add support for tuning healing to make healing more aggressive (#11003)

supports `mc admin config set <alias> heal sleep=100ms` to
enable more aggressive healing under certain times.

also optimize some areas that were doing extra checks than
necessary when bitrotscan was enabled, avoid double sleeps
make healing more predictable.

fixes #10497

cmd/fs-v1.go

@@ -55,8 +55,6 @@ type FSObjects struct {
 
 	// The count of concurrent calls on FSObjects API
 	activeIOCount int64
-	// The active IO count ceiling for crawling to work
-	maxActiveIOCount int64
 
 	// Path to be exported over S3 API.
 	fsPath string
@@ -168,8 +166,6 @@ func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
 		listPool:      NewTreeWalkPool(globalLookupTimeout),
 		appendFileMap: make(map[string]*fsAppendFile),
 		diskMount:     mountinfo.IsLikelyMountPoint(fsPath),
-
-		maxActiveIOCount: 10,
 	}
 
 	// Once the filesystem has initialized hold the read lock for
@@ -230,12 +226,6 @@ func (fs *FSObjects) StorageInfo(ctx context.Context, _ bool) (StorageInfo, []er
 	return storageInfo, nil
 }
 
-func (fs *FSObjects) waitForLowActiveIO() {
-	for atomic.LoadInt64(&fs.activeIOCount) >= fs.maxActiveIOCount {
-		time.Sleep(lowActiveIOWaitTick)
-	}
-}
-
 // CrawlAndGetDataUsage returns data usage stats of the current FS deployment
 func (fs *FSObjects) CrawlAndGetDataUsage(ctx context.Context, bf *bloomFilter, updates chan<- DataUsageInfo) error {
 	// Load bucket totals