作为root用户无法修改Shrek.avi文件所有者及移除其不可变属性的问题求助

各位大佬好！我现在在Proxmox上运行Turnkey Core 17.1的LXC容器，文件系统是ext4，已经折腾两天了还是搞不定一个文件的权限问题，实在没办法了来求助！

情况是这样的：我以root身份登录系统，但没办法修改Shrek.avi这个文件的所有者，连移除它的不可变属性都做不到，以下是我执行的命令和对应的输出：

执行chown root Shrek.avi的输出： #

chown: changing ownership of 'Shrek.avi': Operation not permitted

执行chattr -i Shrek.avi的输出： #

chattr: Permission denied while reading flags on Shrek.avi

执行strace chattr -i Shrek.avi的完整输出： #

execve("/usr/bin/chattr", ["chattr", "-i", "Shrek.avi"], 0x7ffd5a2a56f0 /* 24 vars */) = 0

brk(NULL)                               = 0x55a268bd4000

access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)

openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3

fstat(3, {st_mode=S_IFREG|0644, st_size=32282, ...}) = 0

mmap(NULL, 32282, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fd25ebeb000

close(3)                                = 0

openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libe2p.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\0p3\0\0\0\0\0\0"..., 832) = 832

fstat(3, {st_mode=S_IFREG|0644, st_size=44976, ...}) = 0

mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd25ebe9000

mmap(NULL, 47680, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd25ebdd000

mprotect(0x7fd25ebe0000, 28672, PROT_NONE) = 0

mmap(0x7fd25ebe0000, 16384, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3000) = 0x7fd25ebe0000

mmap(0x7fd25ebe4000, 8192, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x7000) = 0x7fd25ebe4000

mmap(0x7fd25ebe7000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x9000) = 0x7fd25ebe7000

close(3)                                = 0

openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libcom_err.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\300\"\0\0\0\0\0\0"..., 832) = 832

fstat(3, {st_mode=S_IFREG|0644, st_size=18344, ...}) = 0

mmap(NULL, 20648, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd25ebd7000

mmap(0x7fd25ebd9000, 4096, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7fd25ebd9000

mmap(0x7fd25ebda000, 4096, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3000) = 0x7fd25ebda000

mmap(0x7fd25ebdb000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3000) = 0x7fd25ebdb000

close(3)                                = 0

openat(AT_FDCWD, "/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 l\0\0\0\0\0\0"..., 832) = 832

fstat(3, {st_mode=S_IFREG|0755, st_size=149520, ...}) = 0

mmap(NULL, 136304, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd25ebb5000

mmap(0x7fd25ebbb000, 65536, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6000) = 0x7fd25ebbb000

mmap(0x7fd25ebcb000, 24576, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16000) = 0x7fd25ebcb000

mmap(0x7fd25ebd1000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1b000) = 0x7fd25ebd1000

mmap(0x7fd25ebd3000, 13424, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fd25ebd3000

close(3)                                = 0

openat(AT_FDCWD, "/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\0@>\2\0\0\0\0\0"..., 832) = 832

fstat(3, {st_mode=S_IFREG|0755, st_size=1905632, ...}) = 0

mmap(NULL, 1918592, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd25e9e0000

mmap(0x7fd25ea02000, 1417216, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0x7fd25ea02000

mmap(0x7fd25eb5c000, 323584, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x17c000) = 0x7fd25eb5c000

mmap(0x7fd25ebab000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1ca000) = 0x7fd25ebab000

mmap(0x7fd25ebb1000, 13952, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fd25ebb1000

close(3)                                = 0

mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd25e9de000

arch_prctl(ARCH_SET_FS, 0x7fd25e9deb80) = 0

mprotect(0x7fd25ebab000, 16384, PROT_READ) = 0

mprotect(0x7fd25ebd1000, 4096, PROT_READ) = 0

mprotect(0x7fd25ebdb000, 4096, PROT_READ) = 0

mprotect(0x7fd25ebe7000, 4096, PROT_READ) = 0

mprotect(0x55a266c1c000, 4096, PROT_READ) = 0

mprotect(0x7fd25ec1d000, 4096, PROT_READ) = 0

munmap(0x7fd25ebeb000, 32282)           = 0

set_tid_address(0x7fd25e9dee50)         = 1259

set_robust_list(0x7fd25e9dee60, 24)     = 0

rt_sigaction(SIGRTMIN, {sa_handler=0x7fd25ebbb690, sa_mask=[], sa_flags=SA_RESTORER|SA_SIGINFO, sa_restorer=0x7fd25ebc8140}, NULL, 8) = 0

rt_sigaction(SIGRT_1, {sa_handler=0x7fd25ebbb730, sa_mask=[], sa_flags=SA_RESTORER|SA_RESTART|SA_SIGINFO, sa_restorer=0x7fd25ebc8140}, NULL, 8) = 0

rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0

prlimit64(0, RLIMIT_STACK, NULL, {rlim_cur=8192*1024, rlim_max=RLIM64_INFINITY}) = 0

brk(NULL)                               = 0x55a268bd4000

brk(0x55a268bf5000)                     = 0x55a268bf5000

lstat("Shrek.avi", {st_mode=S_IFREG|0400, st_size=2302464000, ...}) = 0

openat(AT_FDCWD, "Shrek.avi", O_RDONLY|O_NONBLOCK|O_NOFOLLOW) = -1 EACCES (Permission denied)

write(2, "chattr", 6chattr)                   = 6

write(2, ": ", 2: )                       = 2

write(2, "Permission denied", 17Permission denied)       = 17

write(2, " ", 1 )                        = 1

write(2, "while reading flags on Shrek.avi", 32while reading flags on Shrek.avi) = 32

ioctl(2, TCGETS, {B38400 opost isig icanon echo ...}) = 0

ioctl(2, TCGETS, {B38400 opost isig icanon echo ...}) = 0

write(2, "\n", 1

)                       = 1

exit_group(1)                           = ?

+++ exited with 1 +++

从strace里能看到，lstat能正常获取文件信息，但openat调用的时候直接返回了EACCES权限拒绝，实在搞不懂为什么root都会被拒绝，有没有大佬能指点一下？

备注：内容来源于stack exchange，提问作者Wojciechgc