afs: Fix checker warnings

Fix warnings raised by checker, including:

 (*) Warnings raised by unequal comparison for the purposes of sorting,
     where the endianness doesn't matter:

fs/afs/addr_list.c:246:21: warning: restricted __be16 degrades to integer
fs/afs/addr_list.c:246:30: warning: restricted __be16 degrades to integer
fs/afs/addr_list.c:248:21: warning: restricted __be32 degrades to integer
fs/afs/addr_list.c:248:49: warning: restricted __be32 degrades to integer
fs/afs/addr_list.c:283:21: warning: restricted __be16 degrades to integer
fs/afs/addr_list.c:283:30: warning: restricted __be16 degrades to integer

 (*) afs_set_cb_interest() is not actually used and can be removed.

 (*) afs_cell_gc_delay() should be provided with a sysctl.

 (*) afs_cell_destroy() needs to use rcu_access_pointer() to read
     cell->vl_addrs.

 (*) afs_init_fs_cursor() should be static.

 (*) struct afs_vnode::permit_cache needs to be marked __rcu.

 (*) afs_server_rcu() needs to use rcu_access_pointer().

 (*) afs_destroy_server() should use rcu_access_pointer() on
     server->addresses as the server object is no longer accessible.

 (*) afs_find_server() casts __be16/__be32 values to int in order to
     directly compare them for the purpose of finding a match in a list,
     but is should also annotate the cast with __force to avoid checker
     warnings.

 (*) afs_check_permit() accesses vnode->permit_cache outside of the RCU
     readlock, though it doesn't then access the value; the extraneous
     access is deleted.

False positives:

 (*) Conditional locking around the code in xdr_decode_AFSFetchStatus.  This
     can be dealt with in a separate patch.

fs/afs/fsclient.c:148:9: warning: context imbalance in 'xdr_decode_AFSFetchStatus' - different lock contexts for basic block

 (*) Incorrect handling of seq-retry lock context balance:

fs/afs/inode.c:455:38: warning: context imbalance in 'afs_getattr' - different
lock contexts for basic block
fs/afs/server.c:52:17: warning: context imbalance in 'afs_find_server' - different lock contexts for basic block
fs/afs/server.c:128:17: warning: context imbalance in 'afs_find_server_by_uuid' - different lock contexts for basic block

Errors:

 (*) afs_lookup_cell_rcu() needs to break out of the seq-retry loop, not go
     round again if it successfully found the workstation cell.

 (*) Fix UUID decode in afs_deliver_cb_probe_uuid().

 (*) afs_cache_permit() has a missing rcu_read_unlock() before one of the
     jumps to the someone_else_changed_it label.  Move the unlock to after
     the label.

 (*) afs_vl_get_addrs_u() is using ntohl() rather than htonl() when
     encoding to XDR.

 (*) afs_deliver_yfsvl_get_endpoints() is using htonl() rather than ntohl()
     when decoding from XDR.

Signed-off-by: David Howells <dhowells@redhat.com>

11 files changed, 35 insertions, 50 deletions

diff --git a/fs/afs/addr_list.c b/fs/afs/addr_list.c
index fd9f28b8a933..3bedfed608a2 100644
--- a/fs/afs/addr_list.c
+++ b/fs/afs/addr_list.c
@@ -243,9 +243,9 @@ void afs_merge_fs_addr4(struct afs_addr_list *alist, __be32 xdr, u16 port)
                     xport == a->sin6_port)
                         return;
                 if (xdr == a->sin6_addr.s6_addr32[3] &&
-                    xport < a->sin6_port)
+                    (u16 __force)xport < (u16 __force)a->sin6_port)
                         break;
-                if (xdr < a->sin6_addr.s6_addr32[3])
+                if ((u32 __force)xdr < (u32 __force)a->sin6_addr.s6_addr32[3])
                         break;
         }
 
@@ -280,7 +280,7 @@ void afs_merge_fs_addr6(struct afs_addr_list *alist, __be32 *xdr, u16 port)
                     xport == a->sin6_port)
                         return;
                 if (diff == 0 &&
-                    xport < a->sin6_port)
+                    (u16 __force)xport < (u16 __force)a->sin6_port)
                         break;
                 if (diff < 0)
                         break;
diff --git a/fs/afs/callback.c b/fs/afs/callback.c
index f4291b576054..bf082c719645 100644
--- a/fs/afs/callback.c
+++ b/fs/afs/callback.c
@@ -97,26 +97,6 @@ again:
 }
 
