fs: dlm: change dflags to use atomic bits

Currently manipulating lkb_dflags assumes to held the rsb lock assigned
to the lkb. This is held by dlm message processing after certain
time to lookup the right rsb from the received lkb message id. For user
space locks flags, which is currently the only use case for lkb_dflags,
flags are also being set during dlm character device handling without
holding the rsb lock. To minimize the risk that bit operations are
getting corrupted we switch to atomic bit operations. This patch will
also introduce helpers to snapshot atomic bit values in an non atomic
way. There might be still issues with the flag handling e.g. running in
case of manipulating bit ops and snapshot them at the same time, but this
patch minimize them and will start to use atomic bit operations.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 13 insertions, 13 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 21c7abd7ef77..70737352d595 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -3410,7 +3410,7 @@ static void send_args(struct dlm_rsb *r, struct dlm_lkb *lkb,
 	ms->m_remid    = cpu_to_le32(lkb->lkb_remid);
 	ms->m_exflags  = cpu_to_le32(lkb->lkb_exflags);
 	ms->m_sbflags  = cpu_to_le32(lkb->lkb_sbflags);
-	ms->m_flags    = cpu_to_le32(lkb->lkb_flags);
+	ms->m_flags    = cpu_to_le32(dlm_dflags_val(lkb));
 	ms->m_lvbseq   = cpu_to_le32(lkb->lkb_lvbseq);
 	ms->m_status   = cpu_to_le32(lkb->lkb_status);
 	ms->m_grmode   = cpu_to_le32(lkb->lkb_grmode);
@@ -3675,7 +3675,7 @@ static void receive_flags(struct dlm_lkb *lkb, struct dlm_message *ms)
 {
 	lkb->lkb_exflags = le32_to_cpu(ms->m_exflags);
 	lkb->lkb_sbflags = le32_to_cpu(ms->m_sbflags);
-	lkb->lkb_dflags = le32_to_cpu(ms->m_flags);
+	dlm_set_dflags_val(lkb, le32_to_cpu(ms->m_flags));
 }
 
 static void receive_flags_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
@@ -3685,7 +3685,7 @@ static void receive_flags_reply(struct dlm_lkb *lkb, struct dlm_message *ms,
 		return;
 
 	lkb->lkb_sbflags = le32_to_cpu(ms->m_sbflags);
-	lkb->lkb_dflags = le32_to_cpu(ms->m_flags);
+	dlm_set_dflags_val(lkb, le32_to_cpu(ms->m_flags));
 }
 
 static int receive_extralen(struct dlm_message *ms)
@@ -3786,8 +3786,8 @@ static int validate_message(struct dlm_lkb *lkb, struct dlm_message *ms)
 	int error = 0;
 
 	/* currently mixing of user/kernel locks are not supported */
-	if (ms->m_flags & cpu_to_le32(DLM_DFL_USER) &&
-	    ~lkb->lkb_dflags & DLM_DFL_USER) {
+	if (ms->m_flags & cpu_to_le32(BIT(DLM_DFL_USER_BIT)) &&
+	    !test_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags)) {
 		log_error(lkb->lkb_resource->res_ls,
 			  "got user dlm message for a kernel lock");
 		error = -EINVAL;
@@ -5345,7 +5345,7 @@ static int receive_rcom_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
 	lkb->lkb_ownpid = le32_to_cpu(rl->rl_ownpid);
 	lkb->lkb_remid = le32_to_cpu(rl->rl_lkid);
 	lkb->lkb_exflags = le32_to_cpu(rl->rl_exflags);
-	lkb->lkb_dflags = le32_to_cpu(rl->rl_flags);
+	dlm_set_dflags_val(lkb, le32_to_cpu(rl->rl_flags));
 	lkb->lkb_flags |= DLM_IFL_MSTCPY;
 	lkb->lkb_lvbseq = le32_to_cpu(rl->rl_lvbseq);
 	lkb->lkb_rqmode = rl->rl_rqmode;
@@ -5571,9 +5571,9 @@ int dlm_user_request(struct dlm_ls *ls, struct dlm_user_args *ua,
 	}
 
 	/* After ua is attached to lkb it will be freed by dlm_free_lkb().
-	   When DLM_DFL_USER is set, the dlm knows that this is a userspace
+	   When DLM_DFL_USER_BIT is set, the dlm knows that this is a userspace
 	   lock and that lkb_astparam is the dlm_user_args structure. */
-	lkb->lkb_dflags |= DLM_DFL_USER;
+	set_bit(DLM_DFL_USER_BIT, &lkb->lkb_dflags);
 	error = request_lock(ls, lkb, name, namelen, &args);
 
 	switch (error) {
@@ -5688,7 +5688,7 @@ int dlm_user_adopt_orphan(struct dlm_ls *ls, struct dlm_user_args *ua_tmp,
 
 		lkb = iter;
 		list_del_init(&iter->lkb_ownqueue);
-		iter->lkb_dflags &= ~DLM_DFL_ORPHAN;
+		clear_bit(DLM_DFL_ORPHAN_BIT, &iter->lkb_dflags);
 		*lkid = iter->lkb_id;
 		break;
 	}
@@ -5932,7 +5932,7 @@ static struct dlm_lkb *del_proc_lock(struct dlm_ls *ls,
 	list_del_init(&lkb->lkb_ownqueue);
 
 	if (lkb->lkb_exflags & DLM_LKF_PERSISTENT)
-		lkb->lkb_dflags |= DLM_DFL_ORPHAN;
+		set_bit(DLM_DFL_ORPHAN_BIT, &lkb->lkb_dflags);
 	else
 		lkb->lkb_flags |= DLM_IFL_DEAD;
  out:
@@ -6091,7 +6091,7 @@ int dlm_debug_add_lkb(struct dlm_ls *ls, uint32_t lkb_id, char *name, int len,
 	int error;
 
 	/* we currently can't set a valid user lock */
-	if (lkb_dflags & DLM_DFL_USER)
+	if (lkb_dflags & BIT(DLM_DFL_USER_BIT))
 		return -EOPNOTSUPP;
 
 	lksb = kzalloc(sizeof(*lksb), GFP_NOFS);
@@ -6104,11 +6104,11 @@ int dlm_debug_add_lkb(struct dlm_ls *ls, uint32_t lkb_id, char *name, int len,
 		return error;
 	}
 
-	lkb->lkb_dflags = lkb_dflags;
+	dlm_set_dflags_val(lkb, lkb_dflags);
 	lkb->lkb_nodeid = lkb_nodeid;
 	lkb->lkb_lksb = lksb;
 	/* user specific pointer, just don't have it NULL for kernel locks */
-	if (~lkb_dflags & DLM_DFL_USER)
+	if (~lkb_dflags & BIT(DLM_DFL_USER_BIT))
 		lkb->lkb_astparam = (void *)0xDEADBEEF;
 
 	error = find_rsb(ls, name, len, 0, R_REQUEST, &r);