// LOCKS_EXCLUDED(fs.mu)
func (fs *fileSystem) Rename(
ctx context.Context,
op *fuseops.RenameOp) (err error) {
// Find the old and new parents.
fs.mu.Lock()
oldParent := fs.inodes[op.OldParent].(inode.DirInode)
newParent := fs.inodes[op.NewParent].(inode.DirInode)
fs.mu.Unlock()
// Find the object in the old location.
oldParent.Lock()
lr, err := oldParent.LookUpChild(ctx, op.OldName)
oldParent.Unlock()
if err != nil {
err = fmt.Errorf("LookUpChild: %v", err)
return
}
if !lr.Exists() {
err = fuse.ENOENT
return
}
// We don't support renaming directories.
if inode.IsDirName(lr.FullName) {
err = fuse.ENOSYS
return
}
// Clone into the new location.
newParent.Lock()
_, err = newParent.CloneToChildFile(
ctx,
op.NewName,
lr.Object)
newParent.Unlock()
if err != nil {
err = fmt.Errorf("CloneToChildFile: %v", err)
return
}
// Delete behind. Make sure to delete exactly the generation we cloned, in
// case the referent of the name has changed in the meantime.
oldParent.Lock()
err = oldParent.DeleteChildFile(
ctx,
op.OldName,
lr.Object.Generation,
&lr.Object.MetaGeneration)
oldParent.Unlock()
if err != nil {
err = fmt.Errorf("DeleteChildFile: %v", err)
return
}
return
}
// Attempt to find an inode for the given name, backed by the supplied object
// record (or nil for implicit directories). Create one if one has never yet
// existed and, if the record is non-nil, the record is newer than any inode
// we've yet recorded.
//
// If the record is stale (i.e. some newer inode exists), return nil. In this
// case, the caller may obtain a fresh record and try again. Otherwise,
// increment the inode's lookup count and return it locked.
//
// UNLOCK_FUNCTION(fs.mu)
// LOCK_FUNCTION(in)
func (fs *fileSystem) lookUpOrCreateInodeIfNotStale(
name string,
o *gcs.Object) (in inode.Inode) {
// Sanity check.
if o != nil && name != o.Name {
panic(fmt.Sprintf("Name mismatch: %q vs. %q", name, o.Name))
}
// Ensure that no matter which inode we return, we increase its lookup count
// on the way out.
defer func() {
if in != nil {
in.IncrementLookupCount()
}
}()
// Handle implicit directories.
if o == nil {
if !inode.IsDirName(name) {
panic(fmt.Sprintf("Unexpected name for an implicit directory: %q", name))
}
// If we don't have an entry, create one.
var ok bool
in, ok = fs.implicitDirInodes[name]
if !ok {
in = fs.mintInode(name, nil)
fs.implicitDirInodes[in.Name()] = in.(inode.DirInode)
}
fs.mu.Unlock()
in.Lock()
return
}
oGen := inode.Generation{
Object: o.Generation,
Metadata: o.MetaGeneration,
}
// Retry loop for the stale index entry case below. On entry, we hold fs.mu
// but no inode lock.
for {
// Look at the current index entry.
existingInode, ok := fs.generationBackedInodes[o.Name]
// If we have no existing record for this name, mint an inode and return it.
if !ok {
in = fs.mintInode(o.Name, o)
fs.generationBackedInodes[in.Name()] = in.(inode.GenerationBackedInode)
fs.mu.Unlock()
in.Lock()
return
}
// Otherwise we need to grab the inode lock to find out if this is our
// inode, our record is stale, or the inode is stale. We must exclude
// concurrent actions on the inode to get a definitive answer.
//
// Drop the file system lock and acquire the inode lock.
fs.mu.Unlock()
existingInode.Lock()
// Have we found the correct inode?
cmp := oGen.Compare(existingInode.SourceGeneration())
if cmp == 0 {
in = existingInode
return
}
// Are we stale?
if cmp == -1 {
existingInode.Unlock()
return
}
// We've observed that the record is newer than the existing inode, while
// holding the inode lock, excluding concurrent actions by the inode (in
// particular concurrent calls to Sync, which changes generation numbers).
// This means we've proven that the record cannot have been caused by the
// inode's actions, and therefore it is not the inode we want.
//
// Re-acquire the file system lock. If the index entry still points at
// existingInode, we have proven we can replace it with an entry for a a
// newly-minted inode.
fs.mu.Lock()
if fs.generationBackedInodes[o.Name] == existingInode {
in = fs.mintInode(o.Name, o)
fs.generationBackedInodes[in.Name()] = in.(inode.GenerationBackedInode)
fs.mu.Unlock()
existingInode.Unlock()
in.Lock()
return
}
// The index entry has been changed in the meantime, so there may be a new
// inode that we have to contend with. Go around and try again.
existingInode.Unlock()
}
}
// Implementation detail of lookUpOrCreateInodeIfNotStale; do not use outside
// of that function.
