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DLM: fix conversion deadlock when DLM_LKF_NODLCKWT flag is set 

When the DLM_LKF_NODLCKWT flag was set, even if conversion deadlock
was detected, the caller of can_be_granted() was unknown.
We change the behavior of can_be_granted() and change it to detect
conversion deadlock regardless of whether the DLM_LKF_NODLCKWT flag
is set or not. And depending on whether the DLM_LKF_NODLCKWT flag
is set or not, we change the behavior at the caller of can_be_granted().

This fix has no effect except when using DLM_LKF_NODLCKWT flag.
Currently, ocfs2 uses the DLM_LKF_NODLCKWT flag and does not expect a
cancel operation from conversion deadlock when calling dlm_lock().
ocfs2 is implemented to perform a cancel operation by requesting
BASTs (callback).

Signed-off-by: Tadashi Miyauchi <miyauchi@toshiba-tops.co.jp>
Signed-off-by: Tsutomu Owa <tsutomu.owa@toshiba.co.jp>
Signed-off-by: David Teigland <teigland@redhat.com>
This commit is contained in:
tsutomu.owa@toshiba.co.jp 2017-09-15 14:17:23 -05:00 committed by David Teigland
parent 173a31fe2b
commit 294e7e4587
1 changed files with 23 additions and 19 deletions
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42
fs/dlm/lock.c
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@ -2465,14 +2465,12 @@ static int can_be_granted(struct dlm_rsb *r, struct dlm_lkb *lkb, int now,
if (lkb->lkb_exflags & DLM_LKF_CONVDEADLK) {
lkb->lkb_grmode = DLM_LOCK_NL;
lkb->lkb_sbflags |= DLM_SBF_DEMOTED;
} else if (!(lkb->lkb_exflags & DLM_LKF_NODLCKWT)) {
if (err)
*err = -EDEADLK;
else {
log_print("can_be_granted deadlock %x now %d",
lkb->lkb_id, now);
dlm_dump_rsb(r);
}
} else if (err) {
*err = -EDEADLK;
} else {
log_print("can_be_granted deadlock %x now %d",
lkb->lkb_id, now);
dlm_dump_rsb(r);
}
goto out;
}
@ -2501,13 +2499,6 @@ static int can_be_granted(struct dlm_rsb *r, struct dlm_lkb *lkb, int now,
return rv;
}
/* FIXME: I don't think that can_be_granted() can/will demote or find deadlock
for locks pending on the convert list. Once verified (watch for these
log_prints), we should be able to just call _can_be_granted() and not
bother with the demote/deadlk cases here (and there's no easy way to deal
with a deadlk here, we'd have to generate something like grant_lock with
the deadlk error.) */
/* Returns the highest requested mode of all blocked conversions; sets
cw if there's a blocked conversion to DLM_LOCK_CW. */
@ -2545,9 +2536,22 @@ static int grant_pending_convert(struct dlm_rsb *r, int high, int *cw,
}
if (deadlk) {
log_print("WARN: pending deadlock %x node %d %s",
lkb->lkb_id, lkb->lkb_nodeid, r->res_name);
dlm_dump_rsb(r);
/*
* If DLM_LKB_NODLKWT flag is set and conversion
* deadlock is detected, we request blocking AST and
* down (or cancel) conversion.
*/
if (lkb->lkb_exflags & DLM_LKF_NODLCKWT) {
if (lkb->lkb_highbast < lkb->lkb_rqmode) {
queue_bast(r, lkb, lkb->lkb_rqmode);
lkb->lkb_highbast = lkb->lkb_rqmode;
}
} else {
log_print("WARN: pending deadlock %x node %d %s",
lkb->lkb_id, lkb->lkb_nodeid,
r->res_name);
dlm_dump_rsb(r);
}
continue;
}
@ -3123,7 +3127,7 @@ static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
deadlock, so we leave it on the granted queue and return EDEADLK in
the ast for the convert. */
if (deadlk) {
if (deadlk && !(lkb->lkb_exflags & DLM_LKF_NODLCKWT)) {
/* it's left on the granted queue */
revert_lock(r, lkb);
queue_cast(r, lkb, -EDEADLK);