diff options
Diffstat (limited to 'drivers/md/dm-flakey.c')
-rw-r--r-- | drivers/md/dm-flakey.c | 447 |
1 files changed, 447 insertions, 0 deletions
diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c new file mode 100644 index 000000000..b257e4687 --- /dev/null +++ b/drivers/md/dm-flakey.c @@ -0,0 +1,447 @@ +/* + * 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 +}; + +struct per_bio_data { + bool bio_submitted; +}; + +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; + char dummy; + + 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 context"; + return -ENOMEM; + } + fc->start_time = jiffies; + + devname = dm_shift_arg(&as); + + if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 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_bios = 1; + ti->num_discard_bios = 1; + ti->per_bio_data_size = sizeof(struct per_bio_data); + 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_iter.bi_sector = + flakey_map_sector(ti, bio->bi_iter.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_iter.bi_sector, bio_bytes); + } +} + +static int flakey_map(struct dm_target *ti, struct bio *bio) +{ + struct flakey_c *fc = ti->private; + unsigned elapsed; + struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); + pb->bio_submitted = false; + + /* 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. + */ + pb->bio_submitted = true; + + /* + * 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) +{ + struct flakey_c *fc = ti->private; + struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); + + /* + * Corrupt successful READs while in down state. + * If flags were specified, only corrupt those that match. + */ + if (fc->corrupt_bio_byte && !error && pb->bio_submitted && + (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 void flakey_status(struct dm_target *ti, status_type_t type, + unsigned status_flags, char *result, unsigned 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; + } +} + +static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg) +{ + struct flakey_c *fc = ti->private; + struct dm_dev *dev = fc->dev; + int r = 0; + + /* + * Only pass ioctls through if the device sizes match exactly. + */ + if (fc->start || + ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT) + r = scsi_verify_blk_ioctl(NULL, cmd); + + return r ? : __blkdev_driver_ioctl(dev->bdev, 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, 3, 1}, + .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"); |