 /*
- * Set a vnode's interest on a server.
- */
-void afs_set_cb_interest(struct afs_vnode *vnode, struct afs_cb_interest *cbi)
-{
-        struct afs_cb_interest *old_cbi = NULL;
-
-        if (vnode->cb_interest == cbi)
-                return;
-
-        write_seqlock(&vnode->cb_lock);
-        if (vnode->cb_interest != cbi) {
-                afs_get_cb_interest(cbi);
-                old_cbi = vnode->cb_interest;
-                vnode->cb_interest = cbi;
-        }
-        write_sequnlock(&vnode->cb_lock);
-        afs_put_cb_interest(afs_v2net(vnode), cbi);
-}
-
-/*
  * Remove an interest on a server.
  */
 void afs_put_cb_interest(struct afs_net *net, struct afs_cb_interest *cbi)
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 4235a05afc76..69b95faacc5e 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -18,7 +18,7 @@
 #include <keys/rxrpc-type.h>
 #include "internal.h"
 
-unsigned __read_mostly afs_cell_gc_delay = 10;
+static unsigned __read_mostly afs_cell_gc_delay = 10;
 
 static void afs_manage_cell(struct work_struct *);
 
@@ -75,7 +75,7 @@ struct afs_cell *afs_lookup_cell_rcu(struct afs_net *net,
                         cell = rcu_dereference_raw(net->ws_cell);
                         if (cell) {
                                 afs_get_cell(cell);
-                                continue;
+                                break;
                         }
                         ret = -EDESTADDRREQ;
                         continue;
@@ -411,7 +411,7 @@ static void afs_cell_destroy(struct rcu_head *rcu)
 
         ASSERTCMP(atomic_read(&cell->usage), ==, 0);
 
-        afs_put_addrlist(cell->vl_addrs);
+        afs_put_addrlist(rcu_access_pointer(cell->vl_addrs));
         key_put(cell->anonymous_key);
         kfree(cell);
 
diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
index 41e277f57b20..83ff283979a4 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -500,9 +500,9 @@ static int afs_deliver_cb_probe_uuid(struct afs_call *call)
 
                 b = call->buffer;
                 r = call->request;
-                r->time_low                     = ntohl(b[0]);
-                r->time_mid                     = ntohl(b[1]);
-                r->time_hi_and_version          = ntohl(b[2]);
+                r->time_low                     = b[0];
+                r->time_mid                     = htons(ntohl(b[1]));
+                r->time_hi_and_version          = htons(ntohl(b[2]));
                 r->clock_seq_hi_and_reserved    = ntohl(b[3]);
                 r->clock_seq_low                = ntohl(b[4]);
 
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 65c5b1edd338..d5db9dead18c 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -544,7 +544,7 @@ void afs_evict_inode(struct inode *inode)
         }
 #endif
 
-        afs_put_permits(vnode->permit_cache);
+        afs_put_permits(rcu_access_pointer(vnode->permit_cache));
         _leave("");
 }
 
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index a6a1d75eee41..135192b7dc04 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -458,7 +458,7 @@ struct afs_vnode {
 #ifdef CONFIG_AFS_FSCACHE
         struct fscache_cookie   *cache;         /* caching cookie */
 #endif
-        struct afs_permits      *permit_cache;  /* cache of permits so far obtained */
+        struct afs_permits __rcu *permit_cache; /* cache of permits so far obtained */
         struct mutex            io_lock;        /* Lock for serialising I/O on this mutex */
         struct mutex            validate_lock;  /* lock for validating this vnode */
         spinlock_t              wb_lock;        /* lock for wb_keys */
diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 4508dd54f789..1c95756335b7 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -183,6 +183,7 @@ static int afs_proc_cells_open(struct inode *inode, struct file *file)
  * first item
  */
 static void *afs_proc_cells_start(struct seq_file *m, loff_t *_pos)
+        __acquires(rcu)
 {
         struct afs_net *net = afs_seq2net(m);
 
