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5502fe55ab01263f1145cf85034210583c35ad77
littlefs/bd/lfs_emubd.c
T
Christopher Haster 5502fe55ab Implemented ckfetches 
Ckfetches implements what might be your first idea on how to check
checksums in a filesystem: Check each block/mdir on first access
(fetch) to make sure the data is sound.

Unfortunately, there are two problems with this approach, both which
come from the fact that blocks are big and can't fit in RAM:

1. We still have a checksum-read hole.

   We can't keep a whole block around in RAM, so reads after a fetch may
   need to reread from disk, at which point new bit-errors may slip in
   undetected.

   This is especially problematic for traversing our rbyds, which
   involves a lot of small reads in a block.

2. Ckfetches may have a surprisingly negative performance impact.

   Consider the case of reading a large file with a bunch of small
   reads. Because we don't cache blocks, each read may need a btree
   lookup, and a full block fetch. On paper this can quickly end up
   O(b^2), which is not great.

   Though this is helped by the file buffer. It will be interesting to
   benchmark and see if this theoretical O(b^2) translates to poor
   performance in practice.

   Note ckreads has this same performance issue.

Still, despite these problems, ckfetches may be useful for cases where
you just want an extra layer of safety, or don't care about the tiny
chance an error is introduced between a fetch an subsequent read.

---

Like ckprogs/ckreads, ckfetches is an opt-in feature, and requires both
1. defining LFS_CKFETCHES, and 2. passing LFS_M_CKFETCHES during mount.

This is a bit of a quick implementation to get testing in place, so the
code cost is probably higher than strictly necessary. If we can refactor
the code internally to avoid all the duplicate lfsr_rbyd_fetchck/
lfsr_bptr_ck calls, we can probably bring this down a bit:

                  code          stack
  before:        36428           2680
  yes-ckfetches: 36848 (+1.2%)   2680 (+0.0%)
  no-ckfetches:  36428 (+0.0%)   2680 (+0.0%)

Oh, and also added lfs_emubd_flipbit to allow tests to manually flip
bits themselves. LFS_EMUBD_BADBLOCK_PROGFLIP is quick to find the above
mentioned checksum-read hole.

This could be done manually with read+erase+prog, but no reason to make
it harder than it needs to be.
2024-08-16 01:04:26 -05:00

