+++ /dev/null
-// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
-// vim: ts=8 sw=2 smarttab ft=cpp
-
-#include "cls/log/cls_log_client.h"
-#include "cls/version/cls_version_client.h"
-
-#include "rgw_log_backing.h"
-#include "rgw_tools.h"
-#include "cls_fifo_legacy.h"
-
-using namespace std::chrono_literals;
-namespace cb = ceph::buffer;
-
-static constexpr auto dout_subsys = ceph_subsys_rgw;
-
-enum class shard_check { dne, omap, fifo, corrupt };
-inline std::ostream& operator <<(std::ostream& m, const shard_check& t) {
- switch (t) {
- case shard_check::dne:
- return m << "shard_check::dne";
- case shard_check::omap:
- return m << "shard_check::omap";
- case shard_check::fifo:
- return m << "shard_check::fifo";
- case shard_check::corrupt:
- return m << "shard_check::corrupt";
- }
-
- return m << "shard_check::UNKNOWN=" << static_cast<uint32_t>(t);
-}
-
-namespace {
-/// Return the shard type, and a bool to see whether it has entries.
-shard_check
-probe_shard(const DoutPrefixProvider *dpp, librados::IoCtx& ioctx, const std::string& oid,
- bool& fifo_unsupported, optional_yield y)
-{
- ldpp_dout(dpp, 20) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << " probing oid=" << oid
- << dendl;
- if (!fifo_unsupported) {
- std::unique_ptr<rgw::cls::fifo::FIFO> fifo;
- auto r = rgw::cls::fifo::FIFO::open(dpp, ioctx, oid,
- &fifo, y,
- std::nullopt, true);
- switch (r) {
- case 0:
- ldpp_dout(dpp, 20) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": oid=" << oid << " is FIFO"
- << dendl;
- return shard_check::fifo;
-
- case -ENODATA:
- ldpp_dout(dpp, 20) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": oid=" << oid << " is empty and therefore OMAP"
- << dendl;
- return shard_check::omap;
-
- case -ENOENT:
- ldpp_dout(dpp, 20) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": oid=" << oid << " does not exist"
- << dendl;
- return shard_check::dne;
-
- case -EPERM:
- ldpp_dout(dpp, 20) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": FIFO is unsupported, marking."
- << dendl;
- fifo_unsupported = true;
- return shard_check::omap;
-
- default:
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": error probing: r=" << r
- << ", oid=" << oid << dendl;
- return shard_check::corrupt;
- }
- } else {
- // Since FIFO is unsupported, OMAP is the only alternative
- return shard_check::omap;
- }
-}
-
-tl::expected<log_type, bs::error_code>
-handle_dne(const DoutPrefixProvider *dpp, librados::IoCtx& ioctx,
- log_type def,
- std::string oid,
- bool fifo_unsupported,
- optional_yield y)
-{
- if (def == log_type::fifo) {
- if (fifo_unsupported) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << " WARNING: FIFO set as default but not supported by OSD. "
- << "Falling back to OMAP." << dendl;
- return log_type::omap;
- }
- std::unique_ptr<rgw::cls::fifo::FIFO> fifo;
- auto r = rgw::cls::fifo::FIFO::create(dpp, ioctx, oid,
- &fifo, y,
- std::nullopt);
- if (r < 0) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << " error creating FIFO: r=" << r
- << ", oid=" << oid << dendl;
- return tl::unexpected(bs::error_code(-r, bs::system_category()));
- }
- }
- return def;
-}
-}
-
-tl::expected<log_type, bs::error_code>
-log_backing_type(const DoutPrefixProvider *dpp,
- librados::IoCtx& ioctx,
- log_type def,
- int shards,
- const fu2::unique_function<std::string(int) const>& get_oid,
- optional_yield y)
-{
- auto check = shard_check::dne;
- bool fifo_unsupported = false;
- for (int i = 0; i < shards; ++i) {
- auto c = probe_shard(dpp, ioctx, get_oid(i), fifo_unsupported, y);
- if (c == shard_check::corrupt)
- return tl::unexpected(bs::error_code(EIO, bs::system_category()));
- if (c == shard_check::dne) continue;
- if (check == shard_check::dne) {
- check = c;
- continue;
- }
-
- if (check != c) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << " clashing types: check=" << check
- << ", c=" << c << dendl;
- return tl::unexpected(bs::error_code(EIO, bs::system_category()));
- }