//
// LOCKS_REQUIRED(fs.mu)
func (fs *fileSystem) mintInode(name string, o *gcs.Object) (in inode.Inode) {
// Choose an ID.
id := fs.nextInodeID
fs.nextInodeID++
// Create the inode.
switch {
// Explicit directories
case o != nil && inode.IsDirName(o.Name):
in = inode.NewExplicitDirInode(
id,
o,
fuseops.InodeAttributes{
Uid: fs.uid,
Gid: fs.gid,
Mode: fs.dirMode,
},
fs.implicitDirs,
fs.dirTypeCacheTTL,
fs.bucket,
fs.mtimeClock,
fs.cacheClock)
// Implicit directories
case inode.IsDirName(name):
in = inode.NewDirInode(
id,
name,
fuseops.InodeAttributes{
Uid: fs.uid,
Gid: fs.gid,
Mode: fs.dirMode,
},
fs.implicitDirs,
fs.dirTypeCacheTTL,
fs.bucket,
fs.mtimeClock,
fs.cacheClock)
case inode.IsSymlink(o):
in = inode.NewSymlinkInode(
id,
o,
fuseops.InodeAttributes{
Uid: fs.uid,
Gid: fs.gid,
Mode: fs.fileMode | os.ModeSymlink,
})
default:
in = inode.NewFileInode(
id,
o,
fuseops.InodeAttributes{
Uid: fs.uid,
Gid: fs.gid,
Mode: fs.fileMode,
},
fs.bucket,
fs.syncer,
fs.tempDir,
fs.mtimeClock)
}
// Place it in our map of IDs to inodes.
fs.inodes[in.ID()] = in
return
}
func (fs *fileSystem) checkInvariants() {
//////////////////////////////////
// inodes
//////////////////////////////////
// INVARIANT: For all keys k, fuseops.RootInodeID <= k < nextInodeID
for id, _ := range fs.inodes {
if id < fuseops.RootInodeID || id >= fs.nextInodeID {
panic(fmt.Sprintf("Illegal inode ID: %v", id))
}
}
// INVARIANT: For all keys k, inodes[k].ID() == k
for id, in := range fs.inodes {
if in.ID() != id {
panic(fmt.Sprintf("ID mismatch: %v vs. %v", in.ID(), id))
}
}
// INVARIANT: inodes[fuseops.RootInodeID] is missing or of type inode.DirInode
//
// The missing case is when we've received a forget request for the root
// inode, while unmounting.
switch in := fs.inodes[fuseops.RootInodeID].(type) {
case nil:
case inode.DirInode:
default:
panic(fmt.Sprintf("Unexpected type for root: %v", reflect.TypeOf(in)))
}
// INVARIANT: For all v, if IsDirName(v.Name()) then v is inode.DirInode
for _, in := range fs.inodes {
if inode.IsDirName(in.Name()) {
_, ok := in.(inode.DirInode)
if !ok {
panic(fmt.Sprintf(
"Unexpected inode type for name \"%s\": %v",
in.Name(),
reflect.TypeOf(in)))
}
}
}
//////////////////////////////////
// generationBackedInodes
//////////////////////////////////
// INVARIANT: For each k/v, v.Name() == k
for k, v := range fs.generationBackedInodes {
if !(v.Name() == k) {
panic(fmt.Sprintf(
"Unexpected name: \"%s\" vs. \"%s\"",
v.Name(),
k))
}
}
// INVARIANT: For each value v, inodes[v.ID()] == v
for _, v := range fs.generationBackedInodes {
if fs.inodes[v.ID()] != v {
panic(fmt.Sprintf(
"Mismatch for ID %v: %p %p",
v.ID(),
fs.inodes[v.ID()],
v))
}
}
//////////////////////////////////
// implicitDirInodes
//////////////////////////////////
// INVARIANT: For each k/v, v.Name() == k
for k, v := range fs.implicitDirInodes {
if !(v.Name() == k) {
panic(fmt.Sprintf(
"Unexpected name: \"%s\" vs. \"%s\"",
v.Name(),
k))
}
}
// INVARIANT: For each value v, inodes[v.ID()] == v
for _, v := range fs.implicitDirInodes {
if fs.inodes[v.ID()] != v {
panic(fmt.Sprintf(
"Mismatch for ID %v: %p %p",
v.ID(),
fs.inodes[v.ID()],
v))
}
}
// INVARIANT: For each value v, v is not ExplicitDirInode
for _, v := range fs.implicitDirInodes {
if _, ok := v.(inode.ExplicitDirInode); ok {
panic(fmt.Sprintf(
"Unexpected implicit dir inode %d, type %T",
v.ID(),
v))
}
}
// INVARIANT: For each in in inodes such that in is DirInode but not
// ExplicitDirInode, implicitDirInodes[d.Name()] == d
for _, in := range fs.inodes {
_, dir := in.(inode.DirInode)
_, edir := in.(inode.ExplicitDirInode)
if dir && !edir {
if !(fs.implicitDirInodes[in.Name()] == in) {
panic(fmt.Sprintf(
"implicitDirInodes mismatch: %q %p %p",
in.Name(),
fs.implicitDirInodes[in.Name()],
in))
}
}
}
//////////////////////////////////
// handles
//////////////////////////////////
// INVARIANT: All values are of type *dirHandle or *handle.FileHandle
for _, h := range fs.handles {
switch h.(type) {
case *dirHandle:
case *handle.FileHandle:
default:
panic(fmt.Sprintf("Unexpected handle type: %T", h))
}
}
//////////////////////////////////
// nextHandleID
//////////////////////////////////
// INVARIANT: For all keys k in handles, k < nextHandleID
for k, _ := range fs.handles {
if k >= fs.nextHandleID {
panic(fmt.Sprintf("Illegal handle ID: %v", k))
}
}
}