I don't know why this keeps happening but I run a program that is constantly creating and removing small files and occasionally the rm would hang. I then switched to using mv since I noticed it ran a lot faster but same problem. See the following screenshot for an actual example. Note no other process has that file locked or opened. But if I touch the file, then it "unsticks" the rm/mv command and it runs instantly. The /mnt/ramdisk/ (despite the name) is just a 8GB hdd (/dev/sdc1), as shown below.
$ df /mnt/ramdisk5Filesystem 1K-blocks Used Available Use% Mounted on/dev/sdc1 8152540 2022108 5694720 27% /mnt/ramdisk5$ df -i /mnt/ramdisk5Filesystem Inodes IUsed IFree IUse% Mounted on/dev/sdc1 524288 191565 332723 37% /mnt/ramdisk5