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// Copyright 2019 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 gofer
import (
"fmt"
"math"
"strings"
"sync"
"golang.org/x/sys/unix"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/atomicbitops"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/lisafs"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/host"
"gvisor.dev/gvisor/pkg/sentry/fsmetric"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/kernel/pipe"
"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
"gvisor.dev/gvisor/pkg/sentry/vfs"
)
// Sync implements vfs.FilesystemImpl.Sync.
func (fs *filesystem) Sync(ctx context.Context) error {
// Snapshot current syncable dentries and special file FDs.
fs.syncMu.Lock()
ds := make([]*dentry, 0, fs.syncableDentries.Len())
for elem := fs.syncableDentries.Front(); elem != nil; elem = elem.Next() {
ds = append(ds, elem.d)
}
sffds := make([]*specialFileFD, 0, fs.specialFileFDs.Len())
for sffd := fs.specialFileFDs.Front(); sffd != nil; sffd = sffd.Next() {
sffds = append(sffds, sffd)
}
fs.syncMu.Unlock()
// Return the first error we encounter, but sync everything we can
// regardless.
var retErr error
// Note that lisafs is capable of batching FSync RPCs. However, we can not
// batch all the FDIDs to be synced from ds and sffds. Because the error
// handling varies based on file type. FSync errors are only considered for
// regular file FDIDs that were opened for writing. We could do individual
// RPCs for such FDIDs and batch the rest, but it increases code complexity
// substantially. We could implement it in the future if need be.
// Sync syncable dentries.
for _, d := range ds {
if err := d.syncCachedFile(ctx, true /* forFilesystemSync */); err != nil {
ctx.Infof("gofer.filesystem.Sync: dentry.syncCachedFile failed: %v", err)
if retErr == nil {
retErr = err
}
}
}
// Sync special files, which may be writable but do not use dentry shared
// handles (so they won't be synced by the above).
for _, sffd := range sffds {
if err := sffd.sync(ctx, true /* forFilesystemSync */); err != nil {
ctx.Infof("gofer.filesystem.Sync: specialFileFD.sync failed: %v", err)
if retErr == nil {
retErr = err
}
}
}
return retErr
}
// MaxFilenameLen is the maximum length of a filename. This is dictated by 9P's
// encoding of strings, which uses 2 bytes for the length prefix.
const MaxFilenameLen = (1 << 16) - 1
// dentrySlicePool is a pool of *[]*dentry used to store dentries for which
// dentry.checkCachingLocked() must be called. The pool holds pointers to
// slices because Go lacks generics, so sync.Pool operates on any, so
// every call to (what should be) sync.Pool<[]*dentry>.Put() allocates a copy
// of the slice header on the heap.
var dentrySlicePool = sync.Pool{
New: func() any {
ds := make([]*dentry, 0, 4) // arbitrary non-zero initial capacity
return &ds
},
}
func appendDentry(ds *[]*dentry, d *dentry) *[]*dentry {
if ds == nil {
ds = dentrySlicePool.Get().(*[]*dentry)
}
*ds = append(*ds, d)
return ds
}
// Precondition: !parent.isSynthetic() && !child.isSynthetic().
func appendNewChildDentry(ds **[]*dentry, parent *dentry, child *dentry) {
// The new child was added to parent and took a ref on the parent (hence
// parent can be removed from cache). A new child has 0 refs for now. So
// checkCachingLocked() should be called on both. Call it first on the parent
// as it may create space in the cache for child to be inserted - hence
// avoiding a cache eviction.
*ds = appendDentry(*ds, parent)
*ds = appendDentry(*ds, child)
}
// Preconditions: ds != nil.
func putDentrySlice(ds *[]*dentry) {
// Allow dentries to be GC'd.
for i := range *ds {
(*ds)[i] = nil
}
*ds = (*ds)[:0]
dentrySlicePool.Put(ds)
}
// renameMuRUnlockAndCheckCaching calls fs.renameMu.RUnlock(), then calls
// dentry.checkCachingLocked on all dentries in *dsp with fs.renameMu locked
// for writing.
//
// dsp is a pointer-to-pointer since defer evaluates its arguments immediately,
// but dentry slices are allocated lazily, and it's much easier to say "defer
// fs.renameMuRUnlockAndCheckCaching(&ds)" than "defer func() {
// fs.renameMuRUnlockAndCheckCaching(ds) }()" to work around this.
// +checklocksreleaseread:fs.renameMu
func (fs *filesystem) renameMuRUnlockAndCheckCaching(ctx context.Context, dsp **[]*dentry) {
fs.renameMu.RUnlock()
if *dsp == nil {
return
}
ds := **dsp
for _, d := range ds {
d.checkCachingLocked(ctx, false /* renameMuWriteLocked */)
}
putDentrySlice(*dsp)
}
// +checklocksrelease:fs.renameMu
func (fs *filesystem) renameMuUnlockAndCheckCaching(ctx context.Context, ds **[]*dentry) {
if *ds == nil {
fs.renameMu.Unlock()
return
}
for _, d := range **ds {
d.checkCachingLocked(ctx, true /* renameMuWriteLocked */)
}
fs.renameMu.Unlock()
putDentrySlice(*ds)
}
// stepLocked resolves rp.Component() to an existing file, starting from the
// given directory. If the file at rp.Component is a symlink and
// mayFollowSymlinks is set, the symlink is resolved and the result returned to
// the caller (single step).
//
// Dentries which may become cached as a result of the traversal are appended
// to *ds.
//
// Preconditions:
// - fs.renameMu must be locked.
// - d.dirMu must be locked.
// - !rp.Done().
// - If !d.cachedMetadataAuthoritative(), then d and all children that are
// part of rp must have been revalidated.
func (fs *filesystem) stepLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, mayFollowSymlinks bool, ds **[]*dentry) (*dentry, bool, error) {
if !d.isDir() {
return nil, false, linuxerr.ENOTDIR
}
if err := d.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
return nil, false, err
}
name := rp.Component()
if name == "." {
rp.Advance()
return d, false, nil
}
if name == ".." {
if isRoot, err := rp.CheckRoot(ctx, &d.vfsd); err != nil {
return nil, false, err
} else if isRoot || d.parent == nil {
rp.Advance()
return d, false, nil
}
if err := rp.CheckMount(ctx, &d.parent.vfsd); err != nil {
return nil, false, err
}
rp.Advance()
return d.parent, false, nil
}
child, err := fs.getChildAndWalkPathLocked(ctx, d, rp, ds)
if err != nil {
return nil, false, err
}
if err := rp.CheckMount(ctx, &child.vfsd); err != nil {
return nil, false, err
}
if child.isSymlink() && mayFollowSymlinks && rp.ShouldFollowSymlink() {
target, err := child.readlink(ctx, rp.Mount())
if err != nil {
return nil, false, err
}
if err := rp.HandleSymlink(target); err != nil {
return nil, false, err
}
return d, true, nil
}
rp.Advance()
return child, false, nil
}
// Preconditions:
// - fs.renameMu must be locked.
