diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 5b79cdceefa0..5da83e84952a 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -41,15 +41,15 @@ static void afs_set_cell_timer(struct afs_net *net, time64_t delay)
}
/*
- * Look up and get an activation reference on a cell record under RCU
- * conditions. The caller must hold the RCU read lock.
+ * Look up and get an activation reference on a cell record. The caller must
+ * hold net->cells_lock at least read-locked.
*/
-struct afs_cell *afs_lookup_cell_rcu(struct afs_net *net,
- const char *name, unsigned int namesz)
+static struct afs_cell *afs_find_cell_locked(struct afs_net *net,
+ const char *name, unsigned int namesz)
{
struct afs_cell *cell = NULL;
struct rb_node *p;
- int n, seq = 0, ret = 0;
+ int n;
_enter("%*.*s", namesz, namesz, name);
@@ -58,61 +58,48 @@ struct afs_cell *afs_lookup_cell_rcu(struct afs_net *net,
if (namesz > AFS_MAXCELLNAME)
return ERR_PTR(-ENAMETOOLONG);
- do {
- /* Unfortunately, rbtree walking doesn't give reliable results
- * under just the RCU read lock, so we have to check for
- * changes.
- */
- if (cell)
- afs_put_cell(net, cell);
- cell = NULL;
- ret = -ENOENT;
+ if (!name) {
+ cell = net->ws_cell;
+ if (!cell)
+ return ERR_PTR(-EDESTADDRREQ);
+ afs_get_cell(cell);
+ return cell;
+ }
- read_seqbegin_or_lock(&net->cells_lock, &seq);
+ p = net->cells.rb_node;
+ while (p) {
+ cell = rb_entry(p, struct afs_cell, net_node);
- if (!name) {
- cell = rcu_dereference_raw(net->ws_cell);
- if (cell) {
- afs_get_cell(cell);
- ret = 0;
- break;
- }
- ret = -EDESTADDRREQ;
- continue;
- }
+ n = strncasecmp(cell->name, name,
+ min_t(size_t, cell->name_len, namesz));
+ if (n == 0)
+ n = cell->name_len - namesz;
+ if (n < 0)
+ p = p->rb_left;
+ else if (n > 0)
+ p = p->rb_right;
+ else
+ goto found;
+ }
- p = rcu_dereference_raw(net->cells.rb_node);
- while (p) {
- cell = rb_entry(p, struct afs_cell, net_node);
+ return ERR_PTR(-ENOENT);
- n = strncasecmp(cell->name, name,
- min_t(size_t, cell->name_len, namesz));
- if (n == 0)
- n = cell->name_len - namesz;
- if (n < 0) {
- p = rcu_dereference_raw(p->rb_left);
- } else if (n > 0) {
- p = rcu_dereference_raw(p->rb_right);
- } else {
- if (atomic_inc_not_zero(&cell->usage)) {
- ret = 0;
- break;
- }
- /* We want to repeat the search, this time with
- * the lock properly locked.
- */
- }
- cell = NULL;
- }
+found:
+ if (!atomic_inc_not_zero(&cell->usage))
+ return ERR_PTR(-ENOENT);
- } while (need_seqretry(&net->cells_lock, seq));
+ return cell;
+}
- done_seqretry(&net->cells_lock, seq);
+struct afs_cell *afs_find_cell(struct afs_net *net,
+ const char *name, unsigned int namesz)
+{
+ struct afs_cell *cell;
- if (ret != 0 && cell)
- afs_put_cell(net, cell);
-
- return ret == 0 ? cell : ERR_PTR(ret);
+ down_read(&net->cells_lock);
+ cell = afs_find_cell_locked(net, name, namesz);
+ up_read(&net->cells_lock);
+ return cell;
}
/*
@@ -245,9 +232,7 @@ struct afs_cell *afs_lookup_cell(struct afs_net *net,
_enter("%s,%s", name, vllist);
if (!excl) {
- rcu_read_lock();
- cell = afs_lookup_cell_rcu(net, name, namesz);
- rcu_read_unlock();
+ cell = afs_find_cell(net, name, namesz);
if (!IS_ERR(cell))
goto wait_for_cell;
}
@@ -268,7 +253,7 @@ struct afs_cell *afs_lookup_cell(struct afs_net *net,
/* Find the insertion point and check to see if someone else added a
* cell whilst we were allocating.
*/
- write_seqlock(&net->cells_lock);
+ down_write(&net->cells_lock);
pp = &net->cells.rb_node;
parent = NULL;
@@ -293,7 +278,7 @@ struct afs_cell *afs_lookup_cell(struct afs_net *net,
rb_link_node_rcu(&cell->net_node, parent, pp);
rb_insert_color(&cell->net_node, &net->cells);
atomic_inc(&net->cells_outstanding);
- write_sequnlock(&net->cells_lock);
+ up_write(&net->cells_lock);
queue_work(afs_wq, &cell->manager);
@@ -323,7 +308,7 @@ cell_already_exists:
afs_get_cell(cursor);
ret = 0;
}
- write_sequnlock(&net->cells_lock);
+ up_write(&net->cells_lock);
kfree(candidate);
if (ret == 0)
goto wait_for_cell;
@@ -377,10 +362,10 @@ int afs_cell_init(struct afs_net *net, const char *rootcell)
afs_get_cell(new_root);
/* install the new cell */
- write_seqlock(&net->cells_lock);
- old_root = rcu_access_pointer(net->ws_cell);
- rcu_assign_pointer(net->ws_cell, new_root);
- write_sequnlock(&net->cells_lock);
+ down_write(&net->cells_lock);
+ old_root = net->ws_cell;
+ net->ws_cell = new_root;
+ up_write(&net->cells_lock);
afs_put_cell(net, old_root);
_leave(" = 0");
@@ -674,12 +659,12 @@ again:
switch (cell->state) {
case AFS_CELL_INACTIVE:
case AFS_CELL_FAILED:
- write_seqlock(&net->cells_lock);
+ down_write(&net->cells_lock);
usage = 1;
deleted = atomic_try_cmpxchg_relaxed(&cell->usage, &usage, 0);
if (deleted)
rb_erase(&cell->net_node, &net->cells);
- write_sequnlock(&net->cells_lock);
+ up_write(&net->cells_lock);
if (deleted)
goto final_destruction;
if (cell->state == AFS_CELL_FAILED)
@@ -779,7 +764,7 @@ void afs_manage_cells(struct work_struct *work)
* lack of use and cells whose DNS results have expired and dispatch
* their managers.
