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-rw-r--r--runsc/fsgofer/fsgofer.go164
1 files changed, 86 insertions, 78 deletions
diff --git a/runsc/fsgofer/fsgofer.go b/runsc/fsgofer/fsgofer.go
index 1e422f30b..9955d0750 100644
--- a/runsc/fsgofer/fsgofer.go
+++ b/runsc/fsgofer/fsgofer.go
@@ -175,21 +175,23 @@ func (a *attachPoint) makeQID(stat syscall.Stat_t) p9.QID {
}
// localFile implements p9.File wrapping a local file. The underlying file
-// is opened during Walk() and stored in 'file' to be used with other
-// operations. The file is opened as readonly, unless it's a symlink which
-// requires O_PATH. 'file' is dup'ed when Walk(nil) is called to clone the file.
-// This reduces the number of walks that need to be done by the host file
-// system when files are reused.
+// is opened during Walk() and stored in 'controlFile' to be used with other
+// operations. The control file is opened as readonly, unless it's a symlink
+// which requires O_PATH. 'controlFile' is dup'ed when Walk(nil) is called
+// to clone the file. This reduces the number of walks that need to be done by
+// the host file system when files are reused.
//
-// The file may be reopened if the requested mode in Open() is not a subset of
-// current mode. Consequently, 'file' could have a mode wider than requested and
-// must be verified before read/write operations. Before the file is opened and
-// after it's closed, 'mode' is set to an invalid value to prevent an unopened
-// file from being used.
+// 'openedFile' is assigned when Open() is called. If requested open mode is
+// a subset of controlFile's mode, it's possible to use the same file. If mode
+// is not a subset, then another file is opened. Consequently, 'openedFile'
+// could have a mode wider than requested and must be verified before read/write
+// operations. Before the file is opened and after it's closed, 'mode' is set to
+// an invalid value to prevent an unopened file from being used.
//
-// The reason that the file is not opened initially as read-write is for better
+// The reason that the control file is never opened as read-write is for better
// performance with 'overlay2' storage driver. overlay2 eagerly copies the
// entire file up when it's opened in write mode, and would perform badly when
+// multiple files are being opened for read-only (esp. startup).
type localFile struct {
p9.DefaultWalkGetAttr
@@ -199,9 +201,12 @@ type localFile struct {
// hostPath will be safely updated by the Renamed hook.
hostPath string
- // file is opened when localFile is created and it's never nil. It may be
- // reopened...
- file *os.File
+ // controlFile is opened when localFile is created and it's never nil.
+ controlFile *os.File
+
+ // openedFile is nil until localFile is opened. It may point to controlFile
+ // or be a new file struct. See struct comment for more details.
+ openedFile *os.File
// mode is the mode in which the file was opened. Set to invalidMode
// if localFile isn't opened.
@@ -223,7 +228,7 @@ func openAnyFile(parent *localFile, name string) (*os.File, string, error) {
var err error
var fd int
for i, mode := range modes {
- fd, err = syscall.Openat(parent.fd(), name, openFlags|mode, 0)
+ fd, err = syscall.Openat(parent.controlFD(), name, openFlags|mode, 0)
if err == nil {
// openat succeeded, we're done.
break
@@ -235,11 +240,11 @@ func openAnyFile(parent *localFile, name string) (*os.File, string, error) {
}
// openat failed. Try again with next mode, preserving 'err' in case this
// was the last attempt.
- log.Debugf("Attempt %d to open file failed, mode: %#x, path: %s/%s, err: %v", i, openFlags|mode, parent.file.Name(), name, err)
+ log.Debugf("Attempt %d to open file failed, mode: %#x, path: %s/%s, err: %v", i, openFlags|mode, parent.controlFile.Name(), name, err)
}
if err != nil {
// All attempts to open file have failed, return the last error.