// - parent.dirMu must be locked.
// - parent.isDir().
// - parent and the dentry at name have been revalidated.
func (fs *filesystem) getChildAndWalkPathLocked(ctx context.Context, parent *dentry, rp *vfs.ResolvingPath, ds **[]*dentry) (*dentry, error) {
// Note that pit is a copy of the iterator that does not affect rp.
pit := rp.Pit()
first := pit.String()
if len(first) > MaxFilenameLen {
return nil, linuxerr.ENAMETOOLONG
}
if child, ok := parent.children[first]; ok || parent.isSynthetic() {
if child == nil {
return nil, linuxerr.ENOENT
}
return child, nil
}
if parent.childrenSet != nil {
// Is the first child even there? Don't make RPC if not.
if _, ok := parent.childrenSet[first]; !ok {
return nil, linuxerr.ENOENT
}
}
// Walk as much of the path as possible in 1 RPC.
names := []string{first}
for pit = pit.Next(); pit.Ok(); pit = pit.Next() {
name := pit.String()
if name == "." {
continue
}
if name == ".." {
break
}
names = append(names, name)
}
status, inodes, err := parent.controlFDLisa.WalkMultiple(ctx, names)
if err != nil {
return nil, err
}
if len(inodes) == 0 {
parent.cacheNegativeLookupLocked(first)
return nil, linuxerr.ENOENT
}
// Add the walked inodes into the dentry tree.
curParent := parent
curParentDirMuLock := func() {
if curParent != parent {
curParent.dirMu.Lock()
}
}
curParentDirMuUnlock := func() {
if curParent != parent {
curParent.dirMu.Unlock() // +checklocksforce: locked via curParentDirMuLock().
}
}
var ret *dentry
var dentryCreationErr error
for i := range inodes {
if dentryCreationErr != nil {
fs.client.CloseFD(ctx, inodes[i].ControlFD, false /* flush */)
continue
}
child, err := fs.newDentry(ctx, &inodes[i])
if err != nil {
fs.client.CloseFD(ctx, inodes[i].ControlFD, false /* flush */)
dentryCreationErr = err
continue
}
curParentDirMuLock()
curParent.cacheNewChildLocked(child, names[i])
curParentDirMuUnlock()
// For now, child has 0 references, so our caller should call
// child.checkCachingLocked(). curParent gained a ref so we should also
// call curParent.checkCachingLocked() so it can be removed from the cache
// if needed. We only do that for the first iteration because all
// subsequent parents would have already been added to ds.
if i == 0 {
*ds = appendDentry(*ds, curParent)
}
*ds = appendDentry(*ds, child)
curParent = child
if i == 0 {
ret = child
}
}
if status == lisafs.WalkComponentDoesNotExist && curParent.isDir() {
curParentDirMuLock()
curParent.cacheNegativeLookupLocked(names[len(inodes)])
curParentDirMuUnlock()
}
return ret, dentryCreationErr
}
// getChildLocked returns a dentry representing the child of parent with the
// given name. Returns ENOENT if the child doesn't exist.
//
// Preconditions:
// - fs.renameMu must be locked.
// - parent.dirMu must be locked.
// - parent.isDir().
// - name is not "." or "..".
// - parent and the dentry at name have been revalidated.
func (fs *filesystem) getChildLocked(ctx context.Context, parent *dentry, name string, ds **[]*dentry) (*dentry, error) {
if len(name) > MaxFilenameLen {
return nil, linuxerr.ENAMETOOLONG
}
if child, ok := parent.children[name]; ok || parent.isSynthetic() {
if child == nil {
return nil, linuxerr.ENOENT
}
return child, nil
}
if parent.childrenSet != nil {
// Is the child even there? Don't make RPC if not.
if _, ok := parent.childrenSet[name]; !ok {
return nil, linuxerr.ENOENT
}
}
childInode, err := parent.controlFDLisa.Walk(ctx, name)
if err != nil {
if linuxerr.Equals(linuxerr.ENOENT, err) {
parent.cacheNegativeLookupLocked(name)
}
return nil, err
}
// Create a new dentry representing the file.
child, err := fs.newDentry(ctx, &childInode)
if err != nil {
fs.client.CloseFD(ctx, childInode.ControlFD, false /* flush */)
return nil, err
}
parent.cacheNewChildLocked(child, name)
appendNewChildDentry(ds, parent, child)
return child, nil
}
// walkParentDirLocked resolves all but the last path component of rp to an
// existing directory, starting from the given directory (which is usually
// rp.Start().Impl().(*dentry)). It does not check that the returned directory
// is searchable by the provider of rp.
//
// Preconditions:
// - fs.renameMu must be locked.
// - !rp.Done().
// - If !d.cachedMetadataAuthoritative(), then d's cached metadata must be up
// to date.
func (fs *filesystem) walkParentDirLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, ds **[]*dentry) (*dentry, error) {
if err := fs.revalidateParentDir(ctx, rp, d, ds); err != nil {
return nil, err
}
for !rp.Final() {
d.dirMu.Lock()
next, followedSymlink, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds)
d.dirMu.Unlock()
if err != nil {
return nil, err
}
d = next
if followedSymlink {
if err := fs.revalidateParentDir(ctx, rp, d, ds); err != nil {
return nil, err
}
}
}
if !d.isDir() {
return nil, linuxerr.ENOTDIR
}
return d, nil
}
// resolveLocked resolves rp to an existing file.
//
// Preconditions: fs.renameMu must be locked.
func (fs *filesystem) resolveLocked(ctx context.Context, rp *vfs.ResolvingPath, ds **[]*dentry) (*dentry, error) {
d := rp.Start().Impl().(*dentry)
if err := fs.revalidatePath(ctx, rp, d, ds); err != nil {
return nil, err
}
for !rp.Done() {
d.dirMu.Lock()
next, followedSymlink, err := fs.stepLocked(ctx, rp, d, true /* mayFollowSymlinks */, ds)
d.dirMu.Unlock()
if err != nil {
return nil, err
}
d = next
if followedSymlink {
if err := fs.revalidatePath(ctx, rp, d, ds); err != nil {
return nil, err
}
}
}
if rp.MustBeDir() && !d.isDir() {
return nil, linuxerr.ENOTDIR
}
return d, nil
}
// doCreateAt checks that creating a file at rp is permitted, then invokes
// createInRemoteDir (if the parent directory is a real remote directory) or
// createInSyntheticDir (if the parent directory is synthetic) to do so.