- }
- if (check == shard_check::corrupt) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << " should be unreachable!" << dendl;
- return tl::unexpected(bs::error_code(EIO, bs::system_category()));
- }
-
- if (check == shard_check::dne)
- return handle_dne(dpp, ioctx,
- def,
- get_oid(0),
- fifo_unsupported,
- y);
-
- return (check == shard_check::fifo ? log_type::fifo : log_type::omap);
-}
-
-bs::error_code log_remove(const DoutPrefixProvider *dpp,
- librados::IoCtx& ioctx,
- int shards,
- const fu2::unique_function<std::string(int) const>& get_oid,
- bool leave_zero,
- optional_yield y)
-{
- bs::error_code ec;
- for (int i = 0; i < shards; ++i) {
- auto oid = get_oid(i);
- rados::cls::fifo::info info;
- uint32_t part_header_size = 0, part_entry_overhead = 0;
-
- auto r = rgw::cls::fifo::get_meta(dpp, ioctx, oid, std::nullopt, &info,
- &part_header_size, &part_entry_overhead,
- 0, y, true);
- if (r == -ENOENT) continue;
- if (r == 0 && info.head_part_num > -1) {
- for (auto j = info.tail_part_num; j <= info.head_part_num; ++j) {
- librados::ObjectWriteOperation op;
- op.remove();
- auto part_oid = info.part_oid(j);
- auto subr = rgw_rados_operate(dpp, ioctx, part_oid, &op, null_yield);
- if (subr < 0 && subr != -ENOENT) {
- if (!ec)
- ec = bs::error_code(-subr, bs::system_category());
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed removing FIFO part: part_oid=" << part_oid
- << ", subr=" << subr << dendl;
- }
- }
- }
- if (r < 0 && r != -ENODATA) {
- if (!ec)
- ec = bs::error_code(-r, bs::system_category());
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed checking FIFO part: oid=" << oid
- << ", r=" << r << dendl;
- }
- librados::ObjectWriteOperation op;
- if (i == 0 && leave_zero) {
- // Leave shard 0 in existence, but remove contents and
- // omap. cls_lock stores things in the xattrs. And sync needs to
- // rendezvous with locks on generation 0 shard 0.
- op.omap_set_header({});
- op.omap_clear();
- op.truncate(0);
- } else {
- op.remove();
- }
- r = rgw_rados_operate(dpp, ioctx, oid, &op, null_yield);
- if (r < 0 && r != -ENOENT) {
- if (!ec)
- ec = bs::error_code(-r, bs::system_category());
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed removing shard: oid=" << oid
- << ", r=" << r << dendl;
- }
- }
- return ec;
-}
-
-logback_generations::~logback_generations() {
- if (watchcookie > 0) {
- auto cct = static_cast<CephContext*>(ioctx.cct());
- auto r = ioctx.unwatch2(watchcookie);
- if (r < 0) {
- lderr(cct) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed unwatching oid=" << oid
- << ", r=" << r << dendl;
- }
- }
-}
-
-bs::error_code logback_generations::setup(const DoutPrefixProvider *dpp,
- log_type def,
- optional_yield y) noexcept
-{
- try {
- // First, read.
- auto cct = static_cast<CephContext*>(ioctx.cct());
- auto res = read(dpp, y);
- if (!res && res.error() != bs::errc::no_such_file_or_directory) {
- return res.error();
- }
- if (res) {
- std::unique_lock lock(m);
- std::tie(entries_, version) = std::move(*res);
- } else {
- // Are we the first? Then create generation 0 and the generations
- // metadata.
- librados::ObjectWriteOperation op;
- auto type = log_backing_type(dpp, ioctx, def, shards,
- [this](int shard) {
- return this->get_oid(0, shard);
- }, y);
- if (!type)
- return type.error();
-
- logback_generation l;
- l.type = *type;
-
- std::unique_lock lock(m);
- version.ver = 1;
- static constexpr auto TAG_LEN = 24;
- version.tag.clear();
- append_rand_alpha(cct, version.tag, version.tag, TAG_LEN);
- op.create(true);
- cls_version_set(op, version);
- cb::list bl;
- entries_.emplace(0, std::move(l));
- encode(entries_, bl);
- lock.unlock();
-
- op.write_full(bl);
- auto r = rgw_rados_operate(dpp, ioctx, oid, &op, y);
- if (r < 0 && r != -EEXIST) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed writing oid=" << oid
- << ", r=" << r << dendl;
- bs::system_error(-r, bs::system_category());
- }
- // Did someone race us? Then re-read.
