fix: improve mount quota enforcement to prevent overflow (#7804)

* fix: improve mount quota enforcement to prevent overflow (fixes seaweedfs-csi-driver#218)

* test: add unit tests for quota enforcement

weed/mount/weedfs_symlink.go

@@ -17,7 +17,7 @@ import (
 /** Create a symbolic link */
 func (wfs *WFS) Symlink(cancel <-chan struct{}, header *fuse.InHeader, target string, name string, out *fuse.EntryOut) (code fuse.Status) {
 
-	if wfs.IsOverQuota {
+	if wfs.IsOverQuotaWithUncommitted() {
 		return fuse.Status(syscall.ENOSPC)
 	}
 	if s := checkName(name); s != fuse.OK {