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/*
* Emulating block device, wraps filebd and rambd while providing a bunch
* of hooks for testing littlefs in various conditions.
*
* Copyright (c) 2022, The littlefs authors.
* Copyright (c) 2017, Arm Limited. All rights reserved.
* SPDX-License-Identifier: BSD-3-Clause
*/
#ifndef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 199309L
#endif
#include "bd/lfs_emubd.h"
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#ifdef _WIN32
#include <windows.h>
#endif
// access to lazily-allocated/copy-on-write blocks
//
// Note we can only modify a block if we have exclusive access to it (rc == 1)
//
static lfs_emubd_block_t *lfs_emubd_incblock(lfs_emubd_block_t *block) {
if (block) {
block->rc += 1;
}
return block;
}
static void lfs_emubd_decblock(lfs_emubd_block_t *block) {
if (block) {
block->rc -= 1;
if (block->rc == 0) {
free(block);
}
}
}
static lfs_emubd_block_t *lfs_emubd_mutblock(
const struct lfs_config *cfg,
lfs_emubd_block_t *block) {
if (block && block->rc == 1) {
// rc == 1? can modify
return block;
} else if (block) {
// rc > 1? need to create a copy
lfs_emubd_block_t *block_ = malloc(
sizeof(lfs_emubd_block_t) + cfg->block_size);
if (!block_) {
return NULL;
}
memcpy(block_, block,
sizeof(lfs_emubd_block_t) + cfg->block_size);
block_->rc = 1;
lfs_emubd_decblock(block);
return block_;
} else {
// no block? need to allocate
lfs_emubd_block_t *block_ = malloc(
sizeof(lfs_emubd_block_t) + cfg->block_size);
if (!block_) {
return NULL;
}
block_->rc = 1;
block_->wear = 0;
block_->metastable = false;
block_->bad_bit = 0;
// zero for consistency
lfs_emubd_t *bd = cfg->context;
memset(block_->data,
(bd->cfg->erase_value != -1) ? bd->cfg->erase_value : 0,
cfg->block_size);
return block_;
}
}
// prng used for some emulation things
static uint32_t lfs_emubd_prng(uint32_t *state) {
// A simple xorshift32 generator, easily reproducible. Keep in mind
// determinism is much more important than actual randomness here.
uint32_t x = *state;
// must be non-zero, use uintmax here so that seed=0 is different
// from seed=1 and seed=range(0,n) makes a bit more sense
if (x == 0) {
x = -1;
}
x ^= x << 13;
x ^= x >> 17;
x ^= x << 5;
*state = x;
return x;
}
// emubd create/destroy
int lfs_emubd_createcfg(const struct lfs_config *cfg, const char *path,
const struct lfs_emubd_config *bdcfg) {
LFS_EMUBD_TRACE("lfs_emubd_createcfg(%p {.context=%p, "
".read=%p, .prog=%p, .erase=%p, .sync=%p, "
".read_size=%"PRIu32", .prog_size=%"PRIu32", "
".block_size=%"PRIu32", .block_count=%"PRIu32"}, "
"\"%s\", "
"%p {.erase_value=%"PRId32", .erase_cycles=%"PRIu32", "
".badblock_behavior=%"PRIu8", .power_cycles=%"PRIu32", "
".powerloss_behavior=%"PRIu8", .powerloss_cb=%p, "
".powerloss_data=%p, seed=%"PRIu32"})",
(void*)cfg, cfg->context,
(void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog,
(void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync,
cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count,
path, (void*)bdcfg, bdcfg->erase_value, bdcfg->erase_cycles,
bdcfg->badblock_behavior, bdcfg->power_cycles,
bdcfg->powerloss_behavior, (void*)(uintptr_t)bdcfg->powerloss_cb,
bdcfg->powerloss_data, bdcfg->seed);
lfs_emubd_t *bd = cfg->context;
bd->cfg = bdcfg;
// setup testing things
bd->blocks = NULL;
bd->readed = 0;
bd->proged = 0;
bd->erased = 0;
bd->prng = bd->cfg->seed;
bd->power_cycles = bd->cfg->power_cycles;
bd->ooo_before = NULL;
bd->ooo_after = NULL;
bd->disk = NULL;
// allocate our block array, all blocks start as uninitialized
bd->blocks = malloc(
cfg->block_count * sizeof(lfs_emubd_block_t*));
int err;
if (!bd->blocks) {
err = LFS_ERR_NOMEM;
goto failed;
}
memset(bd->blocks, 0,
cfg->block_count * sizeof(lfs_emubd_block_t*));
// allocate extra block arrays to hold our ooo snapshots
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO) {
bd->ooo_before = malloc(
cfg->block_count * sizeof(lfs_emubd_block_t*));
if (!bd->ooo_before) {
