Preparation for removal of the client_mutex.
Currently, no lock aside from the client_mutex is held when calling
find_lock_state. Ensure that the cl_lock is held by adding a lockdep
assertion.
Once we remove the client_mutex, it'll be possible for another thread to
race in and insert a lock state for the same file after we search but
before we insert a new one. Ensure that doesn't happen by redoing the
search after allocating a new stid that we plan to insert. If one is
found just put the one we just allocated.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 58 +++++++++++++++++++++++++++++++++++++----------------
1 file changed, 41 insertions(+), 17 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 05d0fac2e50a..60cc162cc8a5 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4652,16 +4652,14 @@ alloc_init_lock_stateowner(unsigned int strhashval, struct nfs4_client *clp, str
return lo;
}
-static struct nfs4_ol_stateid *
-alloc_init_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp, struct nfs4_ol_stateid *open_stp)
+static void
+init_lock_stateid(struct nfs4_ol_stateid *stp, struct nfs4_lockowner *lo,
+ struct nfs4_file *fp, struct nfs4_ol_stateid *open_stp)
{
- struct nfs4_openowner *oo = openowner(open_stp->st_stateowner);
- struct nfs4_ol_stateid *stp;
struct nfs4_client *clp = lo->lo_owner.so_client;
- stp = nfs4_alloc_stateid(clp);
- if (stp == NULL)
- return NULL;
+ lockdep_assert_held(&clp->cl_lock);
+
stp->st_stid.sc_type = NFS4_LOCK_STID;
stp->st_stateowner = &lo->lo_owner;
get_nfs4_file(fp);
@@ -4670,20 +4668,20 @@ alloc_init_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp, struct
stp->st_access_bmap = 0;
stp->st_deny_bmap = open_stp->st_deny_bmap;
stp->st_openstp = open_stp;
- spin_lock(&oo->oo_owner.so_client->cl_lock);
list_add(&stp->st_locks, &open_stp->st_locks);
list_add(&stp->st_perstateowner, &lo->lo_owner.so_stateids);
spin_lock(&fp->fi_lock);
list_add(&stp->st_perfile, &fp->fi_stateids);
spin_unlock(&fp->fi_lock);
- spin_unlock(&oo->oo_owner.so_client->cl_lock);
- return stp;
}
static struct nfs4_ol_stateid *
find_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp)
{
struct nfs4_ol_stateid *lst;
+ struct nfs4_client *clp = lo->lo_owner.so_client;
+
+ lockdep_assert_held(&clp->cl_lock);
list_for_each_entry(lst, &lo->lo_owner.so_stateids, st_perstateowner) {
if (lst->st_stid.sc_file == fp)
@@ -4692,6 +4690,36 @@ find_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp)
return NULL;
}
+static struct nfs4_ol_stateid *
+find_or_create_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fi,
+ struct nfs4_ol_stateid *ost, bool *new)
+{
+ struct nfs4_ol_stateid *lst, *nst = NULL;
+ struct nfs4_openowner *oo = openowner(ost->st_stateowner);
+ struct nfs4_client *clp = oo->oo_owner.so_client;
+
+ spin_lock(&clp->cl_lock);
+ lst = find_lock_stateid(lo, fi);
+ if (lst == NULL) {
+ spin_unlock(&clp->cl_lock);
+ nst = nfs4_alloc_stateid(clp);
+ if (nst == NULL)
+ return NULL;
+
+ spin_lock(&clp->cl_lock);
+ lst = find_lock_stateid(lo, fi);
+ if (likely(!lst)) {
+ init_lock_stateid(nst, lo, fi, ost);
+ lst = nst;
+ nst = NULL;
+ *new = true;
+ }
+ }
+ spin_unlock(&clp->cl_lock);
+ if (nst)
+ put_generic_stateid(nst);
+ return lst;
+}
static int
check_lock_length(u64 offset, u64 length)
@@ -4739,14 +4767,10 @@ static __be32 lookup_or_create_lock_state(struct nfsd4_compound_state *cstate, s
return nfserr_bad_seqid;
}
- *lst = find_lock_stateid(lo, fi);
+ *lst = find_or_create_lock_stateid(lo, fi, ost, new);
if (*lst == NULL) {
- *lst = alloc_init_lock_stateid(lo, fi, ost);
- if (*lst == NULL) {
- release_lockowner_if_empty(lo);
- return nfserr_jukebox;
- }
- *new = true;
+ release_lockowner_if_empty(lo);
+ return nfserr_jukebox;
}
return nfs_ok;
}
--
1.9.3
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