[PATCH 3.14 34/59] NFS: Use raw_write_seqcount_begin/end int nfs4_reclaim_open_state

Greg Kroah-Hartman
2014-07-04T22:21:09Z

From: Trond Myklebust <trond.myklebust@primarydata.com>

commit abbec2da13f0e4c5d9b78b7e2c025a3e617228ba upstream.

The addition of lockdep code to write_seqcount_begin/end has lead to
a bunch of false positive claims of ABBA deadlocks with the so_lock
spinlock. Audits show that this simply cannot happen because the
read side code does not spin while holding so_lock.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/nfs/nfs4state.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1456,7 +1456,7 @@ static int nfs4_reclaim_open_state(struc
* server that doesn't support a grace period.
*/
spin_lock(&sp->so_lock);
- write_seqcount_begin(&sp->so_reclaim_seqcount);
+ raw_write_seqcount_begin(&sp->so_reclaim_seqcount);
restart:
list_for_each_entry(state, &sp->so_states, open_states) {
if (!test_and_clear_bit(ops->state_flag_bit, &state->flags))
@@ -1519,13 +1519,13 @@ restart:
spin_lock(&sp->so_lock);
goto restart;
}
- write_seqcount_end(&sp->so_reclaim_seqcount);
+ raw_write_seqcount_end(&sp->so_reclaim_seqcount);
spin_unlock(&sp->so_lock);
return 0;
out_err:
nfs4_put_open_state(state);
spin_lock(&sp->so_lock);
- write_seqcount_end(&sp->so_reclaim_seqcount);
+ raw_write_seqcount_end(&sp->so_reclaim_seqcount);
spin_unlock(&sp->so_lock);
return status;
}