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Fixed allocation bugs near the end of storage
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Also added better testing specifically for these corner cases
around the end of storage
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@geky
geky committed May 8, 2017
1 parent 210b487 commit a30142e
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Showing 3 changed files with 108 additions and 25 deletions.
68 changes: 43 additions & 25 deletions lfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -256,34 +256,39 @@ static inline bool lfs_pairisnull(const lfs_block_t pair[2]) {
static inline int lfs_paircmp(
const lfs_block_t paira[2],
const lfs_block_t pairb[2]) {
return !((paira[0] == pairb[0] && paira[1] == pairb[1]) ||
(paira[0] == pairb[1] && paira[1] == pairb[0]));
return !(paira[0] == pairb[0] || paira[1] == pairb[1] ||
paira[0] == pairb[1] || paira[1] == pairb[0]);
}

static int lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
// Allocate pair of dir blocks
// allocate pair of dir blocks
for (int i = 0; i < 2; i++) {
int err = lfs_alloc(lfs, &dir->pair[i]);
if (err) {
return err;
}
}

// Rather than clobbering one of the blocks we just pretend
// we couldn't find unique blocks, we're out of space
if (dir->pair[0] == dir->pair[1]) {
return LFS_ERR_NOSPC;
}

// rather than clobbering one of the blocks we just pretend
// the revision may be valid
int err = lfs_bd_read(lfs, dir->pair[0], 0, &dir->d.rev, 4);
if (err) {
return err;
}

// Set defaults
// set defaults
dir->d.rev += 1;
dir->d.size = sizeof(dir->d);
dir->d.tail[0] = 0;
dir->d.tail[1] = 0;
dir->off = sizeof(dir->d);

// Don't write out yet, let caller take care of that
// don't write out yet, let caller take care of that
return 0;
}

Expand Down Expand Up @@ -484,13 +489,21 @@ static int lfs_dir_append(lfs_t *lfs, lfs_dir_t *dir,
return lfs_dir_commit(lfs, dir, entry, data);
}

// we need to allocate a new dir block
if (!(0x80000000 & dir->d.size)) {
lfs_dir_t newdir;
int err = lfs_dir_alloc(lfs, &newdir);
if (err) {
return err;
}

// our allocator doesn't track blocks before being appended,
// so even if we found some blocks, they may not be unique
if (entry->d.type == LFS_TYPE_DIR &&
lfs_paircmp(entry->d.u.dir, newdir.pair) == 0) {
return LFS_ERR_NOSPC;
}

newdir.d.tail[0] = dir->d.tail[0];
newdir.d.tail[1] = dir->d.tail[1];
entry->off = newdir.d.size;
Expand Down Expand Up @@ -1677,7 +1690,7 @@ static int lfs_parent(lfs_t *lfs, const lfs_block_t dir[2]) {
.d.tail[1] = lfs->root[1],
};

while (parent.d.tail[0]) {
while (true) {
lfs_entry_t entry;
int err = lfs_dir_fetch(lfs, &parent, parent.d.tail);
if (err) {
Expand All @@ -1699,9 +1712,11 @@ static int lfs_parent(lfs_t *lfs, const lfs_block_t dir[2]) {
return true;
}
}
}

return false;
if (lfs_pairisnull(parent.d.tail)) {
return false;
}
}
}

int lfs_deorphan(lfs_t *lfs) {
Expand All @@ -1715,31 +1730,34 @@ int lfs_deorphan(lfs_t *lfs) {
return err;
}

while (pdir.d.tail[0]) {
while (!lfs_pairisnull(pdir.d.tail)) {
int err = lfs_dir_fetch(lfs, &cdir, pdir.d.tail);
if (err) {
return err;
}

