diff --git a/src/libfs/write.c b/src/libfs/write.c
index 5652b49..bae2083 100644
--- a/src/libfs/write.c
+++ b/src/libfs/write.c
@@ -7,8 +7,8 @@
 #include <fs.h>
 #include "fsimpl.h"
 
-long
-fspwrite(Fid *fid, void *buf, long n, vlong offset)
+static long
+_fspwrite(Fid *fid, void *buf, long n, vlong offset)
 {
 	Fcall tx, rx;
 	void *freep;
@@ -40,6 +40,31 @@
 }
 
 long
+fspwrite(Fid *fid, void *buf, long n, vlong offset)
+{
+	long tot, want, got;
+	uint msize;
+
+	msize = fid->fs->msize - IOHDRSZ;
+	tot = 0;
+	while(tot < n){
+		want = n - tot;
+		if(want > msize)
+			want = msize;
+		got = _fspwrite(fid, buf, want, offset);
+		if(got < 0){
+			if(tot == 0)
+				return got;
+			break;
+		}
+		tot += got;
+		if(offset != -1)
+			offset += got;
+	}
+	return tot;
+}
+
+long
 fswrite(Fid *fid, void *buf, long n)
 {
 	return fspwrite(fid, buf, n, -1);