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Refactor attach loop device in pure Go

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This commit is contained in:
Guillaume J. Charmes 2013-11-27 07:16:34 +00:00
parent 8b99e4ed37
commit 74c8f7af75
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GPG key ID: B33E4642CB6E3FF3
4 changed files with 160 additions and 161 deletions
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10
graphdriver/devmapper/deviceset.go
View file

@ -383,7 +383,7 @@ func (devices *DeviceSet) ResizePool(size int64) error {
return fmt.Errorf("Can't shrink file")
}
dataloopback := FindLoopDeviceFor(&osFile{File: datafile})
dataloopback := FindLoopDeviceFor(datafile)
if dataloopback == nil {
return fmt.Errorf("Unable to find loopback mount for: %s", datafilename)
}
@ -395,7 +395,7 @@ func (devices *DeviceSet) ResizePool(size int64) error {
}
defer metadatafile.Close()
metadataloopback := FindLoopDeviceFor(&osFile{File: metadatafile})
metadataloopback := FindLoopDeviceFor(metadatafile)
if metadataloopback == nil {
return fmt.Errorf("Unable to find loopback mount for: %s", metadatafilename)
}
@ -491,14 +491,14 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
if info.Exists == 0 {
utils.Debugf("Pool doesn't exist. Creating it.")
dataFile, err := AttachLoopDevice(data)
dataFile, err := attachLoopDevice(data)
if err != nil {
utils.Debugf("\n--->Err: %s\n", err)
return err
}
defer dataFile.Close()
metadataFile, err := AttachLoopDevice(metadata)
metadataFile, err := attachLoopDevice(metadata)
if err != nil {
utils.Debugf("\n--->Err: %s\n", err)
return err
@ -637,7 +637,7 @@ func (devices *DeviceSet) deactivateDevice(hash string) error {
// or b) the 1 second timeout expires.
func (devices *DeviceSet) waitRemove(hash string) error {
utils.Debugf("[deviceset %s] waitRemove(%s)", devices.devicePrefix, hash)
defer utils.Debugf("[deviceset %s] waitRemove END", devices.devicePrefix, hash)
defer utils.Debugf("[deviceset %s] waitRemove(%) END", devices.devicePrefix, hash)
devname, err := devices.byHash(hash)
if err != nil {
return err

