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[DLM] fix grant_after_purge softlockup

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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: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
David Teigland 2006-05-02 13:34:03 -04:00 committed by Steven Whitehouse
parent d2d7b8a2a7
commit 97a35d1e5f
3 changed files with 30 additions and 15 deletions
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1
fs/dlm/dlm_internal.h
View file

@ -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)

42
fs/dlm/lock.c
View file

@ -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))
@ -3334,27 +3335,40 @@ 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);
lock_rsb(r);
if (is_master(r)) {
grant_pending_locks(r);
confirm_master(r, 0);
}
unlock_rsb(r);
put_rsb(r);
r = find_purged_rsb(ls, i);
if (!r)
continue;
lock_rsb(r);
if (is_master(r)) {
grant_pending_locks(r);
confirm_master(r, 0);
}
read_unlock(&ls->ls_rsbtbl[i].lock);
unlock_rsb(r);
put_rsb(r);
}
return 0;
}
static struct dlm_lkb *search_remid_list(struct list_head *head, int nodeid,

2
fs/dlm/lock.h
View file

@ -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);