On Tue, May 12, 2020 at 4:29 AM Eryu Guan <eguan@xxxxxxxxxxxxxxxxx> wrote: > > Under writeback mode, inode->i_blocks is not updated, making utils du > read st.blocks as 0. > > For example, when using virtiofs (cache=always & nondax mode) with > writeback_cache enabled, writing a new file and check its disk usage > with du, du reports 0 usage. > > # uname -r > 5.6.0-rc6+ > # mount -t virtiofs virtiofs /mnt/virtiofs > # rm -f /mnt/virtiofs/testfile > > # create new file and do extend write > # xfs_io -fc "pwrite 0 4k" /mnt/virtiofs/testfile > wrote 4096/4096 bytes at offset 0 > 4 KiB, 1 ops; 0.0001 sec (28.103 MiB/sec and 7194.2446 ops/sec) > # du -k /mnt/virtiofs/testfile > 0 <==== disk usage is 0 > # stat -c %s,%b /mnt/virtiofs/testfile > 4096,0 <==== i_size is correct, but st_blocks is 0 > > Fix it by invalidating attr in fuse_flush(), so we get up-to-date attr > from server on next getattr. Thanks, applied. I started thinking: why is fuse_flush() only writing out dirty pages if fc->no_flush is false? It just doesn't make sense... But that's an independent bug, and I'll do a separate patch for that. Thanks, Miklos
