286 lines
9.0 KiB
Go
286 lines
9.0 KiB
Go
// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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// +build linux darwin freebsd
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package fuse
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import (
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"context"
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"errors"
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"fmt"
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"os"
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"path/filepath"
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"strings"
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"sync"
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"time"
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"bazil.org/fuse"
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"bazil.org/fuse/fs"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/swarm/api"
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"github.com/ethereum/go-ethereum/swarm/log"
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)
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var (
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errEmptyMountPoint = errors.New("need non-empty mount point")
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errNoRelativeMountPoint = errors.New("invalid path for mount point (need absolute path)")
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errMaxMountCount = errors.New("max FUSE mount count reached")
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errMountTimeout = errors.New("mount timeout")
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errAlreadyMounted = errors.New("mount point is already serving")
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)
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func isFUSEUnsupportedError(err error) bool {
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if perr, ok := err.(*os.PathError); ok {
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return perr.Op == "open" && perr.Path == "/dev/fuse"
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}
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return err == fuse.ErrOSXFUSENotFound
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}
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// MountInfo contains information about every active mount
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type MountInfo struct {
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MountPoint string
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StartManifest string
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LatestManifest string
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rootDir *SwarmDir
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fuseConnection *fuse.Conn
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swarmApi *api.API
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lock *sync.RWMutex
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serveClose chan struct{}
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}
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func NewMountInfo(mhash, mpoint string, sapi *api.API) *MountInfo {
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log.Debug("swarmfs NewMountInfo", "hash", mhash, "mount point", mpoint)
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newMountInfo := &MountInfo{
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MountPoint: mpoint,
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StartManifest: mhash,
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LatestManifest: mhash,
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rootDir: nil,
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fuseConnection: nil,
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swarmApi: sapi,
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lock: &sync.RWMutex{},
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serveClose: make(chan struct{}),
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}
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return newMountInfo
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}
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func (swarmfs *SwarmFS) Mount(mhash, mountpoint string) (*MountInfo, error) {
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log.Info("swarmfs", "mounting hash", mhash, "mount point", mountpoint)
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if mountpoint == "" {
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return nil, errEmptyMountPoint
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}
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if !strings.HasPrefix(mountpoint, "/") {
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return nil, errNoRelativeMountPoint
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}
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cleanedMountPoint, err := filepath.Abs(filepath.Clean(mountpoint))
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if err != nil {
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return nil, err
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}
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log.Trace("swarmfs mount", "cleanedMountPoint", cleanedMountPoint)
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swarmfs.swarmFsLock.Lock()
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defer swarmfs.swarmFsLock.Unlock()
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noOfActiveMounts := len(swarmfs.activeMounts)
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log.Debug("swarmfs mount", "# active mounts", noOfActiveMounts)
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if noOfActiveMounts >= maxFuseMounts {
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return nil, errMaxMountCount
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}
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if _, ok := swarmfs.activeMounts[cleanedMountPoint]; ok {
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return nil, errAlreadyMounted
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}
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log.Trace("swarmfs mount: getting manifest tree")
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_, manifestEntryMap, err := swarmfs.swarmApi.BuildDirectoryTree(context.TODO(), mhash, true)
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if err != nil {
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return nil, err
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}
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log.Trace("swarmfs mount: building mount info")
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mi := NewMountInfo(mhash, cleanedMountPoint, swarmfs.swarmApi)
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dirTree := map[string]*SwarmDir{}
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rootDir := NewSwarmDir("/", mi)
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log.Trace("swarmfs mount", "rootDir", rootDir)
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mi.rootDir = rootDir
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log.Trace("swarmfs mount: traversing manifest map")
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for suffix, entry := range manifestEntryMap {
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if suffix == "" { //empty suffix means that the file has no name - i.e. this is the default entry in a manifest. Since we cannot have files without a name, let us ignore this entry
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log.Warn("Manifest has an empty-path (default) entry which will be ignored in FUSE mount.")
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continue
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}
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addr := common.Hex2Bytes(entry.Hash)
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fullpath := "/" + suffix
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basepath := filepath.Dir(fullpath)
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parentDir := rootDir
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dirUntilNow := ""
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paths := strings.Split(basepath, "/")
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for i := range paths {
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if paths[i] != "" {
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thisDir := paths[i]
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dirUntilNow = dirUntilNow + "/" + thisDir
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if _, ok := dirTree[dirUntilNow]; !ok {
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dirTree[dirUntilNow] = NewSwarmDir(dirUntilNow, mi)
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parentDir.directories = append(parentDir.directories, dirTree[dirUntilNow])
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parentDir = dirTree[dirUntilNow]
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} else {
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parentDir = dirTree[dirUntilNow]
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}
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}
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}
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thisFile := NewSwarmFile(basepath, filepath.Base(fullpath), mi)
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thisFile.addr = addr
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parentDir.files = append(parentDir.files, thisFile)
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}
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fconn, err := fuse.Mount(cleanedMountPoint, fuse.FSName("swarmfs"), fuse.VolumeName(mhash))
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if isFUSEUnsupportedError(err) {
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log.Error("swarmfs error - FUSE not installed", "mountpoint", cleanedMountPoint, "err", err)
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return nil, err
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} else if err != nil {
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fuse.Unmount(cleanedMountPoint)
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log.Error("swarmfs error mounting swarm manifest", "mountpoint", cleanedMountPoint, "err", err)
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return nil, err
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}
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mi.fuseConnection = fconn
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serverr := make(chan error, 1)
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go func() {
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log.Info("swarmfs", "serving hash", mhash, "at", cleanedMountPoint)
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filesys := &SwarmRoot{root: rootDir}
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//start serving the actual file system; see note below
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if err := fs.Serve(fconn, filesys); err != nil {
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log.Warn("swarmfs could not serve the requested hash", "error", err)
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serverr <- err
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}
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mi.serveClose <- struct{}{}
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}()
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/*
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IMPORTANT NOTE: the fs.Serve function is blocking;
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Serve builds up the actual fuse file system by calling the
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Attr functions on each SwarmFile, creating the file inodes;
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specifically calling the swarm's LazySectionReader.Size() to set the file size.
