1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
// Copyright 2018 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
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/syserror"
)
// LINT.IfChange
// Sync implements linux system call sync(2).
func Sync(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
t.MountNamespace().SyncAll(t)
// Sync is always successful.
return 0, nil, nil
}
// Syncfs implements linux system call syncfs(2).
func Syncfs(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
file := t.GetFile(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef(t)
// Use "sync-the-world" for now, it's guaranteed that fd is at least
// on the root filesystem.
return Sync(t, args)
}
// Fsync implements linux syscall fsync(2).
func Fsync(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
file := t.GetFile(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef(t)
err := file.Fsync(t, 0, fs.FileMaxOffset, fs.SyncAll)
return 0, nil, syserror.ConvertIntr(err, syserror.ERESTARTSYS)
}
// Fdatasync implements linux syscall fdatasync(2).
//
// At the moment, it just calls Fsync, which is a big hammer, but correct.
func Fdatasync(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
fd := args[0].Int()
file := t.GetFile(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef(t)
err := file.Fsync(t, 0, fs.FileMaxOffset, fs.SyncData)
return 0, nil, syserror.ConvertIntr(err, syserror.ERESTARTSYS)
}
// SyncFileRange implements linux syscall sync_file_rage(2)
func SyncFileRange(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
var err error
fd := args[0].Int()
offset := args[1].Int64()
nbytes := args[2].Int64()
uflags := args[3].Uint()
if offset < 0 || offset+nbytes < offset {
return 0, nil, linuxerr.EINVAL
}
if uflags&^(linux.SYNC_FILE_RANGE_WAIT_BEFORE|
linux.SYNC_FILE_RANGE_WRITE|
linux.SYNC_FILE_RANGE_WAIT_AFTER) != 0 {
return 0, nil, linuxerr.EINVAL
}
if nbytes == 0 {
nbytes = fs.FileMaxOffset
}
file := t.GetFile(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
defer file.DecRef(t)
// SYNC_FILE_RANGE_WAIT_BEFORE waits upon write-out of all pages in the
// specified range that have already been submitted to the device
// driver for write-out before performing any write.
if uflags&linux.SYNC_FILE_RANGE_WAIT_BEFORE != 0 &&
uflags&linux.SYNC_FILE_RANGE_WAIT_AFTER == 0 {
t.Kernel().EmitUnimplementedEvent(t)
return 0, nil, syserror.ENOSYS
}
// SYNC_FILE_RANGE_WRITE initiates write-out of all dirty pages in the
// specified range which are not presently submitted write-out.
//
// It looks impossible to implement this functionality without a
// massive rework of the vfs subsystem. file.Fsync() take a file lock
// for the entire operation, so even if it is running in a go routing,
// it blocks other file operations instead of flushing data in the
// background.
//
// It should be safe to skipped this flag while nobody uses
// SYNC_FILE_RANGE_WAIT_BEFORE.
_ = nbytes
// SYNC_FILE_RANGE_WAIT_AFTER waits upon write-out of all pages in the
// range after performing any write.
//
// In Linux, sync_file_range() doesn't writes out the file's
// meta-data, but fdatasync() does if a file size is changed.
if uflags&linux.SYNC_FILE_RANGE_WAIT_AFTER != 0 {
err = file.Fsync(t, offset, fs.FileMaxOffset, fs.SyncData)
}
return 0, nil, syserror.ConvertIntr(err, syserror.ERESTARTSYS)
}
// LINT.ThenChange(vfs2/sync.go)
|
