[Ocfs2-devel] + ocfs2-dlmfs-not-clear-user_lock_attached-when-destroy-lock.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: ocfs2: dlmfs: don't clear USER_LOCK_ATTACHED when destroying lock
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     ocfs2-dlmfs-not-clear-user_lock_attached-when-destroy-lock.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ocfs2-dlmfs-not-clear-user_lock_attached-when-destroy-lock.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Junxiao Bi <ocfs2-devel at oss.oracle.com>
Subject: ocfs2: dlmfs: don't clear USER_LOCK_ATTACHED when destroying lock
Date: Wed, 18 May 2022 16:52:23 -0700

The following function is the only place that checks USER_LOCK_ATTACHED. 
This flag is set when lock request is granted through user_ast() and only
the following function will clear it.

Checking of this flag here is to make sure ocfs2_dlm_unlock is not issued
if this lock is never granted.  For example, lock file is created and then
get removed, open file never happens.

Clearing the flag here is not necessary because this is the only function
that checks it, if another flow is executing user_dlm_destroy_lock(), it
will bail out at the beginning because of USER_LOCK_IN_TEARDOWN and never
check USER_LOCK_ATTACHED.  Drop the clear, so we don't need take care of
it for the following error handling patch.

int user_dlm_destroy_lock(struct user_lock_res *lockres)
{
    ...

    status = 0;
    if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
        spin_unlock(&lockres->l_lock);
        goto bail;
    }

    lockres->l_flags &= ~USER_LOCK_ATTACHED;
    lockres->l_flags |= USER_LOCK_BUSY;
    spin_unlock(&lockres->l_lock);

	status = ocfs2_dlm_unlock(conn, &lockres->l_lksb, DLM_LKF_VALBLK);
    if (status) {
        user_log_dlm_error("ocfs2_dlm_unlock", status, lockres);
        goto bail;
    }
	...
}

V1 discussion with Joseph:
https://lore.kernel.org/all/7b620c53-0c45-da2c-829e-26195cbe7d4e@linux.alibaba.com/T/

Link: https://lkml.kernel.org/r/20220518235224.87100-1-junxiao.bi@oracle.com
Signed-off-by: Junxiao Bi <junxiao.bi at oracle.com>
Reviewed-by: Joseph Qi <joseph.qi at linux.alibaba.com>
Cc: Mark Fasheh <mark at fasheh.com>
Cc: Joel Becker <jlbec at evilplan.org>
Cc: Junxiao Bi <junxiao.bi at oracle.com>
Cc: Changwei Ge <gechangwei at live.cn>
Cc: Gang He <ghe at suse.com>
Cc: Jun Piao <piaojun at huawei.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
---

 fs/ocfs2/dlmfs/userdlm.c |    1 -
 1 file changed, 1 deletion(-)

--- a/fs/ocfs2/dlmfs/userdlm.c~ocfs2-dlmfs-not-clear-user_lock_attached-when-destroy-lock
+++ a/fs/ocfs2/dlmfs/userdlm.c
@@ -619,7 +619,6 @@ int user_dlm_destroy_lock(struct user_lo
 		goto bail;
 	}
 
-	lockres->l_flags &= ~USER_LOCK_ATTACHED;
 	lockres->l_flags |= USER_LOCK_BUSY;
 	spin_unlock(&lockres->l_lock);
 
_

Patches currently in -mm which might be from ocfs2-devel at oss.oracle.com are

ocfs2-dlmfs-not-clear-user_lock_attached-when-destroy-lock.patch
ocfs2-dlmfs-fix-error-handling-of-user_dlm_destroy_lock.patch