*/
- read_seqlock_excl(&net->cells_lock);
+ down_read(&net->cells_lock);
for (cursor = rb_first(&net->cells); cursor; cursor = rb_next(cursor)) {
struct afs_cell *cell =
@@ -824,7 +809,7 @@ void afs_manage_cells(struct work_struct *work)
queue_work(afs_wq, &cell->manager);
}
- read_sequnlock_excl(&net->cells_lock);
+ up_read(&net->cells_lock);
/* Update the timer on the way out. We have to pass an increment on
* cells_outstanding in the namespace that we are in to the timer or
@@ -854,10 +839,10 @@ void afs_cell_purge(struct afs_net *net)
_enter("");
- write_seqlock(&net->cells_lock);
- ws = rcu_access_pointer(net->ws_cell);
- RCU_INIT_POINTER(net->ws_cell, NULL);
- write_sequnlock(&net->cells_lock);
+ down_write(&net->cells_lock);
+ ws = net->ws_cell;
+ net->ws_cell = NULL;
+ up_write(&net->cells_lock);
afs_put_cell(net, ws);
_debug("del timer");
diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c
index 7b784af604fd..5b8de4fee6cd 100644
--- a/fs/afs/dynroot.c
+++ b/fs/afs/dynroot.c
@@ -123,7 +123,7 @@ static int afs_probe_cell_name(struct dentry *dentry)
len--;
}
- cell = afs_lookup_cell_rcu(net, name, len);
+ cell = afs_find_cell(net, name, len);
if (!IS_ERR(cell)) {
afs_put_cell(net, cell);
return 0;
@@ -179,7 +179,6 @@ static struct dentry *afs_lookup_atcell(struct dentry *dentry)
struct afs_cell *cell;
struct afs_net *net = afs_d2net(dentry);
struct dentry *ret;
- unsigned int seq = 0;
char *name;
int len;
@@ -191,17 +190,13 @@ static struct dentry *afs_lookup_atcell(struct dentry *dentry)
if (!name)
goto out_p;
- rcu_read_lock();
- do {
- read_seqbegin_or_lock(&net->cells_lock, &seq);
- cell = rcu_dereference_raw(net->ws_cell);
- if (cell) {
- len = cell->name_len;
- memcpy(name, cell->name, len + 1);
- }
- } while (need_seqretry(&net->cells_lock, seq));
- done_seqretry(&net->cells_lock, seq);
- rcu_read_unlock();
+ down_read(&net->cells_lock);
+ cell = net->ws_cell;
+ if (cell) {
+ len = cell->name_len;
+ memcpy(name, cell->name, len + 1);
+ }
+ up_read(&net->cells_lock);
ret = ERR_PTR(-ENOENT);
if (!cell)
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index e5f0446f27e5..257c0f07742f 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -263,11 +263,11 @@ struct afs_net {
/* Cell database */
struct rb_root cells;
- struct afs_cell __rcu *ws_cell;
+ struct afs_cell *ws_cell;
struct work_struct cells_manager;
struct timer_list cells_timer;
atomic_t cells_outstanding;
- seqlock_t cells_lock;
+ struct rw_semaphore cells_lock;
struct mutex cells_alias_lock;
struct mutex proc_cells_lock;
@@ -917,7 +917,7 @@ static inline bool afs_cb_is_broken(unsigned int cb_break,
* cell.c
*/
extern int afs_cell_init(struct afs_net *, const char *);
-extern struct afs_cell *afs_lookup_cell_rcu(struct afs_net *, const char *, unsigned);
+extern struct afs_cell *afs_find_cell(struct afs_net *, const char *, unsigned);
extern struct afs_cell *afs_lookup_cell(struct afs_net *, const char *, unsigned,
const char *, bool);
extern struct afs_cell *afs_get_cell(struct afs_cell *);
diff --git a/fs/afs/main.c b/fs/afs/main.c
index 31b472f7c734..accdd8970e7c 100644
--- a/fs/afs/main.c
+++ b/fs/afs/main.c
@@ -78,7 +78,7 @@ static int __net_init afs_net_init(struct net *net_ns)
mutex_init(&net->socket_mutex);
net->cells = RB_ROOT;
- seqlock_init(&net->cells_lock);
+ init_rwsem(&net->cells_lock);
INIT_WORK(&net->cells_manager, afs_manage_cells);
timer_setup(&net->cells_timer, afs_cells_timer, 0);
diff --git a/fs/afs/super.c b/fs/afs/super.c
index b552357b1d13..0be99016ecfb 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -634,9 +634,7 @@ static int afs_init_fs_context(struct fs_context *fc)
ctx->net = afs_net(fc->net_ns);
/* Default to the workstation cell. */
- rcu_read_lock();
- cell = afs_lookup_cell_rcu(ctx->net, NULL, 0);
- rcu_read_unlock();
+ cell = afs_find_cell(ctx->net, NULL, 0);
if (IS_ERR(cell))
cell = NULL;
ctx->cell = cell;