@@ -204,6 +205,7 @@ static void *afs_proc_cells_next(struct seq_file *m, void *v, loff_t *pos)
  * clean up after reading from the cells list
  */
 static void afs_proc_cells_stop(struct seq_file *m, void *v)
+        __releases(rcu)
 {
         rcu_read_unlock();
 }
@@ -413,6 +415,7 @@ static int afs_proc_cell_volumes_open(struct inode *inode, struct file *file)
  * first item
  */
 static void *afs_proc_cell_volumes_start(struct seq_file *m, loff_t *_pos)
+        __acquires(cell->proc_lock)
 {
         struct afs_cell *cell = m->private;
 
@@ -438,6 +441,7 @@ static void *afs_proc_cell_volumes_next(struct seq_file *p, void *v,
  * clean up after reading from the cells list
  */
 static void afs_proc_cell_volumes_stop(struct seq_file *p, void *v)
+        __releases(cell->proc_lock)
 {
         struct afs_cell *cell = p->private;
 
@@ -500,6 +504,7 @@ static int afs_proc_cell_vlservers_open(struct inode *inode, struct file *file)
  * first item
  */
 static void *afs_proc_cell_vlservers_start(struct seq_file *m, loff_t *_pos)
+        __acquires(rcu)
 {
         struct afs_addr_list *alist;
         struct afs_cell *cell = m->private;
@@ -544,6 +549,7 @@ static void *afs_proc_cell_vlservers_next(struct seq_file *p, void *v,
  * clean up after reading from the cells list
  */
 static void afs_proc_cell_vlservers_stop(struct seq_file *p, void *v)
+        __releases(rcu)
 {
         rcu_read_unlock();
 }
@@ -580,6 +586,7 @@ static int afs_proc_servers_open(struct inode *inode, struct file *file)
  * first item.
  */
 static void *afs_proc_servers_start(struct seq_file *m, loff_t *_pos)
+        __acquires(rcu)
 {
         struct afs_net *net = afs_seq2net(m);
 
@@ -601,6 +608,7 @@ static void *afs_proc_servers_next(struct seq_file *m, void *v, loff_t *_pos)
  * clean up after reading from the cells list
  */
 static void afs_proc_servers_stop(struct seq_file *p, void *v)
+        __releases(rcu)
 {
         rcu_read_unlock();
 }
diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
index ad1328d85526..ac0feac9d746 100644
--- a/fs/afs/rotate.c
+++ b/fs/afs/rotate.c
@@ -21,7 +21,7 @@
 /*
  * Initialise a filesystem server cursor for iterating over FS servers.
  */
-void afs_init_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
+static void afs_init_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
 {
         memset(fc, 0, sizeof(*fc));
 }
diff --git a/fs/afs/security.c b/fs/afs/security.c
index b88b7d45fdaa..bd82c5bf4a6a 100644
--- a/fs/afs/security.c
+++ b/fs/afs/security.c
@@ -178,18 +178,14 @@ void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
                 }
         }
 
-        if (cb_break != (vnode->cb_break + vnode->cb_interest->server->cb_s_break)) {
-                rcu_read_unlock();
+        if (cb_break != (vnode->cb_break + vnode->cb_interest->server->cb_s_break))
                 goto someone_else_changed_it;
-        }
 
         /* We need a ref on any permits list we want to copy as we'll have to
          * drop the lock to do memory allocation.
          */
-        if (permits && !refcount_inc_not_zero(&permits->usage)) {
-                rcu_read_unlock();
+        if (permits && !refcount_inc_not_zero(&permits->usage))
                 goto someone_else_changed_it;
-        }
 
         rcu_read_unlock();
 
@@ -278,6 +274,7 @@ someone_else_changed_it:
         /* Someone else changed the cache under us - don't recheck at this
          * time.
          */
+        rcu_read_unlock();
         return;
 }
 
@@ -296,8 +293,6 @@ int afs_check_permit(struct afs_vnode *vnode, struct key *key,
         _enter("{%x:%u},%x",
                vnode->fid.vid, vnode->fid.vnode, key_serial(key));
 
