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nfsd: Fix race in lock stateid creation

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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 <trond.myklebust@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Trond Myklebust 2017-11-03 08:00:14 -04:00 committed by J. Bruce Fields
parent fd1fd685b3
commit beeca19cf1
1 changed files with 42 additions and 28 deletions
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70
fs/nfsd/nfs4state.c
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@ -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);
}