internal/poll: CopyFileRange returns ENOTSUP on Linux 3.10.0 kernel on NFS mount

[nwidger]

What version of Go are you using (go version)?

$ go version
go version go1.15 linux/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

Running on CentOS 7.8 with a 3.10.0 kernel.

$ uname -a
Linux lark.lan 3.10.0-1127.13.1.el7.x86_64 #1 SMP Tue Jun 23 15:46:38 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
$ cat /etc/centos-release
CentOS Linux release 7.8.2003 (Core)

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/niels/.cache/go-build"
GOENV="/home/niels/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/niels/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/niels/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/niels/sdk/go1.15"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/niels/sdk/go1.15/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build44

What did you do?

I ran the following program within a directory on an NFS mount.

https://play.golang.org/p/M_6eEgranwf

What did you expect to see?

I expect the program to exit with a zero status code and for the "dst" file to contain the string "test".

What did you see instead?

Exit with status 1 with the following output:

2020/08/12 12:37:58 readfrom: write dst: copy_file_range: operation not supported

Running the program with strace shows the following output:

copy_file_range(3, NULL, 7, NULL, 1073741824, 0) = -1 EOPNOTSUPP (Operation not supported)

here's the full output in case it helps:

strace Output

execve("./delme", ["./delme"], 0x7fff0f0141c0 /* 33 vars */) = 0
arch_prctl(ARCH_SET_FS, 0x56cf50)       = 0
sched_getaffinity(0, 8192, [0, 1, 2, 3, 4, 5, 6, 7, ...]) = 640
openat(AT_FDCWD, "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", O_RDONLY) = -1 ENOENT (No such file or directory)
uname({sysname="Linux", nodename="cdr-forge7.lan", ...}) = 0
mmap(NULL, 262144, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6477c05000
mmap(NULL, 131072, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6477be5000
mmap(NULL, 1048576, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6477ae5000
mmap(NULL, 8388608, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f64772e5000
mmap(NULL, 67108864, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f64732e5000
mmap(NULL, 536870912, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f64532e5000
mmap(0xc000000000, 67108864, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xc000000000
mmap(0xc000000000, 67108864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xc000000000
mmap(NULL, 33554432, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f64512e5000
mmap(NULL, 2165768, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f64510d4000
mmap(0x7f6477be5000, 131072, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f6477be5000
mmap(0x7f6477b65000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f6477b65000
mmap(0x7f64776eb000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f64776eb000
mmap(0x7f6475315000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f6475315000
mmap(0x7f6463465000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f6463465000
mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6450fd4000
mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6450fc4000
mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f6450fb4000
rt_sigprocmask(SIG_SETMASK, NULL, [], 8) = 0
sigaltstack(NULL, {ss_sp=NULL, ss_flags=SS_DISABLE, ss_size=0}) = 0
sigaltstack({ss_sp=0xc000002000, ss_flags=0, ss_size=32768}, NULL) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
gettid()                                = 732
rt_sigaction(SIGHUP, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGHUP, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGINT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGINT, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGQUIT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGQUIT, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGILL, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGILL, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGTRAP, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGTRAP, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGABRT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGABRT, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGBUS, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGBUS, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGFPE, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGFPE, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGUSR1, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGUSR1, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGSEGV, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGSEGV, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGUSR2, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGUSR2, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGPIPE, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGALRM, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGALRM, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGTERM, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGSTKFLT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGSTKFLT, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGCHLD, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGCHLD, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGURG, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGURG, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGXCPU, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGXCPU, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGXFSZ, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGXFSZ, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGVTALRM, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGVTALRM, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGPROF, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGPROF, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGWINCH, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGWINCH, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGIO, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGIO, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGPWR, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGPWR, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGSYS, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGSYS, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRTMIN, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_1, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_2, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_2, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_3, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_3, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_4, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_4, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_5, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_5, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_6, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_6, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_7, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_7, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_8, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_8, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_9, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_9, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_10, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_10, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_11, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_11, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_12, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_12, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_13, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_13, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_14, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_14, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_15, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_15, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_16, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_16, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_17, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_17, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_18, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_18, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_19, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_19, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_20, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_20, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_21, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_21, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_22, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_22, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_23, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_23, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_24, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_24, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_25, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_25, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_26, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_26, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_27, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_27, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_28, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_28, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_29, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_29, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_30, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_30, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_31, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_31, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigaction(SIGRT_32, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGRT_32, {sa_handler=0x4651a0, sa_mask=~[], sa_flags=SA_RESTORER|SA_ONSTACK|SA_RESTART|SA_SIGINFO, sa_restorer=0x4652e0}, NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, ~[], [], 8) = 0
clone(child_stack=0xc000056000, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM) = 733
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, ~[], [], 8) = 0
clone(child_stack=0xc000058000, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM) = 734
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
--- SIGURG {si_signo=SIGURG, si_code=SI_TKILL, si_pid=732, si_uid=10010} ---
rt_sigreturn({mask=[]})                 = 0
futex(0xc000046548, FUTEX_WAKE_PRIVATE, 1) = 1
futex(0xc000046548, FUTEX_WAKE_PRIVATE, 1) = 1
readlinkat(AT_FDCWD, "/proc/self/exe", "/home/niels/delme/delme", 128) = 23
fcntl(0, F_GETFL)                       = 0x8402 (flags O_RDWR|O_APPEND|O_LARGEFILE)
futex(0xc000046548, FUTEX_WAKE_PRIVATE, 1) = 1
fcntl(1, F_GETFL)                       = 0x8402 (flags O_RDWR|O_APPEND|O_LARGEFILE)
fcntl(2, F_GETFL)                       = 0x8402 (flags O_RDWR|O_APPEND|O_LARGEFILE)
openat(AT_FDCWD, "src", O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0644) = 3
epoll_create1(EPOLL_CLOEXEC)            = 4
pipe2([5, 6], O_NONBLOCK|O_CLOEXEC)     = 0
epoll_ctl(4, EPOLL_CTL_ADD, 5, {EPOLLIN, {u32=5881624, u64=5881624}}) = 0
epoll_ctl(4, EPOLL_CTL_ADD, 3, {EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET, {u32=1358417640, u64=140068831874792}}) = -1 EPERM (Operation not permitted)
epoll_ctl(4, EPOLL_CTL_DEL, 3, 0xc000098d04) = -1 EPERM (Operation not permitted)
write(3, "test", 4)                     = 4
close(3)                                = 0
openat(AT_FDCWD, "src", O_RDONLY|O_CLOEXEC) = 3
epoll_ctl(4, EPOLL_CTL_ADD, 3, {EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET, {u32=1358417640, u64=140068831874792}}) = -1 EPERM (Operation not permitted)
epoll_ctl(4, EPOLL_CTL_DEL, 3, 0xc000098d64) = -1 EPERM (Operation not permitted)
openat(AT_FDCWD, "dst", O_RDWR|O_CREAT|O_TRUNC|O_CLOEXEC, 0666) = 7
epoll_ctl(4, EPOLL_CTL_ADD, 7, {EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET, {u32=1358417640, u64=140068831874792}}) = -1 EPERM (Operation not permitted)
epoll_ctl(4, EPOLL_CTL_DEL, 7, 0xc000098d64) = -1 EPERM (Operation not permitted)
copy_file_range(3, NULL, 7, NULL, 1073741824, 0) = -1 EOPNOTSUPP (Operation not supported)
openat(AT_FDCWD, "/etc/localtime", O_RDONLY) = 8
read(8, "TZif2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\4\0\0\0\4\0\0\0\0"..., 4096) = 3519
read(8, "", 4096)                       = 0
close(8)                                = 0
write(2, "2020/08/12 12:54:07 readfrom: wr"..., 822020/08/12 12:54:07 readfrom: write dst: copy_file_range: operation not supported
) = 82
exit_group(1)                           = ?
+++ exited with 1 +++