err = LFS_ERR_NOMEM;
goto failed;
}
memset(bd->ooo_before, 0,
cfg->block_count * sizeof(lfs_emubd_block_t*));
bd->ooo_after = malloc(
cfg->block_count * sizeof(lfs_emubd_block_t*));
if (!bd->ooo_after) {
err = LFS_ERR_NOMEM;
goto failed;
}
memset(bd->ooo_after, 0,
cfg->block_count * sizeof(lfs_emubd_block_t*));
}
if (bd->cfg->disk_path) {
bd->disk = malloc(sizeof(lfs_emubd_disk_t));
if (!bd->disk) {
err = LFS_ERR_NOMEM;
goto failed;
}
bd->disk->rc = 1;
bd->disk->fd = -1;
bd->disk->scratch = NULL;
#ifdef _WIN32
bd->disk->fd = open(bd->cfg->disk_path,
O_RDWR | O_CREAT | O_BINARY, 0666);
#else
bd->disk->fd = open(bd->cfg->disk_path,
O_RDWR | O_CREAT, 0666);
#endif
if (bd->disk->fd < 0) {
err = -errno;
goto failed;
}
bd->disk->scratch = malloc(cfg->block_size);
if (!bd->disk->scratch) {
err = LFS_ERR_NOMEM;
goto failed;
}
memset(bd->disk->scratch,
(bd->cfg->erase_value != -1) ? bd->cfg->erase_value : 0,
cfg->block_size);
// go ahead and erase all of the disk, otherwise the file will not
// match our internal representation
for (size_t i = 0; i < cfg->block_count; i++) {
ssize_t res = write(bd->disk->fd,
bd->disk->scratch,
cfg->block_size);
if (res < 0) {
err = -errno;
goto failed;
}
}
}
LFS_EMUBD_TRACE("lfs_emubd_createcfg -> %d", 0);
return 0;
failed:;
LFS_EMUBD_TRACE("lfs_emubd_createcfg -> %d", err);
// clean up memory
free(bd->blocks);
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO) {
free(bd->ooo_before);
free(bd->ooo_after);
}
if (bd->disk) {
if (bd->disk->fd != -1) {
close(bd->disk->fd);
}
free(bd->disk->scratch);
free(bd->disk);
}
return err;
}
int lfs_emubd_create(const struct lfs_config *cfg, const char *path) {
LFS_EMUBD_TRACE("lfs_emubd_create(%p {.context=%p, "
".read=%p, .prog=%p, .erase=%p, .sync=%p, "
".read_size=%"PRIu32", .prog_size=%"PRIu32", "
".block_size=%"PRIu32", .block_count=%"PRIu32"}, "
"\"%s\")",
(void*)cfg, cfg->context,
(void*)(uintptr_t)cfg->read, (void*)(uintptr_t)cfg->prog,
(void*)(uintptr_t)cfg->erase, (void*)(uintptr_t)cfg->sync,
cfg->read_size, cfg->prog_size, cfg->block_size, cfg->block_count,
path);
static const struct lfs_emubd_config defaults = {.erase_value=-1};
int err = lfs_emubd_createcfg(cfg, path, &defaults);
LFS_EMUBD_TRACE("lfs_emubd_create -> %d", err);
return err;
}
int lfs_emubd_destroy(const struct lfs_config *cfg) {
LFS_EMUBD_TRACE("lfs_emubd_destroy(%p)", (void*)cfg);
lfs_emubd_t *bd = cfg->context;
// decrement reference counts
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
lfs_emubd_decblock(bd->blocks[i]);
}
free(bd->blocks);
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO) {
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
lfs_emubd_decblock(bd->ooo_before[i]);
}
free(bd->ooo_before);
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
lfs_emubd_decblock(bd->ooo_after[i]);
}
free(bd->ooo_after);
}
// clean up other resources
if (bd->disk) {
bd->disk->rc -= 1;
if (bd->disk->rc == 0) {
close(bd->disk->fd);
free(bd->disk->scratch);
free(bd->disk);
}
}
LFS_EMUBD_TRACE("lfs_emubd_destroy -> %d", 0);
return 0;
}
// block device API
int lfs_emubd_read(const struct lfs_config *cfg, lfs_block_t block,
lfs_off_t off, void *buffer, lfs_size_t size) {
LFS_EMUBD_TRACE("lfs_emubd_read(%p, "
"0x%"PRIx32", %"PRIu32", %p, %"PRIu32")",
(void*)cfg, block, off, buffer, size);
lfs_emubd_t *bd = cfg->context;
// check if read is valid
LFS_ASSERT(block < cfg->block_count);
LFS_ASSERT(off % cfg->read_size == 0);
LFS_ASSERT(size % cfg->read_size == 0);
LFS_ASSERT(off+size <= cfg->block_size);
// get the block
const lfs_emubd_block_t *b = bd->blocks[block];
if (b) {
// block bad?
if (b->wear > bd->cfg->erase_cycles) {
// erroring reads? error
if (bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_READERROR) {
LFS_EMUBD_TRACE("lfs_emubd_read -> %d", LFS_ERR_CORRUPT);
return LFS_ERR_CORRUPT;
}
}
// read data
memcpy(buffer, &b->data[off], size);
// metastable? randomly decide if our bad bit flips
