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Commit 97a35d1e authored by David Teigland's avatar David Teigland Committed by Steven Whitehouse
Browse files

[DLM] fix grant_after_purge softlockup 



In dlm_grant_after_purge() we were holding a hash table read_lock while
calling put_rsb() which potentially removes the rsb from the hash table,
taking the same lock in write.  Fix this by flagging rsb's ahead of time
that have been purged.  Then iteratively read_lock the hash table, find a
flagged rsb, unlock, process rsb.

Signed-off-by: default avatarDavid Teigland <teigland@redhat.com>
Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent d2d7b8a2

fs/dlm/dlm_internal.h

+1 −0
Original line number Diff line number Diff line
@@ -280,6 +280,7 @@ enum rsb_flags { 
	RSB_NEW_MASTER,

	RSB_NEW_MASTER2,

	RSB_RECOVER_CONVERT,

	RSB_LOCKS_PURGED,

};



static inline void rsb_set_flag(struct dlm_rsb *r, enum rsb_flags flag)

fs/dlm/lock.c

+28 −14
Original line number Diff line number Diff line
@@ -3278,6 +3278,7 @@ static void purge_queue(struct dlm_rsb *r, struct list_head *queue, 


	list_for_each_entry_safe(lkb, safe, queue, lkb_statequeue) {

		if (test(ls, lkb)) {

			rsb_set_flag(r, RSB_LOCKS_PURGED);

			del_lkb(r, lkb);

			/* this put should free the lkb */

			if (!dlm_put_lkb(lkb))
@@ -3334,15 +3335,32 @@ int dlm_purge_locks(struct dlm_ls *ls) 
	return 0;

}



int dlm_grant_after_purge(struct dlm_ls *ls)

static struct dlm_rsb *find_purged_rsb(struct dlm_ls *ls, int bucket)

{

	struct dlm_rsb *r, *r_ret = NULL;



	read_lock(&ls->ls_rsbtbl[bucket].lock);

	list_for_each_entry(r, &ls->ls_rsbtbl[bucket].list, res_hashchain) {

		if (!rsb_flag(r, RSB_LOCKS_PURGED))

			continue;

		hold_rsb(r);

		rsb_clear_flag(r, RSB_LOCKS_PURGED);

		r_ret = r;

		break;

	}

	read_unlock(&ls->ls_rsbtbl[bucket].lock);

	return r_ret;

}



void dlm_grant_after_purge(struct dlm_ls *ls)

{

	struct dlm_rsb *r;

	int i;



	for (i = 0; i < ls->ls_rsbtbl_size; i++) {

		read_lock(&ls->ls_rsbtbl[i].lock);

		list_for_each_entry(r, &ls->ls_rsbtbl[i].list, res_hashchain) {

			hold_rsb(r);

		r = find_purged_rsb(ls, i);

		if (!r)

			continue;

		lock_rsb(r);

		if (is_master(r)) {

			grant_pending_locks(r);
@@ -3351,10 +3369,6 @@ int dlm_grant_after_purge(struct dlm_ls *ls) 
		unlock_rsb(r);

		put_rsb(r);

	}

		read_unlock(&ls->ls_rsbtbl[i].lock);

	}



	return 0;

}



static struct dlm_lkb *search_remid_list(struct list_head *head, int nodeid,

fs/dlm/lock.h

+1 −1
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ void dlm_scan_rsbs(struct dlm_ls *ls); 


int dlm_purge_locks(struct dlm_ls *ls);

void dlm_purge_mstcpy_locks(struct dlm_rsb *r);

int dlm_grant_after_purge(struct dlm_ls *ls);

void dlm_grant_after_purge(struct dlm_ls *ls);

int dlm_recover_waiters_post(struct dlm_ls *ls);

void dlm_recover_waiters_pre(struct dlm_ls *ls);

int dlm_recover_master_copy(struct dlm_ls *ls, struct dlm_rcom *rc);