I was able to resolve the issue by editing $GOROOT/src/internal/poll/copy_file_range_linux.go such that syscall.ENOTSUP is handled identically to syscall.ENOSYS in poll.CopyFileRange. However, I don't know if this is the correct solution or if there's something else at play here.

[ianlancetaylor]

@gopherbot Please open a backport to 1.15.

This bug causes failures doing ordinary file operations on files opened on NFS. The code involved is new in 1.15

FYI @acln0

[gopherbot]

Backport issue(s) opened: #40739 (for 1.15).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.

[gopherbot]

Change https://golang.org/cl/248258 mentions this issue: internal/poll: treat copy_file_range EOPNOTSUPP as not-handled

[ianlancetaylor]

@nwidger I sent https://golang.org/cl/248258. I'm pretty sure it will fix the problem, as it's approximately what you tried already. Would you mind giving it a try to see if it fixes the problem? Thanks.

We'll have to backport this to the 1.15 release branch for the 1.15.1 release.

[nwidger]

@ianlancetaylor I gave your fix a try and it does indeed resolve the problem. Thank you for the quick turnaround!

[acln0]

@ianlancetaylor Sorry for the trouble. I wasn't aware of this one. It's not documented in the copy_file_range man page, but, after all, I suppose individual file systems can return any error they please. While we are at it, apart from EOPNOTSUPP (which, in hindsight, seems to be one the code should have been aware of), are any other errors that we may have to treat similarly? I can't think of any at the moment, but now would be the best time to deal with them, if they exist.

[ulikunitz]

@acln0 Linux kernel 3.10 used by the issue reporter doesn't support copy_file_range at all, since the feature has been introduced with 4.5 released in March 2017. So it isn't an individual file system issue.

The copy_file_range man file on man7.org contains following in the VERSION section

The copy_file_range() system call first appeared in Linux 4.5, but glibc 2.27 provides a user-space emulation when it is not available.

[acln0]

But I thought that was the ENOSYS case, which we covered in the initial implementation.

[nwidger]

@ulikunitz I saw that same comment and wondered the same thing. I've checked and I am running the 3.10.0 kernel with glibc 2.17, therefore the system has neither kernel or user-space emulation support for copy_file_range.

After adding some println's to $GOROOT/src/internal/poll/copy_file_range_linux.go, I see that copy_file_range returns EOPNOTSUPP when running my test program within an NFS mount, and ENOSYS within a non-NFS mount such as /tmp. So I think that all makes sense. Let me know if there are any other experiments I can do.

[ulikunitz]

CentOS provides a vendor kernel that includes backports, which may result in the observed behavior.

[gopherbot]

Change https://golang.org/cl/249197 mentions this issue: [release-branch.go1.15] internal/poll: treat copy_file_range EOPNOTSUPP as not-handled