//
// Preconditions:
// - !rp.Done().
// - For the final path component in rp, !rp.ShouldFollowSymlink().
func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool, createInRemoteDir func(parent *dentry, name string, ds **[]*dentry) error, createInSyntheticDir func(parent *dentry, name string) error) error {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
start := rp.Start().Impl().(*dentry)
parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
if err != nil {
return err
}
// Order of checks is important. First check if parent directory can be
// executed, then check for existence, and lastly check if mount is writable.
if err := parent.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
return err
}
name := rp.Component()
if name == "." || name == ".." {
return linuxerr.EEXIST
}
if parent.isDeleted() {
return linuxerr.ENOENT
}
if err := fs.revalidateOne(ctx, rp.VirtualFilesystem(), parent, name, &ds); err != nil {
return err
}
parent.dirMu.Lock()
defer parent.dirMu.Unlock()
if len(name) > MaxFilenameLen {
return linuxerr.ENAMETOOLONG
}
// Check for existence only if caching information is available. Otherwise,
// don't check for existence just yet. We will check for existence if the
// checks for writability fail below. Existence check is done by the creation
// RPCs themselves.
if child, ok := parent.children[name]; ok && child != nil {
return linuxerr.EEXIST
}
if parent.childrenSet != nil {
if _, ok := parent.childrenSet[name]; ok {
return linuxerr.EEXIST
}
}
checkExistence := func() error {
if child, err := fs.getChildLocked(ctx, parent, name, &ds); err != nil && !linuxerr.Equals(linuxerr.ENOENT, err) {
return err
} else if child != nil {
return linuxerr.EEXIST
}
return nil
}
mnt := rp.Mount()
if err := mnt.CheckBeginWrite(); err != nil {
// Existence check takes precedence.
if existenceErr := checkExistence(); existenceErr != nil {
return existenceErr
}
return err
}
defer mnt.EndWrite()
if err := parent.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil {
// Existence check takes precedence.
if existenceErr := checkExistence(); existenceErr != nil {
return existenceErr
}
return err
}
if !dir && rp.MustBeDir() {
return linuxerr.ENOENT
}
if parent.isSynthetic() {
if createInSyntheticDir == nil {
return linuxerr.EPERM
}
if err := createInSyntheticDir(parent, name); err != nil {
return err
}
parent.touchCMtime()
parent.clearDirentsLocked()
ev := linux.IN_CREATE
if dir {
ev |= linux.IN_ISDIR
}
parent.watches.Notify(ctx, name, uint32(ev), 0, vfs.InodeEvent, false /* unlinked */)
return nil
}
// No cached dentry exists; however, in InteropModeShared there might still be
// an existing file at name. Just attempt the file creation RPC anyways. If a
// file does exist, the RPC will fail with EEXIST like we would have.
if err := createInRemoteDir(parent, name, &ds); err != nil {
return err
}
if fs.opts.interop != InteropModeShared {
if child, ok := parent.children[name]; ok && child == nil {
// Delete the now-stale negative dentry.
delete(parent.children, name)
parent.negativeChildren--
}
parent.touchCMtime()
parent.clearDirentsLocked()
}
ev := linux.IN_CREATE
if dir {
ev |= linux.IN_ISDIR
}
parent.watches.Notify(ctx, name, uint32(ev), 0, vfs.InodeEvent, false /* unlinked */)
return nil
}
// Preconditions: !rp.Done().
func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool) error {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
start := rp.Start().Impl().(*dentry)
parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
if err != nil {
return err
}
if err := parent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
return err
}
if err := rp.Mount().CheckBeginWrite(); err != nil {
return err
}
defer rp.Mount().EndWrite()
name := rp.Component()
if dir {
if name == "." {
return linuxerr.EINVAL
}
if name == ".." {
return linuxerr.ENOTEMPTY
}
} else {
if name == "." || name == ".." {
return linuxerr.EISDIR
}
}
vfsObj := rp.VirtualFilesystem()
if err := fs.revalidateOne(ctx, vfsObj, parent, rp.Component(), &ds); err != nil {
return err
}
mntns := vfs.MountNamespaceFromContext(ctx)
defer mntns.DecRef(ctx)
parent.dirMu.Lock()
defer parent.dirMu.Unlock()
if parent.childrenSet != nil {
if _, ok := parent.childrenSet[name]; !ok {
return linuxerr.ENOENT
}
}
// Load child if sticky bit is set because we need to determine whether
// deletion is allowed.
var child *dentry
if parent.mode.Load()&linux.ModeSticky == 0 {
var ok bool
child, ok = parent.children[name]
if ok && child == nil {
// Hit a negative cached entry, child doesn't exist.
return linuxerr.ENOENT
}
} else {
child, _, err = fs.stepLocked(ctx, rp, parent, false /* mayFollowSymlinks */, &ds)
if err != nil {
return err
}
if err := parent.mayDelete(rp.Credentials(), child); err != nil {
return err
}
}
// If a child dentry exists, prepare to delete it. This should fail if it is
// a mount point. We detect mount points by speculatively calling
// PrepareDeleteDentry, which fails if child is a mount point.
//
// Also note that if child is nil, then it can't be a mount point.
if child != nil {
// Hold child.dirMu so we can check child.children and
// child.syntheticChildren. We don't access these fields until a bit later,
// but locking child.dirMu after calling vfs.PrepareDeleteDentry() would
// create an inconsistent lock ordering between dentry.dirMu and
// vfs.Dentry.mu (in the VFS lock order, it would make dentry.dirMu both "a
// FilesystemImpl lock" and "a lock acquired by a FilesystemImpl between
// PrepareDeleteDentry and CommitDeleteDentry). To avoid this, lock
// child.dirMu before calling PrepareDeleteDentry.
child.dirMu.Lock()
defer child.dirMu.Unlock()
if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil {
return err
}
}
flags := uint32(0)
// If a dentry exists, use it for best-effort checks on its deletability.
if dir {
if child != nil {
// child must be an empty directory.
if child.syntheticChildren != 0 {
// This is definitely not an empty directory, irrespective of
// fs.opts.interop.
vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: PrepareDeleteDentry called if child != nil.
return linuxerr.ENOTEMPTY
}
// If InteropModeShared is in effect and the first call to
// PrepareDeleteDentry above succeeded, then child wasn't
// revalidated (so we can't expect its file type to be correct) and
// individually revalidating its children (to confirm that they
// still exist) would be a waste of time.
if child.cachedMetadataAuthoritative() {
if !child.isDir() {
vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above.
return linuxerr.ENOTDIR
}
for _, grandchild := range child.children {
if grandchild != nil {
vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above.
return linuxerr.ENOTEMPTY
}
}
}
}
flags = linux.AT_REMOVEDIR
} else {
// child must be a non-directory file.
if child != nil && child.isDir() {
vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above.
return linuxerr.EISDIR
}
if rp.MustBeDir() {
if child != nil {
vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above.
