frostfs-node/pkg/local_object_storage/blobstor/fstree/fstree.go
Pavel Karpy da8da1c63a
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[#98] fstree: Do not fail iteration over just removed files
A directory is read and files are saved to a local variable. The iteration
over such files may lead to a non-existing files reading due to a normal SN
operation cycle and, therefore, may lead to a returning the OS error to a
caller. Skip just removed (or lost) files as the golang std library does in
similar situations:
5f1a0320b9/src/os/dir_unix.go (L128-L133).

Signed-off-by: Pavel Karpy <p.karpy@yadro.com>
2023-03-22 07:26:27 +00:00

425 lines
11 KiB
Go

package fstree
import (
"crypto/sha256"
"errors"
"fmt"
"io/fs"
"os"
"path/filepath"
"strconv"
"strings"
"syscall"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/compression"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/util/logicerr"
"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util"
apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
)
// FSTree represents an object storage as a filesystem tree.
type FSTree struct {
Info
*compression.Config
Depth uint64
DirNameLen int
noSync bool
readOnly bool
}
// Info groups the information about file storage.
type Info struct {
// Permission bits of the root directory.
Permissions fs.FileMode
// Full path to the root directory.
RootPath string
}
const (
// DirNameLen is how many bytes is used to group keys into directories.
DirNameLen = 1 // in bytes
// MaxDepth is maximum depth of nested directories.
MaxDepth = (sha256.Size - 1) / DirNameLen
)
var _ common.Storage = (*FSTree)(nil)
func New(opts ...Option) *FSTree {
f := &FSTree{
Info: Info{
Permissions: 0700,
RootPath: "./",
},
Config: nil,
Depth: 4,
DirNameLen: DirNameLen,
}
for i := range opts {
opts[i](f)
}
return f
}
func stringifyAddress(addr oid.Address) string {
return addr.Object().EncodeToString() + "." + addr.Container().EncodeToString()
}
func addressFromString(s string) (oid.Address, error) {
before, after, found := strings.Cut(s, ".")
if !found {
return oid.Address{}, errors.New("invalid address")
}
var obj oid.ID
if err := obj.DecodeString(before); err != nil {
return oid.Address{}, err
}
var cnr cid.ID
if err := cnr.DecodeString(after); err != nil {
return oid.Address{}, err
}
var addr oid.Address
addr.SetObject(obj)
addr.SetContainer(cnr)
return addr, nil
}
// Iterate iterates over all stored objects.
func (t *FSTree) Iterate(prm common.IteratePrm) (common.IterateRes, error) {
return common.IterateRes{}, t.iterate(0, []string{t.RootPath}, prm)
}
func (t *FSTree) iterate(depth uint64, curPath []string, prm common.IteratePrm) error {
curName := strings.Join(curPath[1:], "")
des, err := os.ReadDir(filepath.Join(curPath...))
if err != nil {
if prm.IgnoreErrors {
return nil
}
return err
}
isLast := depth >= t.Depth
l := len(curPath)
curPath = append(curPath, "")
for i := range des {
curPath[l] = des[i].Name()
if !isLast && des[i].IsDir() {
err := t.iterate(depth+1, curPath, prm)
if err != nil {
// Must be error from handler in case errors are ignored.
// Need to report.
return err
}
}
if depth != t.Depth {
continue
}
addr, err := addressFromString(curName + des[i].Name())
if err != nil {
continue
}
data, err := os.ReadFile(filepath.Join(curPath...))
if err != nil && os.IsNotExist(err) {
continue
}
if prm.LazyHandler != nil {
err = prm.LazyHandler(addr, func() ([]byte, error) {
return data, err
})
} else {
if err == nil {
data, err = t.Decompress(data)
}
if err != nil {
if prm.IgnoreErrors {
if prm.ErrorHandler != nil {
return prm.ErrorHandler(addr, err)
}
continue
}
return err
}
err = prm.Handler(common.IterationElement{
Address: addr,
ObjectData: data,
StorageID: []byte{},
})
}
if err != nil {
return err
}
}
return nil
}
func (t *FSTree) treePath(addr oid.Address) string {
sAddr := stringifyAddress(addr)
var sb strings.Builder
sb.Grow(len(t.RootPath) + len(sAddr) + int(t.Depth) + 1)
sb.WriteString(t.RootPath)
for i := 0; uint64(i) < t.Depth; i++ {
sb.WriteRune(filepath.Separator)
sb.WriteString(sAddr[:t.DirNameLen])
sAddr = sAddr[t.DirNameLen:]
}
sb.WriteRune(filepath.Separator)
sb.WriteString(sAddr)
return sb.String()
}
// Delete removes the object with the specified address from the storage.
