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| author | Ilya Dryomov <idryomov@gmail.com> | 2018-05-21 16:00:29 +0200 |
|---|---|---|
| committer | Ilya Dryomov <idryomov@gmail.com> | 2018-06-04 20:45:58 +0200 |
| commit | 88bc1922c273c95e84a8955e657401f9bc63a80b (patch) | |
| tree | 4f5f0e45685fc055e2ed6643ed62804b088291de /include | |
| parent | libceph: move more code into __complete_request() (diff) | |
| download | linux-88bc1922c273c95e84a8955e657401f9bc63a80b.tar.xz linux-88bc1922c273c95e84a8955e657401f9bc63a80b.zip | |
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')
| -rw-r--r-- | include/linux/ceph/osd_client.h | 2 |
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) |