}
return linuxerr.ENOTDIR
}
}
if parent.isSynthetic() {
if child == nil {
return linuxerr.ENOENT
}
} else if child == nil || !child.isSynthetic() {
if err := parent.controlFDLisa.UnlinkAt(ctx, name, flags); err != nil {
if child != nil {
vfsObj.AbortDeleteDentry(&child.vfsd) // +checklocksforce: see above.
}
return err
}
}
// Generate inotify events for rmdir or unlink.
if dir {
parent.watches.Notify(ctx, name, linux.IN_DELETE|linux.IN_ISDIR, 0, vfs.InodeEvent, true /* unlinked */)
} else {
var cw *vfs.Watches
if child != nil {
cw = &child.watches
}
vfs.InotifyRemoveChild(ctx, cw, &parent.watches, name)
}
if child != nil {
vfsObj.CommitDeleteDentry(ctx, &child.vfsd) // +checklocksforce: see above.
child.setDeleted()
if child.isSynthetic() {
parent.syntheticChildren--
child.decRefNoCaching()
}
ds = appendDentry(ds, child)
}
parent.cacheNegativeLookupLocked(name)
if parent.cachedMetadataAuthoritative() {
parent.clearDirentsLocked()
parent.touchCMtime()
if dir {
parent.decLinks()
}
}
return nil
}
// AccessAt implements vfs.Filesystem.Impl.AccessAt.
func (fs *filesystem) AccessAt(ctx context.Context, rp *vfs.ResolvingPath, creds *auth.Credentials, ats vfs.AccessTypes) error {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return err
}
if err := d.checkPermissions(creds, ats); err != nil {
return err
}
if ats.MayWrite() && rp.Mount().ReadOnly() {
return linuxerr.EROFS
}
return nil
}
// GetDentryAt implements vfs.FilesystemImpl.GetDentryAt.
func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetDentryOptions) (*vfs.Dentry, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return nil, err
}
if opts.CheckSearchable {
if !d.isDir() {
return nil, linuxerr.ENOTDIR
}
if err := d.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
return nil, err
}
}
d.IncRef()
// Call d.checkCachingLocked() so it can be removed from the cache if needed.
ds = appendDentry(ds, d)
return &d.vfsd, nil
}
// GetParentDentryAt implements vfs.FilesystemImpl.GetParentDentryAt.
func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
start := rp.Start().Impl().(*dentry)
d, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
if err != nil {
return nil, err
}
d.IncRef()
// Call d.checkCachingLocked() so it can be removed from the cache if needed.
ds = appendDentry(ds, d)
return &d.vfsd, nil
}
// LinkAt implements vfs.FilesystemImpl.LinkAt.
func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry) error {
err := fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string, ds **[]*dentry) error {
if rp.Mount() != vd.Mount() {
return linuxerr.EXDEV
}
d := vd.Dentry().Impl().(*dentry)
if d.isDir() {
return linuxerr.EPERM
}
gid := auth.KGID(d.gid.Load())
uid := auth.KUID(d.uid.Load())
mode := linux.FileMode(d.mode.Load())
if err := vfs.MayLink(rp.Credentials(), mode, uid, gid); err != nil {
return err
}
if d.nlink.Load() == 0 {
return linuxerr.ENOENT
}
if d.nlink.Load() == math.MaxUint32 {
return linuxerr.EMLINK
}
linkInode, err := parent.controlFDLisa.LinkAt(ctx, d.controlFDLisa.ID(), childName)
if err != nil {
return err
}
return parent.insertCreatedChildLocked(ctx, &linkInode, childName, nil, ds)
}, nil)
if err == nil {
// Success!
vd.Dentry().Impl().(*dentry).incLinks()
}
return err
}
// MkdirAt implements vfs.FilesystemImpl.MkdirAt.
func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error {
creds := rp.Credentials()
return fs.doCreateAt(ctx, rp, true /* dir */, func(parent *dentry, name string, ds **[]*dentry) error {
// If the parent is a setgid directory, use the parent's GID
// rather than the caller's and enable setgid.
kgid := creds.EffectiveKGID
mode := opts.Mode
if parent.mode.Load()&linux.S_ISGID != 0 {
kgid = auth.KGID(parent.gid.Load())
mode |= linux.S_ISGID
}
childDirInode, err := parent.controlFDLisa.MkdirAt(ctx, name, mode, lisafs.UID(creds.EffectiveKUID), lisafs.GID(kgid))
if err == nil {
if err = parent.insertCreatedChildLocked(ctx, &childDirInode, name, nil, ds); err != nil {
return err
}
if fs.opts.interop != InteropModeShared {
parent.incLinks()
}
return nil
}
if !opts.ForSyntheticMountpoint || linuxerr.Equals(linuxerr.EEXIST, err) {
return err
}
ctx.Infof("Failed to create remote directory %q: %v; falling back to synthetic directory", name, err)
parent.createSyntheticChildLocked(&createSyntheticOpts{
name: name,
mode: linux.S_IFDIR | opts.Mode,
kuid: creds.EffectiveKUID,
kgid: creds.EffectiveKGID,
})
*ds = appendDentry(*ds, parent)
if fs.opts.interop != InteropModeShared {
parent.incLinks()
}
return nil
}, func(parent *dentry, name string) error {
if !opts.ForSyntheticMountpoint {
// Can't create non-synthetic files in synthetic directories.
return linuxerr.EPERM
}
parent.createSyntheticChildLocked(&createSyntheticOpts{
name: name,
mode: linux.S_IFDIR | opts.Mode,
kuid: creds.EffectiveKUID,
kgid: creds.EffectiveKGID,
})
parent.incLinks()
return nil
})
}
// MknodAt implements vfs.FilesystemImpl.MknodAt.
func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error {
return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, name string, ds **[]*dentry) error {
creds := rp.Credentials()
if err := parent.mknodLocked(ctx, name, creds, opts, ds); err == nil {
return nil
} else if !linuxerr.Equals(linuxerr.EPERM, err) {
return err
}
// EPERM means that gofer does not allow creating a socket or pipe. Fallback
// to creating a synthetic one, i.e. one that is kept entirely in memory.
// Check that we're not overriding an existing file with a synthetic one.
