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drivers/md/dm-flakey.c
9.94 KB
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/* * Copyright (C) 2003 Sistina Software (UK) Limited. |
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* Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved. |
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* * 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" |
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#define all_corrupt_bio_flags_match(bio, fc) \ (((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags) |
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/* * 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; |
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unsigned long flags; |
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unsigned corrupt_bio_byte; unsigned corrupt_bio_rw; unsigned corrupt_bio_value; unsigned corrupt_bio_flags; |
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}; |
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enum feature_flag_bits { DROP_WRITES }; |
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struct per_bio_data { bool bio_submitted; }; |
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static int parse_features(struct dm_arg_set *as, struct flakey_c *fc, struct dm_target *ti) |
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{ int r; unsigned argc; const char *arg_name; static struct dm_arg _args[] = { |
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{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"}, |
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}; /* No feature arguments supplied. */ if (!as->argc) return 0; r = dm_read_arg_group(_args, as, &argc, &ti->error); if (r) |
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return r; |
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|
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while (argc) { |
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arg_name = dm_shift_arg(as); argc--; |
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/* * 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; } |
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/* * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags> */ if (!strcasecmp(arg_name, "corrupt_bio_byte")) { |
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if (!argc) { |
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ti->error = "Feature corrupt_bio_byte requires parameters"; |
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return -EINVAL; } |
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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; } |
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ti->error = "Unrecognised flakey feature requested"; |
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return -EINVAL; |
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} |
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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; |
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} |
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/* |
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* Construct a flakey mapping: * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*] |
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* * Feature args: * [drop_writes] |
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* [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. |
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*/ static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv) { |
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static struct dm_arg _args[] = { {0, UINT_MAX, "Invalid up interval"}, {0, UINT_MAX, "Invalid down interval"}, }; int r; |
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struct flakey_c *fc; |
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unsigned long long tmpll; struct dm_arg_set as; const char *devname; |
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char dummy; |
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|
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as.argc = argc; as.argv = argv; if (argc < 4) { ti->error = "Invalid argument count"; |
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return -EINVAL; } |
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fc = kzalloc(sizeof(*fc), GFP_KERNEL); |
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if (!fc) { |
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ti->error = "Cannot allocate context"; |
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return -ENOMEM; } fc->start_time = jiffies; |
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devname = dm_shift_arg(&as); |
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if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) { |
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ti->error = "Invalid device sector"; |
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goto bad; } |
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fc->start = tmpll; |
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|
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r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error); if (r) |
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goto bad; |
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|
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r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error); if (r) |
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goto bad; |
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if (!(fc->up_interval + fc->down_interval)) { |
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ti->error = "Total (up + down) interval is zero"; |
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goto bad; } if (fc->up_interval + fc->down_interval < fc->up_interval) { |
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ti->error = "Interval overflow"; |
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goto bad; } |
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r = parse_features(&as, fc, ti); |
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if (r) goto bad; if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) { ti->error = "Device lookup failed"; |
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goto bad; } |
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ti->num_flush_bios = 1; ti->num_discard_bios = 1; |
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ti->per_bio_data_size = sizeof(struct per_bio_data); |
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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; |
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return fc->start + dm_target_offset(ti, bi_sector); |
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} 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)) |
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bio->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector); |
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} |
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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) ", bio, fc->corrupt_bio_value, fc->corrupt_bio_byte, |
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(bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_rw, (unsigned long long)bio->bi_iter.bi_sector, bio_bytes); |
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} } |
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static int flakey_map(struct dm_target *ti, struct bio *bio) |
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{ struct flakey_c *fc = ti->private; unsigned elapsed; |
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struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); pb->bio_submitted = false; |
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/* Are we alive ? */ elapsed = (jiffies - fc->start_time) / HZ; |
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if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) { |
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/* * Flag this bio as submitted while down. */ |
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pb->bio_submitted = true; |
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/* * Map reads as normal. */ if (bio_data_dir(bio) == READ) goto map_bio; |
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/* |
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* Drop writes? |
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*/ if (test_bit(DROP_WRITES, &fc->flags)) { |
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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); |
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goto map_bio; } /* |
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* By default, error all I/O. |
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*/ |
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return -EIO; |
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} |
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|
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map_bio: |
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flakey_map_bio(ti, bio); return DM_MAPIO_REMAPPED; } |
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static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error) |
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{ struct flakey_c *fc = ti->private; |
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struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data)); |
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/* * Corrupt successful READs while in down state. * If flags were specified, only corrupt those that match. */ |
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if (fc->corrupt_bio_byte && !error && pb->bio_submitted && |
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(bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) && all_corrupt_bio_flags_match(bio, fc)) corrupt_bio_data(bio, fc); return error; } |
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static void flakey_status(struct dm_target *ti, status_type_t type, unsigned status_flags, char *result, unsigned maxlen) |
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{ |
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unsigned sz = 0; |
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struct flakey_c *fc = ti->private; |
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unsigned drop_writes; |
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switch (type) { case STATUSTYPE_INFO: result[0] = '\0'; break; case STATUSTYPE_TABLE: |
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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); |
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DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5); |
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if (drop_writes) DMEMIT("drop_writes "); |
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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); |
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break; } |
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} static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg) { struct flakey_c *fc = ti->private; |
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struct dm_dev *dev = fc->dev; int r = 0; |
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|
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/* * 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); |
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} 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", |
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.version = {1, 3, 1}, |
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.module = THIS_MODULE, .ctr = flakey_ctr, .dtr = flakey_dtr, .map = flakey_map, |
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.end_io = flakey_end_io, |
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.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"); |