cifs: convert tlink_tree to a rbtree
Radix trees are ideal when you want to track a bunch of pointers and
can't embed a tracking structure within the target of those pointers.
The tradeoff is an increase in memory, particularly if the tree is
sparse.
In CIFS, we use the tlink_tree to track tcon_link structs. A tcon_link
can never be in more than one tlink_tree, so there's no impediment to
using a rb_tree here instead of a radix tree.
Convert the new multiuser mount code to use a rb_tree instead. This
should reduce the memory required to manage the tlink_tree.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 197ac57..c9699ce 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -116,6 +116,7 @@
static int ipv4_connect(struct TCP_Server_Info *server);
static int ipv6_connect(struct TCP_Server_Info *server);
+static void tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink);
static void cifs_prune_tlinks(struct work_struct *work);
/*
@@ -2900,24 +2901,16 @@
goto mount_fail_check;
}
- tlink->tl_index = pSesInfo->linux_uid;
+ tlink->tl_uid = pSesInfo->linux_uid;
tlink->tl_tcon = tcon;
tlink->tl_time = jiffies;
set_bit(TCON_LINK_MASTER, &tlink->tl_flags);
set_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
- rc = radix_tree_preload(GFP_KERNEL);
- if (rc == -ENOMEM) {
- kfree(tlink);
- goto mount_fail_check;
- }
-
- spin_lock(&cifs_sb->tlink_tree_lock);
- radix_tree_insert(&cifs_sb->tlink_tree, pSesInfo->linux_uid, tlink);
- spin_unlock(&cifs_sb->tlink_tree_lock);
- radix_tree_preload_end();
-
cifs_sb->master_tlink = tlink;
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ tlink_rb_insert(&cifs_sb->tlink_tree, tlink);
+ spin_unlock(&cifs_sb->tlink_tree_lock);
queue_delayed_work(system_nrt_wq, &cifs_sb->prune_tlinks,
TLINK_IDLE_EXPIRE);
@@ -3107,32 +3100,25 @@
int
cifs_umount(struct super_block *sb, struct cifs_sb_info *cifs_sb)
{
- int i, ret;
+ struct rb_root *root = &cifs_sb->tlink_tree;
+ struct rb_node *node;
+ struct tcon_link *tlink;
char *tmp;
- struct tcon_link *tlink[8];
- unsigned long index = 0;
cancel_delayed_work_sync(&cifs_sb->prune_tlinks);
- do {
- spin_lock(&cifs_sb->tlink_tree_lock);
- ret = radix_tree_gang_lookup(&cifs_sb->tlink_tree,
- (void **)tlink, index,
- ARRAY_SIZE(tlink));
- /* increment index for next pass */
- if (ret > 0)
- index = tlink[ret - 1]->tl_index + 1;
- for (i = 0; i < ret; i++) {
- cifs_get_tlink(tlink[i]);
- clear_bit(TCON_LINK_IN_TREE, &tlink[i]->tl_flags);
- radix_tree_delete(&cifs_sb->tlink_tree,
- tlink[i]->tl_index);
- }
- spin_unlock(&cifs_sb->tlink_tree_lock);
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ while ((node = rb_first(root))) {
+ tlink = rb_entry(node, struct tcon_link, tl_rbnode);
+ cifs_get_tlink(tlink);
+ clear_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
+ rb_erase(node, root);
- for (i = 0; i < ret; i++)
- cifs_put_tlink(tlink[i]);
- } while (ret != 0);
+ spin_unlock(&cifs_sb->tlink_tree_lock);
+ cifs_put_tlink(tlink);
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ }
+ spin_unlock(&cifs_sb->tlink_tree_lock);
tmp = cifs_sb->prepath;
cifs_sb->prepathlen = 0;
@@ -3290,6 +3276,47 @@
return signal_pending(current) ? -ERESTARTSYS : 0;
}
+/* find and return a tlink with given uid */
+static struct tcon_link *
+tlink_rb_search(struct rb_root *root, uid_t uid)
+{
+ struct rb_node *node = root->rb_node;
+ struct tcon_link *tlink;
+
+ while (node) {
+ tlink = rb_entry(node, struct tcon_link, tl_rbnode);
+
+ if (tlink->tl_uid > uid)
+ node = node->rb_left;
+ else if (tlink->tl_uid < uid)
+ node = node->rb_right;
+ else
+ return tlink;
+ }
+ return NULL;
+}
+
+/* insert a tcon_link into the tree */
+static void
+tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink)
+{
+ struct rb_node **new = &(root->rb_node), *parent = NULL;
+ struct tcon_link *tlink;
+
+ while (*new) {
+ tlink = rb_entry(*new, struct tcon_link, tl_rbnode);
+ parent = *new;
+
+ if (tlink->tl_uid > new_tlink->tl_uid)
+ new = &((*new)->rb_left);
+ else
+ new = &((*new)->rb_right);
+ }
+
+ rb_link_node(&new_tlink->tl_rbnode, parent, new);
+ rb_insert_color(&new_tlink->tl_rbnode, root);
+}
+
/*
* Find or construct an appropriate tcon given a cifs_sb and the fsuid of the
* current task.
