Convert fdLock to an RWMutex and protect the whole transaction
...against concurrent closes. The testcase (set -e; while true; do truncate -s $RANDOM b; done) & (set -e; while true; do truncate -s $RANDOM b; done) & uncovered lots of unnecessary RMW failures that were the result of concurrent closes. With this patch, the only remaining error is "Truncate on forgotten file" that is probably caused by a problem in the go-fuse lib ( https://github.com/hanwen/go-fuse/issues/95 )
This commit is contained in:
Jakob Unterwurzacher
parent
4259c8f7eb
commit
4c9e249e3a
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@ -1,9 +1,9 @@
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package cryptfs
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import (
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"os"
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"fmt"
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"io/ioutil"
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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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@ -20,12 +20,11 @@ import (
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type file struct {
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fd *os.File
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// os.File is not threadsafe. Although fd themselves are
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// constant during the lifetime of an open file, the OS may
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// reuse the fd number after it is closed. When open races
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// with another close, they may lead to confusion as which
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// file gets written in the end.
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fdLock sync.Mutex
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// fdLock prevents the fd to be closed while we are in the middle of
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// an operation.
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// Every FUSE entrypoint should RLock(). The only user of Lock() is
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// Release(), which closes the fd, hence has to acquire an exclusive lock.
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fdLock sync.RWMutex
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// Was the file opened O_WRONLY?
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writeOnly bool
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@ -38,6 +37,8 @@ type file struct {
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// File header
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header *cryptfs.FileHeader
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forgotten bool
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}
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func NewFile(fd *os.File, writeOnly bool, cfs *cryptfs.CryptFS) nodefs.File {
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@ -53,6 +54,12 @@ func NewFile(fd *os.File, writeOnly bool, cfs *cryptfs.CryptFS) nodefs.File {
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}
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}
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// intFd - return the backing file descriptor as an integer. Used for debug
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// messages.
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func (f *file) intFd() int {
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return int(f.fd.Fd())
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}
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func (f *file) InnerFile() nodefs.File {
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return nil
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}
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@ -84,11 +91,9 @@ func (f *file) createHeader() error {
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buf := h.Pack()
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// Prevent partially written (=corrupt) header by preallocating the space beforehand
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f.fdLock.Lock()
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defer f.fdLock.Unlock()
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err := prealloc(int(f.fd.Fd()), 0, cryptfs.HEADER_LEN)
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if err != nil {
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cryptfs.Warn.Printf("createHeader: fallocateRetry failed: %s\n", err.Error())
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cryptfs.Warn.Printf("ino%d: createHeader: prealloc failed: %s\n", f.ino, err.Error())
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return err
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}
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@ -133,9 +138,7 @@ func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
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skip := blocks[0].Skip
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cryptfs.Debug.Printf("JointCiphertextRange(%d, %d) -> %d, %d, %d", off, length, alignedOffset, alignedLength, skip)
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ciphertext := make([]byte, int(alignedLength))
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f.fdLock.Lock()
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n, err := f.fd.ReadAt(ciphertext, int64(alignedOffset))
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f.fdLock.Unlock()
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if err != nil && err != io.EOF {
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cryptfs.Warn.Printf("read: ReadAt: %s", err.Error())
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return nil, fuse.ToStatus(err)
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@ -173,6 +176,8 @@ func (f *file) doRead(off uint64, length uint64) ([]byte, fuse.Status) {
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// Read - FUSE call
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func (f *file) Read(buf []byte, off int64) (resultData fuse.ReadResult, code fuse.Status) {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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cryptfs.Debug.Printf("ino%d: FUSE Read: offset=%d length=%d", f.ino, len(buf), off)
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@ -231,7 +236,7 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
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o, _ := b.PlaintextRange()
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oldData, status := f.doRead(o, f.cfs.PlainBS())
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if status != fuse.OK {
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cryptfs.Warn.Printf("RMW read failed: %s", status.String())
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cryptfs.Warn.Printf("ino%d fh%d: RMW read failed: %s", f.ino, f.intFd(), status.String())
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return written, status
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}
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// Modify
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@ -246,19 +251,15 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
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f.ino, uint64(len(blockData))-f.cfs.BlockOverhead(), b.BlockNo)
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// Prevent partially written (=corrupt) blocks by preallocating the space beforehand
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f.fdLock.Lock()
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err := prealloc(int(f.fd.Fd()), int64(blockOffset), int64(blockLen))
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f.fdLock.Unlock()
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if err != nil {
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cryptfs.Warn.Printf("doWrite: fallocateRetry failed: %s", err.Error())
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cryptfs.Warn.Printf("ino%d fh%d: doWrite: prealloc failed: %s", f.ino, f.intFd(), err.Error())
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status = fuse.ToStatus(err)
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break
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}
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// Write
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f.fdLock.Lock()
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_, err = f.fd.WriteAt(blockData, int64(blockOffset))
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f.fdLock.Unlock()
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if err != nil {
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cryptfs.Warn.Printf("doWrite: Write failed: %s", err.Error())
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@ -272,10 +273,13 @@ func (f *file) doWrite(data []byte, off int64) (uint32, fuse.Status) {
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// Write - FUSE call
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func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) {
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cryptfs.Debug.Printf("ino%d: FUSE Write: offset=%d length=%d", f.ino, off, len(data))
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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wlock.lock(f.ino)
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defer wlock.unlock(f.ino)
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cryptfs.Debug.Printf("ino%d: FUSE Write: offset=%d length=%d", f.ino, off, len(data))
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fi, err := f.fd.Stat()
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if err != nil {
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cryptfs.Warn.Printf("Write: Fstat failed: %v", err)
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@ -292,23 +296,24 @@ func (f *file) Write(data []byte, off int64) (uint32, fuse.Status) {
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return f.doWrite(data, off)
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}
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// Release - FUSE call, forget file
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// Release - FUSE call, close file
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func (f *file) Release() {
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f.fdLock.Lock()
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defer f.fdLock.Unlock()
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f.fd.Close()
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f.fdLock.Unlock()
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wlock.unregister(f.ino)
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f.forgotten = true
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}
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// Flush - FUSE call
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func (f *file) Flush() fuse.Status {
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f.fdLock.Lock()
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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// Since Flush() may be called for each dup'd fd, we don't
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// want to really close the file, we just want to flush. This
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// is achieved by closing a dup'd fd.
