NFS/ro: mv: cannot move 'foo' to a subdirectory of itself, 'bar'

NFS/ro: mv: cannot move 'foo' to a subdirectory of itself, 'bar'

[André Roth]

Hello,

I try to use overlay for network boot clients using an NFS read-only
filesystem. This works pretty well, except renaming files with the mv
command fails:

==========================
# ls -l
-rw-r--r-- 1 root root 785 Mar 27  2016 foo

# mv foo bar
mv: cannot move 'foo' to a subdirectory of itself, 'bar'
==========================

I mount the overlay filesystem as follows in the initrd, where /root is
already mounted read-only from NFS:
==========================
mkdir /writable
mkfs.ext2 /dev/ram0 >/dev/null
mount -n /dev/ram0 /writable >/dev/null

mkdir /writable/upper
mkdir /writable/work

modprobe overlay
mount -t overlay overlay -olowerdir=/root,upperdir=/writable/upper,workdir=/writable/work,default_permissions /root
==========================

kernel version is 4.7.0-rc2, git cloned from
git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git,
using the overlayfs-next branch.

is this a bug ?
can I help anything debugging fixing this ?


Regards,

 André

Re: NFS/ro: mv: cannot move 'foo' to a subdirectory of itself, 'bar'

[Miklos Szeredi]

On Mon, Jun 13, 2016 at 1:07 PM, André Roth <neolynx@gmail.com> wrote:
>
> Hello,
>
> I try to use overlay for network boot clients using an NFS read-only
> filesystem. This works pretty well, except renaming files with the mv
> command fails:
>
> ==========================
> # ls -l
> -rw-r--r-- 1 root root 785 Mar 27  2016 foo
>
> # mv foo bar
> mv: cannot move 'foo' to a subdirectory of itself, 'bar'
> ==========================
>
> I mount the overlay filesystem as follows in the initrd, where /root is
> already mounted read-only from NFS:
> ==========================
> mkdir /writable
> mkfs.ext2 /dev/ram0 >/dev/null
> mount -n /dev/ram0 /writable >/dev/null
>
> mkdir /writable/upper
> mkdir /writable/work
>
> modprobe overlay
> mount -t overlay overlay -olowerdir=/root,upperdir=/writable/upper,workdir=/writable/work,default_permissions /root
> ==========================
>
> kernel version is 4.7.0-rc2, git cloned from
> git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git,
> using the overlayfs-next branch.
>
> is this a bug ?
> can I help anything debugging fixing this ?

 # echo 'module overlay +mp' > /sys/kernel/debug/dynamic_debug/control
 # strace -o /tmp/strace mv foo bar
 # dmesg | grep overlay > /tmp/debug

And post the /tmp/strace and /tmp/debug files.

Thanks,
Miklos

Re: NFS/ro: mv: cannot move 'foo' to a subdirectory of itself, 'bar'

[André Roth]

[-- Attachment #1: Type: text/plain, Size: 379 bytes --]


Hello,

>  # echo 'module overlay +mp' > /sys/kernel/debug/dynamic_debug/control
>  # strace -o /tmp/strace mv foo bar
>  # dmesg | grep overlay > /tmp/debug
> 
> And post the /tmp/strace and /tmp/debug files.

# strace -o /tmp/strace mv OVERLAYFS foo
mv: cannot move ‘OVERLAYFS’ to a subdirectory of itself, ‘foo’

files attached...

Regards,

 André

[-- Attachment #2: debug --]
[-- Type: application/octet-stream, Size: 280 bytes --]

[  141.989522] overlay: create(work/#ffff880000c1d000, 0100000) = 0
[  141.989918] overlay: rename2(work/#ffff880000c1d000, root/OVERLAYFS, 0x0)
[  141.989927] overlay: rename2(root/OVERLAYFS, root/foo, 0x4)
[  141.989929] overlay: ...rename2(root/OVERLAYFS, root/foo, ...) = -22

[-- Attachment #3: strace --]
[-- Type: application/octet-stream, Size: 9275 bytes --]

