142 lines
4.2 KiB
Go
142 lines
4.2 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package linux
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import (
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/sentry/arch"
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"gvisor.dev/gvisor/pkg/sentry/fs"
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"gvisor.dev/gvisor/pkg/sentry/kernel"
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"gvisor.dev/gvisor/pkg/syserror"
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)
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// LINT.IfChange
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// Sync implements linux system call sync(2).
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func Sync(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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t.MountNamespace().SyncAll(t)
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// Sync is always successful.
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return 0, nil, nil
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}
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// Syncfs implements linux system call syncfs(2).
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func Syncfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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// Use "sync-the-world" for now, it's guaranteed that fd is at least
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// on the root filesystem.
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return Sync(t, args)
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}
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// Fsync implements linux syscall fsync(2).
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func Fsync(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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err := file.Fsync(t, 0, fs.FileMaxOffset, fs.SyncAll)
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return 0, nil, syserror.ConvertIntr(err, kernel.ERESTARTSYS)
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}
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// Fdatasync implements linux syscall fdatasync(2).
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//
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// At the moment, it just calls Fsync, which is a big hammer, but correct.
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func Fdatasync(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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fd := args[0].Int()
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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err := file.Fsync(t, 0, fs.FileMaxOffset, fs.SyncData)
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return 0, nil, syserror.ConvertIntr(err, kernel.ERESTARTSYS)
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}
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// SyncFileRange implements linux syscall sync_file_rage(2)
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func SyncFileRange(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
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var err error
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fd := args[0].Int()
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offset := args[1].Int64()
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nbytes := args[2].Int64()
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uflags := args[3].Uint()
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if offset < 0 || offset+nbytes < offset {
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return 0, nil, syserror.EINVAL
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}
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if uflags&^(linux.SYNC_FILE_RANGE_WAIT_BEFORE|
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linux.SYNC_FILE_RANGE_WRITE|
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linux.SYNC_FILE_RANGE_WAIT_AFTER) != 0 {
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return 0, nil, syserror.EINVAL
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}
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if nbytes == 0 {
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nbytes = fs.FileMaxOffset
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}
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file := t.GetFile(fd)
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if file == nil {
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return 0, nil, syserror.EBADF
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}
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defer file.DecRef()
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// SYNC_FILE_RANGE_WAIT_BEFORE waits upon write-out of all pages in the
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// specified range that have already been submitted to the device
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// driver for write-out before performing any write.
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if uflags&linux.SYNC_FILE_RANGE_WAIT_BEFORE != 0 &&
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uflags&linux.SYNC_FILE_RANGE_WAIT_AFTER == 0 {
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t.Kernel().EmitUnimplementedEvent(t)
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return 0, nil, syserror.ENOSYS
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}
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// SYNC_FILE_RANGE_WRITE initiates write-out of all dirty pages in the
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// specified range which are not presently submitted write-out.
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//
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// It looks impossible to implement this functionality without a
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// massive rework of the vfs subsystem. file.Fsync() take a file lock
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// for the entire operation, so even if it is running in a go routing,
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// it blocks other file operations instead of flushing data in the
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// background.
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//
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// It should be safe to skipped this flag while nobody uses
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// SYNC_FILE_RANGE_WAIT_BEFORE.
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// SYNC_FILE_RANGE_WAIT_AFTER waits upon write-out of all pages in the
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// range after performing any write.
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//
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// In Linux, sync_file_range() doesn't writes out the file's
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// meta-data, but fdatasync() does if a file size is changed.
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if uflags&linux.SYNC_FILE_RANGE_WAIT_AFTER != 0 {
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err = file.Fsync(t, offset, fs.FileMaxOffset, fs.SyncData)
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}
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return 0, nil, syserror.ConvertIntr(err, kernel.ERESTARTSYS)
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}
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// LINT.ThenChange(vfs2/sync.go)
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