125
graphdriver/devmapper/devmapper.go
View file

@ -5,6 +5,7 @@ import (
"fmt"
"github.com/dotcloud/docker/utils"
"runtime"
"unsafe"
)
type DevmapperLogger interface {
@ -177,15 +178,6 @@ func (t *Task) GetNextTarget(next uintptr) (nextPtr uintptr, start uint64,
start, length, targetType, params
}
func AttachLoopDevice(filename string) (*osFile, error) {
var fd int
res := DmAttachLoopDevice(filename, &fd)
if res == "" {
return nil, ErrAttachLoopbackDevice
}
return &osFile{File: osNewFile(uintptr(fd), res)}, nil
}
func getLoopbackBackingFile(file *osFile) (uint64, uint64, error) {
dev, inode, err := DmGetLoopbackBackingFile(file.Fd())
if err != 0 {
@ -223,11 +215,10 @@ func FindLoopDeviceFor(file *osFile) *osFile {
continue
}
dev, inode, err := getLoopbackBackingFile(&osFile{File: file})
dev, inode, err := getLoopbackBackingFile(file)
if err == nil && dev == targetDevice && inode == targetInode {
return &osFile{File: file}
return file
}
file.Close()
}
@ -420,7 +411,7 @@ func suspendDevice(name string) error {
return err
}
if err := task.Run(); err != nil {
return fmt.Errorf("Error running DeviceSuspend")
return fmt.Errorf("Error running DeviceSuspend: %s", err)
}
return nil
}
@ -437,7 +428,7 @@ func resumeDevice(name string) error {
}
if err := task.Run(); err != nil {
return fmt.Errorf("Error running DeviceSuspend")
return fmt.Errorf("Error running DeviceResume")
}
UdevWait(cookie)
@ -574,3 +565,109 @@ func (devices *DeviceSet) createSnapDevice(poolName string, deviceId int, baseNa
return nil
}
type LoopInfo64 struct {
loDevice uint64 /* ioctl r/o */
loInode uint64 /* ioctl r/o */
loRdevice uint64 /* ioctl r/o */
loOffset uint64
loSizelimit uint64 /* bytes, 0 == max available */
loNumber uint32 /* ioctl r/o */
loEncrypt_type uint32
loEncrypt_key_size uint32 /* ioctl w/o */
loFlags uint32 /* ioctl r/o */
loFileName [LoNameSize]uint8
loCryptName [LoNameSize]uint8
loEncryptKey [LoKeySize]uint8 /* ioctl w/o */
loInit [2]uint64
}
// attachLoopDevice attaches the given sparse file to the next
// available loopback device. It returns an opened *osFile.
func attachLoopDevice(filename string) (loop *osFile, err error) {
startIndex := 0
// Try to retrieve the next available loopback device via syscall.
// If it fails, we discard error and start loopking for a
// loopback from index 0.
if f, err := osOpenFile("/dev/loop-control", osORdOnly, 0644); err == nil {
if index, _, err := sysSyscall(sysSysIoctl, f.Fd(), LoopCtlGetFree, 0); err != 0 {
utils.Debugf("Error retrieving the next available loopback: %s", err)
} else if index > 0 {
startIndex = int(index)
}
f.Close()
}
// Open the given sparse file (use OpenFile because Open sets O_CLOEXEC)
f, err := osOpenFile(filename, osORdWr, 0644)
if err != nil {
return nil, err
}
defer f.Close()
var (
target string
loopFile *osFile
)
// Start looking for a free /dev/loop
for i := startIndex; ; {
target = fmt.Sprintf("/dev/loop%d", i)
fi, err := osStat(target)
if err != nil {
if osIsNotExist(err) {
utils.Errorf("There are no more loopback device available.")
}
}
// FIXME: Check here if target is a block device (in C: S_ISBLK(mode))
if fi.IsDir() {
}
// Open the targeted loopback (use OpenFile because Open sets O_CLOEXEC)
loopFile, err = osOpenFile(target, osORdWr, 0644)
if err != nil {
return nil, err
}
// Try to attach to the loop file
if _, _, err := sysSyscall(sysSysIoctl, loopFile.Fd(), LoopSetFd, f.Fd()); err != 0 {
loopFile.Close()
// If the error is EBUSY, then try the next loopback
if err != sysEBusy {
utils.Errorf("Cannot set up loopback device %s: %s", target, err)
return nil, err
}
} else {
// In case of success, we finished. Break the loop.
break
}
// In case of EBUSY error, the loop keep going.
}
// This can't happen, but let's be sure
if loopFile == nil {
return nil, fmt.Errorf("Unreachable code reached! Error attaching %s to a loopback device.", filename)
}
// Set the status of the loopback device
var loopInfo LoopInfo64
// Due to type incompatibility (string vs [64]uint8), we copy data
copy(loopInfo.loFileName[:], target[:])
loopInfo.loOffset = 0
loopInfo.loFlags = LoFlagsAutoClear
if _, _, err := sysSyscall(sysSysIoctl, loopFile.Fd(), LoopSetStatus64, uintptr(unsafe.Pointer(&loopInfo))); err != 0 {
// If the call failed, then free the loopback device
utils.Errorf("Cannot set up loopback device info: %s", err)
if _, _, err := sysSyscall(sysSysIoctl, loopFile.Fd(), LoopClrFd, 0); err != 0 {
utils.Errorf("Error while cleaning up the loopback device")
}
loopFile.Close()
return nil, err
}
return loopFile, nil
}

