Commit Graph

181 Commits

Author SHA1 Message Date
Kubernetes Submit Queue
e6b6e5c4b4 Merge pull request #63045 from msau42/fix-subpath-readonly
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

passthrough readOnly to subpath

**What this PR does / why we need it**:
If a volume is mounted as readonly, or subpath volumeMount is configured as readonly, then the subpath bind mount should be readonly.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #62752

**Special notes for your reviewer**:

**Release note**:

```release-note
Fixes issue where subpath readOnly mounts failed
```
2018-05-07 23:36:49 -07:00
Kubernetes Submit Queue
54cf942a05 Merge pull request #63399 from andyzhangx/mount-windows-test-fix
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

use TempDir func in mount_windows_test.go

**What this PR does / why we need it**:
Use `c:\tmp` dir is not correct in windows test, this PR use `ioutil.TempDir("", xx)` to create temp dir instead.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:

**Release note**:

```
none
```

/assign @jsafrane @msau42
2018-05-04 05:30:42 -07:00
andyzhangx
3db442bcd0 use TempDir func in mount_windows_test.go
fix comments
2018-05-03 12:58:32 +00:00
Kubernetes Submit Queue
186dd7beb1 Merge pull request #62903 from cofyc/fixfsgroupcheckinlocal
Automatic merge from submit-queue (batch tested with PRs 62657, 63278, 62903, 63375). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add more volume types in e2e and fix part of them.

**What this PR does / why we need it**:

- Add dir-link/dir-bindmounted/dir-link-bindmounted/bockfs volume types for e2e tests.
- Fix fsGroup related e2e tests partially.
- Return error if we cannot resolve volume path.
  - Because we should not fallback to volume path, if it's a symbolic link, we may get wrong results.

To safely set fsGroup on local volume, we need to implement these two methods correctly for all volume types both on the host and in container:

- get volume path kubelet can access
  - paths on the host and in container are different
- get mount references
  - for directories, we cannot use its mount source (device field) to identify mount references, because directories on same filesystem have same mount source (e.g. tmpfs), we need to check filesystem's major:minor and directory root path on it

Here is current status:

| | (A) volume-path (host) | (B) volume-path (container) | (C) mount-refs (host) | (D) mount-refs (container) |
| --- | --- | --- | --- | --- |
| (1) dir | OK | FAIL | FAIL | FAIL |
| (2) dir-link | OK | FAIL | FAIL | FAIL |
| (3) dir-bindmounted | OK | FAIL | FAIL | FAIL |
| (4) dir-link-bindmounted | OK | FAIL | FAIL | FAIL |
| (5) tmpfs| OK | FAIL | FAIL | FAIL |
| (6) blockfs| OK | FAIL | OK | FAIL |
| (7) block| NOTNEEDED | NOTNEEDED | NOTNEEDED | NOTNEEDED |
| (8) gce-localssd-scsi-fs| NOTTESTED | NOTTESTED | NOTTESTED | NOTTESTED |

- This PR uses `nsenter ... readlink` to resolve path in container as @msau42  @jsafrane [suggested](https://github.com/kubernetes/kubernetes/pull/61489#pullrequestreview-110032850). This fixes B1:B6 and D6, , the rest will be addressed in https://github.com/kubernetes/kubernetes/pull/62102.
- C5:D5 marked `FAIL` because `tmpfs` filesystems can share same mount source, we cannot rely on it to check mount references. e2e tests passes due to we use unique mount source string in tests.
- A7:D7 marked `NOTNEEDED` because we don't set fsGroup on block devices in local plugin. (TODO: Should we set fsGroup on block device?)
- A8:D8 marked `NOTTESTED` because I didn't test it, I leave it to `pull-kubernetes-e2e-gce`. I think it should be same as `blockfs`.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```
2018-05-02 20:13:11 -07:00
Yecheng Fu
3748197876 Add more volume types in e2e and fix part of them.
- Add dir-link/dir-bindmounted/dir-link-bindmounted/blockfs volume types for e2e
tests.
- Return error if we cannot resolve volume path.
- Add GetFSGroup/GetMountRefs methods for mount.Interface.
- Fix fsGroup related e2e tests partially.
2018-05-02 10:31:42 +08:00
Michelle Au
6b1947c9ba passthrough readOnly to subpath 2018-04-26 11:18:36 -07:00
Davanum Srinivas
2f98d7a3ea Support nsenter in non-systemd environments
In our CI, we run kubekins image for most of the jobs. This is a
debian image with upstart and does not enable systemd. So we should:

