afs: Fix cell proc list
Access to the list of cells by /proc/net/afs/cells has a couple of
problems:
(1) It should be checking against SEQ_START_TOKEN for the keying the
header line.
(2) It's only holding the RCU read lock, so it can't just walk over the
list without following the proper RCU methods.
Fix these by using an hlist instead of an ordinary list and using the
appropriate accessor functions to follow it with RCU.
Since the code that adds a cell to the list must also necessarily change,
sort the list on insertion whilst we're at it.
Fixes: 989782dcdc91 ("afs: Overhaul cell database management")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index f3d0bef..6127f0f 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -514,6 +514,8 @@
*/
static int afs_activate_cell(struct afs_net *net, struct afs_cell *cell)
{
+ struct hlist_node **p;
+ struct afs_cell *pcell;
int ret;
if (!cell->anonymous_key) {
@@ -534,7 +536,18 @@
return ret;
mutex_lock(&net->proc_cells_lock);
- list_add_tail(&cell->proc_link, &net->proc_cells);
+ for (p = &net->proc_cells.first; *p; p = &(*p)->next) {
+ pcell = hlist_entry(*p, struct afs_cell, proc_link);
+ if (strcmp(cell->name, pcell->name) < 0)
+ break;
+ }
+
+ cell->proc_link.pprev = p;
+ cell->proc_link.next = *p;
+ rcu_assign_pointer(*p, &cell->proc_link.next);
+ if (cell->proc_link.next)
+ cell->proc_link.next->pprev = &cell->proc_link.next;
+
afs_dynroot_mkdir(net, cell);
mutex_unlock(&net->proc_cells_lock);
return 0;
@@ -550,7 +563,7 @@
afs_proc_cell_remove(cell);
mutex_lock(&net->proc_cells_lock);
- list_del_init(&cell->proc_link);
+ hlist_del_rcu(&cell->proc_link);
afs_dynroot_rmdir(net, cell);
mutex_unlock(&net->proc_cells_lock);
diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c
index 1cde710a..f29c6da 100644
--- a/fs/afs/dynroot.c
+++ b/fs/afs/dynroot.c
@@ -265,7 +265,7 @@
return -ERESTARTSYS;
net->dynroot_sb = sb;
- list_for_each_entry(cell, &net->proc_cells, proc_link) {
+ hlist_for_each_entry(cell, &net->proc_cells, proc_link) {
ret = afs_dynroot_mkdir(net, cell);
if (ret < 0)
goto error;
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 871a228..34c02fd 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -242,7 +242,7 @@
seqlock_t cells_lock;
struct mutex proc_cells_lock;
- struct list_head proc_cells;
+ struct hlist_head proc_cells;
/* Known servers. Theoretically each fileserver can only be in one
* cell, but in practice, people create aliases and subsets and there's
@@ -320,7 +320,7 @@
struct afs_net *net;
struct key *anonymous_key; /* anonymous user key for this cell */
struct work_struct manager; /* Manager for init/deinit/dns */
- struct list_head proc_link; /* /proc cell list link */
+ struct hlist_node proc_link; /* /proc cell list link */
#ifdef CONFIG_AFS_FSCACHE
struct fscache_cookie *cache; /* caching cookie */
#endif
diff --git a/fs/afs/main.c b/fs/afs/main.c
index e84fe82..1074276 100644
--- a/fs/afs/main.c
+++ b/fs/afs/main.c
@@ -87,7 +87,7 @@
timer_setup(&net->cells_timer, afs_cells_timer, 0);
mutex_init(&net->proc_cells_lock);
- INIT_LIST_HEAD(&net->proc_cells);
+ INIT_HLIST_HEAD(&net->proc_cells);
seqlock_init(&net->fs_lock);
net->fs_servers = RB_ROOT;
diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 476dcbb..9101f62 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -33,9 +33,8 @@
static int afs_proc_cells_show(struct seq_file *m, void *v)
{
struct afs_cell *cell = list_entry(v, struct afs_cell, proc_link);
- struct afs_net *net = afs_seq2net(m);
- if (v == &net->proc_cells) {
+ if (v == SEQ_START_TOKEN) {
/* display header on line 1 */
seq_puts(m, "USE NAME\n");
return 0;
@@ -50,12 +49,12 @@
__acquires(rcu)
{
rcu_read_lock();
- return seq_list_start_head(&afs_seq2net(m)->proc_cells, *_pos);
+ return seq_hlist_start_head_rcu(&afs_seq2net(m)->proc_cells, *_pos);
}
static void *afs_proc_cells_next(struct seq_file *m, void *v, loff_t *pos)
{
- return seq_list_next(v, &afs_seq2net(m)->proc_cells, pos);
+ return seq_hlist_next_rcu(v, &afs_seq2net(m)->proc_cells, pos);
}
static void afs_proc_cells_stop(struct seq_file *m, void *v)