178
graphdriver/devmapper/devmapper_wrapper.go
View file

@ -2,124 +2,14 @@ package devmapper
/*
#cgo LDFLAGS: -L. -ldevmapper
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <libdevmapper.h>
#include <linux/loop.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/fs.h>
#include <errno.h>
#ifndef LOOP_CTL_GET_FREE
#define LOOP_CTL_GET_FREE 0x4C82
#endif
// FIXME: this could easily be rewritten in go
char* attach_loop_device(const char *filename, int *loop_fd_out)
{
struct loop_info64 loopinfo = {0};
struct stat st;
char buf[64];
int i, loop_fd, fd, start_index;
char* loopname;
*loop_fd_out = -1;
start_index = 0;
fd = open("/dev/loop-control", O_RDONLY);
if (fd >= 0) {
start_index = ioctl(fd, LOOP_CTL_GET_FREE);
close(fd);
if (start_index < 0)
start_index = 0;
}
fd = open(filename, O_RDWR);
if (fd < 0) {
perror("open");
return NULL;
}
loop_fd = -1;
for (i = start_index ; loop_fd < 0 ; i++ ) {
if (sprintf(buf, "/dev/loop%d", i) < 0) {
close(fd);
return NULL;
}
if (stat(buf, &st)) {
if (!S_ISBLK(st.st_mode)) {
fprintf(stderr, "[error] Loopback device %s is not a block device.\n", buf);
} else if (errno == ENOENT) {
fprintf(stderr, "[error] There are no more loopback device available.\n");
} else {
fprintf(stderr, "[error] Unkown error trying to stat the loopback device %s (errno: %d).\n", buf, errno);
}
close(fd);
return NULL;
}
loop_fd = open(buf, O_RDWR);
if (loop_fd < 0 && errno == ENOENT) {
fprintf(stderr, "[error] The loopback device %s does not exists.\n", buf);
close(fd);
return NULL;
} else if (loop_fd < 0) {
fprintf(stderr, "[error] Unkown error openning the loopback device %s. (errno: %d)\n", buf, errno);
continue;
}
if (ioctl(loop_fd, LOOP_SET_FD, (void *)(size_t)fd) < 0) {
int errsv = errno;
close(loop_fd);
loop_fd = -1;
if (errsv != EBUSY) {
close(fd);
fprintf(stderr, "cannot set up loopback device %s: %s", buf, strerror(errsv));
return NULL;
}
continue;
}
close(fd);
strncpy((char*)loopinfo.lo_file_name, buf, LO_NAME_SIZE);
loopinfo.lo_offset = 0;
loopinfo.lo_flags = LO_FLAGS_AUTOCLEAR;
if (ioctl(loop_fd, LOOP_SET_STATUS64, &loopinfo) < 0) {
perror("ioctl LOOP_SET_STATUS64");
if (ioctl(loop_fd, LOOP_CLR_FD, 0) < 0) {
perror("ioctl LOOP_CLR_FD");
}
close(loop_fd);
fprintf (stderr, "cannot set up loopback device info");
return (NULL);
}
loopname = strdup(buf);
if (loopname == NULL) {
close(loop_fd);
return (NULL);
}
*loop_fd_out = loop_fd;
return (loopname);
}
return (NULL);
}
#include <linux/loop.h> // FIXME: present only for defines, maybe we can remove it?
#include <linux/fs.h> // FIXME: present only for BLKGETSIZE64, maybe we can remove it?
// FIXME: Can't we find a way to do the logging in pure Go?
extern void DevmapperLogCallback(int level, char *file, int line, int dm_errno_or_class, char *str);
static void log_cb(int level, const char *file, int line,
int dm_errno_or_class, const char *f, ...)
static void log_cb(int level, const char *file, int line, int dm_errno_or_class, const char *f, ...)
{
char buffer[256];
va_list ap;
@ -135,7 +25,6 @@ static void log_with_errno_init()
{
dm_log_with_errno_init(log_cb);
}
*/
import "C"
@ -147,6 +36,19 @@ type (
CDmTask C.struct_dm_task
)
// FIXME: Make sure the values are defined in C
const (
LoopSetFd = C.LOOP_SET_FD
LoopCtlGetFree = C.LOOP_CTL_GET_FREE
LoopSetStatus64 = C.LOOP_SET_STATUS64
LoopClrFd = C.LOOP_CLR_FD
LoFlagsAutoClear = C.LO_FLAGS_AUTOCLEAR
LoFlagsReadOnly = C.LO_FLAGS_READ_ONLY
LoFlagsPartScan = C.LO_FLAGS_PARTSCAN
LoKeySize = C.LO_KEY_SIZE
LoNameSize = C.LO_NAME_SIZE
)
var (
DmAttachLoopDevice = dmAttachLoopDeviceFct
DmGetBlockSize = dmGetBlockSizeFct
@ -185,28 +87,26 @@ func dmTaskCreateFct(taskType int) *CDmTask {
}
func dmTaskRunFct(task *CDmTask) int {
return int(C.dm_task_run((*C.struct_dm_task)(task)))