* Bailout if any binary is missing other than systemd-run.
* SupportsSystemd should check the binary path to correctly
  identify if the systemd-run is present or not
* Pass the errors back to the callers so kubelet is forced to
  fail early when there is a problem. We currently assume
  that all binaries are in the root directory by default which
  is wrong.
2018-04-22 22:10:36 -04:00
andyzhangx
1e00396fc8 add andyzhangx as Reviewer 2018-04-16 07:13:15 +00:00
Kubernetes Submit Queue
f5e8dcad9e Merge pull request #62467 from andyzhangx/nsenter-getfiletype-fix
Automatic merge from submit-queue (batch tested with PRs 62467, 62482, 62211). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

fix nsenter GetFileType issue in containerized kubelet

**What this PR does / why we need it**:
UnmountDevice would fail in containerized kubelet in v1.9.x, and in the end, pod with volume mount could not be scheduled from one node to another since the original volume will never be released. This PR fixed this issue.

In [nsenter_mount.GetFileType func](https://github.com/kubernetes/kubernetes/blob/master/pkg/util/mount/nsenter_mount.go#L238), return error of following code will be different than [mount_linux.GetFileType func](https://github.com/kubernetes/kubernetes/blob/master/pkg/util/mount/mount.go#L347)
```
outputBytes, err := mounter.ne.Exec("stat", []string{"-L", `--printf "%F"`, pathname}).CombinedOutput()
```
Return error and output would be like following in nsenter_mount.GetFileType func:
error: `exit status 1`
output: `/usr/bin/stat: cannot stat '2': No such file or directory`

This PR makes the return error consistent as mount_linux.GetFileType func, and finally makes [isDeviceOpened func](https://github.com/kubernetes/kubernetes/blob/master/pkg/volume/util/operationexecutor/operation_generator.go#L1340) work.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #62282

**Special notes for your reviewer**:
/assign @dixudx 

**Release note**:

```
fix nsenter GetFileType issue in containerized kubelet
```

/sig node
2018-04-13 07:25:14 -07:00
Kubernetes Submit Queue
06c5afe275 Merge pull request #62304 from msau42/remove-err-check
Automatic merge from submit-queue (batch tested with PRs 61608, 62304). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Remove isNotDir error check

**What this PR does / why we need it**:
This check was supposed to handle the "subpath file" scenario, but:
1. It's wrong (should have been !)
2. It's not needed anymore. `IsLikelyNotMountPoint` was fixed to handle file mounts via https://github.com/kubernetes/kubernetes/pull/58433


**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```
2018-04-13 05:34:05 -07:00
Kubernetes Submit Queue
2f394a4168 Merge pull request #61914 from ianchakeres/mount-unsupported-err
Automatic merge from submit-queue (batch tested with PRs 62324, 61459, 62475, 62476, 61914). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Return error in mount_unsupported for unsupported platforms

**What this PR does / why we need it**:

Presently, `util/mount_unsupported.go` does not return any errors. For unsupported platforms, this hides failures. This PR returns errors, thereby properly informing users attempting to run on an unsupported platform.

**Which issue(s) this PR fixes** :
Fixes https://github.com/kubernetes/kubernetes/issues/61919

**Special notes for your reviewer**:

There are a few methods that simply call through to other methods. I did not return errors from those methods.

I've also updated an error check and message in `volume/fc/fc_test.go`, since it was ignoring an error on unsupported platforms.