- if (r != 0) {
- res = read(dpp, y);
- if (!res)
- return res.error();
- if (res->first.empty())
- return bs::error_code(EIO, bs::system_category());
- auto l = res->first.begin()->second;
- // In the unlikely event that someone raced us, created
- // generation zero, incremented, then erased generation zero,
- // don't leave generation zero lying around.
- if (l.gen_id != 0) {
- auto ec = log_remove(dpp, ioctx, shards,
- [this](int shard) {
- return this->get_oid(0, shard);
- }, true, y);
- if (ec) return ec;
- }
- std::unique_lock lock(m);
- std::tie(entries_, version) = std::move(*res);
- }
- }
- // Pass all non-empty generations to the handler
- std::unique_lock lock(m);
- auto i = lowest_nomempty(entries_);
- entries_t e;
- std::copy(i, entries_.cend(),
- std::inserter(e, e.end()));
- m.unlock();
- auto ec = watch();
- if (ec) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed to re-establish watch, unsafe to continue: oid="
- << oid << ", ec=" << ec.message() << dendl;
- }
- return handle_init(std::move(e));
- } catch (const std::bad_alloc&) {
- return bs::error_code(ENOMEM, bs::system_category());
- }
-}
-
-bs::error_code logback_generations::update(const DoutPrefixProvider *dpp, optional_yield y) noexcept
-{
- try {
- auto res = read(dpp, y);
- if (!res) {
- return res.error();
- }
-
- std::unique_lock l(m);
- auto& [es, v] = *res;
- if (v == version) {
- // Nothing to do!
- return {};
- }
-
- // Check consistency and prepare update
- if (es.empty()) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": INCONSISTENCY! Read empty update." << dendl;
- return bs::error_code(EFAULT, bs::system_category());
- }
- auto cur_lowest = lowest_nomempty(entries_);
- // Straight up can't happen
- assert(cur_lowest != entries_.cend());
- auto new_lowest = lowest_nomempty(es);
- if (new_lowest == es.cend()) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": INCONSISTENCY! Read update with no active head." << dendl;
- return bs::error_code(EFAULT, bs::system_category());
- }
- if (new_lowest->first < cur_lowest->first) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": INCONSISTENCY! Tail moved wrong way." << dendl;
- return bs::error_code(EFAULT, bs::system_category());
- }
-
- std::optional<uint64_t> highest_empty;
- if (new_lowest->first > cur_lowest->first && new_lowest != es.begin()) {
- --new_lowest;
- highest_empty = new_lowest->first;
- }
-
- entries_t new_entries;
-
- if ((es.end() - 1)->first < (entries_.end() - 1)->first) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": INCONSISTENCY! Head moved wrong way." << dendl;
- return bs::error_code(EFAULT, bs::system_category());
- }
-
- if ((es.end() - 1)->first > (entries_.end() - 1)->first) {
- auto ei = es.lower_bound((entries_.end() - 1)->first + 1);
- std::copy(ei, es.end(), std::inserter(new_entries, new_entries.end()));
- }
-
- // Everything checks out!