if (b->metastable) {
lfs_size_t bit = b->bad_bit & 0x7fffffff;
if (bit/8 >= off
&& bit/8 < off+size
&& (lfs_emubd_prng(&bd->prng) & 1)) {
((uint8_t*)buffer)[(bit/8) - off] ^= 1 << (bit%8);
}
}
// no block yet
} else {
// zero for consistency
memset(buffer,
(bd->cfg->erase_value != -1) ? bd->cfg->erase_value : 0,
size);
}
// track reads
bd->readed += size;
if (bd->cfg->read_sleep) {
int err = nanosleep(&(struct timespec){
.tv_sec=bd->cfg->read_sleep/1000000000,
.tv_nsec=bd->cfg->read_sleep%1000000000},
NULL);
if (err) {
err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_read -> %d", err);
return err;
}
}
LFS_EMUBD_TRACE("lfs_emubd_read -> %d", 0);
return 0;
}
int lfs_emubd_prog(const struct lfs_config *cfg, lfs_block_t block,
lfs_off_t off, const void *buffer, lfs_size_t size) {
LFS_EMUBD_TRACE("lfs_emubd_prog(%p, "
"0x%"PRIx32", %"PRIu32", %p, %"PRIu32")",
(void*)cfg, block, off, buffer, size);
lfs_emubd_t *bd = cfg->context;
// check if write is valid
LFS_ASSERT(block < cfg->block_count);
LFS_ASSERT(off % cfg->prog_size == 0);
LFS_ASSERT(size % cfg->prog_size == 0);
LFS_ASSERT(off+size <= cfg->block_size);
// were we erased properly?
LFS_ASSERT(bd->blocks[block]);
if (bd->cfg->erase_value != -1
&& bd->blocks[block]->wear <= bd->cfg->erase_cycles) {
for (lfs_off_t i = 0; i < size; i++) {
LFS_ASSERT(bd->blocks[block]->data[off+i] == bd->cfg->erase_value);
}
}
// losing power?
if (bd->power_cycles > 0) {
bd->power_cycles -= 1;
if (bd->power_cycles == 0) {
// emulating some bits? choose a random bit to flip
if (bd->cfg->powerloss_behavior
== LFS_EMUBD_POWERLOSS_SOMEBITS) {
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg,
bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// flip bit
lfs_size_t bit = lfs_emubd_prng(&bd->prng)
% (cfg->prog_size*8);
b->data[off + (bit/8)] ^= 1 << (bit%8);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)block*cfg->block_size + (off_t)off,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd, &b->data[off], size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
}
// emulating most bits? prog data and choose a random bit
// to flip
} else if (bd->cfg->powerloss_behavior
== LFS_EMUBD_POWERLOSS_MOSTBITS) {
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg,
bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// prog data
memcpy(&b->data[off], buffer, size);
// flip bit
lfs_size_t bit = lfs_emubd_prng(&bd->prng)
% (cfg->prog_size*8);
b->data[off + (bit/8)] ^= 1 << (bit%8);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)block*cfg->block_size + (off_t)off,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd, &b->data[off], size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
}
// emulating out-of-order writes? revert everything unsynced
// except for our current block
} else if (bd->cfg->powerloss_behavior
== LFS_EMUBD_POWERLOSS_OOO) {
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
lfs_emubd_decblock(bd->ooo_after[i]);
bd->ooo_after[i] = lfs_emubd_incblock(bd->blocks[i]);
if (i != block && bd->blocks[i] != bd->ooo_before[i]) {
lfs_emubd_decblock(bd->blocks[i]);
bd->blocks[i] = lfs_emubd_incblock(bd->ooo_before[i]);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)i*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd,
(bd->blocks[i])
? bd->blocks[i]->data
: bd->disk->scratch,
cfg->block_size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
}
}
}
// emulating metastability? prog data, choose a random bad bit,
// and mark as metastable
} else if (bd->cfg->powerloss_behavior
== LFS_EMUBD_POWERLOSS_METASTABLE) {
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg,
bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// prog data
memcpy(&b->data[off], buffer, size);
// choose a new bad bit unless overridden
if (!(0x80000000 & b->bad_bit)) {
b->bad_bit = lfs_emubd_prng(&bd->prng)
% (cfg->block_size*8);
}
// mark as metastable
b->metastable = true;