func (t *FSTree) Delete(prm common.DeletePrm) (common.DeleteRes, error) {
if t.readOnly {
return common.DeleteRes{}, common.ErrReadOnly
}
p := t.treePath(prm.Address)
err := os.Remove(p)
if err != nil && os.IsNotExist(err) {
err = logicerr.Wrap(apistatus.ObjectNotFound{})
}
return common.DeleteRes{}, err
}
// Exists returns the path to the file with object contents if it exists in the storage
// and an error otherwise.
func (t *FSTree) Exists(prm common.ExistsPrm) (common.ExistsRes, error) {
p := t.treePath(prm.Address)
_, err := os.Stat(p)
found := err == nil
if os.IsNotExist(err) {
err = nil
}
return common.ExistsRes{Exists: found}, err
}
// Put puts an object in the storage.
func (t *FSTree) Put(prm common.PutPrm) (common.PutRes, error) {
if t.readOnly {
return common.PutRes{}, common.ErrReadOnly
}
p := t.treePath(prm.Address)
if err := util.MkdirAllX(filepath.Dir(p), t.Permissions); err != nil {
return common.PutRes{}, err
}
if !prm.DontCompress {
prm.RawData = t.Compress(prm.RawData)
}
// Here is a situation:
// Feb 09 13:10:37 buky neofs-node[32445]: 2023-02-09T13:10:37.161Z info log/log.go:13 local object storage operation {"shard_id": "SkT8BfjouW6t93oLuzQ79s", "address": "7NxFz4SruSi8TqXacr2Ae22nekMhgYk1sfkddJo9PpWk/5enyUJGCyU1sfrURDnHEjZFdbGqANVhayYGfdSqtA6wA", "op": "PUT", "type": "fstree", "storage_id": ""}
// Feb 09 13:10:37 buky neofs-node[32445]: 2023-02-09T13:10:37.183Z info log/log.go:13 local object storage operation {"shard_id": "SkT8BfjouW6t93oLuzQ79s", "address": "7NxFz4SruSi8TqXacr2Ae22nekMhgYk1sfkddJo9PpWk/5enyUJGCyU1sfrURDnHEjZFdbGqANVhayYGfdSqtA6wA", "op": "metabase PUT"}
// Feb 09 13:10:37 buky neofs-node[32445]: 2023-02-09T13:10:37.862Z debug policer/check.go:231 shortage of object copies detected {"component": "Object Policer", "object": "7NxFz4SruSi8TqXacr2Ae22nekMhgYk1sfkddJo9PpWk/5enyUJGCyU1sfrURDnHEjZFdbGqANVhayYGfdSqtA6wA", "shortage": 1}
// Feb 09 13:10:37 buky neofs-node[32445]: 2023-02-09T13:10:37.862Z debug shard/get.go:124 object is missing in write-cache {"shard_id": "SkT8BfjouW6t93oLuzQ79s", "addr": "7NxFz4SruSi8TqXacr2Ae22nekMhgYk1sfkddJo9PpWk/5enyUJGCyU1sfrURDnHEjZFdbGqANVhayYGfdSqtA6wA", "skip_meta": false}
//
// 1. We put an object on node 1.
// 2. Relentless policer sees that it has only 1 copy and tries to PUT it to node 2.
// 3. PUT operation started by client at (1) also puts an object here.
// 4. Now we have concurrent writes and one of `Rename` calls will return `no such file` error.
// Even more than that, concurrent writes can corrupt data.
//
// So here is a solution:
// 1. Write a file to 'name + 1'.
// 2. If it exists, retry with temporary name being 'name + 2'.
// 3. Set some reasonable number of attempts.
//
// It is a bit kludgey, but I am unusually proud about having found this out after
// hours of research on linux kernel, dirsync mount option and ext4 FS, turned out
// to be so hecking simple.
