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authorRaghavendra G <rgowdapp@redhat.com>2019-05-07 10:35:06 +0530
committerRaghavendra G <rgowdapp@redhat.com>2019-05-07 11:35:40 +0530
commitdc7f464d019ebe980232263cad8528456253e9dd (patch)
tree12a11c0b167fd7247caaaff739384ede47a384bf
parente26fc565990091ac18acd2859296029d3b7609b4 (diff)
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. Change-Id: Iab47437613591699d4c8ad18bc0b32de6affcc31 Signed-off-by: Raghavendra G <rgowdapp@redhat.com> Fixes: bz#1707200
-rw-r--r--xlators/performance/write-behind/src/write-behind.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/xlators/performance/write-behind/src/write-behind.c b/xlators/performance/write-behind/src/write-behind.c
index 6093ec2..9561ca3 100644
--- a/xlators/performance/write-behind/src/write-behind.c
+++ b/xlators/performance/write-behind/src/write-behind.c
@@ -1750,6 +1750,12 @@ wb_writev_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
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 */