulas patocka mikulas patocka 1 0.47% 1 9.09%
mike snitzer mike snitzer 1 0.47% 1 9.09%
Total 215 100.00% 11 100.00%



static int stripe_end_io(struct dm_target *ti, struct bio *bio, int error)
{
	unsigned i;
	char major_minor[16];
	struct stripe_c *sc = ti->private;

	if (!error)
		return 0; /* I/O complete */

	if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
		return error;

	if (error == -EOPNOTSUPP)
		return error;

	memset(major_minor, 0, sizeof(major_minor));
	sprintf(major_minor, "%d:%d",
		MAJOR(disk_devt(bio->bi_bdev->bd_disk)),
		MINOR(disk_devt(bio->bi_bdev->bd_disk)));

	/*
         * Test to see which stripe drive triggered the event
         * and increment error count for all stripes on that device.
         * If the error count for a given device exceeds the threshold
         * value we will no longer trigger any further events.
         */
	for (i = 0; i < sc->stripes; i++)
		if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
			atomic_inc(&(sc->stripe[i].error_count));
			if (atomic_read(&(sc->stripe[i].error_count)) <
			    DM_IO_ERROR_THRESHOLD)
				schedule_work(&sc->trigger_event);
		}

	return error;
}

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tejun heo tejun heo 14 6.97% 2 50.00%
christoph hellwig christoph hellwig 6 2.99% 1 25.00%
Total 201 100.00% 4 100.00%



static int stripe_iterate_devices(struct dm_target *ti,
				  iterate_devices_callout_fn fn, void *data)
{
	struct stripe_c *sc = ti->private;
	int ret = 0;
	unsigned i = 0;

	do {
		ret = fn(ti, sc->stripe[i].dev,
			 sc->stripe[i].physical_start,
			 sc->stripe_width, data);
	} while (!ret && ++i < sc->stripes);

	return ret;
}

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mike snitzer mike snitzer 87 100.00% 2 100.00%
Total 87 100.00% 2 100.00%



static void stripe_io_hints(struct dm_target *ti,
			    struct queue_limits *limits)
{
	struct stripe_c *sc = ti->private;
	unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;

	blk_limits_io_min(limits, chunk_size);
	blk_limits_io_opt(limits, chunk_size * sc->stripes);
}

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martin k. petersen martin k. petersen 4 7.69% 1 33.33%
Total 52 100.00% 3 100.00%


static struct target_type stripe_target = {
	.name   = "striped",
	.version = {1, 5, 1},
	.module = THIS_MODULE,
	.ctr    = stripe_ctr,
	.dtr    = stripe_dtr,
	.map    = stripe_map,
	.end_io = stripe_end_io,
	.status = stripe_status,
	.iterate_devices = stripe_iterate_devices,
	.io_hints = stripe_io_hints,
};



int __init dm_stripe_init(void)
{
	int r;

	r = dm_register_target(&stripe_target);
	if (r < 0)
		DMWARN("target registration failed");

	return r;
}

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alan cox alan cox 28 84.85% 1 33.33%
heinz mauelshagen heinz mauelshagen 4 12.12% 1 33.33%
alasdair kergon alasdair kergon 1 3.03% 1 33.33%
Total 33 100.00% 3 100.00%



void dm_stripe_exit(void)
{
	dm_unregister_target(&stripe_target);
}
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alan cox alan cox 13 100.00% 1 100.00%
Total 13 100.00% 1 100.00%

Overall Contributors
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alan cox alan cox 714 35.00% 1 1.75%
mikulas patocka mikulas patocka 502 24.61% 12 21.05%
brian wood brian wood 360 17.65% 2 3.51%
mike snitzer mike snitzer 234 11.47% 9 15.79%
joe thornber joe thornber 45 2.21% 3 5.26%
andrew morton andrew morton 35 1.72% 5 8.77%
alasdair kergon alasdair kergon 31 1.52% 6 10.53%
kevin corry kevin corry 28 1.37% 3 5.26%
tejun heo tejun heo 26 1.27% 4 7.02%
ma jianpeng ma jianpeng 13 0.64% 1 1.75%
kent overstreet kent overstreet 13 0.64% 2 3.51%
vivek goyal vivek goyal 10 0.49% 1 1.75%
pavitra kumar pavitra kumar 7 0.34% 1 1.75%
christoph hellwig christoph hellwig 6 0.29% 1 1.75%
heinz mauelshagen heinz mauelshagen 4 0.20% 1 1.75%
martin k. petersen martin k. petersen 4 0.20% 1 1.75%
vignesh babu vignesh babu 3 0.15% 1 1.75%
nikanth karthikesan nikanth karthikesan 2 0.10% 1 1.75%
lars marowsky-bree lars marowsky-bree 2 0.10% 1 1.75%
kiyoshi ueda kiyoshi ueda 1 0.05% 1 1.75%
Total 2040 100.00% 57 100.00%
  Directory: drivers/md

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tejun heo	tejun heo	1	2.86%	1	50.00%
	Total	35	100.00%	2	100.00%
cregit-Linux how code gets into the kernel

Release 4.7 drivers/md/dm-stripe.c

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