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)block*cfg->block_size + (off_t)off,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd, &b->data[off], size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
}
}
// powerloss!
bd->cfg->powerloss_cb(bd->cfg->powerloss_data);
// oh, continuing? undo out-of-order write emulation
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO) {
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
if (bd->blocks[i] != bd->ooo_after[i]) {
lfs_emubd_decblock(bd->blocks[i]);
bd->blocks[i] = lfs_emubd_incblock(bd->ooo_after[i]);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)i*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd,
(bd->blocks[i])
? bd->blocks[i]->data
: bd->disk->scratch,
cfg->block_size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
}
}
}
}
}
}
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// block bad?
if (b->wear > bd->cfg->erase_cycles) {
// erroring progs? error
if (bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_PROGERROR) {
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", LFS_ERR_CORRUPT);
return LFS_ERR_CORRUPT;
// noop progs? skip
} else if (bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_PROGNOOP
|| bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_ERASENOOP) {
goto progged;
// progs flipping bits? flip our bad bit, exactly which bit
// is chosen during erase
} else if (bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_PROGFLIP) {
lfs_size_t bit = b->bad_bit & 0x7fffffff;
if (bit/8 >= off && bit/8 < off+size) {
memcpy(&b->data[off], buffer, size);
b->data[bit/8] ^= 1 << (bit%8);
goto progged;
}
// reads flipping bits? prog as normal but mark as metastable
} else if (bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_READFLIP) {
memcpy(&b->data[off], buffer, size);
b->metastable = true;
goto progged;
}
}
// prog data
memcpy(&b->data[off], buffer, size);
// clear any metastability
b->metastable = false;
progged:;
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)block*cfg->block_size + (off_t)off,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd, &b->data[off], size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
}
// track progs
bd->proged += size;
if (bd->cfg->prog_sleep) {
int err = nanosleep(&(struct timespec){
.tv_sec=bd->cfg->prog_sleep/1000000000,
.tv_nsec=bd->cfg->prog_sleep%1000000000},
NULL);
if (err) {
err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
}
}
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", 0);
return 0;
}
int lfs_emubd_erase(const struct lfs_config *cfg, lfs_block_t block) {
LFS_EMUBD_TRACE("lfs_emubd_erase(%p, 0x%"PRIx32" (%"PRIu32"))",
(void*)cfg, block, cfg->block_size);
lfs_emubd_t *bd = cfg->context;
// check if erase is valid
LFS_ASSERT(block < cfg->block_count);
// losing power?
if (bd->power_cycles > 0) {
bd->power_cycles -= 1;
if (bd->power_cycles == 0) {
// emulating some bits? choose a random bit to flip
if (bd->cfg->powerloss_behavior
== LFS_EMUBD_POWERLOSS_SOMEBITS) {
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg,
bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// flip bit
lfs_size_t bit = lfs_emubd_prng(&bd->prng)
% (cfg->block_size*8);
b->data[(bit/8)] ^= 1 << (bit%8);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)block*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd,
b->data, cfg->block_size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
}
// emulating most bits? erase data and choose a random bit
// to flip
} else if (bd->cfg->powerloss_behavior
== LFS_EMUBD_POWERLOSS_MOSTBITS) {
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg,
bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// emulate an erase value?
if (bd->cfg->erase_value != -1) {
memset(b->data, bd->cfg->erase_value, cfg->block_size);
}
// flip bit
lfs_size_t bit = lfs_emubd_prng(&bd->prng)
% (cfg->block_size*8);
b->data[(bit/8)] ^= 1 << (bit%8);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)block*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd,