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newFd, err := syscall.Dup(int(f.fd.Fd()))
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f.fdLock.Unlock()
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if err != nil {
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return fuse.ToStatus(err)
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@ -318,25 +323,28 @@ func (f *file) Flush() fuse.Status {
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}
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func (f *file) Fsync(flags int) (code fuse.Status) {
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f.fdLock.Lock()
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r := fuse.ToStatus(syscall.Fsync(int(f.fd.Fd())))
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f.fdLock.Unlock()
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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return r
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return fuse.ToStatus(syscall.Fsync(int(f.fd.Fd())))
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}
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// Truncate - FUSE call
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func (f *file) Truncate(newSize uint64) fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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wlock.lock(f.ino)
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defer wlock.unlock(f.ino)
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if f.forgotten {
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cryptfs.Warn.Printf("ino%d fh%d: Truncate on forgotten file", f.ino, f.intFd())
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}
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// Common case first: Truncate to zero
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if newSize == 0 {
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f.fdLock.Lock()
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err := syscall.Ftruncate(int(f.fd.Fd()), 0)
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f.fdLock.Unlock()
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if err != nil {
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cryptfs.Warn.Printf("ino%d: Ftruncate(fd, 0) returned error: %v", f.ino, err)
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cryptfs.Warn.Printf("ino%d fh%d: Ftruncate(fd, 0) returned error: %v", f.ino, f.intFd(), err)
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return fuse.ToStatus(err)
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}
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// Truncate to zero kills the file header
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@ -348,7 +356,7 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
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// the file
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fi, err := f.fd.Stat()
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if err != nil {
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cryptfs.Warn.Printf("ino%d: Truncate: Fstat failed: %v", f.ino, err)
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cryptfs.Warn.Printf("ino%d fh%d: Truncate: Fstat failed: %v", f.ino, f.intFd(), err)
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return fuse.ToStatus(err)
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}
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oldSize := f.cfs.CipherSizeToPlainSize(uint64(fi.Size()))
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cryptfs.Debug.Printf("ino%d: FUSE Truncate from %.2f to %.2f blocks (%d to %d bytes)", f.ino, oldB, newB, oldSize, newSize)
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}
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// File size stays the same - nothing to do
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if newSize == oldSize {
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return fuse.OK
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}
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// File grows
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if newSize > oldSize {
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@ -381,9 +394,7 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
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}
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} else {
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off, length := b.CiphertextRange()
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f.fdLock.Lock()
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err := syscall.Ftruncate(int(f.fd.Fd()), int64(off+length))
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f.fdLock.Unlock()
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if err != nil {
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cryptfs.Warn.Printf("grow Ftruncate returned error: %v", err)
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return fuse.ToStatus(err)
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@ -407,9 +418,7 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
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}
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}
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// Truncate down to last complete block
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f.fdLock.Lock()
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err = syscall.Ftruncate(int(f.fd.Fd()), int64(cipherOff))
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f.fdLock.Unlock()
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if err != nil {
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cryptfs.Warn.Printf("shrink Ftruncate returned error: %v", err)
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return fuse.ToStatus(err)
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@ -424,27 +433,26 @@ func (f *file) Truncate(newSize uint64) fuse.Status {
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}
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func (f *file) Chmod(mode uint32) fuse.Status {
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f.fdLock.Lock()
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r := fuse.ToStatus(f.fd.Chmod(os.FileMode(mode)))
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f.fdLock.Unlock()
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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return r
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return fuse.ToStatus(f.fd.Chmod(os.FileMode(mode)))
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}
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func (f *file) Chown(uid uint32, gid uint32) fuse.Status {
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f.fdLock.Lock()
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r := fuse.ToStatus(f.fd.Chown(int(uid), int(gid)))
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f.fdLock.Unlock()
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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return r
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return fuse.ToStatus(f.fd.Chown(int(uid), int(gid)))
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}
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func (f *file) GetAttr(a *fuse.Attr) fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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cryptfs.Debug.Printf("file.GetAttr()")
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st := syscall.Stat_t{}
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f.fdLock.Lock()
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err := syscall.Fstat(int(f.fd.Fd()), &st)
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f.fdLock.Unlock()
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if err != nil {
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return fuse.ToStatus(err)
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}
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@ -469,6 +477,9 @@ func (f *file) Allocate(off uint64, sz uint64, mode uint32) fuse.Status {
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const _UTIME_OMIT = ((1 << 30) - 2)
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func (f *file) Utimens(a *time.Time, m *time.Time) fuse.Status {
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f.fdLock.RLock()
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defer f.fdLock.RUnlock()
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ts := make([]syscall.Timespec, 2)
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if a == nil {
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@ -483,9 +494,6 @@ func (f *file) Utimens(a *time.Time, m *time.Time) fuse.Status {
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ts[1].Sec = m.Unix()
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}
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f.fdLock.Lock()
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fn := fmt.Sprintf("/proc/self/fd/%d", f.fd.Fd())
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err := syscall.UtimesNano(fn, ts)
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f.fdLock.Unlock()
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return fuse.ToStatus(err)
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return fuse.ToStatus(syscall.UtimesNano(fn, ts))
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}
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