| /* |
| * Copyright (C) 2003 Sistina Software (UK) Limited. |
| * Copyright (C) 2004, 2010 Red Hat, Inc. All rights reserved. |
| * |
| * This file is released under the GPL. |
| */ |
| |
| #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> |
| |
| #define DM_MSG_PREFIX "flakey" |
| |
| /* |
| * Flakey: Used for testing only, simulates intermittent, |
| * catastrophic device failure. |
| */ |
| struct flakey_c { |
| struct dm_dev *dev; |
| unsigned long start_time; |
| sector_t start; |
| unsigned up_interval; |
| unsigned down_interval; |
| unsigned long flags; |
| }; |
| |
| enum feature_flag_bits { |
| DROP_WRITES |
| }; |
| |
| static int parse_features(struct dm_arg_set *as, struct flakey_c *fc, |
| struct dm_target *ti) |
| { |
| int r; |
| unsigned argc; |
| const char *arg_name; |
| |
| static struct dm_arg _args[] = { |
| {0, 1, "Invalid number of feature args"}, |
| }; |
| |
| /* No feature arguments supplied. */ |
| if (!as->argc) |
| return 0; |
| |
| r = dm_read_arg_group(_args, as, &argc, &ti->error); |
| if (r) |
| return -EINVAL; |
| |
| while (argc && !r) { |
| arg_name = dm_shift_arg(as); |
| argc--; |
| |
| /* |
| * drop_writes |
| */ |
| if (!strcasecmp(arg_name, "drop_writes")) { |
| if (test_and_set_bit(DROP_WRITES, &fc->flags)) { |
| ti->error = "Feature drop_writes duplicated"; |
| return -EINVAL; |
| } |
| |
| continue; |
| } |
| |
| ti->error = "Unrecognised flakey feature requested"; |
| r = -EINVAL; |
| } |
| |
| return r; |
| } |
| |
| /* |
| * Construct a flakey mapping: |
| * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*] |
| * |
| * Feature args: |
| * [drop_writes] |
| */ |
| static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv) |
| { |
| static struct dm_arg _args[] = { |
| {0, UINT_MAX, "Invalid up interval"}, |
| {0, UINT_MAX, "Invalid down interval"}, |
| }; |
| |
| int r; |
| struct flakey_c *fc; |
| unsigned long long tmpll; |
| struct dm_arg_set as; |
| const char *devname; |
| |
| as.argc = argc; |
| as.argv = argv; |
| |
| if (argc < 4) { |
| ti->error = "Invalid argument count"; |
| return -EINVAL; |
| } |
| |
| fc = kzalloc(sizeof(*fc), GFP_KERNEL); |
| if (!fc) { |
| ti->error = "Cannot allocate linear context"; |
| return -ENOMEM; |
| } |
| fc->start_time = jiffies; |
| |
| devname = dm_shift_arg(&as); |
| |
| if (sscanf(dm_shift_arg(&as), "%llu", &tmpll) != 1) { |
| ti->error = "Invalid device sector"; |
| goto bad; |
| } |
| fc->start = tmpll; |
| |
| r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error); |
| if (r) |
| goto bad; |
| |
| r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error); |
| if (r) |
| goto bad; |
| |
| if (!(fc->up_interval + fc->down_interval)) { |
| ti->error = "Total (up + down) interval is zero"; |
| goto bad; |
| } |
| |
| if (fc->up_interval + fc->down_interval < fc->up_interval) { |
| ti->error = "Interval overflow"; |
| goto bad; |
| } |
| |
| r = parse_features(&as, fc, ti); |
| if (r) |
| goto bad; |
| |
| if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) { |
| ti->error = "Device lookup failed"; |
| goto bad; |
| } |
| |
| ti->num_flush_requests = 1; |
| ti->num_discard_requests = 1; |
| ti->private = fc; |
| return 0; |
| |
| bad: |
| kfree(fc); |
| return -EINVAL; |
| } |
| |
| static void flakey_dtr(struct dm_target *ti) |
| { |
| struct flakey_c *fc = ti->private; |
| |
| dm_put_device(ti, fc->dev); |
| kfree(fc); |
| } |
| |