-        permits = vnode->permit_cache;
-
         /* check the permits to see if we've got one yet */
         if (key == vnode->volume->cell->anonymous_key) {
                 _debug("anon");
diff --git a/fs/afs/server.c b/fs/afs/server.c
index a43ef77dabae..e23be63998a8 100644
--- a/fs/afs/server.c
+++ b/fs/afs/server.c
@@ -59,7 +59,8 @@ struct afs_server *afs_find_server(struct afs_net *net,
                                 alist = rcu_dereference(server->addresses);
                                 for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
                                         b = &alist->addrs[i].transport.sin6;
-                                        diff = (u16)a->sin6_port - (u16)b->sin6_port;
+                                        diff = ((u16 __force)a->sin6_port -
+                                                (u16 __force)b->sin6_port);
                                         if (diff == 0)
                                                 diff = memcmp(&a->sin6_addr,
                                                               &b->sin6_addr,
@@ -79,10 +80,11 @@ struct afs_server *afs_find_server(struct afs_net *net,
                                 alist = rcu_dereference(server->addresses);
                                 for (i = 0; i < alist->nr_ipv4; i++) {
                                         b = &alist->addrs[i].transport.sin6;
-                                        diff = (u16)a->sin6_port - (u16)b->sin6_port;
+                                        diff = ((u16 __force)a->sin6_port -
+                                                (u16 __force)b->sin6_port);
                                         if (diff == 0)
-                                                diff = ((u32)a->sin6_addr.s6_addr32[3] -
-                                                        (u32)b->sin6_addr.s6_addr32[3]);
+                                                diff = ((u32 __force)a->sin6_addr.s6_addr32[3] -
+                                                        (u32 __force)b->sin6_addr.s6_addr32[3]);
                                         if (diff == 0)
                                                 goto found;
                                         if (diff < 0) {
@@ -381,7 +383,7 @@ static void afs_server_rcu(struct rcu_head *rcu)
 {
         struct afs_server *server = container_of(rcu, struct afs_server, rcu);
 
-        afs_put_addrlist(server->addresses);
+        afs_put_addrlist(rcu_access_pointer(server->addresses));
         kfree(server);
 }
 
@@ -390,7 +392,7 @@ static void afs_server_rcu(struct rcu_head *rcu)
  */
 static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
 {
-        struct afs_addr_list *alist = server->addresses;
+        struct afs_addr_list *alist = rcu_access_pointer(server->addresses);
         struct afs_addr_cursor ac = {
                 .alist  = alist,
                 .addr   = &alist->addrs[0],
diff --git a/fs/afs/vlclient.c b/fs/afs/vlclient.c
index 5d8562f1ad4a..f9d89795e41b 100644
--- a/fs/afs/vlclient.c
+++ b/fs/afs/vlclient.c
@@ -303,7 +303,7 @@ struct afs_addr_list *afs_vl_get_addrs_u(struct afs_net *net,
         r->uuid.clock_seq_hi_and_reserved       = htonl(u->clock_seq_hi_and_reserved);
         r->uuid.clock_seq_low                   = htonl(u->clock_seq_low);
         for (i = 0; i < 6; i++)
-                r->uuid.node[i] = ntohl(u->node[i]);
+                r->uuid.node[i] = htonl(u->node[i]);
 
         trace_afs_make_vl_call(call);
         return (struct afs_addr_list *)afs_make_call(ac, call, GFP_KERNEL, false);
@@ -504,7 +504,7 @@ again:
                 /* Got either the type of the next entry or the count of
                  * volEndpoints if no more fsEndpoints.
                  */
-                call->count2 = htonl(*bp++);
+                call->count2 = ntohl(*bp++);
 
                 call->offset = 0;
                 call->count--;
@@ -531,7 +531,7 @@ again:
                         return ret;
 
                 bp = call->buffer;
-                call->count2 = htonl(*bp++);
+                call->count2 = ntohl(*bp++);
                 call->offset = 0;
                 call->unmarshall = 4;
 
@@ -576,7 +576,7 @@ again:
                 call->offset = 0;
                 call->count--;
                 if (call->count > 0) {
-                        call->count2 = htonl(*bp++);
+                        call->count2 = ntohl(*bp++);
                         goto again;
                 }