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Remove creepy "metadata copying" during overwrite

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Instead of it, just do not verify checksums of currently mutated objects.
When clean data modification during flush runs in parallel to a read request,
that request may read a mix of old and new data. It may even read a mix of
multiple flushed versions if it lasts too long... And attempts to verify it
using temporary copies of metadata make the algorithm too complex and creepy.
This commit is contained in:
Vitaliy Filippov
2023-07-29 12:17:18 +03:00
parent a8464c19af
commit 4181add1f4
4 changed files with 83 additions and 89 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/blockstore_flush.cpp
+39 -35
View File
@@ -160,6 +160,22 @@ void journal_flusher_t::remove_flush(object_id oid)
}
}
bool journal_flusher_t::is_flushed_over(obj_ver_id ov)
{
auto r_it = sync_to_repeat.find(ov.oid);
if (r_it != sync_to_repeat.end())
{
for (int i = 0; i < cur_flusher_count; i++)
{
if (co[i].wait_state != 0 && co[i].cur.oid == ov.oid)
{
return co[i].cur.version > ov.version;
}
}
}
return false;
}
void journal_flusher_t::request_trim()
{
dequeuing = true;
@@ -444,6 +460,7 @@ stop_flusher:
else
{
clean_loc = old_clean_loc;
clean_ver = old_clean_ver;
}
}
// Submit dirty data and old checksum data reads
@@ -479,6 +496,15 @@ resume_2:
wait_state = wait_base+13;
return false;
}
if (bs->dsk.csum_block_size)
{
// Mark objects used by reads as modified
auto uo_it = bs->used_clean_objects.find((obj_ver_id){ .oid = cur.oid, .version = clean_ver });
if (uo_it != bs->used_clean_objects.end())
{
uo_it->second.was_changed = true;
}
}
// Submit data writes
for (it = v.begin(); it != v.end(); it++)
{
@@ -601,34 +627,6 @@ void journal_flusher_co::update_metadata_entry()
}
else
{
if (bs->dsk.csum_block_size)
{
// Copy the whole old metadata entry before updating it if the updated object is being read
obj_ver_id ov = { .oid = new_entry->oid, .version = new_entry->version };
auto uo_it = bs->used_clean_objects.upper_bound(ov);
if (uo_it != bs->used_clean_objects.begin())
{
uo_it--;
if (uo_it->first.oid == new_entry->oid)
{
uint8_t *meta_copy = (uint8_t*)malloc_or_die(bs->dsk.clean_entry_size);
memcpy(meta_copy, new_entry, bs->dsk.clean_entry_size);
// The reads should free all metadata entry backups when they don't need them anymore
if (uo_it->first.version < new_entry->version)
{
// If ==, write in place
uo_it++;
bs->used_clean_objects.insert(uo_it, std::make_pair(ov, (used_clean_obj_t){
.meta = meta_copy,
}));
}
else
{
uo_it->second.meta = meta_copy;
}
}
}
}
// Set initial internal bitmap bits from the big write
if (clean_init_bitmap)
{
@@ -725,6 +723,7 @@ bool journal_flusher_co::write_meta_block(flusher_meta_write_t & meta_block, int
return true;
}
// Punch holes in incomplete checksum blocks
bool journal_flusher_co::clear_incomplete_csum_block_bits(int wait_base)
{
if (wait_state == wait_base) goto resume_0;
@@ -805,12 +804,6 @@ bool journal_flusher_co::clear_incomplete_csum_block_bits(int wait_base)
});
}
}
// Actually clear bits
for (auto it = v.begin(); it != v.end(); it++)
{
if (it->copy_flags == COPY_BUF_JOURNAL || it->copy_flags == (COPY_BUF_JOURNAL|COPY_BUF_COALESCED))