**Release note**:
```release-note
NONE
```
2018-04-12 13:18:18 -07:00
andyzhangx
d154f8d021 fix nsenter GetFileType issue
use outputBytes as return error
2018-04-12 13:12:13 +00:00
Di Xu
ed506328c5 add tests for GetFileType 2018-04-10 10:53:11 +08:00
Di Xu
9c7604fe10 fix incompatible file type checking on Windows 2018-04-10 10:53:11 +08:00
Michelle Au
b79e7cabbc Remove isNotDir error check 2018-04-09 17:32:13 -07:00
Ian Chakeres
3fc5601e35 Return error in mount_unsupported for unsupported platforms 2018-03-29 14:17:07 -07:00
Hemant Kumar
cd36a0bca9 Use relative path for creating socket files 2018-03-28 12:27:33 -04:00
Hemant Kumar
32de642fa1 Use O_PATH to avoid errors on Openat
Also add tests for sockets and fifos
Replace use of syscall for flags with unix
2018-03-22 18:56:58 -04:00
Michelle Au
91c557f504 Use inner volume name instead of outer volume name for subpath directory 2018-03-21 17:13:38 -07:00
Jan Safranek
e55164c42d Fix creation of subpath with SUID/SGID directories.
SafeMakeDir() should apply SUID/SGID/sticky bits to the directory it creates.
2018-03-16 16:58:47 +01:00
Jordan Liggitt
3fafdb7001 Detect backsteps correctly in base path detection
Avoid false positives with atomic writer ..<timestamp> directories
2018-03-13 02:23:06 -04:00
Jan Safranek
5110db5087 Lock subPath volumes
Users must not be allowed to step outside the volume with subPath.
Therefore the final subPath directory must be "locked" somehow
and checked if it's inside volume.

On Windows, we lock the directories. On Linux, we bind-mount the final
subPath into /var/lib/kubelet/pods/<uid>/volume-subpaths/<container name>/<subPathName>,
it can't be changed to symlink user once it's bind-mounted.
2018-03-05 09:14:44 +01:00
andrewsykim
d856a97da1 fix bug where character devices are not recognized 2018-02-26 17:18:05 -05:00
Jeff Grafton
ef56a8d6bb Autogenerated: hack/update-bazel.sh 2018-02-16 13:43:01 -08:00
Kubernetes Submit Queue
f2b6e49e6c Merge pull request #58433 from yue9944882/bugfix/lstat-parent-with-abs-path
Automatic merge from submit-queue (batch tested with PRs 59103, 58433). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

bugfix(mount): lstat with abs path of parent instead of '/..'

**What this PR does / why we need it**:

If a nfs volume with improper permission is mounted on a Pod, operation of deleting this Pod will fail and the pod itself will be stuck at a 'TERMINATING' status. Kubelet cannot reconcile it correctly.

This is because kubelet will try to find the mount-point with '..' file which needs `x` permission of dir.  When it's forbidden, the nfs volume will never umount without a correct mount-point finded.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #57095

**Special notes for your reviewer**:

**Release note**:

```release-note
Get parent dir via canonical absolute path when trying to judge mount-point
```
2018-02-14 03:55:34 -08:00
Kubernetes Submit Queue
2cd6cd6e86 Merge pull request #59818 from msau42/owners
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add reviewers to util/mount

**What this PR does / why we need it**:
Add some more reviewers

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```
2018-02-13 11:13:04 -08:00
Michelle Au
377bff614d add reviewers to util/mount 2018-02-13 10:06:27 -08:00
Kubernetes Submit Queue
317853c90c Merge pull request #59464 from dixudx/fix_all_typos
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

fix all the typos across the project

**What this PR does / why we need it**:
There are lots of typos across the project. We should avoid small PRs on fixing those annoying typos, which is time-consuming and low efficient.

This PR does fix all the typos across the project currently. And with #59463, typos could be avoided when a new PR gets merged.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:
/sig testing
/area test-infra
/sig release
/cc @ixdy 
/assign @fejta 

**Release note**:

```release-note
None
```
2018-02-10 22:12:45 -08:00
Di Xu
48388fec7e fix all the typos across the project 2018-02-11 11:04:14 +08:00
Kubernetes Submit Queue
28b4bb0fd6 Merge pull request #59540 from andyzhangx/azurefile-windows-fix
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

return error if New-SmbGlobalMapping failed when mounting azure file on Windows

**What this PR does / why we need it**:
This PR will return error if New-SmbGlobalMapping failed when mounting azure file on Windows.
User wants to create a pod moutning with azure file pvc using static provisioning([doc](https://github.com/andyzhangx/Demo/tree/master/windows/azurefile#static-provisioning-for-azure-file-on-windows-server-version-1709support-from-v17x])) and user uses a wrong storage account name or key, current behavior is if mount azure file on Windows, it will create an empty directory, and user would not know actually it fails.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #59538 

