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-rw-r--r--fs/afs/cell.c131
1 files changed, 58 insertions, 73 deletions
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;
-
- read_seqbegin_or_lock(&net->cells_lock, &seq);
-
- if (!name) {
- cell = rcu_dereference_raw(net->ws_cell);
- if (cell) {
- afs_get_cell(cell);
- ret = 0;
- break;
- }
- ret = -EDESTADDRREQ;
- continue;
- }
+ if (!name) {
+ cell = net->ws_cell;
+ if (!cell)
+ return ERR_PTR(-EDESTADDRREQ);
+ afs_get_cell(cell);
+ return cell;
+ }
- p = rcu_dereference_raw(net->cells.rb_node);
- while (p) {
- cell = rb_entry(p, struct afs_cell, net_node);
-
- 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;
- }
+ p = net->cells.rb_node;
+ while (p) {
+ cell = rb_entry(p, struct afs_cell, net_node);
- } while (need_seqretry(&net->cells_lock, seq));
+ 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;
+ }
+
+ return ERR_PTR(-ENOENT);
- done_seqretry(&net->cells_lock, seq);
+found:
+ if (!atomic_inc_not_zero(&cell->usage))
+ return ERR_PTR(-ENOENT);
- if (ret != 0 && cell)
- afs_put_cell(net, cell);
+ return cell;
+}
- return ret == 0 ? cell : ERR_PTR(ret);
+struct afs_cell *afs_find_cell(struct afs_net *net,
+ const char *name, unsigned int namesz)
+{
+ struct afs_cell *cell;
+
+ 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");
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-10 18:36:26 +0000