- log.Debugf("Failed to open file, path: %s/%s, err: %v", parent.file.Name(), name, err)
+ log.Debugf("Failed to open file, path: %s/%s, err: %v", parent.controlFile.Name(), name, err)
return nil, "", extractErrno(err)
}
@@ -262,7 +267,7 @@ func newLocalFile(a *attachPoint, file *os.File, path string, stat syscall.Stat_
return &localFile{
attachPoint: a,
hostPath: path,
- file: file,
+ controlFile: file,
mode: invalidMode,
ft: ft,
}, nil
@@ -297,26 +302,33 @@ func fchown(fd int, uid p9.UID, gid p9.GID) error {
return syscall.Fchownat(fd, "", int(uid), int(gid), linux.AT_EMPTY_PATH|unix.AT_SYMLINK_NOFOLLOW)
}
-func (l *localFile) fd() int {
- return int(l.file.Fd())
+func (l *localFile) controlFD() int {
+ return int(l.controlFile.Fd())
+}
+
+func (l *localFile) openedFD() int {
+ if l.openedFile == nil {
+ panic(fmt.Sprintf("trying to use an unopened file: %q", l.controlFile.Name()))
+ }
+ return int(l.openedFile.Fd())
}
// Open implements p9.File.
func (l *localFile) Open(mode p9.OpenFlags) (*fd.FD, p9.QID, uint32, error) {
- if l.isOpen() {
- panic(fmt.Sprintf("attempting to open already opened file: %q", l.file.Name()))
+ if l.openedFile != nil {
+ panic(fmt.Sprintf("attempting to open already opened file: %q", l.controlFile.Name()))
}
// Check if control file can be used or if a new open must be created.
var newFile *os.File
if mode == p9.ReadOnly {
- log.Debugf("Open reusing control file, mode: %v, %q", mode, l.file.Name())
- newFile = l.file
+ log.Debugf("Open reusing control file, mode: %v, %q", mode, l.controlFile.Name())
+ newFile = l.controlFile
} else {
// Ideally reopen would call name_to_handle_at (with empty name) and
// open_by_handle_at to reopen the file without using 'hostPath'. However,
// name_to_handle_at and open_by_handle_at aren't supported by overlay2.
- log.Debugf("Open reopening file, mode: %v, %q", mode, l.file.Name())
+ log.Debugf("Open reopening file, mode: %v, %q", mode, l.controlFile.Name())
var err error
newFile, err = os.OpenFile(l.hostPath, openFlags|mode.OSFlags(), 0)
@@ -327,9 +339,7 @@ func (l *localFile) Open(mode p9.OpenFlags) (*fd.FD, p9.QID, uint32, error) {
stat, err := stat(int(newFile.Fd()))
if err != nil {
- if newFile != l.file {
- newFile.Close()
- }
+ newFile.Close()
return nil, p9.QID{}, 0, extractErrno(err)
}
@@ -339,13 +349,8 @@ func (l *localFile) Open(mode p9.OpenFlags) (*fd.FD, p9.QID, uint32, error) {
fd = newFDMaybe(newFile)
}
- // Close old file in case a new one was created.
- if newFile != l.file {
- if err := l.file.Close(); err != nil {
- log.Warningf("Error closing file %q: %v", l.file.Name(), err)
- }
- l.file = newFile
- }
+ // Set fields on success
+ l.openedFile = newFile
l.mode = mode
return fd, l.attachPoint.makeQID(stat), 0, nil
}
@@ -360,9 +365,10 @@ func (l *localFile) Create(name string, mode p9.OpenFlags, perm p9.FileMode, uid
return nil, nil, p9.QID{}, 0, syscall.EBADF
}
- // 'file' may be used for other operations (e.g. Walk), so read access is
- // always added to flags. Note that resulting file might have a wider mode
- // than needed for each particular case.
+ // Use a single file for both 'controlFile' and 'openedFile'. Mode must
+ // include read for control and whichever else was requested by caller. Note
+ // that resulting file might have a wider mode than needed for each particular
+ // case.
flags := openFlags | syscall.O_CREAT | syscall.O_EXCL
if mode == p9.WriteOnly {
flags |= syscall.O_RDWR
@@ -370,14 +376,14 @@ func (l *localFile) Create(name string, mode p9.OpenFlags, perm p9.FileMode, uid
flags |= mode.OSFlags()
}
- fd, err := syscall.Openat(l.fd(), name, flags, uint32(perm.Permissions()))
+ fd, err := syscall.Openat(l.controlFD(), name, flags, uint32(perm.Permissions()))
if err != nil {
return nil, nil, p9.QID{}, 0, extractErrno(err)
}
cu := specutils.MakeCleanup(func() {
syscall.Close(fd)
// Best effort attempt to remove the file in case of failure.