| static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector) |
| { |
| struct flakey_c *fc = ti->private; |
| |
| return fc->start + dm_target_offset(ti, bi_sector); |
| } |
| |
| static void flakey_map_bio(struct dm_target *ti, struct bio *bio) |
| { |
| struct flakey_c *fc = ti->private; |
| |
| bio->bi_bdev = fc->dev->bdev; |
| if (bio_sectors(bio)) |
| bio->bi_sector = flakey_map_sector(ti, bio->bi_sector); |
| } |
| |
| static int flakey_map(struct dm_target *ti, struct bio *bio, |
| union map_info *map_context) |
| { |
| struct flakey_c *fc = ti->private; |
| unsigned elapsed; |
| unsigned rw; |
| |
| /* Are we alive ? */ |
| elapsed = (jiffies - fc->start_time) / HZ; |
| if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) { |
| rw = bio_data_dir(bio); |
| |
| /* |
| * Drop writes. Map reads as normal. |
| */ |
| if (test_bit(DROP_WRITES, &fc->flags)) { |
| if (rw == WRITE) { |
| bio_endio(bio, 0); |
| return DM_MAPIO_SUBMITTED; |
| } |
| goto map_bio; |
| } |
| |
| /* |
| * Default setting errors all I/O. |
| */ |
| return -EIO; |
| } |
| |
| map_bio: |
| flakey_map_bio(ti, bio); |
| |
| return DM_MAPIO_REMAPPED; |
| } |
| |
| static int flakey_status(struct dm_target *ti, status_type_t type, |
| char *result, unsigned int maxlen) |
| { |
| unsigned sz = 0; |
| struct flakey_c *fc = ti->private; |
| unsigned drop_writes; |
| |
| switch (type) { |
| case STATUSTYPE_INFO: |
| result[0] = '\0'; |
| break; |
| |
| case STATUSTYPE_TABLE: |
| DMEMIT("%s %llu %u %u ", fc->dev->name, |
| (unsigned long long)fc->start, fc->up_interval, |
| fc->down_interval); |
| |
| drop_writes = test_bit(DROP_WRITES, &fc->flags); |
| DMEMIT("%u ", drop_writes); |
| if (drop_writes) |
| DMEMIT("drop_writes "); |
| break; |
| } |
| return 0; |
| } |
| |
| static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg) |
| { |
| struct flakey_c *fc = ti->private; |
| |
| return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg); |
| } |
| |
| static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm, |
| struct bio_vec *biovec, int max_size) |
| { |
| struct flakey_c *fc = ti->private; |
| struct request_queue *q = bdev_get_queue(fc->dev->bdev); |
| |
| if (!q->merge_bvec_fn) |
| return max_size; |
| |
| bvm->bi_bdev = fc->dev->bdev; |
| bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector); |
| |
| return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); |
| } |
| |
| static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data) |
| { |
| struct flakey_c *fc = ti->private; |
| |
| return fn(ti, fc->dev, fc->start, ti->len, data); |
| } |
| |
| static struct target_type flakey_target = { |
| .name = "flakey", |
| .version = {1, 2, 0}, |
| .module = THIS_MODULE, |
| .ctr = flakey_ctr, |
| .dtr = flakey_dtr, |
| .map = flakey_map, |
| .status = flakey_status, |
| .ioctl = flakey_ioctl, |
| .merge = flakey_merge, |
| .iterate_devices = flakey_iterate_devices, |
| }; |
| |
| static int __init dm_flakey_init(void) |
| { |
| int r = dm_register_target(&flakey_target); |
| |
| if (r < 0) |
| DMERR("register failed %d", r); |
| |
| return r; |
| } |
| |
| static void __exit dm_flakey_exit(void) |
| { |
| dm_unregister_target(&flakey_target); |
| } |
| |
| /* Module hooks */ |
| module_init(dm_flakey_init); |
| module_exit(dm_flakey_exit); |
| |
| MODULE_DESCRIPTION(DM_NAME " flakey target"); |
| MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); |
| MODULE_LICENSE("GPL"); |