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[vfs] Refactor hostfs mmap into kernfs util.

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PiperOrigin-RevId: 339505487
This commit is contained in:
Ayush Ranjan
2020-10-28 11:50:11 -07:00
committed by gVisor bot
parent 17e0a4adde
commit 4cc3894b27
6 changed files with 86 additions and 54 deletions
Download Patch File Download Diff File Expand all files Collapse all files
pkg/sentry/fsimpl/host/BUILD
-1
View File
@@ -33,7 +33,6 @@ go_library(
"host.go",
"inode_refs.go",
"ioctl_unsafe.go",
"mmap.go",
"save_restore.go",
"socket.go",
"socket_iovec.go",
pkg/sentry/fsimpl/host/host.go
+4 -20
View File
@@ -48,6 +48,7 @@ type inode struct {
kernfs.InodeNoStatFS
kernfs.InodeNotDirectory
kernfs.InodeNotSymlink
kernfs.CachedMappable
kernfs.InodeTemporary // This holds no meaning as this inode can't be Looked up and is always valid.
locks vfs.FileLocks
@@ -96,16 +97,6 @@ type inode struct {
// Event queue for blocking operations.
queue waiter.Queue
// mapsMu protects mappings.
mapsMu sync.Mutex `state:"nosave"`
// If this file is mmappable, mappings tracks mappings of hostFD into
// memmap.MappingSpaces.
mappings memmap.MappingSet
// pf implements platform.File for mappings of hostFD.
pf inodePlatformFile
// If haveBuf is non-zero, hostFD represents a pipe, and buf contains data
// read from the pipe from previous calls to inode.beforeSave(). haveBuf
// and buf are protected by bufMu. haveBuf is accessed using atomic memory
@@ -135,7 +126,7 @@ func newInode(ctx context.Context, fs *filesystem, hostFD int, savable bool, fil
isTTY: isTTY,
savable: savable,
}
i.pf.inode = i
i.CachedMappable.Init(hostFD)
i.EnableLeakCheck()
// If the hostFD can return EWOULDBLOCK when set to non-blocking, do so and
@@ -439,14 +430,7 @@ func (i *inode) SetStat(ctx context.Context, fs *vfs.Filesystem, creds *auth.Cre
oldpgend, _ := usermem.PageRoundUp(oldSize)
newpgend, _ := usermem.PageRoundUp(s.Size)
if oldpgend != newpgend {
i.mapsMu.Lock()
i.mappings.Invalidate(memmap.MappableRange{newpgend, oldpgend}, memmap.InvalidateOpts{
// Compare Linux's mm/truncate.c:truncate_setsize() =>
// truncate_pagecache() =>
// mm/memory.c:unmap_mapping_range(evencows=1).
InvalidatePrivate: true,
})
i.mapsMu.Unlock()
i.CachedMappable.InvalidateRange(memmap.MappableRange{newpgend, oldpgend})
}
}
}
@@ -797,7 +781,7 @@ func (f *fileDescription) ConfigureMMap(_ context.Context, opts *memmap.MMapOpts
return syserror.ENODEV
}
i := f.inode
i.pf.fileMapperInitOnce.Do(i.pf.fileMapper.Init)
i.CachedMappable.InitFileMapperOnce()
return vfs.GenericConfigureMMap(&f.vfsfd, i, opts)
}
pkg/sentry/fsimpl/host/save_restore.go
-8
View File
@@ -68,11 +68,3 @@ func (i *inode) afterLoad() {
}
}
}
// afterLoad is invoked by stateify.
func (i *inodePlatformFile) afterLoad() {
if i.fileMapper.IsInited() {
// Ensure that we don't call i.fileMapper.Init() again.
i.fileMapperInitOnce.Do(func() {})
}
}
pkg/sentry/fsimpl/kernfs/BUILD
+3
View File
@@ -92,6 +92,8 @@ go_library(
"fstree.go",
"inode_impl_util.go",
"kernfs.go",
"mmap_util.go",
"save_restore.go",
"slot_list.go",
"static_directory_refs.go",
"symlink.go",
@@ -106,6 +108,7 @@ go_library(
"//pkg/log",
"//pkg/refs",
"//pkg/refsvfs2",
"//pkg/safemem",
"//pkg/sentry/fs/fsutil",
"//pkg/sentry/fs/lock",
"//pkg/sentry/kernel/auth",
pkg/sentry/fsimpl/host/mmap.go → pkg/sentry/fsimpl/kernfs/mmap_util.go
+56 -25
View File
@@ -12,7 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.
package host
package kernfs
import (
"gvisor.dev/gvisor/pkg/context"
@@ -26,11 +26,14 @@ import (
// inodePlatformFile implements memmap.File. It exists solely because inode
// cannot implement both kernfs.Inode.IncRef and memmap.File.IncRef.
//
// inodePlatformFile should only be used if inode.canMap is true.
//
// +stateify savable
type inodePlatformFile struct {
*inode
// hostFD contains the host fd that this file was originally created from,
// which must be available at time of restore.
//
// This field is initialized at creation time and is immutable.
// inodePlatformFile does not own hostFD and hence should not close it.
hostFD int
// fdRefsMu protects fdRefs.
fdRefsMu sync.Mutex `state:"nosave"`
@@ -46,9 +49,9 @@ type inodePlatformFile struct {
fileMapperInitOnce sync.Once `state:"nosave"`
}
var _ memmap.File = (*inodePlatformFile)(nil)
// IncRef implements memmap.File.IncRef.