execve("/bin/mv", ["mv", "OVERLAYFS", "foo"], [/* 27 vars */]) = 0
brk(0)                                  = 0x2336000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd4263d7000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=19191, ...}) = 0
mmap(NULL, 19191, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fd4263d2000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libselinux.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\20c\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=142728, ...}) = 0
mmap(NULL, 2246896, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd425f94000
mprotect(0x7fd425fb5000, 2097152, PROT_NONE) = 0
mmap(0x7fd4261b5000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x21000) = 0x7fd4261b5000
mmap(0x7fd4261b7000, 6384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fd4261b7000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libacl.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\200\37\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=35288, ...}) = 0
mmap(NULL, 2130592, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd425d8b000
mprotect(0x7fd425d93000, 2093056, PROT_NONE) = 0
mmap(0x7fd425f92000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x7000) = 0x7fd425f92000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libattr.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320\23\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=18640, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd4263d1000
mmap(NULL, 2113912, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd425b86000
mprotect(0x7fd425b8a000, 2093056, PROT_NONE) = 0
mmap(0x7fd425d89000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3000) = 0x7fd425d89000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\34\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1729984, ...}) = 0
mmap(NULL, 3836448, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd4257dd000
mprotect(0x7fd42597c000, 2097152, PROT_NONE) = 0
mmap(0x7fd425b7c000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x19f000) = 0x7fd425b7c000
mmap(0x7fd425b82000, 14880, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fd425b82000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libpcre.so.3", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\20\27\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=448440, ...}) = 0
mmap(NULL, 2543976, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd42556f000
mprotect(0x7fd4255db000, 2097152, PROT_NONE) = 0
mmap(0x7fd4257db000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6c000) = 0x7fd4257db000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320\16\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=14664, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd4263d0000
mmap(NULL, 2109712, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd42536b000
mprotect(0x7fd42536e000, 2093056, PROT_NONE) = 0
mmap(0x7fd42556d000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7fd42556d000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\20o\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=137440, ...}) = 0
mmap(NULL, 2213008, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd42514e000
mprotect(0x7fd425166000, 2093056, PROT_NONE) = 0
mmap(0x7fd425365000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x17000) = 0x7fd425365000
mmap(0x7fd425367000, 13456, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fd425367000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd4263cf000
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd4263cd000
arch_prctl(ARCH_SET_FS, 0x7fd4263cd800) = 0
mprotect(0x7fd425b7c000, 16384, PROT_READ) = 0
mprotect(0x7fd425365000, 4096, PROT_READ) = 0
mprotect(0x7fd42556d000, 4096, PROT_READ) = 0
mprotect(0x7fd4257db000, 4096, PROT_READ) = 0
mprotect(0x7fd425d89000, 4096, PROT_READ) = 0
mprotect(0x7fd425f92000, 4096, PROT_READ) = 0
mprotect(0x7fd4261b5000, 4096, PROT_READ) = 0
mprotect(0x61e000, 4096, PROT_READ)     = 0
mprotect(0x7fd4263d9000, 4096, PROT_READ) = 0
munmap(0x7fd4263d2000, 19191)           = 0
set_tid_address(0x7fd4263cdad0)         = 793
set_robust_list(0x7fd4263cdae0, 24)     = 0
rt_sigaction(SIGRTMIN, {0x7fd4251549f0, [], SA_RESTORER|SA_SIGINFO, 0x7fd42515d8d0}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0x7fd425154a80, [], SA_RESTORER|SA_RESTART|SA_SIGINFO, 0x7fd42515d8d0}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0
statfs("/sys/fs/selinux", 0x7fff169f5bf0) = -1 ENOENT (No such file or directory)
statfs("/selinux", 0x7fff169f5bf0)      = -1 ENOENT (No such file or directory)
brk(0)                                  = 0x2336000
brk(0x2357000)                          = 0x2357000
open("/proc/filesystems", O_RDONLY)     = 3
fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd4263d6000
read(3, "nodev\tsysfs\nnodev\trootfs\nnodev\tt"..., 1024) = 299
read(3, "", 1024)                       = 0
close(3)                                = 0
munmap(0x7fd4263d6000, 4096)            = 0
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=1867856, ...}) = 0
mmap(NULL, 1867856, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fd426204000
close(3)                                = 0
geteuid()                               = 0
ioctl(0, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
stat("foo", 0x7fff169f5bc0)             = -1 ENOENT (No such file or directory)
lstat("OVERLAYFS", {st_mode=S_IFREG|0644, st_size=785, ...}) = 0
lstat("foo", 0x7fff169f5890)            = -1 ENOENT (No such file or directory)
rename("OVERLAYFS", "foo")              = -1 EINVAL (Invalid argument)
open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2492, ...}) = 0
mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd42504e000
read(3, "# Locale name alias data base.\n#"..., 1048576) = 2492
read(3, "", 1048576)                    = 0
close(3)                                = 0
munmap(0x7fd42504e000, 1048576)         = 0
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/charset.alias", O_RDONLY|O_NOFOLLOW) = -1 ENOENT (No such file or directory)
write(2, "mv: ", 4)                     = 4
write(2, "cannot move \342\200\230OVERLAYFS\342\200\231 to a"..., 66) = 66
write(2, "\n", 1)                       = 1
lseek(0, 0, SEEK_CUR)                   = -1 ESPIPE (Illegal seek)
close(0)                                = 0
close(1)                                = 0
close(2)                                = 0
exit_group(1)                           = ?
+++ exited with 1 +++

Re: NFS/ro: mv: cannot move 'foo' to a subdirectory of itself, 'bar'

[Miklos Szeredi]

On Sat, Jun 18, 2016 at 1:32 PM, André Roth <neolynx@gmail.com> wrote:
>
> Hello,
>
>>  # echo 'module overlay +mp' > /sys/kernel/debug/dynamic_debug/control
>>  # strace -o /tmp/strace mv foo bar
>>  # dmesg | grep overlay > /tmp/debug
>>
>> And post the /tmp/strace and /tmp/debug files.
>
> # strace -o /tmp/strace mv OVERLAYFS foo
> mv: cannot move ‘OVERLAYFS’ to a subdirectory of itself, ‘foo’
>
> files attached...

Overlayfs cannot create a whiteout on the upper fs.

Do you have

  CONFIG_EXT4_USE_FOR_EXT2=y

in your kernel's .config?  If not, then you should.

You'll also need

  a4859d75944a ("ovl: fix dentry leak for default_permissions")

from the overlayfs-linus branch of

  git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git

otherwise "default_permissions" will misbehave.

Thanks,
Miklos

Re: NFS/ro: mv: cannot move 'foo' to a subdirectory of itself, 'bar'

[André Roth]

> Do you have
> 
>   CONFIG_EXT4_USE_FOR_EXT2=y
> 
> in your kernel's .config?  If not, then you should.  

nope

> You'll also need
> 
>   a4859d75944a ("ovl: fix dentry leak for default_permissions")
> 
> from the overlayfs-linus branch of
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git  

works like a charm now :)
 
> otherwise "default_permissions" will misbehave.  

thanks for the information !

regards,

 andré