- if err := syscall.Unlinkat(l.fd(), name); err != nil {
+ if err := syscall.Unlinkat(l.controlFD(), name); err != nil {
log.Warningf("error unlinking file %q after failure: %v", path.Join(l.hostPath, name), err)
}
})
@@ -396,12 +402,13 @@ func (l *localFile) Create(name string, mode p9.OpenFlags, perm p9.FileMode, uid
c := &localFile{
attachPoint: l.attachPoint,
hostPath: cPath,
- file: f,
+ controlFile: f,
+ openedFile: f,
mode: mode,
}
cu.Release()
- return newFDMaybe(c.file), c, l.attachPoint.makeQID(stat), 0, nil
+ return newFDMaybe(c.openedFile), c, l.attachPoint.makeQID(stat), 0, nil
}
// Mkdir implements p9.File.
@@ -414,12 +421,12 @@ func (l *localFile) Mkdir(name string, perm p9.FileMode, uid p9.UID, gid p9.GID)
return p9.QID{}, syscall.EBADF
}
- if err := syscall.Mkdirat(l.fd(), name, uint32(perm.Permissions())); err != nil {
+ if err := syscall.Mkdirat(l.controlFD(), name, uint32(perm.Permissions())); err != nil {
return p9.QID{}, extractErrno(err)
}
cu := specutils.MakeCleanup(func() {
// Best effort attempt to remove the dir in case of failure.
- if err := unix.Unlinkat(l.fd(), name, unix.AT_REMOVEDIR); err != nil {
+ if err := unix.Unlinkat(l.controlFD(), name, unix.AT_REMOVEDIR); err != nil {
log.Warningf("error unlinking dir %q after failure: %v", path.Join(l.hostPath, name), err)
}
})
@@ -427,7 +434,7 @@ func (l *localFile) Mkdir(name string, perm p9.FileMode, uid p9.UID, gid p9.GID)
// Open directory to change ownership and stat it.
flags := syscall.O_DIRECTORY | syscall.O_RDONLY | openFlags
- fd, err := syscall.Openat(l.fd(), name, flags, 0)
+ fd, err := syscall.Openat(l.controlFD(), name, flags, 0)
if err != nil {
return p9.QID{}, extractErrno(err)
}
@@ -449,7 +456,7 @@ func (l *localFile) Mkdir(name string, perm p9.FileMode, uid p9.UID, gid p9.GID)
func (l *localFile) Walk(names []string) ([]p9.QID, p9.File, error) {
// Duplicate current file if 'names' is empty.
if len(names) == 0 {
- newFd, err := syscall.Dup(l.fd())
+ newFd, err := syscall.Dup(l.controlFD())
if err != nil {
return nil, nil, extractErrno(err)
}
@@ -462,7 +469,7 @@ func (l *localFile) Walk(names []string) ([]p9.QID, p9.File, error) {
c := &localFile{
attachPoint: l.attachPoint,
hostPath: l.hostPath,
- file: os.NewFile(uintptr(newFd), l.hostPath),
+ controlFile: os.NewFile(uintptr(newFd), l.hostPath),
mode: invalidMode,
}
return []p9.QID{l.attachPoint.makeQID(stat)}, c, nil
@@ -477,12 +484,10 @@ func (l *localFile) Walk(names []string) ([]p9.QID, p9.File, error) {
}
stat, err := stat(int(f.Fd()))
if err != nil {
- f.Close()
return nil, nil, extractErrno(err)
}
c, err := newLocalFile(last.attachPoint, f, path, stat)
if err != nil {
- f.Close()
return nil, nil, extractErrno(err)
}
@@ -495,7 +500,7 @@ func (l *localFile) Walk(names []string) ([]p9.QID, p9.File, error) {
// StatFS implements p9.File.