// In a very rare situation we can have multiple partially written copies on disk,
// this will be fixed in another issue (we should remove garbage on start).
const retryCount = 5
for i := 0; i < retryCount; i++ {
tmpPath := p + "#" + strconv.FormatUint(uint64(i), 10)
err := t.writeAndRename(tmpPath, p, prm.RawData)
if err != syscall.EEXIST || i == retryCount-1 {
return common.PutRes{StorageID: []byte{}}, err
}
}
// unreachable, but precaution never hurts, especially 1 day before release.
return common.PutRes{StorageID: []byte{}}, fmt.Errorf("couldn't read file after %d retries", retryCount)
}
// writeAndRename opens tmpPath exclusively, writes data to it and renames it to p.
func (t *FSTree) writeAndRename(tmpPath, p string, data []byte) error {
err := t.writeFile(tmpPath, data)
if err != nil {
var pe *fs.PathError
if errors.As(err, &pe) {
switch pe.Err {
case syscall.ENOSPC:
err = common.ErrNoSpace
_ = os.RemoveAll(tmpPath)
case syscall.EEXIST:
return syscall.EEXIST
}
}
} else {
err = os.Rename(tmpPath, p)
}
return err
}
func (t *FSTree) writeFlags() int {
flags := os.O_WRONLY | os.O_CREATE | os.O_TRUNC | os.O_EXCL
if t.noSync {
return flags
}
return flags | os.O_SYNC
}
// writeFile writes data to a file with path p.
// The code is copied from `os.WriteFile` with minor corrections for flags.
func (t *FSTree) writeFile(p string, data []byte) error {
f, err := os.OpenFile(p, t.writeFlags(), t.Permissions)
if err != nil {
return err
}
_, err = f.Write(data)
if err1 := f.Close(); err1 != nil && err == nil {
err = err1
}
return err
}
// PutStream puts executes handler on a file opened for write.
func (t *FSTree) PutStream(addr oid.Address, handler func(*os.File) error) error {
if t.readOnly {
return common.ErrReadOnly
}
p := t.treePath(addr)
if err := util.MkdirAllX(filepath.Dir(p), t.Permissions); err != nil {
return err
}
f, err := os.OpenFile(p, t.writeFlags(), t.Permissions)
if err != nil {
return err
}
defer f.Close()
return handler(f)
}
// Get returns an object from the storage by address.
func (t *FSTree) Get(prm common.GetPrm) (common.GetRes, error) {
p := t.treePath(prm.Address)
if _, err := os.Stat(p); os.IsNotExist(err) {
return common.GetRes{}, logicerr.Wrap(apistatus.ObjectNotFound{})
}
data, err := os.ReadFile(p)
if err != nil {
return common.GetRes{}, err
}
data, err = t.Decompress(data)
if err != nil {
return common.GetRes{}, err
}
obj := objectSDK.New()
if err := obj.Unmarshal(data); err != nil {
return common.GetRes{}, err
}
return common.GetRes{Object: obj, RawData: data}, err
}
// GetRange implements common.Storage.
func (t *FSTree) GetRange(prm common.GetRangePrm) (common.GetRangeRes, error) {
res, err := t.Get(common.GetPrm{Address: prm.Address})
if err != nil {
return common.GetRangeRes{}, err
}
payload := res.Object.Payload()
from := prm.Range.GetOffset()
to := from + prm.Range.GetLength()
if pLen := uint64(len(payload)); to < from || pLen < from || pLen < to {
return common.GetRangeRes{}, logicerr.Wrap(apistatus.ObjectOutOfRange{})
}
return common.GetRangeRes{
Data: payload[from:to],
}, nil
}
// NumberOfObjects walks the file tree rooted at FSTree's root
// and returns number of stored objects.
func (t *FSTree) NumberOfObjects() (uint64, error) {
var counter uint64
// it is simpler to just consider every file
// that is not directory as an object
err := filepath.WalkDir(t.RootPath,
func(_ string, d fs.DirEntry, _ error) error {
if !d.IsDir() {
counter++
}
return nil
},
)
if err != nil {
return 0, fmt.Errorf("could not walk through %s directory: %w", t.RootPath, err)
}
return counter, nil
}
// Type is fstree storage type used in logs and configuration.
const Type = "fstree"
// Type implements common.Storage.
func (*FSTree) Type() string {
return Type
}
// Path implements common.Storage.
func (t *FSTree) Path() string {
return t.RootPath
}
// SetCompressor implements common.Storage.
func (t *FSTree) SetCompressor(cc *compression.Config) {
t.Config = cc
}
// SetReportErrorFunc implements common.Storage.
func (t *FSTree) SetReportErrorFunc(f func(string, error)) {
// Do nothing, FSTree can encounter only one error which is returned.
}