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author | Tariq Saeed <tariq.x.saeed@oracle.com> | 2014-06-23 20:22:08 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-23 23:47:45 (GMT) |
commit | 27bf6305cf85cb474295c300c99cc3d10d68f50a (patch) | |
tree | 5bc23238696ad5156d8e6676f30ed6b4710cc6be /fs/open.c | |
parent | 5fb1beb069dcf616e88be9d330b86878a79aa4ff (diff) | |
download | linux-27bf6305cf85cb474295c300c99cc3d10d68f50a.tar.xz |
ocfs2: fix deadlock when two nodes are converting same lock from PR to EX and idletimeout closes conn
Orabug: 18639535
Two node cluster and both nodes hold a lock at PR level and both want to
convert to EX at the same time. Master node 1 has sent BAST and then
closes the connection due to idletime out. Node 0 receives BAST, sends
unlock req with cancel flag but gets error -ENOTCONN. The problem is
this error is ignored in dlm_send_remote_unlock_request() on the
**incorrect** assumption that the master is dead. See NOTE in comment
why it returns DLM_NORMAL. Upon getting DLM_NORMAL, node 0 proceeds to
sends convert (without cancel flg) which fails with -ENOTCONN. waits 5
sec and resends.
This time gets DLM_IVLOCKID from the master since lock not found in
grant, it had been moved to converting queue in response to conv PR->EX
req. No way out.
Node 1 (master) Node 0
============== ======
lock mode PR PR
convert PR -> EX
mv grant -> convert and que BAST
...
<-------- convert PR -> EX
convert que looks like this: ((node 1, PR -> EX) (node 0, PR -> EX))
...
BAST (want PR -> NL)
------------------>
...
idle timout, conn closed
...
In response to BAST,
sends unlock with cancel convert flag
gets -ENOTCONN. Ignores and
sends remote convert request
gets -ENOTCONN, waits 5 Sec, retries
...
reconnects
<----------------- convert req goes through on next try
does not find lock on grant que
status DLM_IVLOCKID
------------------>
...
No way out. Fix is to keep retrying unlock with cancel flag until it
succeeds or the master dies.
Signed-off-by: Tariq Saeed <tariq.x.saeed@oracle.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/open.c')
0 files changed, 0 insertions, 0 deletions