func (l *localFile) StatFS() (p9.FSStat, error) {
var s syscall.Statfs_t
- if err := syscall.Fstatfs(l.fd(), &s); err != nil {
+ if err := syscall.Fstatfs(l.controlFD(), &s); err != nil {
return p9.FSStat{}, extractErrno(err)
}
@@ -514,10 +519,10 @@ func (l *localFile) StatFS() (p9.FSStat, error) {
// FSync implements p9.File.
func (l *localFile) FSync() error {
- if !l.isOpen() {
+ if l.openedFile == nil {
return syscall.EBADF
}
- if err := l.file.Sync(); err != nil {
+ if err := l.openedFile.Sync(); err != nil {
return extractErrno(err)
}
return nil
@@ -525,7 +530,7 @@ func (l *localFile) FSync() error {
// GetAttr implements p9.File.
func (l *localFile) GetAttr(_ p9.AttrMask) (p9.QID, p9.AttrMask, p9.Attr, error) {
- stat, err := stat(l.fd())
+ stat, err := stat(l.controlFD())
if err != nil {
return p9.QID{}, p9.AttrMask{}, p9.Attr{}, extractErrno(err)
}
@@ -593,11 +598,11 @@ func (l *localFile) SetAttr(valid p9.SetAttrMask, attr p9.SetAttr) error {
// Handle all the sanity checks up front so that the client gets a
// consistent result that is not attribute dependent.
if !valid.IsSubsetOf(allowed) {
- log.Warningf("SetAttr() failed for %q, mask: %v", l.file.Name(), valid)
+ log.Warningf("SetAttr() failed for %q, mask: %v", l.controlFile.Name(), valid)
return syscall.EPERM
}
- fd := l.fd()
+ fd := l.controlFD()
if l.ft == regular {
// Regular files are opened in RO mode, thus it needs to be reopened here
// for write.
@@ -714,7 +719,7 @@ func (l *localFile) RenameAt(oldName string, directory p9.File, newName string)
}
newParent := directory.(*localFile)
- if err := renameat(l.fd(), oldName, newParent.fd(), newName); err != nil {
+ if err := renameat(l.controlFD(), oldName, newParent.controlFD(), newName); err != nil {
return extractErrno(err)
}
return nil
@@ -725,11 +730,11 @@ func (l *localFile) ReadAt(p []byte, offset uint64) (int, error) {
if l.mode != p9.ReadOnly && l.mode != p9.ReadWrite {
return 0, syscall.EBADF
}
- if !l.isOpen() {
+ if l.openedFile == nil {
return 0, syscall.EBADF
}
- r, err := l.file.ReadAt(p, int64(offset))
+ r, err := l.openedFile.ReadAt(p, int64(offset))
switch err {
case nil, io.EOF:
return r, nil
@@ -743,11 +748,11 @@ func (l *localFile) WriteAt(p []byte, offset uint64) (int, error) {
if l.mode != p9.WriteOnly && l.mode != p9.ReadWrite {
return 0, syscall.EBADF
}
- if !l.isOpen() {
+ if l.openedFile == nil {
return 0, syscall.EBADF
}
- w, err := l.file.WriteAt(p, int64(offset))
+ w, err := l.openedFile.WriteAt(p, int64(offset))
if err != nil {
return w, extractErrno(err)
}
@@ -764,19 +769,19 @@ func (l *localFile) Symlink(target, newName string, uid p9.UID, gid p9.GID) (p9.
return p9.QID{}, syscall.EBADF
}
- if err := unix.Symlinkat(target, l.fd(), newName); err != nil {
+ if err := unix.Symlinkat(target, l.controlFD(), newName); err != nil {
return p9.QID{}, extractErrno(err)
}
cu := specutils.MakeCleanup(func() {
// Best effort attempt to remove the symlink in case of failure.
- if err := syscall.Unlinkat(l.fd(), newName); err != nil {
+ if err := syscall.Unlinkat(l.controlFD(), newName); err != nil {
log.Warningf("error unlinking file %q after failure: %v", path.Join(l.hostPath, newName), err)
}
})
defer cu.Clean()
// Open symlink to change ownership and stat it.
