syscallcompat: retry ops on EINTR

Retry operations that have been shown to throw EINTR
errors on CIFS.

Todo: Solution for this pain in the back:

	warning: unix.Getdents returned errno 2 in the middle of data
	rm: cannot remove 'linux-3.0.old3/Documentation/ABI/removed': Input/output error

Progress towards fixing https://github.com/rfjakob/gocryptfs/issues/483 .
libgocryptfs
Jakob Unterwurzacher 2 years ago
parent 803fdf410b
commit af4c1fb7a3
  1. 2
      internal/fusefrontend/file.go
  2. 2
      internal/fusefrontend/node_dir_ops.go
  3. 4
      internal/fusefrontend/root_node.go
  4. 1
      internal/nametransform/diriv.go
  5. 48
      internal/syscallcompat/eintr.go
  6. 5
      internal/syscallcompat/open_nofollow.go
  7. 34
      internal/syscallcompat/sys_common.go
  8. 12
      internal/syscallcompat/sys_linux.go

@ -409,7 +409,7 @@ func (f *File) Flush(ctx context.Context) syscall.Errno {
if err != nil {
return fs.ToErrno(err)
}
err = syscall.Close(newFd)
err = syscallcompat.Close(newFd)
return fs.ToErrno(err)
}

@ -306,7 +306,7 @@ retry:
return fs.ToErrno(err)
}
if err != nil {
tlog.Warn.Printf("Rmdir: Readdirnames: %v", err)
tlog.Warn.Printf("Rmdir: Getdents: %v", err)
return fs.ToErrno(err)
}
// MacOS sprinkles .DS_Store files everywhere. This is hard to avoid for

@ -203,6 +203,8 @@ func (rn *RootNode) openWriteOnlyFile(dirfd int, cName string, newFlags int) (rw
//
// openBackingDir is secure against symlink races by using Openat and
// ReadDirIVAt.
//
// Retries on EINTR.
func (rn *RootNode) openBackingDir(relPath string) (dirfd int, cName string, err error) {
dirRelPath := nametransform.Dir(relPath)
// With PlaintextNames, we don't need to read DirIVs. Easy.
@ -216,7 +218,7 @@ func (rn *RootNode) openBackingDir(relPath string) (dirfd int, cName string, err
return dirfd, cName, nil
}
// Open cipherdir (following symlinks)
dirfd, err = syscall.Open(rn.args.Cipherdir, syscall.O_DIRECTORY|syscallcompat.O_PATH, 0)
dirfd, err = syscallcompat.Open(rn.args.Cipherdir, syscall.O_DIRECTORY|syscallcompat.O_PATH, 0)
if err != nil {
return -1, "", err
}

@ -23,6 +23,7 @@ const (
// ReadDirIVAt reads "gocryptfs.diriv" from the directory that is opened as "dirfd".
// Using the dirfd makes it immune to concurrent renames of the directory.
// Retries on EINTR.
func ReadDirIVAt(dirfd int) (iv []byte, err error) {
fdRaw, err := syscallcompat.Openat(dirfd, DirIVFilename,
syscall.O_RDONLY|syscall.O_NOFOLLOW, 0)

@ -0,0 +1,48 @@
package syscallcompat
import (
"syscall"
)
// retryEINTR executes operation `op` and retries if it gets EINTR.
//
// Like ignoringEINTR() in the Go stdlib:
// https://github.com/golang/go/blob/d2a80f3fb5b44450e0b304ac5a718f99c053d82a/src/os/file_posix.go#L243
//
// This is needed because CIFS throws lots of EINTR errors:
// https://github.com/rfjakob/gocryptfs/issues/483
func retryEINTR(op func() error) error {
for {
err := op()
if err != syscall.EINTR {
return err
}
}
}
// retryEINTR2 is like retryEINTR but for functions that return an (int, error)
// pair like syscall.Create().
func retryEINTR2(op func() (int, error)) (int, error) {
for {
ret, err := op()
if err != syscall.EINTR {
return ret, err
}
}
}
// Open wraps syscall.Open.
// Retries on EINTR.
func Open(path string, mode int, perm uint32) (fd int, err error) {
fd, err = retryEINTR2(func() (int, error) {
return syscall.Open(path, mode, perm)
})
return fd, err
}
// Close wraps syscall.Close.
// Retries on EINTR.
func Close(fd int) (err error) {
err = retryEINTR(func() error { return syscall.Close(fd) })
return err
}

