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Replace stat syscall with statx

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statx with AT_STATX_DONT_SYNC will not stuck kubelet syncLoop.

Signed-off-by: j4ckstraw <j4ckstraw@foxmail.com>

fix remove useless comment

Signed-off-by: j4ckstraw <j4ckstraw@foxmail.com>
This commit is contained in:
j4ckstraw 2023-08-16 17:10:34 +08:00
parent b51ad13bf7
commit dbb6927ec2
1 changed files with 48 additions and 21 deletions
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69
staging/src/k8s.io/mount-utils/mount_linux.go
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@ -29,10 +29,10 @@ import (
"path/filepath" "path/filepath"
"strconv" "strconv"
"strings" "strings"
"syscall"
"time" "time"
"github.com/moby/sys/mountinfo" "github.com/moby/sys/mountinfo"
"golang.org/x/sys/unix"
"k8s.io/klog/v2" "k8s.io/klog/v2"
utilexec "k8s.io/utils/exec" utilexec "k8s.io/utils/exec"
@ -385,28 +385,55 @@ func (*Mounter) List() ([]MountPoint, error) {
return ListProcMounts(procMountsPath) return ListProcMounts(procMountsPath)
} }
// IsLikelyNotMountPoint determines if a directory is not a mountpoint. // statx support since Linux 4.11, glibc 2.28
// It is fast but not necessarily ALWAYS correct. If the path is in fact // refer: https://man7.org/linux/man-pages/man2/statx.2.html
// a bind mount from one part of a mount to another it will not be detected. var errNotSupport = errors.New("The statx syscall is not supported. At least Linux kernel 4.11 is needed")
// It also can not distinguish between mountpoints and symbolic links.
// mkdir /tmp/a /tmp/b; mount --bind /tmp/a /tmp/b; IsLikelyNotMountPoint("/tmp/b") func statx(file string) (unix.Statx_t, error) {
// will return true. When in fact /tmp/b is a mount point. If this situation var stat unix.Statx_t
// is of interest to you, don't use this function... if err := unix.Statx(0, file, unix.AT_STATX_DONT_SYNC, 0, &stat); err != nil {
func (mounter *Mounter) IsLikelyNotMountPoint(file string) (bool, error) { if err == unix.ENOSYS {
stat, err := os.Stat(file) return stat, errNotSupport
if err != nil { }
return true, err
} return stat, err
rootStat, err := os.Stat(filepath.Dir(strings.TrimSuffix(file, "/")))
if err != nil {
return true, err
}
// If the directory has a different device as parent, then it is a mountpoint.
if stat.Sys().(*syscall.Stat_t).Dev != rootStat.Sys().(*syscall.Stat_t).Dev {
return false, nil
} }
return true, nil return stat, nil
}
// IsLikelyNotMountPoint determines if a directory is not a mountpoint.
// If fast check failed, fall back to slow path. If the path is in fact
// a bind mount from one part of a mount to another it will be detected.
// It also can distinguish between mountpoints and symbolic links.
// mkdir /tmp/a /tmp/b; mount --bind /tmp/a /tmp/b; IsLikelyNotMountPoint("/tmp/b")
// will return false. When in fact /tmp/b is a mount point.
// TODO(j4ckstraw) add test
func (mounter *Mounter) IsLikelyNotMountPoint(file string) (bool, error) {
var stat, rootStat unix.Statx_t
var err error
if stat, err = statx(file); err != nil {
if errors.Is(err, errNotSupport) {
// not support statx, go slow path
mnt, mntErr := mounter.IsMountPoint(file)
return !mnt, mntErr
}
return false, err
}
root := filepath.Dir(strings.TrimSuffix(file, "/"))
if rootStat, err = statx(root); err != nil {
return false, err
}
// TODO add STATX_ATTR_MOUNT_ROOT support, which can check mountpoint correctly.
// Linux 5.8 commit 80340fe3605c0e78cfe496c3b3878be828cfdbfe
// stat->attributes |= STATX_ATTR_MOUNT_ROOT;
// stat->attributes_mask |= STATX_ATTR_MOUNT_ROOT;
return !(stat.Dev_major == rootStat.Dev_major && stat.Dev_minor == rootStat.Dev_minor), nil
} }
// CanSafelySkipMountPointCheck relies on the detected behavior of umount when given a target that is not a mount point. // CanSafelySkipMountPointCheck relies on the detected behavior of umount when given a target that is not a mount point.