**Special notes for your reviewer**:

**Release note**:

```
return error if New-SmbGlobalMapping failed when mounting azure file on Windows
```
2018-02-09 23:21:53 -08:00
Kubernetes Submit Queue
3ee818c259 Merge pull request #58912 from mlmhl/volume_mount
Automatic merge from submit-queue (batch tested with PRs 59466, 58912, 59605, 59548). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

return a more human readable error message if mount an unformatted vo…

**What this PR does / why we need it**:

If an unformatted volume is requested as read only mode, according device mount operation will fail, and the message is verbose and obscure. We should check this scenario and return a more human readable message.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #58911

**Release note**:

```release-note
NONE
```

/sig storage
2018-02-09 03:44:35 -08:00
Kubernetes Submit Queue
d6625f857a Merge pull request #58177 from jingxu97/Jan/reconstruct
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Redesign and implement volume reconstruction work

This PR is the first part of redesign of volume reconstruction work. The detailed design information is https://github.com/kubernetes/community/pull/1601

The changes include
1. Remove dependency on volume spec stored in actual state for volume
cleanup process (UnmountVolume and UnmountDevice)

Modify AttachedVolume struct to add DeviceMountPath so that volume
unmount operation can use this information instead of constructing from
volume spec

2. Modify reconciler's volume reconstruction process (syncState). Currently workflow
is when kubelet restarts, syncState() is only called once before
reconciler starts its loop.
a. If volume plugin supports reconstruction, it will use the
reconstructed volume spec information to update actual state as before.
b. If volume plugin cannot support reconstruction, it will use the
scanned mount path information to clean up the mounts.

In this PR, all the plugins still support reconstruction (except
glusterfs), so reconstruction of some plugins will still have issues.
The next PR will modify those plugins that cannot support reconstruction
well.

This PR addresses issue #52683
2018-02-08 18:21:34 -08:00
mlmhl
2f46df3540 return a more human readable error message if mount an unformatted volume as readonly 2018-02-08 20:01:41 +08:00
andyzhangx
0a63d7cc9a return error if New-SmbGlobalMapping failed in azure file mount 2018-02-08 05:56:16 +00:00
Jing Xu
9588d2098a Redesign and implement volume reconstruction work
This PR is the first part of redesign of volume reconstruction work. The
changes include
1. Remove dependency on volume spec stored in actual state for volume
cleanup process (UnmountVolume and UnmountDevice)

Modify AttachedVolume struct to add DeviceMountPath so that volume
unmount operation can use this information instead of constructing from
volume spec

2. Modify reconciler's volume reconstruction process (syncState). Currently workflow
is when kubelet restarts, syncState() is only called once before
reconciler starts its loop.
a. If volume plugin supports reconstruction, it will use the
reconstructed volume spec information to update actual state as before.
b. If volume plugin cannot support reconstruction, it will use the
scanned mount path information to clean up the mounts.

In this PR, all the plugins still support reconstruction (except
glusterfs), so reconstruction of some plugins will still have issues.
The next PR will modify those plugins that cannot support reconstruction
well.

This PR addresses issue #52683, #54108 (This PR includes the changes to
update devicePath after local attach finishes)
2018-02-05 13:14:09 -08:00
Yecheng Fu
322c094841 Use blkid to get fs type of device.
For `blkid`, if the specified token (TYPE/PTTYPE, etc) was
not found, or no (specified) devices could be identified, an
exit code of 2 is returned.
2018-02-05 11:21:35 +08:00
Yecheng Fu
5136938ff6 Use blkid to get fs type of device.
If a parition table type is detected, returns a special non-empty string
as filesystem type.
2018-02-03 00:24:21 +08:00
Yecheng Fu
75359c0b94 Use blkid to get fs type of device.
`lsblk` reads fs type info from udev files. If udev rules are not
installed. `lsblk` could not get correct fs type. This will cause
problems, e.g. expanding volume depends on fs type of disk.
2018-01-31 13:33:15 +08:00
yue9944882
c3982691ac bugfix(mount): lstat with abs path of parent instead of '/..' 2018-01-21 23:08:01 +08:00
Kubernetes Submit Queue
6369a10004 Merge pull request #58284 from mfojtik/findmnt-out
Automatic merge from submit-queue (batch tested with PRs 57868, 58284, 56370, 58400, 58439). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Show findmnt command output in case of error

**What this PR does / why we need it**:

We don't print the error output from the `findmnt` command, which makes it pretty hard to debug. 

