/* * Copyright (C) 2003 Sistina Software (UK) Limited. * Copyright (C) 2004, 2010-2011 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" #define all_corrupt_bio_flags_match(bio, fc) \ (((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags) /* * 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; unsigned corrupt_bio_byte; unsigned corrupt_bio_rw; unsigned corrupt_bio_value; unsigned corrupt_bio_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, 6, "Invalid number of feature args"}, {1, UINT_MAX, "Invalid corrupt bio byte"}, {0, 255, "Invalid corrupt value to write into bio byte (0-255)"}, {0, UINT_MAX, "Invalid corrupt bio flags mask"}, }; /* No feature arguments supplied. */ if (!as->argc) return 0; r = dm_read_arg_group(_args, as, &argc, &ti->error); if (r) return r; while (argc) { 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; } /* * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags> */ if (!strcasecmp(arg_name, "corrupt_bio_byte")) { if (!argc) { ti->error = "Feature corrupt_bio_byte requires parameters"; return -EINVAL; } r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error); if (r) return r; argc--; /* * Direction r or w? */ arg_name = dm_shift_arg(as); if (!strcasecmp(arg_name, "w")) fc->corrupt_bio_rw = WRITE; else if (!strcasecmp(arg_name, "r")) fc->corrupt_bio_rw = READ; else { ti->error = "Invalid corrupt bio direction (r or w)"; return -EINVAL; } argc--; /* * Value of byte (0-255) to write in place of correct one. */ r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error); if (r) return r; argc--; /* * Only corrupt bios with these flags set. */ r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error); if (r) return r; argc--; continue; } ti->error = "Unrecognised flakey feature requested"; return -EINVAL; } if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) { ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set"; return -EINVAL; } return 0; } /* * Construct a flakey mapping: * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*] * * Feature args: * [drop_writes] * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>] * * Nth_byte starts from 1 for the first byte. * Direction is r for READ or w for WRITE. * bio_flags is ignored if 0. */ 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 void corrupt_bio_data(struct bio *bio, struct flakey_c *fc) { unsigned bio_bytes = bio_cur_bytes(bio); char *data = bio_data(bio); /* * Overwrite the Nth byte of the data returned. */ if (data && bio_bytes >= fc->corrupt_bio_byte) { data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value; DMDEBUG("Corrupting data bio=%p by writing %u to byte %u " "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n", bio, fc->corrupt_bio_value, fc->corrupt_bio_byte, (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes); } } static int flakey_map(struct dm_target *ti, struct bio *bio, union map_info *map_context) { struct flakey_c *fc = ti->private; unsigned elapsed; /* Are we alive ? */ elapsed = (jiffies - fc->start_time) / HZ; if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) { /* * Flag this bio as submitted while down. */ map_context->ll = 1; /* * Map reads as normal. */ if (bio_data_dir(bio) == READ) goto map_bio; /* * Drop writes? */ if (test_bit(DROP_WRITES, &fc->flags)) { bio_endio(bio, 0); return DM_MAPIO_SUBMITTED; } /* * Corrupt matching writes. */ if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) { if (all_corrupt_bio_flags_match(bio, fc)) corrupt_bio_data(bio, fc); goto map_bio; } /* * By default, error all I/O. */ return -EIO; } map_bio: flakey_map_bio(ti, bio); return DM_MAPIO_REMAPPED; } static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error, union map_info *map_context) { struct flakey_c *fc = ti->private; unsigned bio_submitted_while_down = map_context->ll; /* * Corrupt successful READs while in down state. * If flags were specified, only corrupt those that match. */ if (!error && bio_submitted_while_down && (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) && all_corrupt_bio_flags_match(bio, fc)) corrupt_bio_data(bio, fc); return error; } 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 + (fc->corrupt_bio_byte > 0) * 5); if (drop_writes) DMEMIT("drop_writes "); if (fc->corrupt_bio_byte) DMEMIT("corrupt_bio_byte %u %c %u %u ", fc->corrupt_bio_byte, (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r', fc->corrupt_bio_value, fc->corrupt_bio_flags); 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, .end_io = flakey_end_io, .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");