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Merge pull request #13653 from rzarzynski/wip-bs-bitmap-fast-exhausted-check

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os/bluestore: the exhausted check in BitMapZone can be lock-less.

Reviewed-by: Sage Weil <sage@redhat.com>
This commit is contained in:
Kefu Chai 2017-02-27 17:44:18 +08:00 committed by GitHub
commit 2db2f05535
1 changed files with 8 additions and 6 deletions
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14
src/os/bluestore/BitAllocator.cc
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@ -421,7 +421,7 @@ BitMapZone::~BitMapZone()
*/
bool BitMapZone::is_exhausted()
{
alloc_assert(check_locked());
/* BitMapZone::get_used_blocks operates atomically. No need for lock. */
return get_used_blocks() == size();
}
@ -1098,14 +1098,16 @@ BitMapAreaLeaf::~BitMapAreaLeaf()
bool BitMapAreaLeaf::child_check_n_lock(BitMapArea *child, int64_t required, bool lock)
{
if (lock) {
child->lock_excl();
} else if (!child->lock_excl_try()) {
/* The exhausted check can be performed without acquiring the lock. This
* is because 1) BitMapZone::is_exhausted() actually operates atomically
* and 2) it's followed by the exclusive, required-aware re-verification. */
if (child->is_exhausted()) {
return false;
}
if (child->is_exhausted()) {
child->unlock();
if (lock) {
child->lock_excl();
} else if (!child->lock_excl_try()) {
return false;
}