[$] A filesystem "change journal" and other topics

At the 2017 Linux Storage, Filesystem, and Memory-Management Summit(LSFMM), Amir Goldstein presented his workon adding a superblock watch mechanism to provide a scalable way to notifyapplicationsof changes in a filesystem. At the 2018 edition of LSFMM, he was back todiscuss adding NTFS-like changejournals to the kernel in support of backup solutions of varioussorts. As a second topic for the session, he also wanted to discuss doingmore performance-regression testing for filesystems.