The current implementation just print:

`
I0115 11:59:36.078285   18230 nsenter_mount.go:168] Failed findmnt command for path /var/lib/origin/openshift.local.volumes/pods/8d723ec8-f9e9-11e7-bc52-025000000001/volumes/kubernetes.io~secret/pvinstaller-token-bxh42: exit status 1
`

With this patch, we can actually see the error:

`
I0115 12:04:30.908164   23301 nsenter_mount.go:168] Failed findmnt command for path /var/lib/origin/openshift.local.volumes/pods/8ff8bb98-f9e9-11e7-bc52-025000000001/volumes/kubernetes.io~secret/deployer-token-g4sg9: nsenter: failed to execute /findmnt: No such file or directory
 exit status 1
`

**Release note**:
```release-note
NONE
```
2018-01-18 13:11:30 -08:00
Kubernetes Submit Queue
74f2305c4f Merge pull request #57967 from jsafrane/fix-nfs-root-squash
Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Fixed TearDown of NFS with root squash.

NFS plugin should not use `IsLikelyNotMountPoint()`, as it uses `lstat()` / `stat()` to determine if the NFS volume is still mounted - NFS server may use root_squash and kubelet may not be allowed to do `lstat()` / `stat()` there.

It must use slower `IsNotMountPoint()` instead, including in `TearDown()` function.

**Release note**:

```release-note
NONE
```

/assign @gnufied @rootfs
2018-01-17 13:32:03 -08:00
Michal Fojtik
fd520aef61 Show findmt command output in case of error 2018-01-15 13:02:31 +01:00
Jan Safranek
da1eec2853 Add jsafrane as util/mount approver. 2018-01-08 14:19:22 +01:00
Jan Safranek
45d21ee36b Fixed TearDown of NFS with root squash.
NFS plugin should not use IsLikelyNotMountPoint(), as it uses lstat() / stat()
to determine if the NFS volume is still mounted - NFS server may use
root_squash and kubelet may not be allowed to do lstat() / stat() there.

It must use slower IsNotMountPoint() instead, including TearDown() function.
2018-01-08 14:01:33 +01:00
Jeff Grafton
efee0704c6 Autogenerate BUILD files 2017-12-23 13:12:11 -08:00
Hemant Kumar
2f2a643684 Implement file system resizing support on kubelet start
Update bazel files
Fix operation executor tests
2017-11-22 16:06:10 -05:00
Jan Safranek
790f513d23 Fix cross-compliation of mount_exec.go
Add dummy implementation for non-linux platforms
2017-11-14 16:30:00 +01:00
Jan Safranek
1dd32ce7eb Add ExecMounter 2017-11-10 13:14:40 +01:00
Clayton Coleman
b844ac44f5 Tmpdir can be a symlink, also fake mount needs to call nested mounter 2017-11-03 22:21:29 -04:00
Kubernetes Submit Queue
618b705a4b Merge pull request #53629 from andyzhangx/azurefile-improve
Automatic merge from submit-queue (batch tested with PRs 46341, 53629). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

fix azure file mount limit issue on windows due to using drive letter

**What this PR does / why we need it**:
It's not necessary to use drive letter in azure file mount, correct usage for New-SmbGlobalMapping is like following:
```
New-SmbGlobalMapping -RemotePath $AzureFilePath -Credential $Credential
mklink /D $mountPath $AzureFilePath 
```
I removed the `LocalPath` parameter in New-SmbGlobalMapping

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #54668
Without this PR, there is a limit(25) for azure file mount number on each node because only 25 drive letters could be used on each windows node, With this PR, there would be no such limit.

**Special notes for your reviewer**:
@PatrickLang 

**Release note**:

```
fix azure file mount limit issue on windows due to using drive letter
```
/sig azure
/sig windows
2017-11-01 04:38:12 -07:00