b->data, cfg->block_size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
}
// emulating out-of-order writes? revert everything unsynced
// except for our current block
} else if (bd->cfg->powerloss_behavior
== LFS_EMUBD_POWERLOSS_OOO) {
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
if (i != block && bd->blocks[i] != bd->ooo_before[i]) {
lfs_emubd_decblock(bd->blocks[i]);
bd->blocks[i] = lfs_emubd_incblock(bd->ooo_before[i]);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)i*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd,
(bd->blocks[i])
? bd->blocks[i]->data
: bd->disk->scratch,
cfg->block_size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
}
}
}
// emulating metastability? erase data, choose a random bad bit,
// and mark as metastable
} else if (bd->cfg->powerloss_behavior
== LFS_EMUBD_POWERLOSS_METASTABLE) {
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg,
bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// emulate an erase value?
if (bd->cfg->erase_value != -1) {
memset(b->data, bd->cfg->erase_value, cfg->block_size);
}
// choose a new bad bit unless overridden
if (!(0x80000000 & b->bad_bit)) {
b->bad_bit = lfs_emubd_prng(&bd->prng)
% (cfg->block_size*8);
}
// mark as metastable
b->metastable = true;
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)block*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd,
b->data, cfg->block_size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
}
}
// powerloss!
bd->cfg->powerloss_cb(bd->cfg->powerloss_data);
// oh, continuing? undo out-of-order write emulation
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO) {
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
if (bd->blocks[i] != bd->ooo_after[i]) {
lfs_emubd_decblock(bd->blocks[i]);
bd->blocks[i] = lfs_emubd_incblock(bd->ooo_after[i]);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)i*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd,
(bd->blocks[i])
? bd->blocks[i]->data
: bd->disk->scratch,
cfg->block_size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
}
}
}
}
}
}
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// keep track of wear
if (bd->cfg->erase_cycles && b->wear <= bd->cfg->erase_cycles) {
b->wear += 1;
}
// block bad?
if (b->wear > bd->cfg->erase_cycles) {
// erroring erases? error
if (bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_ERASEERROR) {
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", LFS_ERR_CORRUPT);
return LFS_ERR_CORRUPT;
// noop erases? skip
} else if (bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_ERASENOOP) {
goto erased;
// flipping bits? if we're not manually overridden, choose a
// new bad bit on erase, this makes it more likely to
// eventually cause problems
} else if (bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_PROGFLIP
|| bd->cfg->badblock_behavior
== LFS_EMUBD_BADBLOCK_READFLIP) {
if (!(0x80000000 & b->bad_bit)) {
b->bad_bit = lfs_emubd_prng(&bd->prng)
% (cfg->block_size*8);
}
}
}
// emulate an erase value?
if (bd->cfg->erase_value != -1) {
memset(b->data, bd->cfg->erase_value, cfg->block_size);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)block*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
ssize_t res2 = write(bd->disk->fd, b->data, cfg->block_size);
if (res2 < 0) {
int err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
}
}
// clear any metastability
b->metastable = false;
erased:;
// track erases
bd->erased += cfg->block_size;
if (bd->cfg->erase_sleep) {
int err = nanosleep(&(struct timespec){
.tv_sec=bd->cfg->erase_sleep/1000000000,
.tv_nsec=bd->cfg->erase_sleep%1000000000},
NULL);
if (err) {
err = -errno;
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
}
}
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", 0);
return 0;
}
int lfs_emubd_sync(const struct lfs_config *cfg) {
LFS_EMUBD_TRACE("lfs_emubd_sync(%p)", (void*)cfg);
lfs_emubd_t *bd = cfg->context;