_, _, err := fs.stepLocked(ctx, rp, parent, false, ds)
switch {
case err == nil:
// Step succeeded, another file exists.
return linuxerr.EEXIST
case !linuxerr.Equals(linuxerr.ENOENT, err):
// Unexpected error.
return err
}
switch opts.Mode.FileType() {
case linux.S_IFSOCK:
parent.createSyntheticChildLocked(&createSyntheticOpts{
name: name,
mode: opts.Mode,
kuid: creds.EffectiveKUID,
kgid: creds.EffectiveKGID,
endpoint: opts.Endpoint,
})
*ds = appendDentry(*ds, parent)
return nil
case linux.S_IFIFO:
parent.createSyntheticChildLocked(&createSyntheticOpts{
name: name,
mode: opts.Mode,
kuid: creds.EffectiveKUID,
kgid: creds.EffectiveKGID,
pipe: pipe.NewVFSPipe(true /* isNamed */, pipe.DefaultPipeSize),
})
*ds = appendDentry(*ds, parent)
return nil
}
// Retain error from gofer if synthetic file cannot be created internally.
return linuxerr.EPERM
}, nil)
}
// OpenAt implements vfs.FilesystemImpl.OpenAt.
func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
// Reject O_TMPFILE, which is not supported; supporting it correctly in the
// presence of other remote filesystem users requires remote filesystem
// support, and it isn't clear that there's any way to implement this in
// 9P.
if opts.Flags&linux.O_TMPFILE != 0 {
return nil, linuxerr.EOPNOTSUPP
}
mayCreate := opts.Flags&linux.O_CREAT != 0
mustCreate := opts.Flags&(linux.O_CREAT|linux.O_EXCL) == (linux.O_CREAT | linux.O_EXCL)
var ds *[]*dentry
fs.renameMu.RLock()
unlocked := false
unlock := func() {
if !unlocked {
fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
unlocked = true
}
}
defer unlock()
start := rp.Start().Impl().(*dentry)
if rp.Done() {
// Reject attempts to open mount root directory with O_CREAT.
if mayCreate && rp.MustBeDir() {
return nil, linuxerr.EISDIR
}
if mustCreate {
return nil, linuxerr.EEXIST
}
if !start.cachedMetadataAuthoritative() {
// Refresh dentry's attributes before opening.
if err := start.updateMetadata(ctx, nil); err != nil {
return nil, err
}
}
start.IncRef()
defer start.DecRef(ctx)
unlock()
// start is intentionally not added to ds (which would remove it from the
// cache) because doing so regresses performance in practice.
return start.open(ctx, rp, &opts)
}
afterTrailingSymlink:
parent, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
if err != nil {
return nil, err
}
// Check for search permission in the parent directory.
if err := parent.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
return nil, err
}
// Reject attempts to open directories with O_CREAT.
if mayCreate && rp.MustBeDir() {
return nil, linuxerr.EISDIR
}
if err := fs.revalidateOne(ctx, rp.VirtualFilesystem(), parent, rp.Component(), &ds); err != nil {
return nil, err
}
// Determine whether or not we need to create a file.
parent.dirMu.Lock()
child, _, err := fs.stepLocked(ctx, rp, parent, false /* mayFollowSymlinks */, &ds)
if linuxerr.Equals(linuxerr.ENOENT, err) && mayCreate {
if parent.isSynthetic() {
parent.dirMu.Unlock()
return nil, linuxerr.EPERM
}
fd, err := parent.createAndOpenChildLocked(ctx, rp, &opts, &ds)
parent.dirMu.Unlock()
return fd, err
}
parent.dirMu.Unlock()
if err != nil {
return nil, err
}
if mustCreate {
return nil, linuxerr.EEXIST
}
// Open existing child or follow symlink.
if child.isSymlink() && rp.ShouldFollowSymlink() {
target, err := child.readlink(ctx, rp.Mount())
if err != nil {
return nil, err
}
if err := rp.HandleSymlink(target); err != nil {
return nil, err
}
start = parent
goto afterTrailingSymlink
}
if rp.MustBeDir() && !child.isDir() {
return nil, linuxerr.ENOTDIR
}
child.IncRef()
defer child.DecRef(ctx)
unlock()
// child is intentionally not added to ds (which would remove it from the
// cache) because doing so regresses performance in practice.
return child.open(ctx, rp, &opts)
}
// Preconditions: The caller must hold no locks (since opening pipes may block
// indefinitely).
func (d *dentry) open(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions) (*vfs.FileDescription, error) {
ats := vfs.AccessTypesForOpenFlags(opts)
if err := d.checkPermissions(rp.Credentials(), ats); err != nil {
return nil, err
}
trunc := opts.Flags&linux.O_TRUNC != 0 && d.fileType() == linux.S_IFREG
if trunc {
// Lock metadataMu *while* we open a regular file with O_TRUNC because
// open(2) will change the file size on server.
d.metadataMu.Lock()
defer d.metadataMu.Unlock()
}
var vfd *vfs.FileDescription
var err error
mnt := rp.Mount()
switch d.fileType() {
case linux.S_IFREG:
if !d.fs.opts.regularFilesUseSpecialFileFD {
if err := d.ensureSharedHandle(ctx, ats.MayRead(), ats.MayWrite(), trunc); err != nil {
return nil, err
}
fd, err := newRegularFileFD(mnt, d, opts.Flags)
if err != nil {
return nil, err
}
vfd = &fd.vfsfd
}
case linux.S_IFDIR:
// Can't open directories with O_CREAT.
if opts.Flags&linux.O_CREAT != 0 {
return nil, linuxerr.EISDIR
}
// Can't open directories writably.
if ats&vfs.MayWrite != 0 {
return nil, linuxerr.EISDIR
}
if opts.Flags&linux.O_DIRECT != 0 {
return nil, linuxerr.EINVAL
}
if !d.isSynthetic() {
if err := d.ensureSharedHandle(ctx, ats&vfs.MayRead != 0, false /* write */, false /* trunc */); err != nil {
return nil, err
}
}
fd := &directoryFD{}
fd.LockFD.Init(&d.locks)
if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &d.vfsd, &vfs.FileDescriptionOptions{}); err != nil {
return nil, err
}
if d.readFD.Load() >= 0 {
fsmetric.GoferOpensHost.Increment()
} else {
fsmetric.GoferOpens9P.Increment()
}
return &fd.vfsfd, nil
case linux.S_IFLNK:
// Can't open symlinks without O_PATH, which is handled at the VFS layer.
return nil, linuxerr.ELOOP
case linux.S_IFSOCK:
if d.isSynthetic() {
return nil, linuxerr.ENXIO
}
if d.fs.iopts.OpenSocketsByConnecting {
return d.openSocketByConnecting(ctx, opts)
}
case linux.S_IFIFO:
if d.isSynthetic() {
return d.pipe.Open(ctx, mnt, &d.vfsd, opts.Flags, &d.locks)
}
}
if vfd == nil {
if vfd, err = d.openSpecialFile(ctx, mnt, opts); err != nil {
return nil, err
}
}
if trunc {
// If no errors occured so far then update file size in memory. This
// step is required even if !d.cachedMetadataAuthoritative() because
// d.mappings has to be updated.
