When we remove the client_mutex, we'll have a potential race between
FREE_STATEID and CLOSE.
The root of the problem is that we are walking the st_locks list,
dropping the spinlock and then trying to release the persistent
reference to the lockstateid. In between, a FREE_STATEID call can come
along and take the lock, find the stateid and then try to put the
reference. That leads to a double put.
Fix this by not releasing the cl_lock in order to release each lock
stateid. Use put_generic_stateid_locked to unhash them and gather them
onto a list, and free_ol_stateid_reaplist to free any that end up on the
list.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index da8e2ad8dd8e..58448637dd44 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1045,27 +1045,26 @@ static void release_lockowner(struct nfs4_lockowner *lo)
nfs4_put_stateowner(&lo->lo_owner);
}
-static void release_open_stateid_locks(struct nfs4_ol_stateid *open_stp)
- __releases(&open_stp->st_stateowner->so_client->cl_lock)
- __acquires(&open_stp->st_stateowner->so_client->cl_lock)
+static void release_open_stateid_locks(struct nfs4_ol_stateid *open_stp,
+ struct list_head *reaplist)
{
struct nfs4_ol_stateid *stp;
while (!list_empty(&open_stp->st_locks)) {
stp = list_entry(open_stp->st_locks.next,
struct nfs4_ol_stateid, st_locks);
- spin_unlock(&open_stp->st_stateowner->so_client->cl_lock);
- release_lock_stateid(stp);
- spin_lock(&open_stp->st_stateowner->so_client->cl_lock);
+ unhash_lock_stateid(stp);
+ put_generic_stateid_locked(stp, reaplist);
}
}
-static void unhash_open_stateid(struct nfs4_ol_stateid *stp)
+static void unhash_open_stateid(struct nfs4_ol_stateid *stp,
+ struct list_head *reaplist)
{
lockdep_assert_held(&stp->st_stid.sc_client->cl_lock);
unhash_generic_stateid(stp);
- release_open_stateid_locks(stp);
+ release_open_stateid_locks(stp, reaplist);
}
static void release_open_stateid(struct nfs4_ol_stateid *stp)
@@ -1073,7 +1072,7 @@ static void release_open_stateid(struct nfs4_ol_stateid *stp)
LIST_HEAD(reaplist);
spin_lock(&stp->st_stid.sc_client->cl_lock);
- unhash_open_stateid(stp);
+ unhash_open_stateid(stp, &reaplist);
put_generic_stateid_locked(stp, &reaplist);
spin_unlock(&stp->st_stid.sc_client->cl_lock);
free_ol_stateid_reaplist(&reaplist);
@@ -1113,7 +1112,7 @@ static void release_openowner(struct nfs4_openowner *oo)
while (!list_empty(&oo->oo_owner.so_stateids)) {
stp = list_first_entry(&oo->oo_owner.so_stateids,
struct nfs4_ol_stateid, st_perstateowner);
- unhash_open_stateid(stp);
+ unhash_open_stateid(stp, &reaplist);
put_generic_stateid_locked(stp, &reaplist);
}
spin_unlock(&clp->cl_lock);
@@ -4693,16 +4692,21 @@ out:
static void nfsd4_close_open_stateid(struct nfs4_ol_stateid *s)
{
struct nfs4_client *clp = s->st_stid.sc_client;
+ LIST_HEAD(reaplist);
s->st_stid.sc_type = NFS4_CLOSED_STID;
spin_lock(&clp->cl_lock);
- unhash_open_stateid(s);
- spin_unlock(&clp->cl_lock);
+ unhash_open_stateid(s, &reaplist);
- if (clp->cl_minorversion)
- put_generic_stateid(s);
- else
+ if (clp->cl_minorversion) {
+ put_generic_stateid_locked(s, &reaplist);
+ spin_unlock(&clp->cl_lock);
+ free_ol_stateid_reaplist(&reaplist);
+ } else {
+ spin_unlock(&clp->cl_lock);
+ free_ol_stateid_reaplist(&reaplist);
move_to_close_lru(s, clp->net);
+ }
}
/*
--
1.9.3
--
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