-
- version = v;
- entries_ = es;
- l.unlock();
-
- if (highest_empty) {
- auto ec = handle_empty_to(*highest_empty);
- if (ec) return ec;
- }
-
- if (!new_entries.empty()) {
- auto ec = handle_new_gens(std::move(new_entries));
- if (ec) return ec;
- }
- } catch (const std::bad_alloc&) {
- return bs::error_code(ENOMEM, bs::system_category());
- }
- return {};
-}
-
-auto logback_generations::read(const DoutPrefixProvider *dpp, optional_yield y) noexcept ->
- tl::expected<std::pair<entries_t, obj_version>, bs::error_code>
-{
- try {
- librados::ObjectReadOperation op;
- std::unique_lock l(m);
- cls_version_check(op, version, VER_COND_GE);
- l.unlock();
- obj_version v2;
- cls_version_read(op, &v2);
- cb::list bl;
- op.read(0, 0, &bl, nullptr);
- auto r = rgw_rados_operate(dpp, ioctx, oid, &op, nullptr, y);
- if (r < 0) {
- if (r == -ENOENT) {
- ldpp_dout(dpp, 5) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": oid=" << oid
- << " not found" << dendl;
- } else {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed reading oid=" << oid
- << ", r=" << r << dendl;
- }
- return tl::unexpected(bs::error_code(-r, bs::system_category()));
- }
- auto bi = bl.cbegin();
- entries_t e;
- try {
- decode(e, bi);
- } catch (const cb::error& err) {
- return tl::unexpected(err.code());
- }
- return std::pair{ std::move(e), std::move(v2) };
- } catch (const std::bad_alloc&) {
- return tl::unexpected(bs::error_code(ENOMEM, bs::system_category()));
- }
-}
-
-bs::error_code logback_generations::write(const DoutPrefixProvider *dpp, entries_t&& e,
- std::unique_lock<std::mutex>&& l_,
- optional_yield y) noexcept
-{
- auto l = std::move(l_);
- ceph_assert(l.mutex() == &m &&
- l.owns_lock());
- try {
- librados::ObjectWriteOperation op;
- cls_version_check(op, version, VER_COND_GE);
- cb::list bl;
- encode(e, bl);
- op.write_full(bl);
- cls_version_inc(op);
- auto r = rgw_rados_operate(dpp, ioctx, oid, &op, y);
- if (r == 0) {
- entries_ = std::move(e);
- version.inc();
- return {};
- }
- l.unlock();
- if (r < 0 && r != -ECANCELED) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed reading oid=" << oid
- << ", r=" << r << dendl;
- return { -r, bs::system_category() };
- }
- if (r == -ECANCELED) {
- auto ec = update(dpp, y);
- if (ec) {
- return ec;
- } else {
- return { ECANCELED, bs::system_category() };
- }
- }
- } catch (const std::bad_alloc&) {
- return { ENOMEM, bs::system_category() };
- }
- return {};
-}
-
-
-bs::error_code logback_generations::watch() noexcept {
- try {
- auto cct = static_cast<CephContext*>(ioctx.cct());
- auto r = ioctx.watch2(oid, &watchcookie, this);
- if (r < 0) {
- lderr(cct) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed to set watch oid=" << oid
- << ", r=" << r << dendl;
- return { -r, bs::system_category() };
- }
- } catch (const std::bad_alloc&) {
- return bs::error_code(ENOMEM, bs::system_category());
- }
- return {};
-}
-
-bs::error_code logback_generations::new_backing(const DoutPrefixProvider *dpp,
- log_type type,
- optional_yield y) noexcept {
- static constexpr auto max_tries = 10;
- try {
- auto ec = update(dpp, y);
- if (ec) return ec;
- auto tries = 0;
- entries_t new_entries;
- do {
- std::unique_lock l(m);
- auto last = entries_.end() - 1;
- if (last->second.type == type) {
- // Nothing to be done
- return {};
- }
- auto newgenid = last->first + 1;
- logback_generation newgen;
- newgen.gen_id = newgenid;
- newgen.type = type;
- new_entries.emplace(newgenid, newgen);
- auto es = entries_;
- es.emplace(newgenid, std::move(newgen));
- ec = write(dpp, std::move(es), std::move(l), y);
- ++tries;
- } while (ec == bs::errc::operation_canceled &&
- tries < max_tries);
- if (tries >= max_tries) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": exhausted retry attempts." << dendl;
- return ec;
- }
-
- if (ec) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": write failed with ec=" << ec.message() << dendl;
- return ec;
- }
-
- cb::list bl, rbl;
-
- auto r = rgw_rados_notify(dpp, ioctx, oid, bl, 10'000, &rbl, y);
- if (r < 0) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": notify failed with r=" << r << dendl;
- return { -r, bs::system_category() };
- }
- ec = handle_new_gens(new_entries);
- } catch (const std::bad_alloc&) {
- return bs::error_code(ENOMEM, bs::system_category());
- }
- return {};
-}
-
-bs::error_code logback_generations::empty_to(const DoutPrefixProvider *dpp,
- uint64_t gen_id,
- optional_yield y) noexcept {
- static constexpr auto max_tries = 10;
- try {
- auto ec = update(dpp, y);
- if (ec) return ec;
- auto tries = 0;
- uint64_t newtail = 0;
- do {
- std::unique_lock l(m);
- {
- auto last = entries_.end() - 1;
- if (gen_id >= last->first) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": Attempt to trim beyond the possible." << dendl;
- return bs::error_code(EINVAL, bs::system_category());
- }
- }
- auto es = entries_;
- auto ei = es.upper_bound(gen_id);
- if (ei == es.begin()) {
- // Nothing to be done.