// d.metadataMu has already been acquired if trunc == true.
d.updateSizeLocked(0)
if d.cachedMetadataAuthoritative() {
d.touchCMtimeLocked()
}
}
return vfd, err
}
func (d *dentry) openSocketByConnecting(ctx context.Context, opts *vfs.OpenOptions) (*vfs.FileDescription, error) {
if opts.Flags&linux.O_DIRECT != 0 {
return nil, linuxerr.EINVAL
}
// Note that special value of linux.SockType = 0 is interpreted by lisafs
// as "do not care about the socket type". Analogous to p9.AnonymousSocket.
sockFD, err := d.controlFDLisa.Connect(ctx, 0 /* sockType */)
if err != nil {
return nil, err
}
fd, err := host.NewFD(ctx, kernel.KernelFromContext(ctx).HostMount(), sockFD, &host.NewFDOptions{
HaveFlags: true,
Flags: opts.Flags,
})
if err != nil {
unix.Close(sockFD)
return nil, err
}
return fd, nil
}
func (d *dentry) openSpecialFile(ctx context.Context, mnt *vfs.Mount, opts *vfs.OpenOptions) (*vfs.FileDescription, error) {
ats := vfs.AccessTypesForOpenFlags(opts)
if opts.Flags&linux.O_DIRECT != 0 && !d.isRegularFile() {
return nil, linuxerr.EINVAL
}
// We assume that the server silently inserts O_NONBLOCK in the open flags
// for all named pipes (because all existing gofers do this).
//
// NOTE(b/133875563): This makes named pipe opens racy, because the
// mechanisms for translating nonblocking to blocking opens can only detect
// the instantaneous presence of a peer holding the other end of the pipe
// open, not whether the pipe was *previously* opened by a peer that has
// since closed its end.
isBlockingOpenOfNamedPipe := d.fileType() == linux.S_IFIFO && opts.Flags&linux.O_NONBLOCK == 0
retry:
h, err := openHandle(ctx, d.controlFDLisa, ats.MayRead(), ats.MayWrite(), opts.Flags&linux.O_TRUNC != 0)
if err != nil {
if isBlockingOpenOfNamedPipe && ats == vfs.MayWrite && linuxerr.Equals(linuxerr.ENXIO, err) {
// An attempt to open a named pipe with O_WRONLY|O_NONBLOCK fails
// with ENXIO if opening the same named pipe with O_WRONLY would
// block because there are no readers of the pipe.
if err := sleepBetweenNamedPipeOpenChecks(ctx); err != nil {
return nil, err
}
goto retry
}
return nil, err
}
if isBlockingOpenOfNamedPipe && ats == vfs.MayRead && h.fd >= 0 {
if err := blockUntilNonblockingPipeHasWriter(ctx, h.fd); err != nil {
h.close(ctx)
return nil, err
}
}
fd, err := newSpecialFileFD(h, mnt, d, opts.Flags)
if err != nil {
h.close(ctx)
return nil, err
}
return &fd.vfsfd, nil
}
// Preconditions:
// - d.fs.renameMu must be locked.
// - d.dirMu must be locked.
// - !d.isSynthetic().
func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vfs.OpenOptions, ds **[]*dentry) (*vfs.FileDescription, error) {
if err := d.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil {
return nil, err
}
if d.isDeleted() {
return nil, linuxerr.ENOENT
}
mnt := rp.Mount()
if err := mnt.CheckBeginWrite(); err != nil {
return nil, err
}
defer mnt.EndWrite()
creds := rp.Credentials()
name := rp.Component()
// If the parent is a setgid directory, use the parent's GID rather
// than the caller's.
kgid := creds.EffectiveKGID
if d.mode.Load()&linux.S_ISGID != 0 {
kgid = auth.KGID(d.gid.Load())
}
ino, openFD, hostFD, err := d.controlFDLisa.OpenCreateAt(ctx, name, opts.Flags&linux.O_ACCMODE, opts.Mode, lisafs.UID(creds.EffectiveKUID), lisafs.GID(kgid))
if err != nil {
return nil, err
}
child, err := d.fs.newDentry(ctx, &ino)
if err != nil {
d.fs.client.CloseFD(ctx, ino.ControlFD, false /* flush */)
d.fs.client.CloseFD(ctx, openFD, false /* flush */)
if hostFD >= 0 {
unix.Close(hostFD)
}
return nil, err
}
// Incorporate the fid that was opened by lcreate.
useRegularFileFD := child.fileType() == linux.S_IFREG && !d.fs.opts.regularFilesUseSpecialFileFD
if useRegularFileFD {
child.handleMu.Lock()
if vfs.MayReadFileWithOpenFlags(opts.Flags) {
child.readFDLisa = d.fs.client.NewFD(openFD)
if hostFD != -1 {
child.readFD = atomicbitops.FromInt32(int32(hostFD))
child.mmapFD = atomicbitops.FromInt32(int32(hostFD))
}
}
if vfs.MayWriteFileWithOpenFlags(opts.Flags) {
child.writeFDLisa = d.fs.client.NewFD(openFD)
child.writeFD = atomicbitops.FromInt32(int32(hostFD))
}
child.handleMu.Unlock()
}
// Insert the dentry into the tree.
d.cacheNewChildLocked(child, name)
appendNewChildDentry(ds, d, child)
if d.cachedMetadataAuthoritative() {
d.touchCMtime()
d.clearDirentsLocked()
}
// Finally, construct a file description representing the created file.
var childVFSFD *vfs.FileDescription
if useRegularFileFD {
fd, err := newRegularFileFD(mnt, child, opts.Flags)
if err != nil {
return nil, err
}
childVFSFD = &fd.vfsfd
} else {
h := handle{
fdLisa: d.fs.client.NewFD(openFD),
fd: int32(hostFD),
}
fd, err := newSpecialFileFD(h, mnt, child, opts.Flags)
if err != nil {
h.close(ctx)
return nil, err
}
childVFSFD = &fd.vfsfd
}
d.watches.Notify(ctx, name, linux.IN_CREATE, 0, vfs.PathEvent, false /* unlinked */)
return childVFSFD, nil
}
// ReadlinkAt implements vfs.FilesystemImpl.ReadlinkAt.
func (fs *filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (string, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return "", err
}
if !d.isSymlink() {
return "", linuxerr.EINVAL
}
return d.readlink(ctx, rp.Mount())
}
// RenameAt implements vfs.FilesystemImpl.RenameAt.
