Re: [PATCH] cifs: Reuse file lease key in compound operations

[Paulo Alcantara <pc@manguebit.com>]

meetakshisetiyaoss@gmail.com writes:

> From: Meetakshi Setiya <msetiya@microsoft.com>
>
> Lock contention during unlink operation causes cifs lease break ack
> worker thread to block and delay sending lease break acks to server.
> This case occurs when multiple threads perform unlink, write and lease
> break acks on the same file. Thhis patch fixes the problem by reusing
> the existing lease keys for rename, unlink and set path size compound
> operations so that the client does not break its own lease.
>
> Signed-off-by: Meetakshi Setiya <msetiya@microsoft.com>
> ---
>  fs/smb/client/cifsglob.h  |  6 ++---
>  fs/smb/client/cifsproto.h |  8 +++----
>  fs/smb/client/cifssmb.c   |  6 ++---
>  fs/smb/client/inode.c     | 12 +++++-----
>  fs/smb/client/smb2inode.c | 49 +++++++++++++++++++++++++--------------
>  fs/smb/client/smb2proto.h |  8 +++----
>  6 files changed, 51 insertions(+), 38 deletions(-)

NAK.  This patch broke some xfstests.

Consider this reproducer:

$ cat repro.sh
#!/bin/sh

umount /mnt/1 &>/dev/null
mount.cifs //srv/share /mnt/1 -o ...,vers=3.1.1
rm /mnt/1/* &>/dev/null
pushd /mnt/1 >/dev/null
touch foo
ln -v foo bar
rm -v bar
popd >/dev/null
umount /mnt/1 &>/dev/null
$ ./repro.sh
'bar' => 'foo'
rm: cannot remove 'bar': Invalid argument

This is what going on

- client creates 'foo' with RHW lease granted.
- client creates hardlink file 'bar'.

At this point, we have two positive dentries (foo & bar) which share
same inode.

- The client then attempts to remove 'bar' by re-using lease key from
'foo' through compound request CREATE(DELETE)+CLOSE, which fails with
STATUS_INVALID_PARAMETER.