I am trying to replicate the setup described below, (from: https://www.spinics.net/lists/linux-unionfs/msg07098.html ) which implies a successful mount, but all of my attempts error with: mount: /e/merged: wrong fs type, bad option, bad superblock on overlay, missing codepage or helper program, or other error. [ 3640.328337] overlayfs: upper fs does not support tmpfile. [ 3640.333245] overlayfs: upper fs does not support RENAME_WHITEOUT. [ 3640.333266] overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off. [ 3640.333281] overlayfs: upper fs missing required features. script and output: #!/bin/bash -x for x in a b c d e do umount /$x/merged umount /$x/lower rm -rf /$x mkdir /$x /$x/lower /$x/upper /$x/work /$x/merged done mount -t nfs -o vers=3,ro,noatime 10.21.0.1:/srv/nfs/rpi/buster/root/merged /a/lower mount -t overlay -o lowerdir=/a/lower,upperdir=/a/upper,workdir=/a/work,default_permissions overlay /a/merged mount -t nfs -o ro,noatime 10.21.0.1:/srv/nfs/rpi/buster/root/merged /b/lower mount -t overlay -o lowerdir=/b/lower,upperdir=/b/upper,workdir=/b/work,default_permissions overlay /b/merged mount -t nfs -o vers=4.1,ro,noatime 10.21.0.1:/srv/nfs/rpi/buster/root/merged /c/lower mount -t overlay -o lowerdir=/c/lower,upperdir=/c/upper,workdir=/c/work,default_permissions overlay /c/merged mount -t nfs -o vers=3,ro,noatime,noacl 10.21.0.1:/srv/nfs/rpi/buster/root/merged /d/lower mount -t overlay -o lowerdir=/d/lower,upperdir=/d/upper,workdir=/d/work,default_permissions overlay /d/merged mount -t nfs -o ro,noatime,noacl 10.21.0.1:/srv/nfs/rpi/buster/root/merged /e/lower mount -t overlay -o vers=4.1,noacl,noatime,lowerdir=/e/lower,upperdir=/e/upper,workdir=/e/work,default_permissions overlay /e/merged + for x in a b c d e + umount /a/merged umount.nfs: remote share not in 'host:dir' format umount.nfs: /a/merged: not mounted + umount /a/lower + rm -rf /a + mkdir /a /a/lower /a/upper /a/work /a/merged (repeat 5 times) + mount -t nfs -o vers=3,ro,noatime 10.21.0.1:/srv/nfs/rpi/buster/root/merged /a/lower + mount -t overlay -o lowerdir=/a/lower,upperdir=/a/upper,workdir=/a/work,default_permissions overlay /a/merged mount: /a/merged: wrong fs type, bad option, bad superblock on overlay, missing codepage or helper program, or other error. + mount -t nfs -o ro,noatime 10.21.0.1:/srv/nfs/rpi/buster/root/merged /b/lower + mount -t overlay -o lowerdir=/b/lower,upperdir=/b/upper,workdir=/b/work,default_permissions overlay /b/merged mount: /b/merged: wrong fs type, bad option, bad superblock on overlay, missing codepage or helper program, or other error. + mount -t nfs -o vers=4.1,ro,noatime 10.21.0.1:/srv/nfs/rpi/buster/root/merged /c/lower + mount -t overlay -o lowerdir=/c/lower,upperdir=/c/upper,workdir=/c/work,default_permissions overlay /c/merged mount: /c/merged: wrong fs type, bad option, bad superblock on overlay, missing codepage or helper program, or other error. + mount -t nfs -o vers=3,ro,noatime,noacl 10.21.0.1:/srv/nfs/rpi/buster/root/merged /d/lower + mount -t overlay -o lowerdir=/d/lower,upperdir=/d/upper,workdir=/d/work,default_permissions overlay /d/merged mount: /d/merged: wrong fs type, bad option, bad superblock on overlay, missing codepage or helper program, or other error. + mount -t nfs -o ro,noatime,noacl 10.21.0.1:/srv/nfs/rpi/buster/root/merged /e/lower + mount -t overlay -o vers=4.1,noacl,noatime,lowerdir=/e/lower,upperdir=/e/upper,workdir=/e/work,default_permissions overlay /e/merged mount: /e/merged: wrong fs type, bad option, bad superblock on overlay, missing codepage or helper program, or other error. > Hi, > > I'm using overlayfs with NFS v3 as a lower (mounted read-only) and a > tmpfs as an upper filesystem. This works nicely since several years. > So I get a writeable directory tree on an nfs client even the nfs was > mounted ro. > > But then I mount the lower filesystem as NFS v4 (4.2) it does not > work. Is this combination supposed to work? > I tested this with kernels up to 5.2 yet but still no success. > > > Here's my current test setup: > > NFS server kernel 5.2.0-0.bpo.2-amd64 (Debian 10 with newer kernel) > NFS client kernel 5.2.0-0.bpo.2-amd64 (Debian 10 with newer kernel) > > On the NFS server I did once > # mkdir /files/scratch/t/etc; echo test-buster > /files/scratch/t/etc/test1 > > /etc/exports: /files/scratch 11.22.33.128/25(async,ro,no_subtree_check,no_root_squash) > > I can do more tests if you tell me what I can change. > Here are the two tests result, one using nfs v3 the other using NFS v4. > > P.S.: After more research I think this may be a problem