@@ -3310,14 +3337,14 @@
cifs_sb_tlink(struct cifs_sb_info *cifs_sb)
{
int ret;
- unsigned long fsuid = (unsigned long) current_fsuid();
+ uid_t fsuid = current_fsuid();
struct tcon_link *tlink, *newtlink;
if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
return cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));
spin_lock(&cifs_sb->tlink_tree_lock);
- tlink = radix_tree_lookup(&cifs_sb->tlink_tree, fsuid);
+ tlink = tlink_rb_search(&cifs_sb->tlink_tree, fsuid);
if (tlink)
cifs_get_tlink(tlink);
spin_unlock(&cifs_sb->tlink_tree_lock);
@@ -3326,36 +3353,24 @@
newtlink = kzalloc(sizeof(*tlink), GFP_KERNEL);
if (newtlink == NULL)
return ERR_PTR(-ENOMEM);
- newtlink->tl_index = fsuid;
+ newtlink->tl_uid = fsuid;
newtlink->tl_tcon = ERR_PTR(-EACCES);
set_bit(TCON_LINK_PENDING, &newtlink->tl_flags);
set_bit(TCON_LINK_IN_TREE, &newtlink->tl_flags);
cifs_get_tlink(newtlink);
- ret = radix_tree_preload(GFP_KERNEL);
- if (ret != 0) {
- kfree(newtlink);
- return ERR_PTR(ret);
- }
-
spin_lock(&cifs_sb->tlink_tree_lock);
/* was one inserted after previous search? */
- tlink = radix_tree_lookup(&cifs_sb->tlink_tree, fsuid);
+ tlink = tlink_rb_search(&cifs_sb->tlink_tree, fsuid);
if (tlink) {
cifs_get_tlink(tlink);
spin_unlock(&cifs_sb->tlink_tree_lock);
- radix_tree_preload_end();
kfree(newtlink);
goto wait_for_construction;
}
- ret = radix_tree_insert(&cifs_sb->tlink_tree, fsuid, newtlink);
- spin_unlock(&cifs_sb->tlink_tree_lock);
- radix_tree_preload_end();
- if (ret) {
- kfree(newtlink);
- return ERR_PTR(ret);
- }
tlink = newtlink;
+ tlink_rb_insert(&cifs_sb->tlink_tree, tlink);
+ spin_unlock(&cifs_sb->tlink_tree_lock);
} else {
wait_for_construction:
ret = wait_on_bit(&tlink->tl_flags, TCON_LINK_PENDING,
@@ -3401,39 +3416,39 @@
{
struct cifs_sb_info *cifs_sb = container_of(work, struct cifs_sb_info,
prune_tlinks.work);
- struct tcon_link *tlink[8];
- unsigned long now = jiffies;
- unsigned long index = 0;
- int i, ret;
+ struct rb_root *root = &cifs_sb->tlink_tree;
+ struct rb_node *node = rb_first(root);
+ struct rb_node *tmp;
+ struct tcon_link *tlink;
- do {
- spin_lock(&cifs_sb->tlink_tree_lock);
- ret = radix_tree_gang_lookup(&cifs_sb->tlink_tree,
- (void **)tlink, index,
- ARRAY_SIZE(tlink));
- /* increment index for next pass */
- if (ret > 0)
- index = tlink[ret - 1]->tl_index + 1;
- for (i = 0; i < ret; i++) {
- if (test_bit(TCON_LINK_MASTER, &tlink[i]->tl_flags) ||
- atomic_read(&tlink[i]->tl_count) != 0 ||
- time_after(tlink[i]->tl_time + TLINK_IDLE_EXPIRE,
- now)) {
- tlink[i] = NULL;
- continue;
- }
- cifs_get_tlink(tlink[i]);
- clear_bit(TCON_LINK_IN_TREE, &tlink[i]->tl_flags);
- radix_tree_delete(&cifs_sb->tlink_tree,
- tlink[i]->tl_index);
- }
+ /*
+ * Because we drop the spinlock in the loop in order to put the tlink
+ * it's not guarded against removal of links from the tree. The only
+ * places that remove entries from the tree are this function and
+ * umounts. Because this function is non-reentrant and is canceled
+ * before umount can proceed, this is safe.
+ */
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ node = rb_first(root);
+ while (node != NULL) {
+ tmp = node;
+ node = rb_next(tmp);
+ tlink = rb_entry(tmp, struct tcon_link, tl_rbnode);
+
+ if (test_bit(TCON_LINK_MASTER, &tlink->tl_flags) ||
+ atomic_read(&tlink->tl_count) != 0 ||
+ time_after(tlink->tl_time + TLINK_IDLE_EXPIRE, jiffies))
+ continue;
+
+ cifs_get_tlink(tlink);
+ clear_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
+ rb_erase(tmp, root);
+
spin_unlock(&cifs_sb->tlink_tree_lock);
-
- for (i = 0; i < ret; i++) {
- if (tlink[i] != NULL)
- cifs_put_tlink(tlink[i]);
- }
- } while (ret != 0);
+ cifs_put_tlink(tlink);
+ spin_lock(&cifs_sb->tlink_tree_lock);
+ }
+ spin_unlock(&cifs_sb->tlink_tree_lock);
queue_delayed_work(system_nrt_wq, &cifs_sb->prune_tlinks,
TLINK_IDLE_EXPIRE);