diff --git a/blocks/blockstore/blockstore.go b/blocks/blockstore/blockstore.go
index bc000df93..59f0f2c72 100644
--- a/blocks/blockstore/blockstore.go
+++ b/blocks/blockstore/blockstore.go
@@ -5,6 +5,7 @@ package blockstore
 import (
 	"errors"
 	"sync"
+	"sync/atomic"
 
 	ds "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore"
 	dsns "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/namespace"
@@ -49,6 +50,10 @@ type GCBlockstore interface {
 	// at the same time, but no GC should not happen simulatenously.
 	// Reading during Pinning is safe, and requires no lock.
 	PinLock() func()
+
+	// GcRequested returns true if GCLock has been called and is waiting to
+	// take the lock
+	GCRequested() bool
 }
 
 func NewBlockstore(d ds.Batching) *blockstore {
@@ -63,7 +68,9 @@ func NewBlockstore(d ds.Batching) *blockstore {
 type blockstore struct {
 	datastore ds.Batching
 
-	lk sync.RWMutex
+	lk      sync.RWMutex
+	gcreq   int32
+	gcreqlk sync.Mutex
 }
 
 func (bs *blockstore) Get(k key.Key) (*blocks.Block, error) {
@@ -192,7 +199,9 @@ func (bs *blockstore) AllKeysChan(ctx context.Context) (<-chan key.Key, error) {
 }
 
 func (bs *blockstore) GCLock() func() {
+	atomic.AddInt32(&bs.gcreq, 1)
 	bs.lk.Lock()
+	atomic.AddInt32(&bs.gcreq, -1)
 	return bs.lk.Unlock
 }
 
@@ -200,3 +209,7 @@ func (bs *blockstore) PinLock() func() {
 	bs.lk.RLock()
 	return bs.lk.RUnlock
 }
+
+func (bs *blockstore) GCRequested() bool {
+	return atomic.LoadInt32(&bs.gcreq) > 0
+}
diff --git a/blocks/blockstore/write_cache.go b/blocks/blockstore/write_cache.go
index 52af696e4..73a7813f5 100644
--- a/blocks/blockstore/write_cache.go
+++ b/blocks/blockstore/write_cache.go
@@ -66,3 +66,7 @@ func (w *writecache) GCLock() func() {
 func (w *writecache) PinLock() func() {
 	return w.blockstore.(GCBlockstore).PinLock()
 }
+
+func (w *writecache) GCRequested() bool {
+	return w.blockstore.(GCBlockstore).GCRequested()
+}
diff --git a/core/coreunix/add.go b/core/coreunix/add.go
index 6ca989b26..80a4bb6ad 100644
--- a/core/coreunix/add.go
+++ b/core/coreunix/add.go
@@ -12,6 +12,7 @@ import (
 	syncds "github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-datastore/sync"
 	context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
 	bstore "github.com/ipfs/go-ipfs/blocks/blockstore"
+	key "github.com/ipfs/go-ipfs/blocks/key"
 	bserv "github.com/ipfs/go-ipfs/blockservice"
 	"github.com/ipfs/go-ipfs/exchange/offline"
 	importer "github.com/ipfs/go-ipfs/importer"
@@ -99,6 +100,8 @@ type Adder struct {
 	Chunker  string
 	root     *dag.Node
 	mr       *mfs.Root
+	unlock   func()
+	tempRoot key.Key
 }
 
 // Perform the actual add & pin locally, outputting results to reader
@@ -157,6 +160,14 @@ func (params *Adder) PinRoot() error {
 		return err
 	}
 
+	if params.tempRoot != "" {
+		err := params.node.Pinning.Unpin(params.ctx, params.tempRoot, true)
+		if err != nil {
+			return err
+		}
+		params.tempRoot = rnk
+	}
+
 	params.node.Pinning.PinWithMode(rnk, pin.Recursive)
 	return params.node.Pinning.Flush()
 }
@@ -256,7 +267,7 @@ func AddR(n *core.IpfsNode, root string) (key string, err error) {
 		return "", err
 	}
 
