Comment 8 for bug 1821395

Regression testing setup/steps
===

fscache
-------

sudo apt-get -y install cachefilesd
echo 'RUN=yes' | sudo tee -a /etc/default/cachefilesd
sudo modprobe fscache
sudo systemctl start cachefilesd

nfs
---

sudo apt-get -y install nfs-kernel-server
sudo systemctl start nfs-kernel-server

sudo mkdir -p /{srv,mnt}/nfs-{test,scratch}

# different fsid if in the same local filesystem
echo '/srv/nfs-test 127.0.0.1(rw,no_subtree_check,no_root_squash,fsid=0)' | sudo tee -a /etc/exports
echo '/srv/nfs-scratch 127.0.0.1(rw,no_subtree_check,no_root_squash,fsid=1)' | sudo tee -a /etc/exports
sudo exportfs -ra

xfs-tests
---------

sudo apt-get -y install automake gcc make git xfsprogs xfslibs-dev \
  uuid-dev uuid-runtime libtool-bin e2fsprogs libuuid1 attr libattr1-dev \
  libacl1-dev libaio-dev libgdbm-dev quota gawk fio dbench python sqlite3

git clone https://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git
cd xfstests-dev

git log --oneline -1 HEAD
  f3c1bca generic: Test that SEEK_HOLE can find a punched hole

make -j$(nproc); echo $? # must be 0

sudo useradd fsgqa
sudo groupadd fsgqa
sudo useradd 123456-fsgqa

export TEST_DEV=127.0.0.1:/srv/nfs-test
export TEST_DIR=/mnt/nfs-test

export SCRATCH_DEV=127.0.0.1:/srv/nfs-scratch
export SCRATCH_MNT=/mnt/nfs-scratch

export TEST_FS_MOUNT_OPTS="-o fsc" # for fscache / test dev
export NFS_MOUNT_OPTIONS="-o fsc" # for fscache / scratch dev

cd ~/xfstests-dev
sudo -E ./check -nfs -g quick 2>&1 | tee ~/xfs-tests.nfs.log.$(uname -r)
<...>

---

In another terminal, check the NFS mounts are indeed with the 'fsc' (fscache) attribute:

$ mount | grep nfs | grep fsc
127.0.0.1:/srv/nfs-test on /mnt/nfs-test type nfs4 (rw,relatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=127.0.0.1,fsc,local_lock=none,addr=127.0.0.1)
127.0.0.1:/srv/nfs-scratch on /mnt/nfs-scratch type nfs4 (rw,relatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=127.0.0.1,fsc,local_lock=none,addr=127.0.0.1)

And compare fscache stats before/after run:

$ cat /proc/fs/fscache/stats
FS-Cache statistics
Cookies: idx=0 dat=0 spc=0
Objects: alc=0 nal=0 avl=0 ded=0
ChkAux : non=0 ok=0 upd=0 obs=0
Pages : mrk=0 unc=0
Acquire: n=0 nul=0 noc=0 ok=0 nbf=0 oom=0
Lookups: n=0 neg=0 pos=0 crt=0 tmo=0
Invals : n=0 run=0
Updates: n=0 nul=0 run=0
Relinqs: n=0 nul=0 wcr=0 rtr=0
AttrChg: n=0 ok=0 nbf=0 oom=0 run=0
Allocs : n=0 ok=0 wt=0 nbf=0 int=0
Allocs : ops=0 owt=0 abt=0
Retrvls: n=0 ok=0 wt=0 nod=0 nbf=0 int=0 oom=0
Retrvls: ops=0 owt=0 abt=0
Stores : n=0 ok=0 agn=0 nbf=0 oom=0
Stores : ops=0 run=0 pgs=0 rxd=0 olm=0
VmScan : nos=0 gon=0 bsy=0 can=0 wt=0
Ops : pend=0 run=0 enq=0 can=0 rej=0
Ops : ini=0 dfr=0 rel=0 gc=0
CacheOp: alo=0 luo=0 luc=0 gro=0
CacheOp: inv=0 upo=0 dro=0 pto=0 atc=0 syn=0
CacheOp: rap=0 ras=0 alp=0 als=0 wrp=0 ucp=0 dsp=0

...

$ cat /proc/fs/fscache/stats
FS-Cache statistics
Cookies: idx=412 dat=2441632 spc=0
Objects: alc=8929 nal=0 avl=8741 ded=8928
ChkAux : non=0 ok=86 upd=0 obs=1123
Pages : mrk=371441 unc=371441
Acquire: n=2442044 nul=0 noc=0 ok=2442044 nbf=0 oom=0
Lookups: n=8929 neg=8817 pos=112 crt=8817 tmo=0
Invals : n=152 run=152
Updates: n=0 nul=0 run=152
Relinqs: n=2442044 nul=0 wcr=0 rtr=0
AttrChg: n=0 ok=0 nbf=0 oom=0 run=0
Allocs : n=0 ok=0 wt=0 nbf=0 int=0
Allocs : ops=0 owt=0 abt=0
Retrvls: n=1498 ok=0 wt=195 nod=1498 nbf=0 int=0 oom=0
Retrvls: ops=1498 owt=575 abt=0
Stores : n=371145 ok=371145 agn=0 nbf=0 oom=0
Stores : ops=1117 run=372234 pgs=371118 rxd=371118 olm=0
VmScan : nos=49 gon=0 bsy=0 can=0 wt=0
Ops : pend=575 run=2767 enq=372387 can=0 rej=0
Ops : ini=372795 dfr=37 rel=372795 gc=37
CacheOp: alo=0 luo=0 luc=0 gro=0
CacheOp: inv=0 upo=0 dro=0 pto=0 atc=0 syn=0
CacheOp: rap=0 ras=0 alp=0 als=0 wrp=0 ucp=0 dsp=0
CacheEv: nsp=1123 stl=0 rtr=0 cul=0

---

Note, in 4.15.0 kernels, some tests apparently run forever:
generic/430, 431 and 434 (same behavior in nfs+fscache, ext4, xfs),
they were killed with 'sudo kill -TERM $(pidof xfs_io)'.

# ref: https://wiki.linux-nfs.org/wiki/index.php/Xfstests