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authorIlya Dryomov <idryomov@gmail.com>2018-05-21 16:00:29 +0200
committerIlya Dryomov <idryomov@gmail.com>2018-06-04 20:45:58 +0200
commit88bc1922c273c95e84a8955e657401f9bc63a80b (patch)
tree4f5f0e45685fc055e2ed6643ed62804b088291de /net/ceph
parent26df726bcdfacf69335de716e7b78c517bc1df65 (diff)
downloadlinux-stericsson-88bc1922c273c95e84a8955e657401f9bc63a80b.tar.gz
libceph: defer __complete_request() to a workqueue
In the common case, req->r_callback is called by handle_reply() on the ceph-msgr worker thread without any locks. If handle_reply() fails, it is called with both osd->lock and osdc->lock. In the map check case, it is called with just osdc->lock but held for write. Finally, if the request is aborted because of -ENOSPC or by ceph_osdc_abort_requests(), it is called directly on the submitter's thread, again with both locks. req->r_callback on the submitter's thread is relatively new (introduced in 4.12) and ripe for deadlocks -- e.g. writeback worker thread waiting on itself: inode_wait_for_writeback+0x26/0x40 evict+0xb5/0x1a0 iput+0x1d2/0x220 ceph_put_wrbuffer_cap_refs+0xe0/0x2c0 [ceph] writepages_finish+0x2d3/0x410 [ceph] __complete_request+0x26/0x60 [libceph] complete_request+0x2e/0x70 [libceph] __submit_request+0x256/0x330 [libceph] submit_request+0x2b/0x30 [libceph] ceph_osdc_start_request+0x25/0x40 [libceph] ceph_writepages_start+0xdfe/0x1320 [ceph] do_writepages+0x1f/0x70 __writeback_single_inode+0x45/0x330 writeback_sb_inodes+0x26a/0x600 __writeback_inodes_wb+0x92/0xc0 wb_writeback+0x274/0x330 wb_workfn+0x2d5/0x3b0 Defer __complete_request() to a workqueue in all failure cases so it's never on the same thread as ceph_osdc_start_request() and always called with no locks held. Link: http://tracker.ceph.com/issues/23978 Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Acked-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Diffstat (limited to 'net/ceph')
-rw-r--r--net/ceph/osd_client.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index a78f578a2da7..a4c12c37aa90 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -2329,6 +2329,14 @@ static void __complete_request(struct ceph_osd_request *req)
ceph_osdc_put_request(req);
}
+static void complete_request_workfn(struct work_struct *work)
+{
+ struct ceph_osd_request *req =
+ container_of(work, struct ceph_osd_request, r_complete_work);
+
+ __complete_request(req);
+}
+
/*
* This is open-coded in handle_reply().
*/
@@ -2338,7 +2346,9 @@ static void complete_request(struct ceph_osd_request *req, int err)
req->r_result = err;
finish_request(req);
- __complete_request(req);
+
+ INIT_WORK(&req->r_complete_work, complete_request_workfn);
+ queue_work(req->r_osdc->completion_wq, &req->r_complete_work);
}
static void cancel_map_check(struct ceph_osd_request *req)
@@ -5058,6 +5068,10 @@ int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
if (!osdc->notify_wq)
goto out_msgpool_reply;
+ osdc->completion_wq = create_singlethread_workqueue("ceph-completion");
+ if (!osdc->completion_wq)
+ goto out_notify_wq;
+
schedule_delayed_work(&osdc->timeout_work,
osdc->client->options->osd_keepalive_timeout);
schedule_delayed_work(&osdc->osds_timeout_work,
@@ -5065,6 +5079,8 @@ int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
return 0;
+out_notify_wq:
+ destroy_workqueue(osdc->notify_wq);
out_msgpool_reply:
ceph_msgpool_destroy(&osdc->msgpool_op_reply);
out_msgpool:
@@ -5079,6 +5095,7 @@ out:
void ceph_osdc_stop(struct ceph_osd_client *osdc)
{
+ destroy_workqueue(osdc->completion_wq);
destroy_workqueue(osdc->notify_wq);
cancel_delayed_work_sync(&osdc->timeout_work);
cancel_delayed_work_sync(&osdc->osds_timeout_work);