NFS: Move cl_delegations to the nfs_server struct

Delegations are per-inode, not per-nfs_client.  When a server file
system is migrated, delegations on the client must be moved from the
source to the destination nfs_server.  Make it easier to manage a
mount point's delegation list across a migration event by moving the
list to the nfs_server struct.

Clean up: I added documenting comments to public functions I changed
in this patch.  For consistency I added comments to all the other
public functions in fs/nfs/delegation.c.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

4 files changed, 250 insertions, 92 deletions

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 32b5fbfab35e..192f2f860265 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -172,7 +172,6 @@ static struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_
         if (err)
                 goto error_cleanup;
 
-        INIT_LIST_HEAD(&clp->cl_delegations);
         spin_lock_init(&clp->cl_lock);
         INIT_DELAYED_WORK(&clp->cl_renewd, nfs4_renew_state);
         rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
@@ -1040,6 +1039,7 @@ static struct nfs_server *nfs_alloc_server(void)
         /* Zero out the NFS state stuff */
         INIT_LIST_HEAD(&server->client_link);
         INIT_LIST_HEAD(&server->master_link);
+        INIT_LIST_HEAD(&server->delegations);
 
         atomic_set(&server->active, 0);
 
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 521d71b81825..364e4328f392 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -40,11 +40,23 @@ static void nfs_free_delegation(struct nfs_delegation *delegation)
         call_rcu(&delegation->rcu, nfs_free_delegation_callback);
 }
 
+/**
+ * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
+ * @delegation: delegation to process
+ *
+ */
 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
 {
         set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
 }
 
+/**
+ * nfs_have_delegation - check if inode has a delegation
+ * @inode: inode to check
+ * @flags: delegation types to check for
+ *
+ * Returns one if inode has the indicated delegation, otherwise zero.
+ */
 int nfs_have_delegation(struct inode *inode, fmode_t flags)
 {
         struct nfs_delegation *delegation;
@@ -119,10 +131,15 @@ again:
         return 0;
 }
 
-/*
- * Set up a delegation on an inode
+/**
+ * nfs_inode_reclaim_delegation - process a delegation reclaim request
+ * @inode: inode to process
+ * @cred: credential to use for request
+ * @res: new delegation state from server
+ *
  */
-void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
+void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred,
+                                  struct nfs_openres *res)
 {
         struct nfs_delegation *delegation;
         struct rpc_cred *oldcred = NULL;
@@ -177,11 +194,11 @@ static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation
 
 static struct nfs_delegation *
 nfs_detach_delegation_locked(struct nfs_inode *nfsi,
-                             struct nfs_client *clp)
+                             struct nfs_server *server)
 {
         struct nfs_delegation *delegation =
                 rcu_dereference_protected(nfsi->delegation,
-                                          lockdep_is_held(&clp->cl_lock));
+                                lockdep_is_held(&server->nfs_client->cl_lock));
 
         if (delegation == NULL)
                 goto nomatch;
@@ -198,22 +215,29 @@ nomatch:
 }
 
 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
-                                                    struct nfs_client *clp)
+                                                    struct nfs_server *server)
 {
+        struct nfs_client *clp = server->nfs_client;
         struct nfs_delegation *delegation;
 
         spin_lock(&clp->cl_lock);
-        delegation = nfs_detach_delegation_locked(nfsi, clp);
+        delegation = nfs_detach_delegation_locked(nfsi, server);
         spin_unlock(&clp->cl_lock);
         return delegation;
 }
 
-/*
- * Set up a delegation on an inode
+/**
+ * nfs_inode_set_delegation - set up a delegation on an inode
+ * @inode: inode to which delegation applies
+ * @cred: cred to use for subsequent delegation processing
+ * @res: new delegation state from server
+ *
+ * Returns zero on success, or a negative errno value.
  */
 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
 {
-        struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
+        struct nfs_server *server = NFS_SERVER(inode);
+        struct nfs_client *clp = server->nfs_client;
         struct nfs_inode *nfsi = NFS_I(inode);
         struct nfs_delegation *delegation, *old_delegation;
         struct nfs_delegation *freeme = NULL;
@@ -234,7 +258,7 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
 
         spin_lock(&clp->cl_lock);
         old_delegation = rcu_dereference_protected(nfsi->delegation,
-                                                   lockdep_is_held(&clp->cl_lock));
+                                        lockdep_is_held(&clp->cl_lock));
         if (old_delegation != NULL) {
                 if (memcmp(&delegation->stateid, &old_delegation->stateid,
                                         sizeof(old_delegation->stateid)) == 0 &&
@@ -253,9 +277,9 @@ int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct
                         delegation = NULL;
                         goto out;
                 }
-                freeme = nfs_detach_delegation_locked(nfsi, clp);
+                freeme = nfs_detach_delegation_locked(nfsi, server);
         }
-        list_add_rcu(&delegation->super_list, &clp->cl_delegations);
+        list_add_rcu(&delegation->super_list, &server->delegations);
         nfsi->delegation_state = delegation->type;
         rcu_assign_pointer(nfsi->delegation, delegation);
         delegation = NULL;
@@ -297,67 +321,85 @@ out:
         return err;
 }
 
