NFSv4: Fix a reboot recovery race when opening a file

If the server reboots after it has replied to our OPEN, but before we
call nfs4_opendata_to_nfs4_state(), then the reboot recovery thread
will not see a stateid for this open, and so will fail to recover it.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 38 insertions, 12 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index d51227371c67..7cbf7aa6c634 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1848,6 +1848,43 @@ static inline void nfs4_exclusive_attrset(struct nfs4_opendata *opendata, struct
                 sattr->ia_valid |= ATTR_MTIME;
 }
 
+static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata,
+                fmode_t fmode,
+                int flags,
+                struct nfs4_state **res)
+{
+        struct nfs4_state_owner *sp = opendata->owner;
+        struct nfs_server *server = sp->so_server;
+        struct nfs4_state *state;
+        unsigned int seq;
+        int ret;
+
+        seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
+
+        ret = _nfs4_proc_open(opendata);
+        if (ret != 0)
+                goto out;
+
+        state = nfs4_opendata_to_nfs4_state(opendata);
+        ret = PTR_ERR(state);
+        if (IS_ERR(state))
+                goto out;
+        if (server->caps & NFS_CAP_POSIX_LOCK)
+                set_bit(NFS_STATE_POSIX_LOCKS, &state->flags);
+
+        ret = nfs4_opendata_access(sp->so_cred, opendata, state, fmode, flags);
+        if (ret != 0)
+                goto out;
+
+        if (read_seqcount_retry(&sp->so_reclaim_seqcount, seq)) {
+                nfs4_schedule_stateid_recovery(server, state);
+                nfs4_wait_clnt_recover(server->nfs_client);
+        }
+        *res = state;
+out:
+        return ret;
+}
+
 /*
  * Returns a referenced nfs4_state
  */
@@ -1892,18 +1929,7 @@ static int _nfs4_do_open(struct inode *dir,
         if (dentry->d_inode != NULL)
                 opendata->state = nfs4_get_open_state(dentry->d_inode, sp);
 
-        status = _nfs4_proc_open(opendata);
-        if (status != 0)
-                goto err_opendata_put;
-
-        state = nfs4_opendata_to_nfs4_state(opendata);
-        status = PTR_ERR(state);
-        if (IS_ERR(state))
-                goto err_opendata_put;
-        if (server->caps & NFS_CAP_POSIX_LOCK)
-                set_bit(NFS_STATE_POSIX_LOCKS, &state->flags);
-
-        status = nfs4_opendata_access(cred, opendata, state, fmode, flags);
+        status = _nfs4_open_and_get_state(opendata, fmode, flags, &state);
         if (status != 0)
                 goto err_opendata_put;