bitmap_clear(new_clean_bitmap, it->offset, it->len, bs->dsk.bitmap_granularity);
}
{
clean_disk_entry *new_entry = (clean_disk_entry*)((uint8_t*)meta_new.buf + meta_new.pos*bs->dsk.clean_entry_size);
if (new_entry->oid != cur.oid)
@@ -822,11 +815,20 @@ bool journal_flusher_co::clear_incomplete_csum_block_bits(int wait_base)
);
}
assert(new_entry->oid == cur.oid);
// Actually clear bits
for (auto it = v.begin(); it != v.end(); it++)
{
if (it->copy_flags == COPY_BUF_JOURNAL || it->copy_flags == (COPY_BUF_JOURNAL|COPY_BUF_COALESCED))
bitmap_clear(new_clean_bitmap, it->offset, it->len, bs->dsk.bitmap_granularity);
}
// Calculate block checksums with new holes
uint32_t *new_data_csums = (uint32_t*)(new_clean_bitmap + 2*bs->dsk.clean_entry_bitmap_size);
calc_block_checksums(new_data_csums, true);
if (!bs->inmemory_meta)
memcpy(&new_entry->bitmap, new_clean_bitmap, bs->dsk.clean_dyn_size);
{
auto inmem_bmp = (uint8_t*)bs->clean_bitmaps + (clean_loc >> bs->dsk.block_order)*2*bs->dsk.clean_entry_bitmap_size;
memcpy(inmem_bmp, new_clean_bitmap, 2*bs->dsk.clean_entry_bitmap_size);
}
if (bs->dsk.meta_format >= BLOCKSTORE_META_FORMAT_V2)
{
// calculate metadata entry checksum
@@ -914,6 +916,7 @@ void journal_flusher_co::scan_dirty()
v.clear();
copy_count = 0;
clean_loc = UINT64_MAX;
clean_ver = 0;
has_delete = false;
has_writes = false;
skip_copy = false;
@@ -989,6 +992,7 @@ void journal_flusher_co::scan_dirty()
// There is an unflushed big write. Copy small writes in its position
has_writes = true;
clean_loc = dirty_it->second.location;
clean_ver = dirty_it->first.version;
clean_init_bitmap = true;
clean_bitmap_offset = dirty_it->second.offset;
clean_bitmap_len = dirty_it->second.len;
src/blockstore_flush.h
+2 -1
View File
@@ -67,7 +67,7 @@ class journal_flusher_co
bool fill_incomplete, cleared_incomplete;
int read_to_fill_incomplete;
int copy_count;
uint64_t clean_loc, old_clean_loc, old_clean_ver;
uint64_t clean_loc, clean_ver, old_clean_loc, old_clean_ver;
flusher_meta_write_t meta_old, meta_new;
bool clean_init_bitmap;
uint64_t clean_bitmap_offset, clean_bitmap_len;
@@ -136,4 +136,5 @@ public:
void unshift_flush(obj_ver_id oid, bool force);
void remove_flush(object_id oid);
void dump_diagnostics();
bool is_flushed_over(obj_ver_id ov);
};
src/blockstore_impl.h
+3 -2
View File
@@ -181,7 +181,7 @@ struct used_clean_obj_t
{
int refs;
uint64_t freed_block; // block+1 if freed, otherwise 0
uint8_t *meta; // metadata copy
bool was_changed; // was changed by a parallel flush?
};
// https://github.com/algorithm-ninja/cpp-btree
@@ -352,7 +352,8 @@ class blockstore_impl_t
iovec *iov, int n_iov, std::function<void(uint32_t, uint32_t, uint32_t)> bad_block_cb);
bool verify_journal_checksums(uint8_t *csums, uint32_t offset,
iovec *iov, int n_iov, std::function<void(uint32_t, uint32_t, uint32_t)> bad_block_cb);
bool verify_clean_padded_checksums(blockstore_op_t *op, uint64_t clean_loc, uint8_t *csum_buf, iovec *iov, int n_iov);
bool verify_clean_padded_checksums(blockstore_op_t *op, uint64_t clean_loc, uint8_t *dyn_data, bool from_journal,
iovec *iov, int n_iov, std::function<void(uint32_t, uint32_t, uint32_t)> bad_block_cb);
int fulfill_read_push(blockstore_op_t *op, void *buf, uint64_t offset, uint64_t len,
uint32_t item_state, uint64_t item_version);
