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resolve: add bees.h constants for balance and logical_ino serialization

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Make these workarounds configurable in src/bees.h instead of #if 0
code blocks.  Someday we'll make the constants in bees.h configurable
through a file or similar.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This commit is contained in:
Zygo Blaxell 2020-11-15 17:49:44 -05:00
parent c0149d72b7
commit 636e69267e
2 changed files with 20 additions and 6 deletions
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20
src/bees-context.cc
View File

@ -803,6 +803,10 @@ BeesResolveAddrResult::BeesResolveAddrResult()
void
BeesContext::wait_for_balance()
{
if (!BEES_SERIALIZE_BALANCE) {
return;
}
Timer balance_timer;
BEESNOTE("WORKAROUND: waiting for balance to stop");
while (true) {
@ -845,17 +849,21 @@ BeesContext::resolve_addr_uncached(BeesAddress addr)
// transaction latency, competing threads, and freeze/SIGSTOP
// pausing the bees process.
#if 0
// There can be only one of these running at a time, or the slow
// backrefs bug will kill the whole system. Also it looks like there
// There can be only one of these running at a time, or some lingering
// backref bug will kill the whole system. Also it looks like there
// are so many locks held while LOGICAL_INO runs that there is no
// point in trying to run two of them on the same filesystem.
// ...but it works most of the time, and the performance hit from
// not running resolve in multiple threads is significant.
BEESNOTE("waiting to resolve addr " << addr);
// But "most of the time" really just means "between forced reboots",
// and with recent improvements in kernel uptime, this is now in the
// top 3 crash causes.
static mutex s_resolve_mutex;
unique_lock<mutex> lock(s_resolve_mutex);
#endif
unique_lock<mutex> lock(s_resolve_mutex, defer_lock);
if (BEES_SERIALIZE_RESOLVE) {
BEESNOTE("waiting to resolve addr " << addr);
lock.lock();
}
// Is there a bug where resolve and balance cause a crash (BUG_ON at fs/btrfs/ctree.c:1227)?
// Apparently yes, and more than one.

6
src/bees.h
View File

@ -116,6 +116,12 @@ const size_t BEES_TRANSID_FACTOR = 10;
// Wait this long for a balance to stop
const double BEES_BALANCE_POLL_INTERVAL = 60.0;
// Workaround for backref bugs
const bool BEES_SERIALIZE_RESOLVE = false;
// Workaround for tree mod log bugs
const bool BEES_SERIALIZE_BALANCE = false;
// Flags
const int FLAGS_OPEN_COMMON = O_NOFOLLOW | O_NONBLOCK | O_CLOEXEC | O_NOATIME | O_LARGEFILE | O_NOCTTY;
const int FLAGS_OPEN_DIR = FLAGS_OPEN_COMMON | O_RDONLY | O_DIRECTORY;