// SPDX-License-Identifier: GPL-2.0-only
#include <linux/wait.h>
+#include <linux/rbtree.h>
#include <linux/backing-dev.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
static struct class *bdi_class;
/*
- * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
- * locking.
+ * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU
+ * reader side locking.
*/
DEFINE_SPINLOCK(bdi_lock);
+static u64 bdi_id_cursor;
+static struct rb_root bdi_tree = RB_ROOT;
LIST_HEAD(bdi_list);
/* bdi_wq serves all asynchronous writeback tasks */
}
/**
- * wb_get_create - get wb for a given memcg, create if necessary
+ * wb_get_lookup - get wb for a given memcg
* @bdi: target bdi
* @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
- * @gfp: allocation mask to use
*
- * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
- * create one. The returned wb has its refcount incremented.
+ * Try to get the wb for @memcg_css on @bdi. The returned wb has its
+ * refcount incremented.
*
* This function uses css_get() on @memcg_css and thus expects its refcnt
* to be positive on invocation. IOW, rcu_read_lock() protection on
* each lookup. On mismatch, the existing wb is discarded and a new one is
* created.
*/
+struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
+ struct cgroup_subsys_state *memcg_css)
+{
+ struct bdi_writeback *wb;
+
+ if (!memcg_css->parent)
+ return &bdi->wb;
+
+ rcu_read_lock();
+ wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
+ if (wb) {
+ struct cgroup_subsys_state *blkcg_css;
+
+ /* see whether the blkcg association has changed */
+ blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
+ if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
+ wb = NULL;
+ css_put(blkcg_css);
+ }
+ rcu_read_unlock();
+
+ return wb;
+}
+
+/**
+ * wb_get_create - get wb for a given memcg, create if necessary
+ * @bdi: target bdi
+ * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
+ * @gfp: allocation mask to use
+ *
+ * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
+ * create one. See wb_get_lookup() for more details.
+ */
struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
struct cgroup_subsys_state *memcg_css,
gfp_t gfp)
return &bdi->wb;
do {
- rcu_read_lock();
- wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
- if (wb) {
- struct cgroup_subsys_state *blkcg_css;
-
- /* see whether the blkcg association has changed */
- blkcg_css = cgroup_get_e_css(memcg_css->cgroup,
- &io_cgrp_subsys);
- if (unlikely(wb->blkcg_css != blkcg_css ||
- !wb_tryget(wb)))
- wb = NULL;
- css_put(blkcg_css);
- }
- rcu_read_unlock();
+ wb = wb_get_lookup(bdi, memcg_css);
} while (!wb && !cgwb_create(bdi, memcg_css, gfp));
return wb;
}
EXPORT_SYMBOL(bdi_alloc_node);
+static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
+{
+ struct rb_node **p = &bdi_tree.rb_node;
+ struct rb_node *parent = NULL;
+ struct backing_dev_info *bdi;
+
+ lockdep_assert_held(&bdi_lock);
+
+ while (*p) {
+ parent = *p;
+ bdi = rb_entry(parent, struct backing_dev_info, rb_node);
+
+ if (bdi->id > id)
+ p = &(*p)->rb_left;
+ else if (bdi->id < id)
+ p = &(*p)->rb_right;
+ else
+ break;
+ }
+
+ if (parentp)
+ *parentp = parent;
+ return p;
+}
+
+/**
+ * bdi_get_by_id - lookup and get bdi from its id
+ * @id: bdi id to lookup
+ *
+ * Find bdi matching @id and get it. Returns NULL if the matching bdi
+ * doesn't exist or is already unregistered.
+ */
+struct backing_dev_info *bdi_get_by_id(u64 id)
+{
+ struct backing_dev_info *bdi = NULL;
+ struct rb_node **p;
+
+ spin_lock_bh(&bdi_lock);
+ p = bdi_lookup_rb_node(id, NULL);
+ if (*p) {
+ bdi = rb_entry(*p, struct backing_dev_info, rb_node);
+ bdi_get(bdi);
+ }
+ spin_unlock_bh(&bdi_lock);
+
+ return bdi;
+}
+
int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
{
struct device *dev;
+ struct rb_node *parent, **p;
if (bdi->dev) /* The driver needs to use separate queues per device */
return 0;
set_bit(WB_registered, &bdi->wb.state);
spin_lock_bh(&bdi_lock);
+
+ bdi->id = ++bdi_id_cursor;
+
+ p = bdi_lookup_rb_node(bdi->id, &parent);
+ rb_link_node(&bdi->rb_node, parent, p);
+ rb_insert_color(&bdi->rb_node, &bdi_tree);
+
list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
+
spin_unlock_bh(&bdi_lock);
trace_writeback_bdi_register(bdi);
static void bdi_remove_from_list(struct backing_dev_info *bdi)
{
spin_lock_bh(&bdi_lock);
+ rb_erase(&bdi->rb_node, &bdi_tree);
list_del_rcu(&bdi->bdi_list);
spin_unlock_bh(&bdi_lock);
projects / linux-2.6-microblaze.git / blobdiff