@ -13,6 +13,7 @@ import (
// This function is implemented by walking the directory tree, starting at
// "baseDir", using the Openat syscall with the O_NOFOLLOW flag.
// Symlinks that are part of the "baseDir" path are followed.
// Retries on EINTR.
func OpenDirNofollow(baseDir string, relPath string) (fd int, err error) {
if !filepath.IsAbs(baseDir) {
tlog.Warn.Printf("BUG: OpenDirNofollow called with relative baseDir=%q", baseDir)
@ -23,7 +24,9 @@ func OpenDirNofollow(baseDir string, relPath string) (fd int, err error) {
return -1, syscall.EINVAL
}
// Open the base dir (following symlinks)
dirfd, err := syscall.Open(baseDir, syscall.O_DIRECTORY|O_PATH, 0)
dirfd, err := retryEINTR2(func() (int, error) {
return syscall.Open(baseDir, syscall.O_DIRECTORY|O_PATH, 0)
})
if err != nil {
return -1, err
}

@ -44,7 +44,8 @@ func Faccessat(dirfd int, path string, mode uint32) error {
return unix.Faccessat(dirfd, path, mode, 0)
}
// Openat wraps the Openat syscall, retrying on EINTR.
// Openat wraps the Openat syscall.
// Retries on EINTR.
func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error) {
if flags&syscall.O_CREAT != 0 {
// O_CREAT should be used with O_EXCL. O_NOFOLLOW has no effect with O_EXCL.
@ -59,24 +60,28 @@ func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
flags |= syscall.O_NOFOLLOW
}
}
// Like ignoringEINTR() in the Go stdlib:
// https://github.com/golang/go/blob/d2a80f3fb5b44450e0b304ac5a718f99c053d82a/src/os/file_posix.go#L243
for {
fd, err = unix.Openat(dirfd, path, flags, mode)
if err != unix.EINTR {
return fd, err
}
}
fd, err = retryEINTR2(func() (int, error) {
return unix.Openat(dirfd, path, flags, mode)
})
return fd, err
}
// Renameat wraps the Renameat syscall.
// Retries on EINTR.
func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error) {
return unix.Renameat(olddirfd, oldpath, newdirfd, newpath)
err = retryEINTR(func() error {
return unix.Renameat(olddirfd, oldpath, newdirfd, newpath)
})
return err
}
// Unlinkat syscall.
// Retries on EINTR.
func Unlinkat(dirfd int, path string, flags int) (err error) {
return unix.Unlinkat(dirfd, path, flags)
err = retryEINTR(func() error {
return unix.Unlinkat(dirfd, path, flags)
})
return err
}
// Fchownat syscall.
@ -105,17 +110,22 @@ func Mkdirat(dirfd int, path string, mode uint32) (err error) {
}
// Fstatat syscall.
// Retries on EINTR.
func Fstatat(dirfd int, path string, stat *unix.Stat_t, flags int) (err error) {
// Why would we ever want to call this without AT_SYMLINK_NOFOLLOW?
if flags&unix.AT_SYMLINK_NOFOLLOW == 0 {
tlog.Warn.Printf("Fstatat: adding missing AT_SYMLINK_NOFOLLOW flag")
flags |= unix.AT_SYMLINK_NOFOLLOW
}
return unix.Fstatat(dirfd, path, stat, flags)
err = retryEINTR(func() error {
return unix.Fstatat(dirfd, path, stat, flags)
})
return err
}
// Fstatat2 is a more convenient version of Fstatat. It allocates a Stat_t
// for you and also handles the Unix2syscall conversion.
// Retries on EINTR.
func Fstatat2(dirfd int, path string, flags int) (*syscall.Stat_t, error) {
var stUnix unix.Stat_t
err := Fstatat(dirfd, path, &stUnix, flags)

@ -265,9 +265,13 @@ func FutimesNano(fd int, a *time.Time, m *time.Time) (err error) {
}
// UtimesNanoAtNofollow is like UtimesNanoAt but never follows symlinks.
// Retries on EINTR.
func UtimesNanoAtNofollow(dirfd int, path string, a *time.Time, m *time.Time) (err error) {
ts := timesToTimespec(a, m)
return unix.UtimesNanoAt(dirfd, path, ts, unix.AT_SYMLINK_NOFOLLOW)
err = retryEINTR(func() error {
return unix.UtimesNanoAt(dirfd, path, ts, unix.AT_SYMLINK_NOFOLLOW)
})
return err
}
// Getdents syscall.
@ -276,6 +280,10 @@ func Getdents(fd int) ([]fuse.DirEntry, error) {
}
// Renameat2 does not exist on Darwin, so we have to wrap it here.
// Retries on EINTR.
func Renameat2(olddirfd int, oldpath string, newdirfd int, newpath string, flags uint) (err error) {
return unix.Renameat2(olddirfd, oldpath, newdirfd, newpath, flags)
err = retryEINTR(func() error {
return unix.Renameat2(olddirfd, oldpath, newdirfd, newpath, flags)
})
return err
}

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