Port fadvise64 to vfs2.

Like vfs1, we have a trivial implementation that ignores all valid advice.

Updates #2923.

PiperOrigin-RevId: 317349505

pkg/abi/linux/BUILD

@@ -23,6 +23,7 @@ go_library(
         "errors.go",
         "eventfd.go",
         "exec.go",
+        "fadvise.go",
         "fcntl.go",
         "file.go",
         "file_amd64.go",

pkg/abi/linux/fadvise.go

@@ -0,0 +1,24 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package linux
+
+const (
+	POSIX_FADV_NORMAL     = 0
+	POSIX_FADV_RANDOM     = 1
+	POSIX_FADV_SEQUENTIAL = 2
+	POSIX_FADV_WILLNEED   = 3
+	POSIX_FADV_DONTNEED   = 4
+	POSIX_FADV_NOREUSE    = 5
+)

pkg/sentry/syscalls/linux/sys_file.go

@@ -1111,17 +1111,6 @@ func Fcntl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
 	}
 }
 
-// LINT.ThenChange(vfs2/fd.go)
-
-const (
-	_FADV_NORMAL     = 0
-	_FADV_RANDOM     = 1
-	_FADV_SEQUENTIAL = 2
-	_FADV_WILLNEED   = 3
-	_FADV_DONTNEED   = 4
-	_FADV_NOREUSE    = 5
-)
-
 // Fadvise64 implements linux syscall fadvise64(2).
 // This implementation currently ignores the provided advice.
 func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
@@ -1146,12 +1135,12 @@ func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
 	}
 
 	switch advice {
-	case _FADV_NORMAL:
-	case _FADV_RANDOM:
-	case _FADV_SEQUENTIAL:
-	case _FADV_WILLNEED:
-	case _FADV_DONTNEED:
-	case _FADV_NOREUSE:
+	case linux.POSIX_FADV_NORMAL:
+	case linux.POSIX_FADV_RANDOM:
+	case linux.POSIX_FADV_SEQUENTIAL:
+	case linux.POSIX_FADV_WILLNEED:
+	case linux.POSIX_FADV_DONTNEED:
+	case linux.POSIX_FADV_NOREUSE:
 	default:
 		return 0, nil, syserror.EINVAL
 	}
@@ -1160,8 +1149,6 @@ func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
 	return 0, nil, nil
 }
 
-// LINT.IfChange
-
 func mkdirAt(t *kernel.Task, dirFD int32, addr usermem.Addr, mode linux.FileMode) error {
 	path, _, err := copyInPath(t, addr, false /* allowEmpty */)
 	if err != nil {

pkg/sentry/syscalls/linux/vfs2/fd.go

@@ -210,3 +210,41 @@ func posixLock(t *kernel.Task, args arch.SyscallArguments, file *vfs.FileDescrip
 		return syserror.EINVAL
 	}
 }
+
+// Fadvise64 implements fadvise64(2).
+// This implementation currently ignores the provided advice.
+func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	fd := args[0].Int()
+	length := args[2].Int64()
+	advice := args[3].Int()
+
+	// Note: offset is allowed to be negative.
+	if length < 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	file := t.GetFileVFS2(fd)
+	if file == nil {
+		return 0, nil, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	// If the FD refers to a pipe or FIFO, return error.
+	if _, isPipe := file.Impl().(*pipe.VFSPipeFD); isPipe {
+		return 0, nil, syserror.ESPIPE
+	}
+
+	switch advice {
+	case linux.POSIX_FADV_NORMAL:
+	case linux.POSIX_FADV_RANDOM:
+	case linux.POSIX_FADV_SEQUENTIAL:
+	case linux.POSIX_FADV_WILLNEED:
+	case linux.POSIX_FADV_DONTNEED:
+	case linux.POSIX_FADV_NOREUSE:
+	default:
+		return 0, nil, syserror.EINVAL
+	}
+
+	// Sure, whatever.
+	return 0, nil, nil
+}

pkg/sentry/syscalls/linux/vfs2/vfs2.go

@@ -108,7 +108,7 @@ func Override() {
 	s.Table[209] = syscalls.PartiallySupported("io_submit", IoSubmit, "Generally supported with exceptions. User ring optimizations are not implemented.", []string{"gvisor.dev/issue/204"})
 	s.Table[213] = syscalls.Supported("epoll_create", EpollCreate)
 	s.Table[217] = syscalls.Supported("getdents64", Getdents64)
-	delete(s.Table, 221) // fdavise64
+	s.Table[221] = syscalls.PartiallySupported("fadvise64", Fadvise64, "The syscall is 'supported', but ignores all provided advice.", nil)
 	s.Table[232] = syscalls.Supported("epoll_wait", EpollWait)
 	s.Table[233] = syscalls.Supported("epoll_ctl", EpollCtl)
 	s.Table[235] = syscalls.Supported("utimes", Utimes)

test/syscalls/BUILD

@@ -191,6 +191,7 @@ syscall_test(
 syscall_test(
     add_overlay = True,
     test = "//test/syscalls/linux:fadvise64_test",
+    vfs2 = "True",
 )
 
 syscall_test(