-/*
- * Return all delegations that have been marked for return
+/**
+ * nfs_client_return_marked_delegations - return previously marked delegations
+ * @clp: nfs_client to process
+ *
+ * Returns zero on success, or a negative errno value.
  */
 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 {
         struct nfs_delegation *delegation;
+        struct nfs_server *server;
         struct inode *inode;
         int err = 0;
 
 restart:
         rcu_read_lock();
-        list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
-                if (!test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
-                        continue;
-                inode = nfs_delegation_grab_inode(delegation);
-                if (inode == NULL)
-                        continue;
-                delegation = nfs_detach_delegation(NFS_I(inode), clp);
-                rcu_read_unlock();
-                if (delegation != NULL) {
-                        filemap_flush(inode->i_mapping);
-                        err = __nfs_inode_return_delegation(inode, delegation, 0);
+        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+                list_for_each_entry_rcu(delegation, &server->delegations,
+                                                                super_list) {
+                        if (!test_and_clear_bit(NFS_DELEGATION_RETURN,
+                                                        &delegation->flags))
+                                continue;
+                        inode = nfs_delegation_grab_inode(delegation);
+                        if (inode == NULL)
+                                continue;
+                        delegation = nfs_detach_delegation(NFS_I(inode),
+                                                                server);
+                        rcu_read_unlock();
+
+                        if (delegation != NULL) {
+                                filemap_flush(inode->i_mapping);
+                                err = __nfs_inode_return_delegation(inode,
+                                                                delegation, 0);
+                        }
+                        iput(inode);
+                        if (!err)
+                                goto restart;
+                        set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
+                        return err;
                 }
-                iput(inode);
-                if (!err)
-                        goto restart;
-                set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
-                return err;
         }
         rcu_read_unlock();
         return 0;
 }
 
-/*
- * This function returns the delegation without reclaiming opens
- * or protecting against delegation reclaims.
- * It is therefore really only safe to be called from
- * nfs4_clear_inode()
+/**
+ * nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
+ * @inode: inode to process
+ *
+ * Does not protect against delegation reclaims, therefore really only safe
+ * to be called from nfs4_clear_inode().
  */
 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 {
-        struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
+        struct nfs_server *server = NFS_SERVER(inode);
         struct nfs_inode *nfsi = NFS_I(inode);
         struct nfs_delegation *delegation;
 
         if (rcu_access_pointer(nfsi->delegation) != NULL) {
-                delegation = nfs_detach_delegation(nfsi, clp);
+                delegation = nfs_detach_delegation(nfsi, server);
                 if (delegation != NULL)
                         nfs_do_return_delegation(inode, delegation, 0);
         }
 }
 
+/**
+ * nfs_inode_return_delegation - synchronously return a delegation
+ * @inode: inode to process
+ *
+ * Returns zero on success, or a negative errno value.
+ */
 int nfs_inode_return_delegation(struct inode *inode)
 {
-        struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
+        struct nfs_server *server = NFS_SERVER(inode);
         struct nfs_inode *nfsi = NFS_I(inode);
         struct nfs_delegation *delegation;
         int err = 0;
 
         if (rcu_access_pointer(nfsi->delegation) != NULL) {
-                delegation = nfs_detach_delegation(nfsi, clp);
+                delegation = nfs_detach_delegation(nfsi, server);
                 if (delegation != NULL) {
                         nfs_wb_all(inode);
                         err = __nfs_inode_return_delegation(inode, delegation, 1);
@@ -366,46 +408,61 @@ int nfs_inode_return_delegation(struct inode *inode)
         return err;
 }
 
-static void nfs_mark_return_delegation(struct nfs_client *clp, struct nfs_delegation *delegation)
+static void nfs_mark_return_delegation(struct nfs_delegation *delegation)
 {
+        struct nfs_client *clp = NFS_SERVER(delegation->inode)->nfs_client;
+
         set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
         set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 }
 
-/*
- * Return all delegations associated to a super block
+/**
+ * nfs_super_return_all_delegations - return delegations for one superblock
+ * @sb: sb to process
+ *
  */
 void nfs_super_return_all_delegations(struct super_block *sb)
 {
-        struct nfs_client *clp = NFS_SB(sb)->nfs_client;
+        struct nfs_server *server = NFS_SB(sb);
+        struct nfs_client *clp = server->nfs_client;
         struct nfs_delegation *delegation;
 
         if (clp == NULL)
                 return;
+
         rcu_read_lock();
-        list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
+        list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
                 spin_lock(&delegation->lock);
-                if (delegation->inode != NULL && delegation->inode->i_sb == sb)
-                        set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
+                set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
                 spin_unlock(&delegation->lock);
         }
         rcu_read_unlock();
+
         if (nfs_client_return_marked_delegations(clp) != 0)
                 nfs4_schedule_state_manager(clp);
 }
 