// check if we have a parent
int parent = lfs_parent(lfs, pdir.d.tail);
if (parent < 0) {
return parent;
}
// only check head blocks
if (!(0x80000000 & pdir.d.size)) {
// check if we have a parent
int parent = lfs_parent(lfs, pdir.d.tail);
if (parent < 0) {
return parent;
}

if (!parent) {
// we are an orphan
LFS_DEBUG("Orphan %d %d", pdir.d.tail[0], pdir.d.tail[1]);
if (!parent) {
// we are an orphan
LFS_DEBUG("Orphan %d %d", pdir.d.tail[0], pdir.d.tail[1]);

pdir.d.tail[0] = cdir.d.tail[0];
pdir.d.tail[1] = cdir.d.tail[1];
pdir.d.tail[0] = cdir.d.tail[0];
pdir.d.tail[1] = cdir.d.tail[1];

err = lfs_dir_commit(lfs, &pdir, NULL, NULL);
if (err) {
return err;
}
err = lfs_dir_commit(lfs, &pdir, NULL, NULL);
if (err) {
return err;
}

break;
break;
}
}

memcpy(&pdir, &cdir, sizeof(pdir));
Expand Down
1 change: 1 addition & 0 deletions lfs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -195,6 +195,7 @@ typedef struct lfs {
lfs_size_t words; // number of 32-bit words that can fit in a block

lfs_block_t root[2];
lfs_dir_t *scratch;
lfs_file_t *files;

struct {
Expand Down
64 changes: 64 additions & 0 deletions tests/test_alloc.sh
View file
Original file line number Diff line number Diff line change
Expand Up @@ -193,5 +193,69 @@ tests/test.py << TEST
lfs_unmount(&lfs) => 0;
TEST

echo "--- Dir exhaustion test ---"
tests/test.py << TEST
lfs_mount(&lfs, &cfg) => 0;
lfs_stat(&lfs, "exhaustion", &info) => 0;
lfs_size_t fullsize = info.size;
lfs_remove(&lfs, "exhaustion") => 0;
lfs_file_open(&lfs, &file[0], "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
size = strlen("blahblahblahblah");
memcpy(buffer, "blahblahblahblah", size);
for (lfs_size_t i = 0; i < fullsize - 2*512; i += size) {
lfs_file_write(&lfs, &file[0], buffer, size) => size;
}
lfs_file_close(&lfs, &file[0]) => 0;
lfs_mkdir(&lfs, "exhaustiondir") => 0;
lfs_remove(&lfs, "exhaustiondir") => 0;
lfs_file_open(&lfs, &file[0], "exhaustion", LFS_O_WRONLY | LFS_O_APPEND);
size = strlen("blahblahblahblah");
memcpy(buffer, "blahblahblahblah", size);
lfs_file_write(&lfs, &file[0], buffer, size) => size;
lfs_file_close(&lfs, &file[0]) => 0;
lfs_mkdir(&lfs, "exhaustiondir") => LFS_ERR_NOSPC;
lfs_unmount(&lfs) => 0;
TEST

echo "--- Chained dir exhaustion test ---"
tests/test.py << TEST
lfs_mount(&lfs, &cfg) => 0;
lfs_stat(&lfs, "exhaustion", &info) => 0;
lfs_size_t fullsize = info.size;
lfs_remove(&lfs, "exhaustion") => 0;
lfs_file_open(&lfs, &file[0], "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
size = strlen("blahblahblahblah");
memcpy(buffer, "blahblahblahblah", size);
for (lfs_size_t i = 0; i < fullsize - 19*512; i += size) {
lfs_file_write(&lfs, &file[0], buffer, size) => size;
}
lfs_file_close(&lfs, &file[0]) => 0;
for (int i = 0; i < 9; i++) {
sprintf((char*)buffer, "dirwithanexhaustivelylongnameforpadding%d", i);
lfs_mkdir(&lfs, (char*)buffer) => 0;
}
lfs_mkdir(&lfs, "exhaustiondir") => LFS_ERR_NOSPC;
lfs_remove(&lfs, "exhaustion") => 0;
lfs_file_open(&lfs, &file[0], "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
size = strlen("blahblahblahblah");
memcpy(buffer, "blahblahblahblah", size);
for (lfs_size_t i = 0; i < fullsize - 20*512; i += size) {
lfs_file_write(&lfs, &file[0], buffer, size) => size;
}
lfs_file_close(&lfs, &file[0]) => 0;
lfs_mkdir(&lfs, "exhaustiondir") => 0;
lfs_mkdir(&lfs, "exhaustiondir2") => LFS_ERR_NOSPC;
TEST


echo "--- Results ---"
tests/stats.py

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