Github/littlefs
1
Fork 0
Code Actions Activity

Implemented much more aggressive OOO-write emulation

Browse Source 
Now, instead of reverting only the first block on powerloss, _all_
blocks since the last sync are reverted (except the in-flight block, if
you reverted that it would be the same as noop powerloss).

It was a bit frustrating trying to reproduce known holes in our sync
logic before this, but reverting all blocks really is the worst case,
so we should have quite a bit more confidence going forward.

This was a bit tricky to implement without memory leaks everywhere,
since we need to be able to resume for exhaustive powerloss testing. But
emubd's copy-on-write block emulation really shines here.
This commit is contained in:
Christopher Haster
2024-06-06 13:13:25 -05:00
parent 76ffb0e7b6
commit 780527d00a
2 changed files with 217 additions and 98 deletions
Download Patch File Download Diff File Expand all files Collapse all files
bd/lfs_emubd.c
+215 -96
View File
@@ -122,18 +122,41 @@ int lfs_emubd_createcfg(const struct lfs_config *cfg, const char *path,
bd->proged = 0;
bd->erased = 0;
bd->power_cycles = bd->cfg->power_cycles;
bd->ooo_block = -1;
bd->ooo_data = NULL;
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*));
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*));
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));
@@ -186,6 +209,10 @@ 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);
@@ -223,8 +250,19 @@ int lfs_emubd_destroy(const struct lfs_config *cfg) {
}
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
lfs_emubd_decblock(bd->ooo_data);
if (bd->disk) {
bd->disk->rc -= 1;
if (bd->disk->rc == 0) {
@@ -239,72 +277,6 @@ int lfs_emubd_destroy(const struct lfs_config *cfg) {
}
// powerloss hook
static int lfs_emubd_powerloss(const struct lfs_config *cfg) {
lfs_emubd_t *bd = cfg->context;
// emulate out-of-order writes?
lfs_emubd_block_t *ooo_data = NULL;
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO
&& bd->ooo_block != -1) {
// since writes between syncs are allowed to be out-of-order, it
// shouldn't hurt to restore the first write on powerloss, right?
ooo_data = bd->blocks[bd->ooo_block];
bd->blocks[bd->ooo_block] = lfs_emubd_incblock(bd->ooo_data);
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)bd->ooo_block*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
return -errno;
}
ssize_t res2 = write(bd->disk->fd,
(bd->blocks[bd->ooo_block])
? bd->blocks[bd->ooo_block]->data
: bd->disk->scratch,
cfg->block_size);
if (res2 < 0) {
return -errno;
}
}
}
// simulate power loss
bd->cfg->powerloss_cb(bd->cfg->powerloss_data);
// if we continue, undo out-of-order write emulation
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO
&& bd->ooo_block != -1) {
lfs_emubd_decblock(bd->blocks[bd->ooo_block]);
bd->blocks[bd->ooo_block] = ooo_data;
// mirror to disk file?
if (bd->disk) {
off_t res1 = lseek(bd->disk->fd,
(off_t)bd->ooo_block*cfg->block_size,
SEEK_SET);
if (res1 < 0) {
return -errno;
}
ssize_t res2 = write(bd->disk->fd,
(bd->blocks[bd->ooo_block])
? bd->blocks[bd->ooo_block]->data
: bd->disk->scratch,
cfg->block_size);
if (res2 < 0) {
return -errno;
}
}
}
return 0;
}
// block device API
int lfs_emubd_read(const struct lfs_config *cfg, lfs_block_t block,
@@ -439,10 +411,77 @@ int lfs_emubd_prog(const struct lfs_config *cfg, lfs_block_t block,
if (bd->power_cycles > 0) {
bd->power_cycles -= 1;
if (bd->power_cycles == 0) {
int err = lfs_emubd_powerloss(cfg);
if (err) {
LFS_EMUBD_TRACE("lfs_emubd_prog -> %d", err);
return err;
// if we're emulating out-of-order writes, revert everything
// unsynced except for our current block
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;
}
}
}
}
}
// 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;
}
}
}
}
}
}
}
@@ -459,13 +498,6 @@ int lfs_emubd_erase(const struct lfs_config *cfg, lfs_block_t block) {
// check if erase is valid
LFS_ASSERT(block < cfg->block_count);
// emulate out-of-order writes? save first write
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO
&& bd->ooo_block == -1) {
bd->ooo_block = block;
bd->ooo_data = lfs_emubd_incblock(bd->blocks[block]);
}
// get the block
lfs_emubd_block_t *b = lfs_emubd_mutblock(cfg, &bd->blocks[block]);
if (!b) {
@@ -533,10 +565,77 @@ int lfs_emubd_erase(const struct lfs_config *cfg, lfs_block_t block) {
if (bd->power_cycles > 0) {
bd->power_cycles -= 1;
if (bd->power_cycles == 0) {
int err = lfs_emubd_powerloss(cfg);
if (err) {
LFS_EMUBD_TRACE("lfs_emubd_erase -> %d", err);
return err;
// if we're emulating out-of-order writes, revert everything
// unsynced except for our current block
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_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;
}
}
}
}
}
// 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;
}
}
}
}
}
}
}
@@ -549,12 +648,12 @@ 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? reset first write, writes
// cannot be out-of-order across sync
// emulate out-of-order writes? save a snapshot on sync
if (bd->cfg->powerloss_behavior == LFS_EMUBD_POWERLOSS_OOO) {
lfs_emubd_decblock(bd->ooo_data);
bd->ooo_block = -1;
bd->ooo_data = NULL;
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);
@@ -731,23 +830,43 @@ int lfs_emubd_copy(const struct lfs_config *cfg, lfs_emubd_t *copy) {
lfs_emubd_t *bd = cfg->context;
// lazily copy over our block array
copy->blocks = malloc(cfg->block_count * sizeof(lfs_emubd_block_t*));
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 (size_t i = 0; i < cfg->block_count; i++) {
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->power_cycles = bd->power_cycles;
copy->ooo_block = bd->ooo_block;
copy->ooo_data = lfs_emubd_incblock(bd->ooo_data);
copy->disk = bd->disk;
if (copy->disk) {
copy->disk->rc += 1;
bd/lfs_emubd.h
+2 -2
View File
@@ -140,8 +140,8 @@ typedef struct lfs_emubd {
lfs_emubd_io_t proged;
lfs_emubd_io_t erased;
lfs_emubd_powercycles_t power_cycles;
lfs_ssize_t ooo_block;
lfs_emubd_block_t *ooo_data;
lfs_emubd_block_t **ooo_before;
lfs_emubd_block_t **ooo_after;
lfs_emubd_disk_t *disk;
const struct lfs_emubd_config *cfg;