// emulate out-of-order writes? save a snapshot on sync
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO) {
for (size_t i = 0; i < cfg->block_count; i++) {
lfs_emubd_decblock(bd->ooo_before[i]);
bd->ooo_before[i] = lfs_emubd_incblock(bd->blocks[i]);
}
}
LFS_EMUBD_TRACE("lfs_emubd_sync -> %d", 0);
return 0;
}
/// Additional extended API for driving test features ///
int lfs_emubd_seed(const struct lfs_config *cfg, uint32_t seed) {
LFS_EMUBD_TRACE("lfs_emubd_seed(%p, 0x%08"PRIx32")",
(void*)cfg, seed);
lfs_emubd_t *bd = cfg->context;
bd->prng = seed;
LFS_EMUBD_TRACE("lfs_emubd_seed -> %d", 0);
return 0;
}
lfs_emubd_sio_t lfs_emubd_readed(const struct lfs_config *cfg) {
LFS_EMUBD_TRACE("lfs_emubd_readed(%p)", (void*)cfg);
lfs_emubd_t *bd = cfg->context;
LFS_EMUBD_TRACE("lfs_emubd_readed -> %"PRIu64, bd->readed);
return bd->readed;
}
lfs_emubd_sio_t lfs_emubd_proged(const struct lfs_config *cfg) {
LFS_EMUBD_TRACE("lfs_emubd_proged(%p)", (void*)cfg);
lfs_emubd_t *bd = cfg->context;
LFS_EMUBD_TRACE("lfs_emubd_proged -> %"PRIu64, bd->proged);
return bd->proged;
}
lfs_emubd_sio_t lfs_emubd_erased(const struct lfs_config *cfg) {
LFS_EMUBD_TRACE("lfs_emubd_erased(%p)", (void*)cfg);
lfs_emubd_t *bd = cfg->context;
LFS_EMUBD_TRACE("lfs_emubd_erased -> %"PRIu64, bd->erased);
return bd->erased;
}
int lfs_emubd_setreaded(const struct lfs_config *cfg, lfs_emubd_io_t readed) {
LFS_EMUBD_TRACE("lfs_emubd_setreaded(%p, %"PRIu64")", (void*)cfg, readed);
lfs_emubd_t *bd = cfg->context;
bd->readed = readed;
LFS_EMUBD_TRACE("lfs_emubd_setreaded -> %d", 0);
return 0;
}
int lfs_emubd_setproged(const struct lfs_config *cfg, lfs_emubd_io_t proged) {
LFS_EMUBD_TRACE("lfs_emubd_setproged(%p, %"PRIu64")", (void*)cfg, proged);
lfs_emubd_t *bd = cfg->context;
bd->proged = proged;
LFS_EMUBD_TRACE("lfs_emubd_setproged -> %d", 0);
return 0;
}
int lfs_emubd_seterased(const struct lfs_config *cfg, lfs_emubd_io_t erased) {
LFS_EMUBD_TRACE("lfs_emubd_seterased(%p, %"PRIu64")", (void*)cfg, erased);
lfs_emubd_t *bd = cfg->context;
bd->erased = erased;
LFS_EMUBD_TRACE("lfs_emubd_seterased -> %d", 0);
return 0;
}
lfs_emubd_swear_t lfs_emubd_wear(const struct lfs_config *cfg,
lfs_block_t block) {
LFS_EMUBD_TRACE("lfs_emubd_wear(%p, %"PRIu32")", (void*)cfg, block);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// get the wear
lfs_emubd_wear_t wear;
const lfs_emubd_block_t *b = bd->blocks[block];
if (b) {
wear = b->wear;
} else {
wear = 0;
}
LFS_EMUBD_TRACE("lfs_emubd_wear -> %"PRIi32, wear);
return wear;
}
int lfs_emubd_setwear(const struct lfs_config *cfg,
lfs_block_t block, lfs_emubd_wear_t wear) {
LFS_EMUBD_TRACE("lfs_emubd_setwear(%p, %"PRIu32", %"PRIi32")",
(void*)cfg, block, wear);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_setwear -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// set the wear
b->wear = wear;
LFS_EMUBD_TRACE("lfs_emubd_setwear -> %d", 0);
return 0;
}
int lfs_emubd_markbad(const struct lfs_config *cfg,
lfs_block_t block) {
LFS_EMUBD_TRACE("lfs_emubd_markbad(%p, %"PRIu32")",
(void*)cfg, block);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_markbad -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// set the wear
b->wear = -1;
LFS_EMUBD_TRACE("lfs_emubd_markbad -> %d", 0);
return 0;
}
int lfs_emubd_markgood(const struct lfs_config *cfg,
lfs_block_t block) {
LFS_EMUBD_TRACE("lfs_emubd_markgood(%p, %"PRIu32")",
(void*)cfg, block);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_markgood -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// set the wear
b->wear = 0;
LFS_EMUBD_TRACE("lfs_emubd_markgood -> %d", 0);
return 0;
}
lfs_ssize_t lfs_emubd_badbit(const struct lfs_config *cfg,
lfs_block_t block) {
LFS_EMUBD_TRACE("lfs_emubd_badbit(%p, %"PRIu32")", (void*)cfg, block);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// get the bad bit
lfs_size_t bad_bit;
const lfs_emubd_block_t *b = bd->blocks[block];
if (b) {
bad_bit = 0x7fffffff & b->bad_bit;
} else {
bad_bit = 0;
