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From 76127f4f8f3c2bf415f66a335e7b37670cb9bd84 Mon Sep 17 00:00:00 2001
From: Raghavendra G <rgowdapp@redhat.com>
Date: Fri, 3 May 2019 10:14:48 +0530
Subject: [PATCH 134/141] performance/write-behind: remove request from wip
list in wb_writev_cbk
There is a race in the way O_DIRECT writes are handled. Assume two
overlapping write requests w1 and w2.
* w1 is issued and is in wb_inode->wip queue as the response is still
pending from bricks. Also wb_request_unref in wb_do_winds is not yet
invoked.
list_for_each_entry_safe (req, tmp, tasks, winds) {
list_del_init (&req->winds);
if (req->op_ret == -1) {
call_unwind_error_keep_stub (req->stub, req->op_ret,
req->op_errno);
} else {
call_resume_keep_stub (req->stub);
}
wb_request_unref (req);
}
* w2 is issued and wb_process_queue is invoked. w2 is not picked up
for winding as w1 is still in wb_inode->wip. w1 is added to todo
list and wb_writev for w2 returns.
* response to w1 is received and invokes wb_request_unref. Assume
wb_request_unref in wb_do_winds (see point 1) is not invoked
yet. Since there is one more refcount, wb_request_unref in
wb_writev_cbk of w1 doesn't remove w1 from wip.
* wb_process_queue is invoked as part of wb_writev_cbk of w1. But, it
fails to wind w2 as w1 is still in wip.
* wb_requet_unref is invoked on w1 as part of wb_do_winds. w1 is
removed from all queues including w1.
* After this point there is no invocation of wb_process_queue unless
new request is issued from application causing w2 to be hung till
the next request.
This bug is similar to bz 1626780 and bz 1379655.
upstream patch: https://review.gluster.org/#/c/glusterfs/+/22654/
BUG: 1702686
Change-Id: Iaa47437613591699d4c8ad18bc0b32de6affcc31
fixes: bz#1702686
Signed-off-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-on: https://code.engineering.redhat.com/gerrit/169552
Tested-by: RHGS Build Bot <nigelb@redhat.com>
Reviewed-by: Sunil Kumar Heggodu Gopala Acharya <sheggodu@redhat.com>
---
xlators/performance/write-behind/src/write-behind.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/xlators/performance/write-behind/src/write-behind.c b/xlators/performance/write-behind/src/write-behind.c
index cf302bd..70e281a 100644
--- a/xlators/performance/write-behind/src/write-behind.c
+++ b/xlators/performance/write-behind/src/write-behind.c
@@ -1813,6 +1813,12 @@ wb_writev_cbk(call_frame_t *frame, void *cookie, xlator_t *this, int32_t op_ret,
frame->local = NULL;
wb_inode = req->wb_inode;
+ LOCK(&req->wb_inode->lock);
+ {
+ list_del_init(&req->wip);
+ }
+ UNLOCK(&req->wb_inode->lock);
+
wb_request_unref(req);
/* requests could be pending while this was in progress */
--
1.8.3.1
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