- return {};
- }
- for (auto i = es.begin(); i < ei; ++i) {
- newtail = i->first;
- i->second.pruned = ceph::real_clock::now();
- }
- ec = write(dpp, std::move(es), std::move(l), y);
- ++tries;
- } while (ec == bs::errc::operation_canceled &&
- tries < max_tries);
- if (tries >= max_tries) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": exhausted retry attempts." << dendl;
- return ec;
- }
-
- if (ec) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": write failed with ec=" << ec.message() << dendl;
- return ec;
- }
-
- cb::list bl, rbl;
-
- auto r = rgw_rados_notify(dpp, ioctx, oid, bl, 10'000, &rbl, y);
- if (r < 0) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": notify failed with r=" << r << dendl;
- return { -r, bs::system_category() };
- }
- ec = handle_empty_to(newtail);
- } catch (const std::bad_alloc&) {
- return bs::error_code(ENOMEM, bs::system_category());
- }
- return {};
-}
-
-bs::error_code logback_generations::remove_empty(const DoutPrefixProvider *dpp, optional_yield y) noexcept {
- static constexpr auto max_tries = 10;
- try {
- auto ec = update(dpp, y);
- if (ec) return ec;
- auto tries = 0;
- entries_t new_entries;
- std::unique_lock l(m);
- ceph_assert(!entries_.empty());
- {
- auto i = lowest_nomempty(entries_);
- if (i == entries_.begin()) {
- return {};
- }
- }
- entries_t es;
- auto now = ceph::real_clock::now();
- l.unlock();
- do {
- std::copy_if(entries_.cbegin(), entries_.cend(),
- std::inserter(es, es.end()),
- [now](const auto& e) {
- if (!e.second.pruned)
- return false;
-
- auto pruned = *e.second.pruned;
- return (now - pruned) >= 1h;
- });
- auto es2 = entries_;
- for (const auto& [gen_id, e] : es) {
- ceph_assert(e.pruned);
- auto ec = log_remove(dpp, ioctx, shards,
- [this, gen_id = gen_id](int shard) {
- return this->get_oid(gen_id, shard);
- }, (gen_id == 0), y);
- if (ec) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": Error pruning: gen_id=" << gen_id
- << " ec=" << ec.message() << dendl;
- }
- if (auto i = es2.find(gen_id); i != es2.end()) {
- es2.erase(i);
- }
- }
- l.lock();
- es.clear();
- ec = write(dpp, std::move(es2), std::move(l), y);
- ++tries;
- } while (ec == bs::errc::operation_canceled &&
- tries < max_tries);
- if (tries >= max_tries) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": exhausted retry attempts." << dendl;
- return ec;
- }
-
- if (ec) {
- ldpp_dout(dpp, -1) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": write failed with ec=" << ec.message() << dendl;
- return ec;
- }
- } catch (const std::bad_alloc&) {
- return bs::error_code(ENOMEM, bs::system_category());
- }
- return {};
-}
-
-void logback_generations::handle_notify(uint64_t notify_id,
- uint64_t cookie,
- uint64_t notifier_id,
- bufferlist& bl)
-{
- auto cct = static_cast<CephContext*>(ioctx.cct());
- const DoutPrefix dp(cct, dout_subsys, "logback generations handle_notify: ");
- if (notifier_id != my_id) {
- auto ec = update(&dp, null_yield);
- if (ec) {
- lderr(cct)
- << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": update failed, no one to report to and no safe way to continue."
- << dendl;
- abort();
- }
- }
- cb::list rbl;
- ioctx.notify_ack(oid, notify_id, watchcookie, rbl);
-}
-
-void logback_generations::handle_error(uint64_t cookie, int err) {
- auto cct = static_cast<CephContext*>(ioctx.cct());
- auto r = ioctx.unwatch2(watchcookie);
- if (r < 0) {
- lderr(cct) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed to set unwatch oid=" << oid
- << ", r=" << r << dendl;
- }
-
- auto ec = watch();
- if (ec) {
- lderr(cct) << __PRETTY_FUNCTION__ << ":" << __LINE__
- << ": failed to re-establish watch, unsafe to continue: oid="
- << oid << ", ec=" << ec.message() << dendl;
- }
-}
projects / ceph.git / blobdiff