nfsd: Extend the mutex holding region around in nfsd4_process_open2()

To avoid racing entry into nfs4_get_vfs_file().
Make init_open_stateid() return with locked stateid to be unlocked
by the caller.

Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c927d36d8ac6..94854a06c9ad 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3487,6 +3487,10 @@ init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp,
         struct nfs4_openowner *oo = open->op_openowner;
         struct nfs4_ol_stateid *retstp = NULL;
 
+        /* We are moving these outside of the spinlocks to avoid the warnings */
+        mutex_init(&stp->st_mutex);
+        mutex_lock(&stp->st_mutex);
+
         spin_lock(&oo->oo_owner.so_client->cl_lock);
         spin_lock(&fp->fi_lock);
 
@@ -3502,13 +3506,17 @@ init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp,
         stp->st_access_bmap = 0;
         stp->st_deny_bmap = 0;
         stp->st_openstp = NULL;
-        mutex_init(&stp->st_mutex);
         list_add(&stp->st_perstateowner, &oo->oo_owner.so_stateids);
         list_add(&stp->st_perfile, &fp->fi_stateids);
 
 out_unlock:
         spin_unlock(&fp->fi_lock);
         spin_unlock(&oo->oo_owner.so_client->cl_lock);
+        if (retstp) {
+                mutex_lock(&retstp->st_mutex);
+                /* Not that we need to, just for neatness */
+                mutex_unlock(&stp->st_mutex);
+        }
         return retstp;
 }
 
@@ -4344,11 +4352,14 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
         } else {
                 stp = open->op_stp;
                 open->op_stp = NULL;
+                /*
+                 * init_open_stateid() either returns a locked stateid
+                 * it found, or initializes and locks the new one we passed in
+                 */
                 swapstp = init_open_stateid(stp, fp, open);
                 if (swapstp) {
                         nfs4_put_stid(&stp->st_stid);
                         stp = swapstp;
-                        mutex_lock(&stp->st_mutex);
                         status = nfs4_upgrade_open(rqstp, fp, current_fh,
                                                 stp, open);
                         if (status) {
@@ -4357,7 +4368,6 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
                         }
                         goto upgrade_out;
                 }
-                mutex_lock(&stp->st_mutex);
                 status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
                 if (status) {
                         mutex_unlock(&stp->st_mutex);