void handle_read_event(ring_data_t *data, blockstore_op_t *op);
src/blockstore_read.cpp
+39 -51
View File
@@ -643,7 +643,7 @@ bool blockstore_impl_t::fulfill_clean_read(blockstore_op_t *read_op, uint64_t &
else
{
bool csum_done = !dsk.csum_block_size || inmemory_meta;
uint8_t *csum_buf = clean_entry_bitmap + 2*dsk.clean_entry_bitmap_size;
uint8_t *csum_buf = clean_entry_bitmap;
uint64_t bmp_start = 0, bmp_end = 0, bmp_size = dsk.data_block_size/dsk.bitmap_granularity;
while (bmp_start < bmp_size)
{
@@ -670,7 +670,7 @@ bool blockstore_impl_t::fulfill_clean_read(blockstore_op_t *read_op, uint64_t &
csum_buf = read_clean_meta_block(read_op, clean_loc, PRIV(read_op)->read_vec.size());
csum_done = true;
}
uint8_t *csum = !dsk.csum_block_size ? 0 : (csum_buf + bmp_start*(dsk.data_csum_type & 0xFF));
uint8_t *csum = !dsk.csum_block_size ? 0 : (csum_buf + 2*dsk.clean_entry_bitmap_size + bmp_start*(dsk.data_csum_type & 0xFF));
if (!fulfill_read(read_op, fulfilled, bmp_start * dsk.bitmap_granularity,
bmp_end * dsk.bitmap_granularity, (BS_ST_BIG_WRITE | BS_ST_STABLE), 0,
clean_loc + bmp_start * dsk.bitmap_granularity, 0, csum, dyn_data))
@@ -685,7 +685,10 @@ bool blockstore_impl_t::fulfill_clean_read(blockstore_op_t *read_op, uint64_t &
if (PRIV(read_op)->clean_version_used)
{
obj_ver_id ov = { .oid = read_op->oid, .version = clean_ver };
used_clean_objects[ov].refs++;
auto & uo = used_clean_objects[ov];
uo.refs++;
if (dsk.csum_block_size && flusher->is_flushed_over(ov))
uo.was_changed = true;
PRIV(read_op)->clean_version_used = ov.version;
}
return true;
@@ -707,8 +710,8 @@ uint8_t* blockstore_impl_t::read_clean_meta_block(blockstore_op_t *op, uint64_t
PRIV(op)->pending_ops++;
my_uring_prep_readv(sqe, dsk.meta_fd, &data->iov, 1, dsk.meta_offset + dsk.meta_block_size + sector);
data->callback = [this, op](ring_data_t *data) { handle_read_event(data, op); };
// return pointer to checksums
return buf + pos + sizeof(clean_disk_entry) + 2*dsk.clean_entry_bitmap_size;
// return pointer to checksums + bitmap
return buf + pos + sizeof(clean_disk_entry);
}
bool blockstore_impl_t::verify_padded_checksums(uint8_t *clean_entry_bitmap, uint8_t *csum_buf, uint32_t offset,
@@ -803,21 +806,19 @@ bool blockstore_impl_t::verify_journal_checksums(uint8_t *csums, uint32_t offset
return true;
}
bool blockstore_impl_t::verify_clean_padded_checksums(blockstore_op_t *op, uint64_t clean_loc, uint8_t *csum_buf, iovec *iov, int n_iov)
bool blockstore_impl_t::verify_clean_padded_checksums(blockstore_op_t *op, uint64_t clean_loc, uint8_t *dyn_data, bool from_journal,
iovec *iov, int n_iov, std::function<void(uint32_t, uint32_t, uint32_t)> bad_block_cb)
{
uint32_t offset = clean_loc % dsk.data_block_size;
if (from_journal)
return verify_padded_checksums(dyn_data, dyn_data + dsk.clean_entry_bitmap_size, offset, iov, n_iov, bad_block_cb);
clean_loc = (clean_loc >> dsk.block_order) << dsk.block_order;
// First verify against the newest checksum version
uint8_t *clean_entry_bitmap = get_clean_entry_bitmap(clean_loc, 0);
if (verify_padded_checksums(clean_entry_bitmap, csum_buf ? csum_buf : (clean_entry_bitmap + 2*dsk.clean_entry_bitmap_size), offset, iov, n_iov, NULL))
return true;
// Check through all relevant "metadata backups" possibly added by flushers
