Re: [PATCH 0/2] ovl: support NFS as lower layer

[sa <sa-dev@rainbow.by>]

On 04.06.2015 16:29, Miklos Szeredi wrote:

> Two small patches implementing this follow.  Comments and testing welcome.
>    git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs-next
> ---
>   fs/overlayfs/super.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++-----
>   1 file changed, 74 insertions(+), 7 deletions(-)

Thank you, it works in our environment mostly as expected, except
of the following:
files already existing in readonly NFS lowerdir can't be opened
for writing (but can be deleted). Newly created files are writable
as expected. The same lowerdir works with aufs without problem.
Is it a bug or am I missing something?


(sid)root@usbsid:/var# ls -l test
-rw-r--r-- 1 root root 6 июн 28 17:01 test

(sid)root@usbsid:/var# cat test
00000

(sid)root@usbsid:/var# strace -e trace=open sh -c 'echo 11111 > test'
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
open("/lib/i386-linux-gnu/i686/cmov/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
open("test", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = -1 EACCES 
(Permission denied)
sh: 1: cannot create test: Permission denied
+++ exited with 2 +++

(sid)root@usbsid:/var# strace -e trace=open sh -c 'echo 11111 >> test'
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
open("/lib/i386-linux-gnu/i686/cmov/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
open("test", O_WRONLY|O_CREAT|O_APPEND|O_LARGEFILE, 0666) = -1 EACCES 
(Permission denied)
sh: 1: cannot create test: Permission denied
+++ exited with 2 +++

(sid)root@usbsid:/var# mount | grep var
tmpfs on /var/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
192.168.211.140:/sid/var on /auvar.ro type nfs 
(ro,relatime,vers=3,rsize=524288,wsize=524288,namlen=255,hard,nolock,proto=tcp,port=2049,timeo=7,retrans=10,sec=sys,local_lock=all,addr=192.168.211.140)
tmpfs on /auvar.ro/lock type tmpfs 
(rw,nosuid,nodev,noexec,relatime,size=5120k)
none on /auvar.rw type tmpfs (rw,relatime)
overlay on /var type overlay 
(rw,relatime,lowerdir=/auvar.ro,upperdir=/auvar.rw/.upperdir,workdir=/auvar.rw/.workdir)

(sid)root@usbsid:/var# uname -r
4.1.0+

user@buildhost:/build/kernel/4 (overlayfs-next)$ git rev-parse HEAD
cdb672795876d7bc1870aed9a2d7cb59f43d1d96


-- 
sa