diff options
Diffstat (limited to 'drivers/md/dm-unstripe.c')
| -rw-r--r-- | drivers/md/dm-unstripe.c | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/drivers/md/dm-unstripe.c b/drivers/md/dm-unstripe.c new file mode 100644 index 000000000000..061b4f10bf5c --- /dev/null +++ b/drivers/md/dm-unstripe.c @@ -0,0 +1,225 @@ +/* + * Copyright (C) 2017 Intel Corporation. + * + * This file is released under the GPL. + */ + +#include "dm.h" + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/blkdev.h> +#include <linux/bio.h> +#include <linux/slab.h> +#include <linux/bitops.h> +#include <linux/device-mapper.h> + +struct unstripe_c { + struct dm_dev *dev; + sector_t physical_start; + + uint32_t stripes; + + uint32_t unstripe; + sector_t unstripe_width; + sector_t unstripe_offset; + + uint32_t chunk_size; + u8 chunk_shift; +}; + +#define DM_MSG_PREFIX "unstriped" + +static void cleanup_unstripe(struct unstripe_c *uc, struct dm_target *ti) +{ + if (uc->dev) + dm_put_device(ti, uc->dev); + kfree(uc); +} + +/* + * Contruct an unstriped mapping. + * <number of stripes> <chunk size> <stripe #> <dev_path> <offset> + */ +static int unstripe_ctr(struct dm_target *ti, unsigned int argc, char **argv) +{ + struct unstripe_c *uc; + sector_t width, tmp_len; + unsigned long long start; + char dummy; + + if (argc != 5) { + ti->error = "Invalid number of arguments"; + return -EINVAL; + } + + uc = kzalloc(sizeof(*uc), GFP_KERNEL); + if (!uc) { + ti->error = "Memory allocation for unstriped context failed"; + return -ENOMEM; + } + + if (kstrtouint(argv[0], 10, &uc->stripes) || !uc->stripes) { + ti->error = "Invalid stripe count"; + goto err; + } + + if (kstrtouint(argv[1], 10, &uc->chunk_size) || !uc->chunk_size) { + ti->error = "Invalid chunk_size"; + goto err; + } + + // FIXME: must support non power of 2 chunk_size, dm-stripe.c does + if (!is_power_of_2(uc->chunk_size)) { + ti->error = "Non power of 2 chunk_size is not supported yet"; + goto err; + } + + if (kstrtouint(argv[2], 10, &uc->unstripe)) { + ti->error = "Invalid stripe number"; + goto err; + } + + if (uc->unstripe > uc->stripes && uc->stripes > 1) { + ti->error = "Please provide stripe between [0, # of stripes]"; + goto err; + } + + if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &uc->dev)) { + ti->error = "Couldn't get striped device"; + goto err; + } + + if (sscanf(argv[4], "%llu%c", &start, &dummy) != 1) { + ti->error = "Invalid striped device offset"; + goto err; + } + uc->physical_start = start; + + uc->unstripe_offset = uc->unstripe * uc->chunk_size; + uc->unstripe_width = (uc->stripes - 1) * uc->chunk_size; + uc->chunk_shift = fls(uc->chunk_size) - 1; + + width = ti->len; + if (sector_div(width, uc->stripes)) { + ti->error = "Target length not divisible by number of stripes"; + goto err; + } + + tmp_len = width; + if (sector_div(tmp_len, uc->chunk_size)) { + ti->error = "Target length not divisible by chunk size"; + goto err; + } + + if (dm_set_target_max_io_len(ti, uc->chunk_size)) { + ti->error = "Failed to set max io len"; + goto err; + } + + ti->private = uc; + return 0; +err: + cleanup_unstripe(uc, ti); + return -EINVAL; +} + +static void unstripe_dtr(struct dm_target *ti) +{ + struct unstripe_c *uc = ti->private; + + cleanup_unstripe(uc, ti); +} + +static sector_t map_to_core(struct dm_target *ti, struct bio *bio) +{ + struct unstripe_c *uc = ti->private; + sector_t sector = bio->bi_iter.bi_sector; + + /* Shift us up to the right "row" on the stripe */ + sector += uc->unstripe_width * (sector >> uc->chunk_shift); + + /* Account for what stripe we're operating on */ + sector += uc->unstripe_offset; + + return sector; +} + +static int unstripe_map(struct dm_target *ti, struct bio *bio) +{ + struct unstripe_c *uc = ti->private; + + bio_set_dev(bio, uc->dev->bdev); + bio->bi_iter.bi_sector = map_to_core(ti, bio) + uc->physical_start; + + return DM_MAPIO_REMAPPED; +} + +static void unstripe_status(struct dm_target *ti, status_type_t type, + unsigned int status_flags, char *result, unsigned int maxlen) +{ + struct unstripe_c *uc = ti->private; + unsigned int sz = 0; + + switch (type) { + case STATUSTYPE_INFO: + break; + + case STATUSTYPE_TABLE: + DMEMIT("%d %llu %d %s %llu", + uc->stripes, (unsigned long long)uc->chunk_size, uc->unstripe, + uc->dev->name, (unsigned long long)uc->physical_start); + break; + } +} + +static int unstripe_iterate_devices(struct dm_target *ti, + iterate_devices_callout_fn fn, void *data) +{ + struct unstripe_c *uc = ti->private; + + return fn(ti, uc->dev, uc->physical_start, ti->len, data); +} + +static void unstripe_io_hints(struct dm_target *ti, + struct queue_limits *limits) +{ + struct unstripe_c *uc = ti->private; + + limits->chunk_sectors = uc->chunk_size; +} + +static struct target_type unstripe_target = { + .name = "unstriped", + .version = {1, 0, 0}, + .module = THIS_MODULE, + .ctr = unstripe_ctr, + .dtr = unstripe_dtr, + .map = unstripe_map, + .status = unstripe_status, + .iterate_devices = unstripe_iterate_devices, + .io_hints = unstripe_io_hints, +}; + +static int __init dm_unstripe_init(void) +{ + int r; + + r = dm_register_target(&unstripe_target); + if (r < 0) + DMERR("target registration failed"); + + return r; +} + +static void __exit dm_unstripe_exit(void) +{ + dm_unregister_target(&unstripe_target); +} + +module_init(dm_unstripe_init); +module_exit(dm_unstripe_exit); + +MODULE_DESCRIPTION(DM_NAME " unstriped target"); +MODULE_AUTHOR("Scott Bauer <scott.bauer@intel.com>"); +MODULE_LICENSE("GPL"); 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