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Message-Id: <1485648328-2141-54-git-send-email-jsimmons@infradead.org>
Date: Sat, 28 Jan 2017 19:05:21 -0500
From: James Simmons <jsimmons@...radead.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
devel@...verdev.osuosl.org,
Andreas Dilger <andreas.dilger@...el.com>,
Oleg Drokin <oleg.drokin@...el.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Lustre Development List <lustre-devel@...ts.lustre.org>,
Niu Yawei <yawei.niu@...el.com>,
James Simmons <jsimmons@...radead.org>
Subject: [PATCH 53/60] staging: lustre: ptlrpc: update replay cursor when close during replay
From: Niu Yawei <yawei.niu@...el.com>
The replay cursor should be updated properly when close happened
during replay, otherwise, ptlrpc_replay_next() could run into a
dead loop due to an invalid replay cursor:
- replay cursor is moved to an open request during replay;
- application close that open file, so the rq_replay of the open
request is cleared;
- ptlrpc_replay_next() calls ptlrpc_free_committed() to free
committed/closed requests, the open request is removed from
the committed list, so the replay cursor is changed to an
empty list_head now. The open request won't be freed now since
it's still held by the pending close request;
- ptlrpc_replay_next() continue to move the replay cursor to
next and run into a dead loop at the end;
Another change in this patch is to remove the out of date comments
in ptlrpc_replay_next() and cover the whole process of finding
replay request within imp_lock, because:
1. With two separated replay lists and replay cursor introduced,
finding replay request won't take much time as before, it's
not necessary to do this "lock -> unlock -> lock -> unlock"
trick anymore;
2. Nowadays there are various kind of non-replay requests are
allowed during recovery, so ptlrpc_free_committed() may run in
parallel to remove an open request while ptlrpc_replay_next()
is iterating the open requests list;
Signed-off-by: Niu Yawei <yawei.niu@...el.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8765
Reviewed-on: https://review.whamcloud.com/23418
Reviewed-by: Yang Sheng <yang.sheng@...el.com>
Reviewed-by: John L. Hammond <john.hammond@...el.com>
Reviewed-by: Oleg Drokin <oleg.drokin@...el.com>
Signed-off-by: James Simmons <jsimmons@...radead.org>
---
drivers/staging/lustre/lustre/ptlrpc/client.c | 15 ++++++++++-----
drivers/staging/lustre/lustre/ptlrpc/recover.c | 23 +----------------------
2 files changed, 11 insertions(+), 27 deletions(-)
diff --git a/drivers/staging/lustre/lustre/ptlrpc/client.c b/drivers/staging/lustre/lustre/ptlrpc/client.c
index 332b360..8dfb40f 100644
--- a/drivers/staging/lustre/lustre/ptlrpc/client.c
+++ b/drivers/staging/lustre/lustre/ptlrpc/client.c
@@ -2662,11 +2662,16 @@ void ptlrpc_free_committed(struct obd_import *imp)
list_for_each_entry_safe(req, saved, &imp->imp_committed_list,
rq_replay_list) {
LASSERT(req->rq_transno != 0);
- if (req->rq_import_generation < imp->imp_generation) {
- DEBUG_REQ(D_RPCTRACE, req, "free stale open request");
- ptlrpc_free_request(req);
- } else if (!req->rq_replay) {
- DEBUG_REQ(D_RPCTRACE, req, "free closed open request");
+ if (req->rq_import_generation < imp->imp_generation ||
+ !req->rq_replay) {
+ DEBUG_REQ(D_RPCTRACE, req, "free %s open request",
+ req->rq_import_generation <
+ imp->imp_generation ? "stale" : "closed");
+
+ if (imp->imp_replay_cursor == &req->rq_replay_list)
+ imp->imp_replay_cursor =
+ req->rq_replay_list.next;
+
ptlrpc_free_request(req);
}
}
diff --git a/drivers/staging/lustre/lustre/ptlrpc/recover.c b/drivers/staging/lustre/lustre/ptlrpc/recover.c
index c03e113..7b58545 100644
--- a/drivers/staging/lustre/lustre/ptlrpc/recover.c
+++ b/drivers/staging/lustre/lustre/ptlrpc/recover.c
@@ -78,28 +78,11 @@ int ptlrpc_replay_next(struct obd_import *imp, int *inflight)
imp->imp_last_transno_checked = 0;
ptlrpc_free_committed(imp);
last_transno = imp->imp_last_replay_transno;
- spin_unlock(&imp->imp_lock);
CDEBUG(D_HA, "import %p from %s committed %llu last %llu\n",
imp, obd2cli_tgt(imp->imp_obd),
imp->imp_peer_committed_transno, last_transno);
- /* Do I need to hold a lock across this iteration? We shouldn't be
- * racing with any additions to the list, because we're in recovery
- * and are therefore not processing additional requests to add. Calls
- * to ptlrpc_free_committed might commit requests, but nothing "newer"
- * than the one we're replaying (it can't be committed until it's
- * replayed, and we're doing that here). l_f_e_safe protects against
- * problems with the current request being committed, in the unlikely
- * event of that race. So, in conclusion, I think that it's safe to
- * perform this list-walk without the imp_lock held.
- *
- * But, the {mdc,osc}_replay_open callbacks both iterate
- * request lists, and have comments saying they assume the
- * imp_lock is being held by ptlrpc_replay, but it's not. it's
- * just a little race...
- */
-
/* Replay all the committed open requests on committed_list first */
if (!list_empty(&imp->imp_committed_list)) {
tmp = imp->imp_committed_list.prev;
@@ -107,10 +90,6 @@ int ptlrpc_replay_next(struct obd_import *imp, int *inflight)
/* The last request on committed_list hasn't been replayed */
if (req->rq_transno > last_transno) {
- /* Since the imp_committed_list is immutable before
- * all of it's requests being replayed, it's safe to
- * use a cursor to accelerate the search
- */
if (!imp->imp_resend_replay ||
imp->imp_replay_cursor == &imp->imp_committed_list)
imp->imp_replay_cursor = imp->imp_replay_cursor->next;
@@ -124,6 +103,7 @@ int ptlrpc_replay_next(struct obd_import *imp, int *inflight)
break;
req = NULL;
+ LASSERT(!list_empty(imp->imp_replay_cursor));
imp->imp_replay_cursor =
imp->imp_replay_cursor->next;
}
@@ -156,7 +136,6 @@ int ptlrpc_replay_next(struct obd_import *imp, int *inflight)
if (req && imp->imp_resend_replay)
lustre_msg_add_flags(req->rq_reqmsg, MSG_RESENT);
- spin_lock(&imp->imp_lock);
/* The resend replay request may have been removed from the
* unreplied list.
*/
--
1.8.3.1
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