ret, _ := C.dm_task_run((*C.struct_dm_task)(task))
return int(ret)
}
func dmTaskSetNameFct(task *CDmTask, name string) int {
Cname := C.CString(name)
defer free(Cname)
return int(C.dm_task_set_name((*C.struct_dm_task)(task),
Cname))
return int(C.dm_task_set_name((*C.struct_dm_task)(task), Cname))
}
func dmTaskSetMessageFct(task *CDmTask, message string) int {
Cmessage := C.CString(message)
defer free(Cmessage)
return int(C.dm_task_set_message((*C.struct_dm_task)(task),
Cmessage))
return int(C.dm_task_set_message((*C.struct_dm_task)(task), Cmessage))
}
func dmTaskSetSectorFct(task *CDmTask, sector uint64) int {
return int(C.dm_task_set_sector((*C.struct_dm_task)(task),
C.uint64_t(sector)))
return int(C.dm_task_set_sector((*C.struct_dm_task)(task), C.uint64_t(sector)))
}
func dmTaskSetCookieFct(task *CDmTask, cookie *uint, flags uint16) int {
@ -214,13 +114,11 @@ func dmTaskSetCookieFct(task *CDmTask, cookie *uint, flags uint16) int {
defer func() {
*cookie = uint(cCookie)
}()
return int(C.dm_task_set_cookie((*C.struct_dm_task)(task), &cCookie,
C.uint16_t(flags)))
return int(C.dm_task_set_cookie((*C.struct_dm_task)(task), &cCookie, C.uint16_t(flags)))
}
func dmTaskSetAddNodeFct(task *CDmTask, addNode AddNodeType) int {
return int(C.dm_task_set_add_node((*C.struct_dm_task)(task),
C.dm_add_node_t(addNode)))
return int(C.dm_task_set_add_node((*C.struct_dm_task)(task), C.dm_add_node_t(addNode)))
}
func dmTaskSetRoFct(task *CDmTask) int {
@ -236,14 +134,12 @@ func dmTaskAddTargetFct(task *CDmTask,
Cparams := C.CString(params)
defer free(Cparams)
return int(C.dm_task_add_target((*C.struct_dm_task)(task),
C.uint64_t(start), C.uint64_t(size), Cttype, Cparams))
return int(C.dm_task_add_target((*C.struct_dm_task)(task), C.uint64_t(start), C.uint64_t(size), Cttype, Cparams))
}
func dmGetLoopbackBackingFileFct(fd uintptr) (uint64, uint64, sysErrno) {
var lo64 C.struct_loop_info64
_, _, err := sysSyscall(sysSysIoctl, fd, C.LOOP_GET_STATUS64,
uintptr(unsafe.Pointer(&lo64)))
_, _, err := sysSyscall(sysSysIoctl, fd, C.LOOP_GET_STATUS64, uintptr(unsafe.Pointer(&lo64)))
return uint64(lo64.lo_device), uint64(lo64.lo_inode), sysErrno(err)
}
@ -287,23 +183,23 @@ func dmGetNextTargetFct(task *CDmTask, next uintptr, start, length *uint64, targ
*params = C.GoString(Cparams)
}()
nextp := C.dm_get_next_target((*C.struct_dm_task)(task),
unsafe.Pointer(next), &Cstart, &Clength, &CtargetType, &Cparams)
nextp := C.dm_get_next_target((*C.struct_dm_task)(task), unsafe.Pointer(next), &Cstart, &Clength, &CtargetType, &Cparams)
return uintptr(nextp)
}
func dmAttachLoopDeviceFct(filename string, fd *int) string {
cFilename := C.CString(filename)
defer free(cFilename)
return ""
// cFilename := C.CString(filename)
// defer free(cFilename)
var cFd C.int
defer func() {
*fd = int(cFd)
}()
// var cFd C.int
// defer func() {
// *fd = int(cFd)
// }()
ret := C.attach_loop_device(cFilename, &cFd)
defer free(ret)
return C.GoString(ret)
// ret := C.attach_loop_device(cFilename, &cFd)
// defer free(ret)
// return C.GoString(ret)
}
func getBlockSizeFct(fd uintptr, size *uint64) sysErrno {

8
graphdriver/devmapper/sys.go
View file

@ -19,7 +19,11 @@ var (
sysCloseOnExec = syscall.CloseOnExec
sysSyscall = syscall.Syscall
osOpenFile = os.OpenFile
osOpenFile = func(name string, flag int, perm os.FileMode) (*osFile, error) {
f, err := os.OpenFile(name, flag, perm)
return &osFile{File: f}, err
}
osOpen = func(name string) (*osFile, error) { f, err := os.Open(name); return &osFile{File: f}, err }
osNewFile = os.NewFile
osCreate = os.Create
osStat = os.Stat
@ -40,7 +44,9 @@ const (
sysMsRdOnly = syscall.MS_RDONLY
sysEInval = syscall.EINVAL
sysSysIoctl = syscall.SYS_IOCTL
sysEBusy = syscall.EBUSY
osORdOnly = os.O_RDONLY
osORdWr = os.O_RDWR
osOCreate = os.O_CREATE
)