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authorIlya Dryomov <idryomov@gmail.com>2018-05-21 17:00:29 +0300
committerIlya Dryomov <idryomov@gmail.com>2018-06-04 21:45:58 +0300
commit88bc1922c273c95e84a8955e657401f9bc63a80b (patch)
tree4f5f0e45685fc055e2ed6643ed62804b088291de /include/linux/ceph/osd_client.h
parent26df726bcdfacf69335de716e7b78c517bc1df65 (diff)
downloadlinux-88bc1922c273c95e84a8955e657401f9bc63a80b.tar.xz
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 'include/linux/ceph/osd_client.h')
-rw-r--r--include/linux/ceph/osd_client.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 874c31c01f80..d4191bde95a4 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -170,6 +170,7 @@ struct ceph_osd_request {
u64 r_tid; /* unique for this client */
struct rb_node r_node;
struct rb_node r_mc_node; /* map check */
+ struct work_struct r_complete_work;
struct ceph_osd *r_osd;
struct ceph_osd_request_target r_t;
@@ -360,6 +361,7 @@ struct ceph_osd_client {
struct ceph_msgpool msgpool_op_reply;
struct workqueue_struct *notify_wq;
+ struct workqueue_struct *completion_wq;
};
static inline bool ceph_osdmap_flag(struct ceph_osd_client *osdc, int flag)