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