Cachefilesd

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Cachefilesd

Check if kernel supports filesystem cache for your filesystem type

# grep  "CONFIG_.*_FSCACHE" /boot/config-`uname -r`
CONFIG_NFS_FSCACHE=y
CONFIG_CEPH_FSCACHE=y
CONFIG_CIFS_FSCACHE=y
CONFIG_AFS_FSCACHE=y
CONFIG_9P_FSCACHE=y

Setup /etc/cachefilesd.conf

###############################################################################
#
# Copyright (C) 2006,2010 Red Hat, Inc. All Rights Reserved.
# Written by David Howells (dhowells@redhat.com)
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version
# 2 of the License, or (at your option) any later version.
#
###############################################################################

#dir /media/ramdisk
dir /var/cache/fscache
secctx cachefiles_kernel_t
tag mycache
debug 1
brun 10%
bcull 7%
bstop 3%
frun 10%
fcull 7%
fstop 3%

# Assuming you're using SELinux with the default security policy included in
# this package
# secctx system_u:system_r:cachefiles_kernel_t:s0

Problems with autofs mounted filesystems

Make sure it is started by systemd

Disable the SYSV way of starting

# update-rc.d cachefilesd disable

Make cachefilesd started by systemd

# systemctl edit --force --full cachefilesd.service
[Unit]
Documentation=man:cachefilesd
Description=LSB: CacheFiles daemon
After=remote-fs.target
Before=autofs.service

[Service]
Type=simple
Restart=no
TimeoutSec=5min
IgnoreSIGPIPE=no
KillMode=process
GuessMainPID=no
RemainAfterExit=yes
SuccessExitStatus=5 6
RuntimeDirectory=cachefilesd
ExecStartPre=-/sbin/modprobe -qab cachefiles
ExecStart=/sbin/cachefilesd -n -p /run/cachefilesd/cachefilesd.pid

[Install]
WantedBy=multi-user.target

Enable starting new service

# systemctl enable cachefilesd.service

Verify autofs is depending on cachefilesd.service

# systemctl show -p After,Before autofs.service | grep cachefilesd.service
After=cachefilesd.service network.target network-online.target sysinit.target ypbind.service basic.target system.slice sssd.service systemd-journald.socket remote-fs.target

Define a cached CIFS share with autofs

Install needed packages

# apt install cachefilesd autofs cifs-utils

Create the credentials file

# mkdir --mode=0700 /etc/cifs_cred
# touch /etc/cifs_cred/credentials
# chmod 0600 /etc/cifs_cred/credentials
# cat > /etc/cifs_cred/credentials <<EOF
username=myuser
password=mypass
EOF

Create basedir of your cifs mounts

# mkdir --mode=0755 /data/cifs

/etc/auto.master

...
/data/cifs /etc/auto.cifs-shares --timeout=0 --ghost
...

/etc/auto.cifs-shares

The option Template:Strong enables caching:

myshare -fstype=cifs,credentials=/etc/cifs_cred/credentials,nounix,file_mode=0644,vers=3.0,dir_mode=0755,noperm,fsc ://cifsserver.my.dom/the_cifs_share

Check if things are getting cached

Initially there is nothing in the cache (almost all values are zero):

# cat /proc/fs/fscache/stats
FS-Cache statistics
Cookies: idx=2 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=2 nul=0 noc=0 ok=2 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
CacheEv: nsp=0 stl=0 rtr=0 cul=0

but after a few requests:

# cat /proc/fs/fscache/stats
FS-Cache statistics
Cookies: idx=3 dat=77 spc=0
Objects: alc=80 nal=0 avl=80 ded=70
ChkAux : non=0 ok=1 upd=0 obs=1
Pages  : mrk=3138215 unc=181438
Acquire: n=150 nul=0 noc=0 ok=80 nbf=0 oom=0
Lookups: n=80 neg=78 pos=2 crt=78 tmo=0
Invals : n=0 run=0
Updates: n=0 nul=0 run=0
Relinqs: n=70 nul=0 wcr=0 rtr=70
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=72447 ok=0 wt=6 nod=72447 nbf=0 int=0 oom=0
Retrvls: ops=72447 owt=15 abt=0
Stores : n=3136954 ok=3136954 agn=0 nbf=0 oom=0
Stores : ops=67042 run=3203996 pgs=3136954 rxd=3136954 olm=0
VmScan : nos=180177 gon=0 bsy=0 can=0 wt=0
Ops    : pend=15 run=139489 enq=3203996 can=0 rej=0
Ops    : ini=3209401 dfr=266 rel=3209401 gc=266
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=1 stl=0 rtr=0 cul=0