- fd, err := syscall.Openat(l.fd(), newName, unix.O_PATH|openFlags, 0)
+ fd, err := syscall.Openat(l.controlFD(), newName, unix.O_PATH|openFlags, 0)
if err != nil {
return p9.QID{}, extractErrno(err)
}
@@ -805,7 +810,7 @@ func (l *localFile) Link(target p9.File, newName string) error {
}
targetFile := target.(*localFile)
- if err := unix.Linkat(targetFile.fd(), "", l.fd(), newName, linux.AT_EMPTY_PATH); err != nil {
+ if err := unix.Linkat(targetFile.controlFD(), "", l.controlFD(), newName, linux.AT_EMPTY_PATH); err != nil {
return extractErrno(err)
}
return nil
@@ -828,7 +833,7 @@ func (l *localFile) UnlinkAt(name string, flags uint32) error {
return syscall.EBADF
}
- if err := unix.Unlinkat(l.fd(), name, int(flags)); err != nil {
+ if err := unix.Unlinkat(l.controlFD(), name, int(flags)); err != nil {
return extractErrno(err)
}
return nil
@@ -839,7 +844,7 @@ func (l *localFile) Readdir(offset uint64, count uint32) ([]p9.Dirent, error) {
if l.mode != p9.ReadOnly && l.mode != p9.ReadWrite {
return nil, syscall.EBADF
}
- if !l.isOpen() {
+ if l.openedFile == nil {
return nil, syscall.EBADF
}
@@ -847,11 +852,11 @@ func (l *localFile) Readdir(offset uint64, count uint32) ([]p9.Dirent, error) {
// reading all directory contents. Take a lock because this operation is
// stateful.
l.readDirMu.Lock()
- if _, err := l.file.Seek(0, 0); err != nil {
+ if _, err := l.openedFile.Seek(0, 0); err != nil {
l.readDirMu.Unlock()
return nil, extractErrno(err)
}
- names, err := l.file.Readdirnames(-1)
+ names, err := l.openedFile.Readdirnames(-1)
if err != nil {
l.readDirMu.Unlock()
return nil, extractErrno(err)
@@ -860,7 +865,7 @@ func (l *localFile) Readdir(offset uint64, count uint32) ([]p9.Dirent, error) {
var dirents []p9.Dirent
for i := int(offset); i >= 0 && i < len(names); i++ {
- stat, err := statAt(l.fd(), names[i])
+ stat, err := statAt(l.openedFD(), names[i])
if err != nil {
continue
}
@@ -878,10 +883,9 @@ func (l *localFile) Readdir(offset uint64, count uint32) ([]p9.Dirent, error) {
// Readlink implements p9.File.
func (l *localFile) Readlink() (string, error) {
// Shamelessly stolen from os.Readlink (added upper bound limit to buffer).
- const limit = 1024 * 1024
- for len := 128; len < limit; len *= 2 {
+ for len := 128; len < 1024*1024; len *= 2 {
b := make([]byte, len)
- n, err := unix.Readlinkat(l.fd(), "", b)
+ n, err := unix.Readlinkat(l.controlFD(), "", b)
if err != nil {
return "", extractErrno(err)
}
@@ -904,16 +908,20 @@ func (l *localFile) Connect(p9.ConnectFlags) (*fd.FD, error) {
// Close implements p9.File.
func (l *localFile) Close() error {
+ err := l.controlFile.Close()
+
+ // Close only once in case opened and control files point to
+ // the same os.File struct.
+ if l.openedFile != nil && l.openedFile != l.controlFile {
+ err = l.openedFile.Close()
+ }
+
+ l.openedFile = nil
+ l.controlFile = nil
l.mode = invalidMode
- err := l.file.Close()
- l.file = nil
return err
}
-func (l *localFile) isOpen() bool {
- return l.mode != invalidMode
-}
-
// Renamed implements p9.Renamed.
func (l *localFile) Renamed(newDir p9.File, newName string) {
l.hostPath = path.Join(newDir.(*localFile).hostPath, newName)
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-15 04:13:19 +0000