of a > filesystem missing xattr support. Do you have any experiences > using overlayfs using NFS v4 as lower fs? > > Any hints would be appreciated. > > regards Thomas > > > > > > > NFS v3 mount > ============ > Result: read and write works > > > + mkdir -p /b/lower /a/upper /a/work /b/merged > + mount -t nfs -overs=3,ro,noatime buster:/files/scratch/t /b/lower > mount -t overlay -olowerdir=$lower,upperdir=$upper,workdir=$work,default_permissions overlay $merged || exit 88 > + cat /b/merged/etc/test1 > test-buster > + sleep 3 > echo "write to merged" > $merged/etc/test1 > + echo 'write to merged' > + sleep 3 > echo "write new file" > $merged/etc/test3 > + echo 'write new file' > > both files test1 and test3 exists with corect content. > > Here's the journalctl output of the overlayfs debug messages: > Sep 16 13:45:04 suenner kernel: overlay: mkdir(work/work, 040000) = 0 > Sep 16 13:45:04 suenner kernel: overlay: tmpfile(work/work, 0100000) = 0 > Sep 16 13:45:04 suenner kernel: overlay: setxattr(work/work, "trusted.overlay.opaque", "0", 1, 0x0) = 0 > Sep 16 13:45:04 suenner kernel: overlay: open(00000000b7f8278e[etc/test1/l], 0100000) -> (00000000df256fc7, 0401100000) > Sep 16 13:45:07 suenner kernel: overlay: setxattr(a/upper, "trusted.overlay.impure", "y", 1, 0x0) = 0 > Sep 16 13:45:07 suenner kernel: overlay: mkdir(work/#7, 040000) = 0 > Sep 16 13:45:07 suenner kernel: [168B blob data] > Sep 16 13:45:07 suenner kernel: overlay: rename(work/#7, upper/etc, 0x0) > Sep 16 13:45:07 suenner kernel: overlay: setxattr(upper/etc, "trusted.overlay.impure", "y", 1, 0x0) = 0 > Sep 16 13:45:07 suenner kernel: overlay: tmpfile(work/work, 0100644) = 0 > Sep 16 13:45:07 suenner kernel: [174B blob data] > Sep 16 13:45:07 suenner kernel: overlay: link(work/#150994, etc/test1) = 0 > Sep 16 13:45:07 suenner kernel: overlay: open(000000001998a069[etc/test1/u], 0100001) -> (0000000009d1ebd4, 0401100001) > Sep 16 13:45:10 suenner kernel: overlay: create(etc/test3, 0100666) = 0 > Sep 16 13:45:10 suenner kernel: overlay: open(0000000009d1ebd4[etc/test3/u], 0100001) -> (000000001998a069, 0401100001) > > > The mount info > buster:/files/scratch/t on /b/lower type nfs (ro,noatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=11.22.33.211,mountvers=3,mountport=45356,mountproto=udp,local_lock=none,addr=11.22.33.211) > overlay on /b/merged type overlay (rw,relatime,lowerdir=/b/lower,upperdir=/a/upper,workdir=/a/work,default_permissions) > > > ----------------------------------------------------------------------------------------------- > NFS v4 mount > ============ > Result: read works, write does not work > > + mkdir -p /b/lower /a/upper /a/work /b/merged > + mount -t nfs -oro,noatime buster:/files/scratch/t /b/lower > + mount -t overlay -olowerdir=/b/lower,upperdir=/a/upper,workdir=/a/work,default_permissions overlay /b/merged > > + cat /b/merged/etc/test1 > test-buster > + sleep 3 > echo "write to merged" > $merged/etc/test1 > + echo 'write to merged' > /home/lange/fairesearch/xfai/overlay-test: line 32: /b/merged/etc/test1: Operation not supported > + sleep 3 > echo "write new file" > $merged/etc/test3 > + echo 'write new file' > /home/lange/fairesearch/xfai/overlay-test: line 34: /b/merged/etc/test3: Operation not supported > > > Here's the journalctl output of the overlayfs debug messages: > Sep 16 13:40:57 suenner kernel: overlay: mkdir(work/work, 040000) = 0 > Sep 16 13:40:57 suenner kernel: overlay: tmpfile(work/work, 0100000) = 0 > Sep 16 13:40:57 suenner kernel: overlay: setxattr(work/work, "trusted.overlay.opaque", "0", 1, 0x0) = 0 > Sep 16 13:40:57 suenner kernel: overlay: open(00000000ca5c0310[etc/test1/l], 0100000) -> (0000000023701f29, 0401100000) > Sep 16 13:41:00 suenner kernel: overlay: setxattr(a/upper, "trusted.overlay.impure", "y", 1, 0x0) = 0 > Sep 16 13:41:00 suenner kernel: overlay: mkdir(work/#3, 040000) = 0 > Sep 16 13:41:00 suenner kernel: overlay: rmdir(work/#3) = 0 > Sep 16 13:41:03 suenner kernel: overlay: mkdir(work/#4, 040000) = 0 > Sep 16 13:41:03 suenner kernel: overlay: rmdir(work/#4) = 0 > > The mount info: > buster:/files/scratch/t on /b/lower type nfs4 (ro,noatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=11.22.33.136,local_lock=none,addr=11.22.33.211) > overlay on /b/merged type overlay (rw,relatime,lowerdir=/b/lower,upperdir=/a/upper,workdir=/a/work,default_permissions) > > A manual test writing to the files using strace shows: > openat(AT_FDCWD, "/b/merged/etc/test1", O_WRONLY|O_CREAT|O_TRUNC, 0666) = -1 EOPNOTSUPP (Operation not supported) > openat(AT_FDCWD, "/ -- Carl K