}
LFS_EMUBD_TRACE("lfs_emubd_badbit -> %"PRIi32, bad_bit);
return bad_bit;
}
int lfs_emubd_setbadbit(const struct lfs_config *cfg,
lfs_block_t block, lfs_size_t bit) {
LFS_EMUBD_TRACE("lfs_emubd_setbadbit(%p, %"PRIu32", %"PRIu32")",
(void*)cfg, block, bit);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_setbadbit -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// set the bad bit and mark as fixed
b->bad_bit = 0x80000000 | bit;
LFS_EMUBD_TRACE("lfs_emubd_setbadbit -> %d", 0);
return 0;
}
int lfs_emubd_randomizebadbit(const struct lfs_config *cfg,
lfs_block_t block) {
LFS_EMUBD_TRACE("lfs_emubd_randomizebadbit(%p, %"PRIu32")",
(void*)cfg, block);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_randomizebadbit -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// mark the bad bit as randomized
b->bad_bit &= ~0x80000000;
LFS_EMUBD_TRACE("lfs_emubd_randomizebadbit -> %d", 0);
return 0;
}
int lfs_emubd_markbadbit(const struct lfs_config *cfg,
lfs_block_t block, lfs_size_t bit) {
LFS_EMUBD_TRACE("lfs_emubd_markbadbit(%p, %"PRIu32", %"PRIu32")",
(void*)cfg, block, bit);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_markbadbit -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// set the wear
b->wear = -1;
// set the bad bit and mark as fixed
b->bad_bit = 0x80000000 | bit;
LFS_EMUBD_TRACE("lfs_emubd_markbadbit -> %d", 0);
return 0;
}
int lfs_emubd_flipbit(const struct lfs_config *cfg,
lfs_block_t block, lfs_size_t bit) {
LFS_EMUBD_TRACE("lfs_emubd_flipbit(%p, %"PRIu32", %"PRIu32")",
(void*)cfg, block, bit);
lfs_emubd_t *bd = cfg->context;
// check if block is valid
LFS_ASSERT(block < cfg->block_count);
// mutate the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, bd->blocks[block]);
if (!b) {
LFS_EMUBD_TRACE("lfs_emubd_flipbit -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
bd->blocks[block] = b;
// flip the bit
b->data[bit/8] ^= 1 << (bit%8);
LFS_EMUBD_TRACE("lfs_emubd_flipbit -> %d", 0);
return 0;
}
lfs_emubd_spowercycles_t lfs_emubd_powercycles(
const struct lfs_config *cfg) {
LFS_EMUBD_TRACE("lfs_emubd_powercycles(%p)", (void*)cfg);
lfs_emubd_t *bd = cfg->context;
LFS_EMUBD_TRACE("lfs_emubd_powercycles -> %"PRIi32, bd->power_cycles);
return bd->power_cycles;
}
int lfs_emubd_setpowercycles(const struct lfs_config *cfg,
lfs_emubd_powercycles_t power_cycles) {
LFS_EMUBD_TRACE("lfs_emubd_setpowercycles(%p, %"PRIi32")",
(void*)cfg, power_cycles);
lfs_emubd_t *bd = cfg->context;
bd->power_cycles = power_cycles;
LFS_EMUBD_TRACE("lfs_emubd_powercycles -> %d", 0);
return 0;
}
int lfs_emubd_copy(const struct lfs_config *cfg, lfs_emubd_t *copy) {
LFS_EMUBD_TRACE("lfs_emubd_copy(%p, %p)", (void*)cfg, (void*)copy);
lfs_emubd_t *bd = cfg->context;
// lazily copy over our block array
copy->blocks = malloc(
cfg->block_count * sizeof(lfs_emubd_block_t*));
if (!copy->blocks) {
LFS_EMUBD_TRACE("lfs_emubd_copy -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
copy->blocks[i] = lfs_emubd_incblock(bd->blocks[i]);
}
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO) {
copy->ooo_before = malloc(
cfg->block_count * sizeof(lfs_emubd_block_t*));
if (!copy->ooo_before) {
LFS_EMUBD_TRACE("lfs_emubd_copy -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
copy->ooo_before[i] = lfs_emubd_incblock(bd->ooo_before[i]);
}
copy->ooo_after = malloc(
cfg->block_count * sizeof(lfs_emubd_block_t*));
if (!copy->ooo_after) {
LFS_EMUBD_TRACE("lfs_emubd_copy -> %d", LFS_ERR_NOMEM);
return LFS_ERR_NOMEM;
}
for (lfs_block_t i = 0; i < cfg->block_count; i++) {
copy->ooo_after[i] = lfs_emubd_incblock(bd->ooo_after[i]);
}
}
// other state
copy->readed = bd->readed;
copy->proged = bd->proged;
copy->erased = bd->erased;
copy->prng = bd->prng;
copy->power_cycles = bd->power_cycles;
copy->disk = bd->disk;
if (copy->disk) {
copy->disk->rc += 1;
}
copy->cfg = bd->cfg;
LFS_EMUBD_TRACE("lfs_emubd_copy -> %d", 0);
return 0;
}
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