-static
-void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp, fmode_t flags)
+static void nfs_mark_return_all_delegation_types(struct nfs_server *server,
+                                                 fmode_t flags)
 {
         struct nfs_delegation *delegation;
 
-        rcu_read_lock();
-        list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
+        list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
                 if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
                         continue;
                 if (delegation->type & flags)
-                        nfs_mark_return_delegation(clp, delegation);
+                        nfs_mark_return_delegation(delegation);
         }
+}
+
+static void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp,
+                                                        fmode_t flags)
+{
+        struct nfs_server *server;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
+                nfs_mark_return_all_delegation_types(server, flags);
         rcu_read_unlock();
 }
 
@@ -420,19 +477,32 @@ static void nfs_delegation_run_state_manager(struct nfs_client *clp)
                 nfs4_schedule_state_manager(clp);
 }
 
+/**
+ * nfs_expire_all_delegation_types
+ * @clp: client to process
+ * @flags: delegation types to expire
+ *
+ */
 void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags)
 {
         nfs_client_mark_return_all_delegation_types(clp, flags);
         nfs_delegation_run_state_manager(clp);
 }
 
+/**
+ * nfs_expire_all_delegations
+ * @clp: client to process
+ *
+ */
 void nfs_expire_all_delegations(struct nfs_client *clp)
 {
         nfs_expire_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 }
 
-/*
- * Return all delegations following an NFS4ERR_CB_PATH_DOWN error.
+/**
+ * nfs_handle_cb_pathdown - return all delegations after NFS4ERR_CB_PATH_DOWN
+ * @clp: client to process
+ *
  */
 void nfs_handle_cb_pathdown(struct nfs_client *clp)
 {
@@ -441,29 +511,43 @@ void nfs_handle_cb_pathdown(struct nfs_client *clp)
         nfs_client_mark_return_all_delegations(clp);
 }
 
-static void nfs_client_mark_return_unreferenced_delegations(struct nfs_client *clp)
+static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 {
         struct nfs_delegation *delegation;
 
-        rcu_read_lock();
-        list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
+        list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
                 if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
                         continue;
-                nfs_mark_return_delegation(clp, delegation);
+                nfs_mark_return_delegation(delegation);
         }
-        rcu_read_unlock();
 }
 
+/**
+ * nfs_expire_unreferenced_delegations - Eliminate unused delegations
+ * @clp: nfs_client to process
+ *
+ */
 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 {
-        nfs_client_mark_return_unreferenced_delegations(clp);
+        struct nfs_server *server;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
+                nfs_mark_return_unreferenced_delegations(server);
+        rcu_read_unlock();
+
         nfs_delegation_run_state_manager(clp);
 }
 
-/*
- * Asynchronous delegation recall!
+/**
+ * nfs_async_inode_return_delegation - asynchronously return a delegation
+ * @inode: inode to process
+ * @stateid: state ID information from CB_RECALL arguments
+ *
+ * Returns zero on success, or a negative errno value.
  */
-int nfs_async_inode_return_delegation(struct inode *inode, const nfs4_stateid *stateid)
+int nfs_async_inode_return_delegation(struct inode *inode,
+                                      const nfs4_stateid *stateid)
 {
         struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
         struct nfs_delegation *delegation;
@@ -475,22 +559,21 @@ int nfs_async_inode_return_delegation(struct inode *inode, const nfs4_stateid *s
                 rcu_read_unlock();
                 return -ENOENT;
         }
-
-        nfs_mark_return_delegation(clp, delegation);
+        nfs_mark_return_delegation(delegation);
         rcu_read_unlock();
+
         nfs_delegation_run_state_manager(clp);
         return 0;
 }
 
