From beeca19cf1249a917ed737729dc92337c7633bea Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Fri, 3 Nov 2017 08:00:14 -0400 Subject: [PATCH] nfsd: Fix race in lock stateid creation If we're looking up a new lock state, and the creation fails, then we want to unhash it, just like we do for OPEN. However in order to do so, we need to that no other LOCK requests can grab the mutex until we have unhashed it (and marked it as closed). Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- fs/nfsd/nfs4state.c | 70 +++++++++++++++++++++++++++------------------ 1 file changed, 42 insertions(+), 28 deletions(-) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 49a9741fa132..6d5993caf9bc 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -5722,14 +5722,22 @@ find_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp) return NULL; } -static void +static struct nfs4_ol_stateid * init_lock_stateid(struct nfs4_ol_stateid *stp, struct nfs4_lockowner *lo, struct nfs4_file *fp, struct inode *inode, struct nfs4_ol_stateid *open_stp) { struct nfs4_client *clp = lo->lo_owner.so_client; + struct nfs4_ol_stateid *retstp; - lockdep_assert_held(&clp->cl_lock); + mutex_init(&stp->st_mutex); + mutex_lock(&stp->st_mutex); +retry: + spin_lock(&clp->cl_lock); + spin_lock(&fp->fi_lock); + retstp = find_lock_stateid(lo, fp); + if (retstp) + goto out_unlock; refcount_inc(&stp->st_stid.sc_count); stp->st_stid.sc_type = NFS4_LOCK_STID; @@ -5739,12 +5747,22 @@ init_lock_stateid(struct nfs4_ol_stateid *stp, struct nfs4_lockowner *lo, stp->st_access_bmap = 0; stp->st_deny_bmap = open_stp->st_deny_bmap; stp->st_openstp = open_stp; - mutex_init(&stp->st_mutex); 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); +out_unlock: spin_unlock(&fp->fi_lock); + spin_unlock(&clp->cl_lock); + if (retstp) { + if (nfsd4_lock_ol_stateid(retstp) != nfs_ok) { + nfs4_put_stid(&retstp->st_stid); + goto retry; + } + /* To keep mutex tracking happy */ + mutex_unlock(&stp->st_mutex); + stp = retstp; + } + return stp; } static struct nfs4_ol_stateid * @@ -5757,26 +5775,25 @@ find_or_create_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fi, struct nfs4_openowner *oo = openowner(ost->st_stateowner); struct nfs4_client *clp = oo->oo_owner.so_client; + *new = false; spin_lock(&clp->cl_lock); lst = find_lock_stateid(lo, fi); - if (lst == NULL) { - spin_unlock(&clp->cl_lock); - ns = nfs4_alloc_stid(clp, stateid_slab, nfs4_free_lock_stateid); - if (ns == NULL) - return NULL; - - spin_lock(&clp->cl_lock); - lst = find_lock_stateid(lo, fi); - if (likely(!lst)) { - lst = openlockstateid(ns); - init_lock_stateid(lst, lo, fi, inode, ost); - ns = NULL; - *new = true; - } - } spin_unlock(&clp->cl_lock); - if (ns) + if (lst != NULL) { + if (nfsd4_lock_ol_stateid(lst) == nfs_ok) + goto out; + nfs4_put_stid(&lst->st_stid); + } + ns = nfs4_alloc_stid(clp, stateid_slab, nfs4_free_lock_stateid); + if (ns == NULL) + return NULL; + + lst = init_lock_stateid(openlockstateid(ns), lo, fi, inode, ost); + if (lst == openlockstateid(ns)) + *new = true; + else nfs4_put_stid(ns); +out: return lst; } @@ -5828,17 +5845,12 @@ lookup_or_create_lock_state(struct nfsd4_compound_state *cstate, goto out; } -retry: lst = find_or_create_lock_stateid(lo, fi, inode, ost, new); if (lst == NULL) { status = nfserr_jukebox; goto out; } - if (nfsd4_lock_ol_stateid(lst) != nfs_ok) { - nfs4_put_stid(&lst->st_stid); - goto retry; - } status = nfs_ok; *plst = lst; out: @@ -6044,14 +6056,16 @@ out: seqid_mutating_err(ntohl(status))) lock_sop->lo_owner.so_seqid++; - mutex_unlock(&lock_stp->st_mutex); - /* * If this is a new, never-before-used stateid, and we are * returning an error, then just go ahead and release it. */ - if (status && new) + if (status && new) { + lock_stp->st_stid.sc_type = NFS4_CLOSED_STID; release_lock_stateid(lock_stp); + } + + mutex_unlock(&lock_stp->st_mutex); nfs4_put_stid(&lock_stp->st_stid); } -- 2.39.5