Example #1
0
// Read all entries for the directory, fix up conflicting names, and fill in
// offset fields.
//
// LOCKS_REQUIRED(in)
func readAllEntries(
	ctx context.Context,
	in inode.DirInode) (entries []fuseutil.Dirent, err error) {
	// Read one batch at a time.
	var tok string
	for {
		// Read a batch.
		var batch []fuseutil.Dirent

		batch, tok, err = in.ReadEntries(ctx, tok)
		if err != nil {
			err = fmt.Errorf("ReadEntries: %v", err)
			return
		}

		// Accumulate.
		entries = append(entries, batch...)

		// Are we done?
		if tok == "" {
			break
		}
	}

	// Ensure that the entries are sorted, for use in fixConflictingNames
	// below.
	sort.Sort(sortedDirents(entries))

	// Fix name conflicts.
	err = fixConflictingNames(entries)
	if err != nil {
		err = fmt.Errorf("fixConflictingNames: %v", err)
		return
	}

	// Fix up offset fields.
	for i := 0; i < len(entries); i++ {
		entries[i].Offset = fuseops.DirOffset(i) + 1
	}

	// Return a bogus inode ID for each entry, but not the root inode ID.
	//
	// NOTE(jacobsa): As far as I can tell this is harmless. Minting and
	// returning a real inode ID is difficult because fuse does not count
	// readdir as an operation that increases the inode ID's lookup count and
	// we therefore don't get a forget for it later, but we would like to not
	// have to remember every inode ID that we've ever minted for readdir.
	//
	// If it turns out this is not harmless, we'll need to switch to something
	// like inode IDs based on (object name, generation) hashes. But then what
	// about the birthday problem? And more importantly, what about our
	// semantic of not minting a new inode ID when the generation changes due
	// to a local action?
	for i, _ := range entries {
		entries[i].Inode = fuseops.RootInodeID + 1
	}

	return
}
Example #2
0
File: fs.go Project: kahing/gcsfuse
// 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
}