auto mb_it = used_clean_objects.lower_bound((obj_ver_id){ .oid = op->oid, .version = PRIV(op)->clean_version_used });
for (; mb_it != used_clean_objects.end() && mb_it->first.oid == op->oid; mb_it++)
if (mb_it->second.meta != NULL && verify_padded_checksums(mb_it->second.meta,
mb_it->second.meta + 2*dsk.clean_entry_bitmap_size, offset, iov, n_iov, NULL))
return true;
return false;
if (!dyn_data)
{
assert(inmemory_meta);
dyn_data = get_clean_entry_bitmap(clean_loc, 0);
}
return verify_padded_checksums(dyn_data, dyn_data + 2*dsk.clean_entry_bitmap_size, offset, iov, n_iov, bad_block_cb);
}
void blockstore_impl_t::handle_read_event(ring_data_t *data, blockstore_op_t *op)
@@ -860,45 +861,37 @@ void blockstore_impl_t::handle_read_event(ring_data_t *data, blockstore_op_t *op
{
ok = false;
printf(
"Checksum mismatch in object %lx:%lx v%lu in journal at block #%u: got %08x, expected %08x\n",
"Checksum mismatch in object %lx:%lx v%lu in journal at 0x%lx, checksum block #%u: got %08x, expected %08x\n",
op->oid.inode, op->oid.stripe, op->version,
bad_block / dsk.csum_block_size, calc_csum, stored_csum
);
}
);
}
else if (rv[i].copy_flags & COPY_BUF_JOURNALED_BIG)
{
// BIG_WRITE from journal
verify_padded_checksums(rv[i].csum_buf, rv[i].csum_buf + dsk.clean_entry_bitmap_size,
rv[i].disk_offset % dsk.data_block_size, iov, n_iov,
[&](uint32_t bad_block, uint32_t calc_csum, uint32_t stored_csum)
{
ok = false;
printf(
"Checksum mismatch in object %lx:%lx v%lu in RoW data at block #%u: got %08x, expected %08x\n",
op->oid.inode, op->oid.stripe, op->version,
bad_block / dsk.csum_block_size, calc_csum, stored_csum
rv[i].disk_offset, bad_block / dsk.csum_block_size, calc_csum, stored_csum
);
}
);
}
else
{
// Clean data
ok = verify_clean_padded_checksums(op, rv[i].disk_offset, rv[i].csum_buf, iov, n_iov);
// BIG_WRITE from journal or clean data
// Do not verify checksums if the data location is/was mutated by flushers
auto & uo = used_clean_objects.at((obj_ver_id){ .oid = op->oid, .version = PRIV(op)->clean_version_used });
if (!uo.was_changed)
{
verify_clean_padded_checksums(
op, rv[i].disk_offset, rv[i].csum_buf, (rv[i].copy_flags & COPY_BUF_JOURNALED_BIG), iov, n_iov,
[&](uint32_t bad_block, uint32_t calc_csum, uint32_t stored_csum)
{
ok = false;
printf(
"Checksum mismatch in object %lx:%lx v%lu in %s data at 0x%lx, checksum block #%u: got %08x, expected %08x\n",
op->oid.inode, op->oid.stripe, op->version,
(rv[i].copy_flags & COPY_BUF_JOURNALED_BIG ? "redirect-write" : "clean"),
rv[i].disk_offset, bad_block / dsk.csum_block_size, calc_csum, stored_csum
);
}
);
}
}
if (!ok)
{
uint64_t read_len = 0;
for (int i = 0; i < n_iov; i++)
read_len += iov[i].iov_len;
printf(
"Checksum mismatch in object %lx:%lx v%lu in %s area at offset 0x%lx (read length 0x%lx)\n",
op->oid.inode, op->oid.stripe, op->version,
(rv[i].copy_flags & COPY_BUF_JOURNAL) ? "journal" : "data",
rv[i].disk_offset, read_len
);
op->retval = -EDOM;
}
free(rv[i].buf);
@@ -992,11 +985,6 @@ void blockstore_impl_t::handle_read_event(ring_data_t *data, blockstore_op_t *op
{
data_alloc->set(uo_it->second.freed_block-1, false);
}
if (uo_it->second.meta)
{
free(uo_it->second.meta);
uo_it->second.meta = NULL;
}
used_clean_objects.erase(uo_it++);
}
}