func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldParentVD vfs.VirtualDentry, oldName string, opts vfs.RenameOptions) error {
// Resolve newParent first to verify that it's on this Mount.
var ds *[]*dentry
fs.renameMu.Lock()
defer fs.renameMuUnlockAndCheckCaching(ctx, &ds)
newParent, err := fs.walkParentDirLocked(ctx, rp, rp.Start().Impl().(*dentry), &ds)
if err != nil {
return err
}
if opts.Flags&^linux.RENAME_NOREPLACE != 0 {
return linuxerr.EINVAL
}
if fs.opts.interop == InteropModeShared && opts.Flags&linux.RENAME_NOREPLACE != 0 {
// Requires 9P support to synchronize with other remote filesystem
// users.
return linuxerr.EINVAL
}
newName := rp.Component()
if newName == "." || newName == ".." {
if opts.Flags&linux.RENAME_NOREPLACE != 0 {
return linuxerr.EEXIST
}
return linuxerr.EBUSY
}
if len(newName) > MaxFilenameLen {
return linuxerr.ENAMETOOLONG
}
mnt := rp.Mount()
if mnt != oldParentVD.Mount() {
return linuxerr.EXDEV
}
if err := mnt.CheckBeginWrite(); err != nil {
return err
}
defer mnt.EndWrite()
oldParent := oldParentVD.Dentry().Impl().(*dentry)
if !oldParent.cachedMetadataAuthoritative() {
if err := oldParent.updateMetadata(ctx, nil); err != nil {
return err
}
}
creds := rp.Credentials()
if err := oldParent.checkPermissions(creds, vfs.MayWrite|vfs.MayExec); err != nil {
return err
}
vfsObj := rp.VirtualFilesystem()
if err := fs.revalidateOne(ctx, vfsObj, newParent, newName, &ds); err != nil {
return err
}
if err := fs.revalidateOne(ctx, vfsObj, oldParent, oldName, &ds); err != nil {
return err
}
// We need a dentry representing the renamed file since, if it's a
// directory, we need to check for write permission on it.
oldParent.dirMu.Lock()
defer oldParent.dirMu.Unlock()
renamed, err := fs.getChildLocked(ctx, oldParent, oldName, &ds)
if err != nil {
return err
}
if err := oldParent.mayDelete(creds, renamed); err != nil {
return err
}
if renamed.isDir() {
if renamed == newParent || genericIsAncestorDentry(renamed, newParent) {
return linuxerr.EINVAL
}
if oldParent != newParent {
if err := renamed.checkPermissions(creds, vfs.MayWrite); err != nil {
return err
}
}
} else {
if opts.MustBeDir || rp.MustBeDir() {
return linuxerr.ENOTDIR
}
}
if oldParent != newParent {
if err := newParent.checkPermissions(creds, vfs.MayWrite|vfs.MayExec); err != nil {
return err
}
newParent.dirMu.Lock()
defer newParent.dirMu.Unlock()
}
if newParent.isDeleted() {
return linuxerr.ENOENT
}
replaced, err := fs.getChildLocked(ctx, newParent, newName, &ds)
if err != nil && !linuxerr.Equals(linuxerr.ENOENT, err) {
return err
}
var replacedVFSD *vfs.Dentry
if replaced != nil {
if opts.Flags&linux.RENAME_NOREPLACE != 0 {
return linuxerr.EEXIST
}
replacedVFSD = &replaced.vfsd
if replaced.isDir() {
if !renamed.isDir() {
return linuxerr.EISDIR
}
if genericIsAncestorDentry(replaced, renamed) {
return linuxerr.ENOTEMPTY
}
} else {
if rp.MustBeDir() || renamed.isDir() {
return linuxerr.ENOTDIR
}
}
}
if oldParent == newParent && oldName == newName {
return nil
}
mntns := vfs.MountNamespaceFromContext(ctx)
defer mntns.DecRef(ctx)
if err := vfsObj.PrepareRenameDentry(mntns, &renamed.vfsd, replacedVFSD); err != nil {
return err
}
// Update the remote filesystem.
if !renamed.isSynthetic() {
if err := oldParent.controlFDLisa.RenameAt(ctx, oldName, newParent.controlFDLisa.ID(), newName); err != nil {
vfsObj.AbortRenameDentry(&renamed.vfsd, replacedVFSD)
return err
}
} else if replaced != nil && !replaced.isSynthetic() {
// We are replacing an existing real file with a synthetic one, so we
// need to unlink the former.
flags := uint32(0)
if replaced.isDir() {
flags = linux.AT_REMOVEDIR
}
if err := newParent.controlFDLisa.UnlinkAt(ctx, newName, flags); err != nil {
vfsObj.AbortRenameDentry(&renamed.vfsd, replacedVFSD)
return err
}
}
// Update the dentry tree.
vfsObj.CommitRenameReplaceDentry(ctx, &renamed.vfsd, replacedVFSD)
if replaced != nil {
replaced.setDeleted()
if replaced.isSynthetic() {
newParent.syntheticChildren--
replaced.decRefNoCaching()
}
ds = appendDentry(ds, replaced)
}
oldParent.cacheNegativeLookupLocked(oldName)
if renamed.isSynthetic() {
oldParent.syntheticChildren--
newParent.syntheticChildren++
}
newParent.cacheNewChildLocked(renamed, newName)
oldParent.decRefNoCaching()
if oldParent != newParent {
ds = appendDentry(ds, newParent)
ds = appendDentry(ds, oldParent)
}
// Update metadata.
if renamed.cachedMetadataAuthoritative() {
renamed.touchCtime()
}
if oldParent.cachedMetadataAuthoritative() {
oldParent.clearDirentsLocked()
oldParent.touchCMtime()
if renamed.isDir() {
oldParent.decLinks()
}
}
if newParent.cachedMetadataAuthoritative() {
newParent.clearDirentsLocked()
newParent.touchCMtime()
if renamed.isDir() && (replaced == nil || !replaced.isDir()) {
// Increase the link count if we did not replace another directory.
newParent.incLinks()
}
}
vfs.InotifyRename(ctx, &renamed.watches, &oldParent.watches, &newParent.watches, oldName, newName, renamed.isDir())
return nil
}
// RmdirAt implements vfs.FilesystemImpl.RmdirAt.
func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error {
return fs.unlinkAt(ctx, rp, true /* dir */)
}
// SetStatAt implements vfs.FilesystemImpl.SetStatAt.
