cregit-Linux how code gets into the kernel

Release 4.14 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/dax.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); }

Contributors

PersonTokensPropCommitsCommitProp
Brian Wood3497.14%150.00%
Tejun Heo12.86%150.00%
Total35100.00%2100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Alan Cox6296.88%133.33%
Mikulas Patocka11.56%133.33%
Joe Thornber11.56%133.33%
Total64100.00%3100.00%

/* * 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; }

Contributors

PersonTokensPropCommitsCommitProp
Alan Cox8980.91%120.00%
Vivek Goyal109.09%120.00%
Mikulas Patocka76.36%120.00%
Andrew Morton32.73%120.00%
Joe Thornber10.91%120.00%
Total110100.00%5100.00%

/* * 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; ti->num_write_zeroes_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; }

Contributors

PersonTokensPropCommitsCommitProp
Alan Cox22448.48%14.00%
Mikulas Patocka6413.85%624.00%
Joe Thornber418.87%312.00%
Mike Snitzer408.66%416.00%
Brian Wood337.14%14.00%
Kevin Corry153.25%14.00%
Jianpeng Ma (马建朋)132.81%14.00%
Alasdair G. Kergon102.16%28.00%
Pavitra Kumar71.52%14.00%
Christoph Hellwig61.30%14.00%
Andrew Morton61.30%28.00%
Nikanth Karthikesan20.43%14.00%
Tejun Heo10.22%14.00%
Total462100.00%25100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Alan Cox6388.73%125.00%
Tejun Heo57.04%250.00%
Brian Wood34.23%125.00%
Total71100.00%4100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka13692.52%480.00%
Mike Snitzer117.48%120.00%
Total147100.00%5100.00%


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 */ }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka8786.14%266.67%
Mike Snitzer1413.86%133.33%
Total101100.00%3100.00%


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_set_dev(bio, 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; } }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka11290.32%120.00%
Kent Overstreet75.65%240.00%
Christoph Hellwig43.23%120.00%
Mike Snitzer10.81%120.00%
Total124100.00%5100.00%


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_opf & REQ_PREFLUSH) { target_bio_nr = dm_bio_get_target_bio_nr(bio); BUG_ON(target_bio_nr >= sc->stripes); bio_set_dev(bio, sc->stripe[target_bio_nr].dev->bdev); return DM_MAPIO_REMAPPED; } if (unlikely(bio_op(bio) == REQ_OP_DISCARD) || unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES) || unlikely(bio_op(bio) == REQ_OP_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_set_dev(bio, sc->stripe[stripe].dev->bdev); return DM_MAPIO_REMAPPED; }

Contributors

PersonTokensPropCommitsCommitProp
Mikulas Patocka7539.27%422.22%
Alan Cox5227.23%15.56%
Christoph Hellwig189.42%211.11%
Mike Snitzer126.28%211.11%
Alasdair G. Kergon115.76%211.11%
Michael Christie115.76%211.11%
Kent Overstreet63.14%15.56%
Tejun Heo21.05%15.56%
Kevin Corry21.05%15.56%
Kiyoshi Ueda10.52%15.56%
Jens Axboe10.52%15.56%
Total191100.00%18100.00%


static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn) { sector_t dev_sector, sector = pgoff * PAGE_SECTORS; struct stripe_c *sc = ti->private; struct dax_device *dax_dev; struct block_device *bdev; uint32_t stripe; long ret; stripe_map_sector(sc, sector, &stripe, &dev_sector); dev_sector += sc->stripe[stripe].physical_start; dax_dev = sc->stripe[stripe].dev->dax_dev; bdev = sc->stripe[stripe].dev->bdev; ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff); if (ret) return ret; return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn); }

