// Look up the child with the given name within the parent, then return an
// existing inode for that child or create a new one if necessary. Return
// ENOENT if the child doesn't exist.
//
// Return the child locked, incrementing its lookup count.
//
// LOCKS_EXCLUDED(fs.mu)
// LOCKS_EXCLUDED(parent)
// LOCK_FUNCTION(child)
func (fs *fileSystem) lookUpOrCreateChildInode(
ctx context.Context,
parent inode.DirInode,
childName string) (child inode.Inode, err error) {
// Set up a function that will find a lookup result for the child with the
// given name. Expects no locks to be held.
getLookupResult := func() (r inode.LookUpResult, err error) {
parent.Lock()
defer parent.Unlock()
r, err = parent.LookUpChild(ctx, childName)
if err != nil {
err = fmt.Errorf("LookUpChild: %v", err)
return
}
return
}
// Run a retry loop around lookUpOrCreateInodeIfNotStale.
const maxTries = 3
for n := 0; n < maxTries; n++ {
// Create a record.
var result inode.LookUpResult
result, err = getLookupResult()
if err != nil {
return
}
if !result.Exists() {
err = fuse.ENOENT
return
}
// Attempt to create the inode. Return if successful.
fs.mu.Lock()
child = fs.lookUpOrCreateInodeIfNotStale(result.FullName, result.Object)
if child != nil {
return
}
}
err = fmt.Errorf("Did not converge after %v tries", maxTries)
return
}