func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error {
var ds *[]*dentry
fs.renameMu.RLock()
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
return err
}
err = d.setStat(ctx, rp.Credentials(), &opts, rp.Mount())
fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
if err != nil {
return err
}
if ev := vfs.InotifyEventFromStatMask(opts.Stat.Mask); ev != 0 {
d.InotifyWithParent(ctx, ev, 0, vfs.InodeEvent)
}
return nil
}
// StatAt implements vfs.FilesystemImpl.StatAt.
func (fs *filesystem) StatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.StatOptions) (linux.Statx, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return linux.Statx{}, err
}
// Since walking updates metadata for all traversed dentries under
// InteropModeShared, including the returned one, we can return cached
// metadata here regardless of fs.opts.interop.
var stat linux.Statx
d.statTo(&stat)
return stat, nil
}
// StatFSAt implements vfs.FilesystemImpl.StatFSAt.
func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linux.Statfs, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return linux.Statfs{}, err
}
// If d is synthetic, invoke statfs on the first ancestor of d that isn't.
for d.isSynthetic() {
d = d.parent
}
var statFS lisafs.StatFS
if err := d.controlFDLisa.StatFSTo(ctx, &statFS); err != nil {
return linux.Statfs{}, err
}
if statFS.NameLength == 0 || statFS.NameLength > MaxFilenameLen {
statFS.NameLength = MaxFilenameLen
}
return linux.Statfs{
// This is primarily for distinguishing a gofer file system in
// tests. Testing is important, so instead of defining
// something completely random, use a standard value.
Type: linux.V9FS_MAGIC,
BlockSize: statFS.BlockSize,
FragmentSize: statFS.BlockSize,
Blocks: statFS.Blocks,
BlocksFree: statFS.BlocksFree,
BlocksAvailable: statFS.BlocksAvailable,
Files: statFS.Files,
FilesFree: statFS.FilesFree,
NameLength: statFS.NameLength,
}, nil
}
// SymlinkAt implements vfs.FilesystemImpl.SymlinkAt.
func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error {
return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, name string, ds **[]*dentry) error {
creds := rp.Credentials()
symlinkInode, err := parent.controlFDLisa.SymlinkAt(ctx, name, target, lisafs.UID(creds.EffectiveKUID), lisafs.GID(creds.EffectiveKGID))
if err != nil {
return err
}
return parent.insertCreatedChildLocked(ctx, &symlinkInode, name, func(child *dentry) {
if fs.opts.interop != InteropModeShared {
// Cache the symlink target on creation. In practice, this
// helps avoid a lot of ReadLink RPCs.
child.haveTarget = true
child.target = target
}
}, ds)
}, nil)
}
// UnlinkAt implements vfs.FilesystemImpl.UnlinkAt.
func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error {
return fs.unlinkAt(ctx, rp, false /* dir */)
}
// BoundEndpointAt implements vfs.FilesystemImpl.BoundEndpointAt.
func (fs *filesystem) BoundEndpointAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.BoundEndpointOptions) (transport.BoundEndpoint, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return nil, err
}
if err := d.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil {
return nil, err
}
if !d.isSocket() {
return nil, linuxerr.ECONNREFUSED
}
if d.endpoint != nil {
return d.endpoint, nil
}
if !d.isSynthetic() {
d.IncRef()
ds = appendDentry(ds, d)
return &endpoint{
dentry: d,
path: opts.Addr,
}, nil
}
return nil, linuxerr.ECONNREFUSED
}
// ListXattrAt implements vfs.FilesystemImpl.ListXattrAt.
func (fs *filesystem) ListXattrAt(ctx context.Context, rp *vfs.ResolvingPath, size uint64) ([]string, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return nil, err
}
return d.listXattr(ctx, size)
}
// GetXattrAt implements vfs.FilesystemImpl.GetXattrAt.
func (fs *filesystem) GetXattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetXattrOptions) (string, error) {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return "", err
}
return d.getXattr(ctx, rp.Credentials(), &opts)
}
// SetXattrAt implements vfs.FilesystemImpl.SetXattrAt.
func (fs *filesystem) SetXattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetXattrOptions) error {
var ds *[]*dentry
fs.renameMu.RLock()
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
return err
}
err = d.setXattr(ctx, rp.Credentials(), &opts)
fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
if err != nil {
return err
}
d.InotifyWithParent(ctx, linux.IN_ATTRIB, 0, vfs.InodeEvent)
return nil
}
// RemoveXattrAt implements vfs.FilesystemImpl.RemoveXattrAt.
func (fs *filesystem) RemoveXattrAt(ctx context.Context, rp *vfs.ResolvingPath, name string) error {
var ds *[]*dentry
fs.renameMu.RLock()
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
return err
}
err = d.removeXattr(ctx, rp.Credentials(), name)
fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
if err != nil {
return err
}
d.InotifyWithParent(ctx, linux.IN_ATTRIB, 0, vfs.InodeEvent)
return nil
}
// PrependPath implements vfs.FilesystemImpl.PrependPath.
func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
fs.renameMu.RLock()
defer fs.renameMu.RUnlock()
return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
}
type mopt struct {
key string
value any
}
func (m mopt) String() string {
if m.value == nil {
return fmt.Sprintf("%s", m.key)
}
return fmt.Sprintf("%s=%v", m.key, m.value)
}
// MountOptions implements vfs.FilesystemImpl.MountOptions.
func (fs *filesystem) MountOptions() string {
optsKV := []mopt{
{moptTransport, transportModeFD}, // Only valid value, currently.
{moptReadFD, fs.opts.fd}, // Currently, read and write FD are the same.
{moptWriteFD, fs.opts.fd}, // Currently, read and write FD are the same.
{moptAname, fs.opts.aname},
{moptDfltUID, fs.opts.dfltuid},
{moptDfltGID, fs.opts.dfltgid},
}
switch fs.opts.interop {
case InteropModeExclusive:
optsKV = append(optsKV, mopt{moptCache, cacheFSCache})
case InteropModeWritethrough:
optsKV = append(optsKV, mopt{moptCache, cacheFSCacheWritethrough})
case InteropModeShared:
if fs.opts.regularFilesUseSpecialFileFD {
optsKV = append(optsKV, mopt{moptCache, cacheNone})
} else {
optsKV = append(optsKV, mopt{moptCache, cacheRemoteRevalidating})
}
}
if fs.opts.forcePageCache {
optsKV = append(optsKV, mopt{moptForcePageCache, nil})
}
if fs.opts.limitHostFDTranslation {
optsKV = append(optsKV, mopt{moptLimitHostFDTranslation, nil})
}
if fs.opts.overlayfsStaleRead {
optsKV = append(optsKV, mopt{moptOverlayfsStaleRead, nil})
}
opts := make([]string, 0, len(optsKV))
for _, opt := range optsKV {
opts = append(opts, opt.String())
}
return strings.Join(opts, ",")
}
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