Contributors

PersonTokensPropCommitsCommitProp
Toshi Kani8557.82%150.00%
Dan J Williams6242.18%150.00%
Total147100.00%2100.00%


static size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i) { sector_t dev_sector, sector = pgoff * PAGE_SECTORS; struct stripe_c *sc = ti->private; struct dax_device *dax_dev; struct block_device *bdev; uint32_t stripe; stripe_map_sector(sc, sector, &stripe, &dev_sector); dev_sector += sc->stripe[stripe].physical_start; dax_dev = sc->stripe[stripe].dev->dax_dev; bdev = sc->stripe[stripe].dev->bdev; if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff)) return 0; return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i); }

Contributors

PersonTokensPropCommitsCommitProp
Dan J Williams143100.00%1100.00%
Total143100.00%1100.00%

/* * 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; } }

Contributors

PersonTokensPropCommitsCommitProp
Alan Cox9343.26%19.09%
Brian Wood8539.53%19.09%
Andrew Morton167.44%218.18%
Kevin Corry115.12%19.09%
Alasdair G. Kergon41.86%218.18%
Lars Marowsky-Bree20.93%19.09%
Joe Thornber20.93%19.09%
Mike Snitzer10.47%19.09%
Mikulas Patocka10.47%19.09%
Total215100.00%11100.00%


static int stripe_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error) { unsigned i; char major_minor[16]; struct stripe_c *sc = ti->private; if (!*error) return DM_ENDIO_DONE; /* I/O complete */ if (bio->bi_opf & REQ_RAHEAD) return DM_ENDIO_DONE; if (*error == BLK_STS_NOTSUPP) return DM_ENDIO_DONE; memset(major_minor, 0, sizeof(major_minor)); sprintf(major_minor, "%d:%d", MAJOR(bio_dev(bio)), MINOR(bio_dev(bio))); /* * 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 DM_ENDIO_DONE; }

Contributors

PersonTokensPropCommitsCommitProp
Brian Wood15985.48%112.50%
Christoph Hellwig147.53%450.00%
Tejun Heo126.45%225.00%
Jens Axboe10.54%112.50%
Total186100.00%8100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Mike Snitzer87100.00%2100.00%
Total87100.00%2100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Mike Snitzer4892.31%266.67%
Martin K. Petersen47.69%133.33%
Total52100.00%3100.00%

static struct target_type stripe_target = { .name = "striped", .version = {1, 6, 0}, .features = DM_TARGET_PASSES_INTEGRITY, .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, .direct_access = stripe_dax_direct_access, .dax_copy_from_iter = stripe_dax_copy_from_iter, };
int __init dm_stripe_init(void) { int r; r = dm_register_target(&stripe_target); if (r < 0) DMWARN("target registration failed"); return r; }

Contributors

PersonTokensPropCommitsCommitProp
Alan Cox2884.85%133.33%
Heinz Mauelshagen412.12%133.33%
Alasdair G. Kergon13.03%133.33%
Total33100.00%3100.00%


void dm_stripe_exit(void) { dm_unregister_target(&stripe_target); }

Contributors

PersonTokensPropCommitsCommitProp
Alan Cox13100.00%1100.00%
Total13100.00%1100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Alan Cox71230.25%11.47%
Mikulas Patocka49521.03%1319.12%
Brian Wood33814.36%22.94%
Mike Snitzer2299.73%913.24%
Dan J Williams2149.09%22.94%
Toshi Kani913.87%11.47%
Joe Thornber451.91%34.41%
Christoph Hellwig421.78%57.35%
Andrew Morton351.49%57.35%
Alasdair G. Kergon311.32%68.82%
Kevin Corry281.19%34.41%
Tejun Heo220.93%45.88%
Jianpeng Ma (马建朋)130.55%11.47%
Kent Overstreet130.55%22.94%
Michael Christie110.47%22.94%
Vivek Goyal100.42%11.47%
Pavitra Kumar70.30%11.47%
Martin K. Petersen40.17%11.47%
Heinz Mauelshagen40.17%11.47%
Vignesh Babu30.13%11.47%
Nikanth Karthikesan20.08%11.47%
Lars Marowsky-Bree20.08%11.47%
Jens Axboe20.08%11.47%
Kiyoshi Ueda10.04%11.47%
Total2354100.00%68100.00%
Directory: drivers/md
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