//
// Precondition: i.inode.canMap must be true.
func (i *inodePlatformFile) IncRef(fr memmap.FileRange) {
i.fdRefsMu.Lock()
i.fdRefs.IncRefAndAccount(fr)
@@ -56,8 +59,6 @@ func (i *inodePlatformFile) IncRef(fr memmap.FileRange) {
}
// DecRef implements memmap.File.DecRef.
//
// Precondition: i.inode.canMap must be true.
func (i *inodePlatformFile) DecRef(fr memmap.FileRange) {
i.fdRefsMu.Lock()
i.fdRefs.DecRefAndAccount(fr)
@@ -65,8 +66,6 @@ func (i *inodePlatformFile) DecRef(fr memmap.FileRange) {
}
// MapInternal implements memmap.File.MapInternal.
//
// Precondition: i.inode.canMap must be true.
func (i *inodePlatformFile) MapInternal(fr memmap.FileRange, at usermem.AccessType) (safemem.BlockSeq, error) {
return i.fileMapper.MapInternal(fr, i.hostFD, at.Write)
}
@@ -76,10 +75,32 @@ func (i *inodePlatformFile) FD() int {
return i.hostFD
}
// AddMapping implements memmap.Mappable.AddMapping.
// CachedMappable implements memmap.Mappable. This utility can be embedded in a
// kernfs.Inode that represents a host file to make the inode mappable.
// CachedMappable caches the mappings of the host file. CachedMappable must be
// initialized (via Init) with a hostFD before use.
//
// Precondition: i.inode.canMap must be true.
func (i *inode) AddMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, writable bool) error {
// +stateify savable
type CachedMappable struct {
// mapsMu protects mappings.
mapsMu sync.Mutex `state:"nosave"`
// mappings tracks mappings of hostFD into memmap.MappingSpaces.
mappings memmap.MappingSet
// pf implements memmap.File for mappings backed by a host fd.
pf inodePlatformFile
}
var _ memmap.Mappable = (*CachedMappable)(nil)
// Init initializes i.pf. This must be called before using CachedMappable.
func (i *CachedMappable) Init(hostFD int) {
i.pf.hostFD = hostFD
}
// AddMapping implements memmap.Mappable.AddMapping.
func (i *CachedMappable) AddMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, writable bool) error {
i.mapsMu.Lock()
mapped := i.mappings.AddMapping(ms, ar, offset, writable)
for _, r := range mapped {
@@ -90,9 +111,7 @@ func (i *inode) AddMapping(ctx context.Context, ms memmap.MappingSpace, ar userm
}
// RemoveMapping implements memmap.Mappable.RemoveMapping.
//
// Precondition: i.inode.canMap must be true.
func (i *inode) RemoveMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, writable bool) {
func (i *CachedMappable) RemoveMapping(ctx context.Context, ms memmap.MappingSpace, ar usermem.AddrRange, offset uint64, writable bool) {
i.mapsMu.Lock()
unmapped := i.mappings.RemoveMapping(ms, ar, offset, writable)
for _, r := range unmapped {
@@ -102,16 +121,12 @@ func (i *inode) RemoveMapping(ctx context.Context, ms memmap.MappingSpace, ar us
}
// CopyMapping implements memmap.Mappable.CopyMapping.
//
// Precondition: i.inode.canMap must be true.
func (i *inode) CopyMapping(ctx context.Context, ms memmap.MappingSpace, srcAR, dstAR usermem.AddrRange, offset uint64, writable bool) error {
func (i *CachedMappable) CopyMapping(ctx context.Context, ms memmap.MappingSpace, srcAR, dstAR usermem.AddrRange, offset uint64, writable bool) error {
return i.AddMapping(ctx, ms, dstAR, offset, writable)
}
// Translate implements memmap.Mappable.Translate.
//
// Precondition: i.inode.canMap must be true.
func (i *inode) Translate(ctx context.Context, required, optional memmap.MappableRange, at usermem.AccessType) ([]memmap.Translation, error) {
func (i *CachedMappable) Translate(ctx context.Context, required, optional memmap.MappableRange, at usermem.AccessType) ([]memmap.Translation, error) {
mr := optional
return []memmap.Translation{
{
@@ -124,10 +139,26 @@ func (i *inode) Translate(ctx context.Context, required, optional memmap.Mappabl
}
// InvalidateUnsavable implements memmap.Mappable.InvalidateUnsavable.
//
// Precondition: i.inode.canMap must be true.
func (i *inode) InvalidateUnsavable(ctx context.Context) error {
func (i *CachedMappable) InvalidateUnsavable(ctx context.Context) error {
// We expect the same host fd across save/restore, so all translations
// should be valid.
return nil
}
// InvalidateRange invalidates the passed range on i.mappings.
func (i *CachedMappable) InvalidateRange(r memmap.MappableRange) {
i.mapsMu.Lock()
i.mappings.Invalidate(r, memmap.InvalidateOpts{
// Compare Linux's mm/truncate.c:truncate_setsize() =>
// truncate_pagecache() =>
// mm/memory.c:unmap_mapping_range(evencows=1).
InvalidatePrivate: true,
})
i.mapsMu.Unlock()
}
// InitFileMapperOnce initializes the host file mapper. It ensures that the
// file mapper is initialized just once.
func (i *CachedMappable) InitFileMapperOnce() {
i.pf.fileMapperInitOnce.Do(i.pf.fileMapper.Init)
}
pkg/sentry/fsimpl/kernfs/save_restore.go
+23
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@@ -0,0 +1,23 @@
// 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 kernfs
// afterLoad is invoked by stateify.
func (i *inodePlatformFile) afterLoad() {
if i.fileMapper.IsInited() {
// Ensure that we don't call i.fileMapper.Init() again.
i.fileMapperInitOnce.Do(func() {})
}
}