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This can take some time, and it appears that if we access the fuse file system
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too early, we can bring the tests to deadlock. The assumption so far is that
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at this point, the fuse driver didn't finish to initialize the file system.
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Accessing files too early not only deadlocks the tests, but locks the access
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of the fuse file completely, resulting in blocked resources at OS system level.
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Even a simple `ls /tmp/testDir/testMountDir` could deadlock in a shell.
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Workaround so far is to wait some time to give the OS enough time to initialize
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the fuse file system. During tests, this seemed to address the issue.
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HOWEVER IT SHOULD BE NOTED THAT THIS MAY ONLY BE AN EFFECT,
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AND THE DEADLOCK CAUSED BY SOMETHING ELSE BLOCKING ACCESS DUE TO SOME RACE CONDITION
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(caused in the bazil.org library and/or the SwarmRoot, SwarmDir and SwarmFile implementations)
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*/
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time.Sleep(2 * time.Second)
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timer := time.NewTimer(mountTimeout)
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defer timer.Stop()
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// Check if the mount process has an error to report.
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select {
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case <-timer.C:
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log.Warn("swarmfs timed out mounting over FUSE", "mountpoint", cleanedMountPoint, "err", err)
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err := fuse.Unmount(cleanedMountPoint)
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if err != nil {
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return nil, err
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}
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return nil, errMountTimeout
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case err := <-serverr:
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log.Warn("swarmfs error serving over FUSE", "mountpoint", cleanedMountPoint, "err", err)
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err = fuse.Unmount(cleanedMountPoint)
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return nil, err
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case <-fconn.Ready:
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//this signals that the actual mount point from the fuse.Mount call is ready;
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//it does not signal though that the file system from fs.Serve is actually fully built up
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if err := fconn.MountError; err != nil {
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log.Error("Mounting error from fuse driver: ", "err", err)
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return nil, err
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}
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log.Info("swarmfs now served over FUSE", "manifest", mhash, "mountpoint", cleanedMountPoint)
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}
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timer.Stop()
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swarmfs.activeMounts[cleanedMountPoint] = mi
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return mi, nil
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}
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func (swarmfs *SwarmFS) Unmount(mountpoint string) (*MountInfo, error) {
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swarmfs.swarmFsLock.Lock()
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defer swarmfs.swarmFsLock.Unlock()
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cleanedMountPoint, err := filepath.Abs(filepath.Clean(mountpoint))
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if err != nil {
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return nil, err
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}
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mountInfo := swarmfs.activeMounts[cleanedMountPoint]
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if mountInfo == nil || mountInfo.MountPoint != cleanedMountPoint {
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return nil, fmt.Errorf("swarmfs %s is not mounted", cleanedMountPoint)
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}
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err = fuse.Unmount(cleanedMountPoint)
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if err != nil {
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err1 := externalUnmount(cleanedMountPoint)
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if err1 != nil {
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errStr := fmt.Sprintf("swarmfs unmount error: %v", err)
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log.Warn(errStr)
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return nil, err1
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}
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}
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err = mountInfo.fuseConnection.Close()
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if err != nil {
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return nil, err
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}
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delete(swarmfs.activeMounts, cleanedMountPoint)
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<-mountInfo.serveClose
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succString := fmt.Sprintf("swarmfs unmounting %v succeeded", cleanedMountPoint)
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log.Info(succString)
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return mountInfo, nil
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}
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func (swarmfs *SwarmFS) Listmounts() []*MountInfo {
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swarmfs.swarmFsLock.RLock()
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defer swarmfs.swarmFsLock.RUnlock()
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rows := make([]*MountInfo, 0, len(swarmfs.activeMounts))
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for _, mi := range swarmfs.activeMounts {
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rows = append(rows, mi)
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}
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return rows
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}
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func (swarmfs *SwarmFS) Stop() bool {
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for mp := range swarmfs.activeMounts {
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mountInfo := swarmfs.activeMounts[mp]
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swarmfs.Unmount(mountInfo.MountPoint)
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}
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return true
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}
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