-	err = fileAdder.AddFile(f)
+	err = fileAdder.addFile(f)
 	if err != nil {
 		return "", err
 	}
@@ -289,7 +300,7 @@ func AddWrapped(n *core.IpfsNode, r io.Reader, filename string) (string, *dag.No
 	unlock := n.Blockstore.PinLock()
 	defer unlock()
 
-	err = fileAdder.AddFile(file)
+	err = fileAdder.addFile(file)
 	if err != nil {
 		return "", nil, err
 	}
@@ -330,12 +341,24 @@ func (params *Adder) addNode(node *dag.Node, path string) error {
 
 // Add the given file while respecting the params.
 func (params *Adder) AddFile(file files.File) error {
+	params.unlock = params.node.Blockstore.PinLock()
+	defer params.unlock()
+
+	return params.addFile(file)
+}
+
+func (adder *Adder) addFile(file files.File) error {
+	err := adder.maybePauseForGC()
+	if err != nil {
+		return err
+	}
+
 	switch {
-	case files.IsHidden(file) && !params.Hidden:
+	case files.IsHidden(file) && !adder.Hidden:
 		log.Debugf("%s is hidden, skipping", file.FileName())
 		return &hiddenFileError{file.FileName()}
 	case file.IsDirectory():
-		return params.addDir(file)
+		return adder.addDir(file)
 	}
 
 	// case for symlink
@@ -346,29 +369,29 @@ func (params *Adder) AddFile(file files.File) error {
 		}
 
 		dagnode := &dag.Node{Data: sdata}
-		_, err = params.node.DAG.Add(dagnode)
+		_, err = adder.node.DAG.Add(dagnode)
 		if err != nil {
 			return err
 		}
 
-		return params.addNode(dagnode, s.FileName())
+		return adder.addNode(dagnode, s.FileName())
 	}
 
 	// case for regular file
 	// if the progress flag was specified, wrap the file so that we can send
 	// progress updates to the client (over the output channel)
 	var reader io.Reader = file
-	if params.Progress {
-		reader = &progressReader{file: file, out: params.out}
+	if adder.Progress {
+		reader = &progressReader{file: file, out: adder.out}
 	}
 
-	dagnode, err := params.add(reader)
+	dagnode, err := adder.add(reader)
 	if err != nil {
 		return err
 	}
 
 	// patch it into the root
-	return params.addNode(dagnode, file.FileName())
+	return adder.addNode(dagnode, file.FileName())
 }
 
 func (params *Adder) addDir(dir files.File) error {
@@ -388,7 +411,7 @@ func (params *Adder) addDir(dir files.File) error {
 			break
 		}
 
-		err = params.AddFile(file)
+		err = params.addFile(file)
 		if _, ok := err.(*hiddenFileError); ok {
 			// hidden file error, skip file
 			continue
@@ -400,6 +423,19 @@ func (params *Adder) addDir(dir files.File) error {
 	return nil
 }
 
+func (adder *Adder) maybePauseForGC() error {
+	if adder.node.Blockstore.GCRequested() {
+		err := adder.PinRoot()
+		if err != nil {
+			return err
+		}
+
+		adder.unlock()
+		adder.unlock = adder.node.Blockstore.PinLock()
+	}
+	return nil
+}
+
 // outputDagnode sends dagnode info over the output channel
 func outputDagnode(out chan interface{}, name string, dn *dag.Node) error {
 	if out == nil {
diff --git a/pin/gc/gc.go b/pin/gc/gc.go
index ec61f816a..df9ddedc6 100644
--- a/pin/gc/gc.go
+++ b/pin/gc/gc.go
@@ -24,7 +24,6 @@ var log = logging.Logger("gc")
 // deletes any block that is not found in the marked set.
 func GC(ctx context.Context, bs bstore.GCBlockstore, pn pin.Pinner) (<-chan key.Key, error) {
 	unlock := bs.GCLock()
-	defer unlock()
 
 	bsrv := bserv.New(bs, offline.Exchange(bs))
 	ds := dag.NewDAGService(bsrv)
@@ -42,6 +41,7 @@ func GC(ctx context.Context, bs bstore.GCBlockstore, pn pin.Pinner) (<-chan key.
 	output := make(chan key.Key)
 	go func() {
 		defer close(output)
+		defer unlock()
 		for {
 			select {
 			case k, ok := <-keychan: