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extent scan: fix crawl_map creation

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There are two crawl_maps in extent scan's next_transid:  one gets
initialized, the other gets used.  This works OK as long as bees is
resuming an existing scan, because the two maps are identical; however,
but it fails if bees is starting without an existing set of crawl data,
and one of the two maps is empty or partially filled.

The failure is intermittent, as the crawl map is being populated at
the same time next_transid runs.  It will eventually be completed after
several transaction cycles, at which point bees runs normally.
It does add significant delays during startup for benchmarks.

There's only one crawl_map in extent scan, it always has the same
crawlers, and extent scan's `next_transid` creates it by itself.
Ignore the map from BeesRoots/BeesCrawl.

Also throw in some missing but helpful trace statements.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This commit is contained in:
Zygo Blaxell 2024-11-30 12:45:58 -05:00
parent 9987aa8583
commit 59f8a467c3
1 changed files with 29 additions and 20 deletions
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49
src/bees-roots.cc
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@ -555,6 +555,8 @@ should_throttle()
bool
BeesScanModeExtent::crawl_one_extent(const BeesScanModeExtent::ExtentRef &bior)
{
BEESTRACE("crawl_one_extent " << bior);
auto inode_mutex = m_ctx->get_inode_mutex(bior.m_inum);
auto inode_lock = inode_mutex->try_lock(Task::current_task());
if (!inode_lock) {
@ -715,6 +717,8 @@ BeesScanModeExtent::create_extent_map(const uint64_t bytenr, const ProgressTrack
void
BeesScanModeExtent::init_tasks()
{
BEESTRACE("init_tasks");
// Make sure all the magic crawlers are inserted in m_crawl_map,
// and each one has a Task
unique_lock<mutex> lock_insert_root(m_insert_root_mutex);
@ -722,7 +726,7 @@ BeesScanModeExtent::init_tasks()
for (const auto &i : s_magic_crawl_map) {
const auto subvol = i.first;
const auto &magic = i.second;
auto found = m_crawl_map.find(subvol);
const auto found = m_crawl_map.find(subvol);
if (found == m_crawl_map.end()) {
lock.unlock();
BeesCrawlState new_bcs;
@ -751,6 +755,8 @@ BeesScanModeExtent::init_tasks()
void
BeesScanModeExtent::scan()
{
BEESTRACE("bsm scan");
if (should_throttle()) return;
unique_lock<mutex> lock(m_mutex);
@ -779,7 +785,8 @@ BeesScanModeExtent::map_next_extent(uint64_t const subvol)
Timer crawl_time;
unique_lock<mutex> lock(m_mutex);
auto found = m_crawl_map.find(subvol);
const auto found = m_crawl_map.find(subvol);
assert(found != m_crawl_map.end());
THROW_CHECK0(runtime_error, found != m_crawl_map.end());
CrawlMap::mapped_type this_crawl = found->second;
lock.unlock();
@ -901,10 +908,13 @@ BeesScanModeExtent::map_next_extent(uint64_t const subvol)
}
void
BeesScanModeExtent::next_transid(const CrawlMap &crawl_map)
BeesScanModeExtent::next_transid(const CrawlMap &crawl_map_unused)
{
BEESTRACE("Extent next_transid");
// We maintain our own crawl map
(void)crawl_map_unused;
// Do the important parts first, the rest can return early or die with an exception
// Can't set this up in the constructor because shared_from_this is a method on a
@ -913,25 +923,22 @@ BeesScanModeExtent::next_transid(const CrawlMap &crawl_map)
// insert_root does this for non-magic subvols, we have to do it ourselves
map<uint64_t,pair<bool,bool>> deferred_map;
for (const auto &i : s_magic_crawl_map) {
const auto subvol = i.first;
const auto found = crawl_map.find(subvol);
if (found != crawl_map.end()) {
// Have to save these for the progress table
deferred_map.insert(make_pair(subvol, make_pair(found->second->deferred(), found->second->finished())));
found->second->deferred(false);
{
unique_lock<mutex> lock(m_mutex);
for (const auto &i : s_magic_crawl_map) {
const auto subvol = i.first;
const auto found = m_crawl_map.find(subvol);
if (found != m_crawl_map.end()) {
// Have to save these for the progress table
deferred_map.insert(make_pair(subvol, make_pair(found->second->deferred(), found->second->finished())));
found->second->deferred(false);
}
}
}
// Kick off tasks if they aren't already running
start_scan();
// Swap in the new crawl map with freshly undeferred crawlers
auto crawl_map_copy = crawl_map;
unique_lock<mutex> lock(m_mutex);
swap(m_crawl_map, crawl_map_copy);
lock.unlock();
// Estimate progress by building a map of where the extent bytenrs are (they are sparse,
// no extents exist between block groups), and report the position within that map.
@ -972,9 +979,10 @@ BeesScanModeExtent::next_transid(const CrawlMap &crawl_map)
return;
}
// Grab a copy of the extent size statistics so we can use it without it changing under us
lock.lock();
// Grab a copy of members
unique_lock<mutex> lock(m_mutex);
const auto mes = m_extent_size;
const auto cmc = m_crawl_map;
// Decay the extent size map averages
static const double decay = .99;
@ -991,8 +999,9 @@ BeesScanModeExtent::next_transid(const CrawlMap &crawl_map)
const auto &subvol = i.first;
const auto &magic = i.second;
const auto found = crawl_map.find(subvol);
if (found == crawl_map.end()) {
const auto found = cmc.find(subvol);
THROW_CHECK1(runtime_error, subvol, found != cmc.end());
if (found == cmc.end()) {
// BEESLOGDEBUG("PROGRESS: crawler not yet created for " << magic);
BEESCOUNT(progress_not_created);
continue;