-/*
- * Retrieve the inode associated with a delegation
- */
-struct inode *nfs_delegation_find_inode(struct nfs_client *clp, const struct nfs_fh *fhandle)
+static struct inode *
+nfs_delegation_find_inode_server(struct nfs_server *server,
+                                 const struct nfs_fh *fhandle)
 {
         struct nfs_delegation *delegation;
         struct inode *res = NULL;
-        rcu_read_lock();
-        list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
+
+        list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
                 spin_lock(&delegation->lock);
                 if (delegation->inode != NULL &&
                     nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
@@ -500,47 +583,121 @@ struct inode *nfs_delegation_find_inode(struct nfs_client *clp, const struct nfs
                 if (res != NULL)
                         break;
         }
+        return res;
+}
+
+/**
+ * nfs_delegation_find_inode - retrieve the inode associated with a delegation
+ * @clp: client state handle
+ * @fhandle: filehandle from a delegation recall
+ *
+ * Returns pointer to inode matching "fhandle," or NULL if a matching inode
+ * cannot be found.
+ */
+struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
+                                        const struct nfs_fh *fhandle)
+{
+        struct nfs_server *server;
+        struct inode *res = NULL;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+                res = nfs_delegation_find_inode_server(server, fhandle);
+                if (res != NULL)
+                        break;
+        }
         rcu_read_unlock();
         return res;
 }
 
-/*
- * Mark all delegations as needing to be reclaimed
+static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
+{
+        struct nfs_delegation *delegation;
+
+        list_for_each_entry_rcu(delegation, &server->delegations, super_list)
+                set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
+}
+
+/**
+ * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
+ * @clp: nfs_client to process
+ *
  */
 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 {
-        struct nfs_delegation *delegation;
+        struct nfs_server *server;
+
         rcu_read_lock();
-        list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list)
-                set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
+        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
+                nfs_delegation_mark_reclaim_server(server);
         rcu_read_unlock();
 }
 
-/*
- * Reap all unclaimed delegations after reboot recovery is done
+/**
+ * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
+ * @clp: nfs_client to process
+ *
  */
 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
 {
         struct nfs_delegation *delegation;
+        struct nfs_server *server;
         struct inode *inode;
+
 restart:
         rcu_read_lock();
-        list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
-                if (test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags) == 0)
-                        continue;
-                inode = nfs_delegation_grab_inode(delegation);
-                if (inode == NULL)
-                        continue;
-                delegation = nfs_detach_delegation(NFS_I(inode), clp);
-                rcu_read_unlock();
-                if (delegation != NULL)
-                        nfs_free_delegation(delegation);
-                iput(inode);
-                goto restart;
+        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+                list_for_each_entry_rcu(delegation, &server->delegations,
+                                                                super_list) {
+                        if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
+                                                &delegation->flags) == 0)
+                                continue;
+                        inode = nfs_delegation_grab_inode(delegation);
+                        if (inode == NULL)
+                                continue;
+                        delegation = nfs_detach_delegation(NFS_I(inode),
+                                                                server);
+                        rcu_read_unlock();
+
+                        if (delegation != NULL)
+                                nfs_free_delegation(delegation);
+                        iput(inode);
+                        goto restart;
+                }
         }
         rcu_read_unlock();
 }
 
+/**
+ * nfs_delegations_present - check for existence of delegations
+ * @clp: client state handle
+ *
+ * Returns one if there are any nfs_delegation structures attached
+ * to this nfs_client.
+ */
+int nfs_delegations_present(struct nfs_client *clp)
+{
+        struct nfs_server *server;
+        int ret = 0;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
+                if (!list_empty(&server->delegations)) {
+                        ret = 1;
+                        break;
+                }
+        rcu_read_unlock();
+        return ret;
+}
+
+/**
+ * nfs4_copy_delegation_stateid - Copy inode's state ID information
+ * @dst: stateid data structure to fill in
+ * @inode: inode to check
+ *
+ * Returns one and fills in "dst->data" * if inode had a delegation,
+ * otherwise zero is returned.
+ */
 int nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
 {
         struct nfs_inode *nfsi = NFS_I(inode);
diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h
index 2026304bda19..d9322e490c56 100644
--- a/fs/nfs/delegation.h
+++ b/fs/nfs/delegation.h
@@ -44,6 +44,7 @@ void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags);
 void nfs_expire_unreferenced_delegations(struct nfs_client *clp);
 void nfs_handle_cb_pathdown(struct nfs_client *clp);
 int nfs_client_return_marked_delegations(struct nfs_client *clp);
+int nfs_delegations_present(struct nfs_client *clp);
 
 void nfs_delegation_mark_reclaim(struct nfs_client *clp);
 void nfs_delegation_reap_unclaimed(struct nfs_client *clp);
diff --git a/fs/nfs/nfs4renewd.c b/fs/nfs/nfs4renewd.c
index cde5650ee5a2..402143d75fc5 100644
--- a/fs/nfs/nfs4renewd.c
+++ b/fs/nfs/nfs4renewd.c
@@ -80,7 +80,7 @@ nfs4_renew_state(struct work_struct *work)
                 cred = ops->get_state_renewal_cred_locked(clp);
                 spin_unlock(&clp->cl_lock);
                 if (cred == NULL) {
-                        if (list_empty(&clp->cl_delegations)) {
+                        if (!nfs_delegations_present(clp)) {
                                 set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
                                 goto out;
                         }