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Diffstat (limited to 'drivers/md/dm-unstripe.c')
-rw-r--r--drivers/md/dm-unstripe.c219
1 files changed, 219 insertions, 0 deletions
diff --git a/drivers/md/dm-unstripe.c b/drivers/md/dm-unstripe.c
new file mode 100644
index 000000000000..65f838fa2e99
--- /dev/null
+++ b/drivers/md/dm-unstripe.c
@@ -0,0 +1,219 @@
+/*
+ * 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 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;
+
+ tmp_len = ti->len;
+ 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");