bdi: add helper function for doing init and register of a bdi for a file system

Pretty trivial helper, just sets up the bdi and registers it. An atomic
sequence count is used to ensure that the registered sysfs names are
unique.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index fcbc26a..e19c677 100644 (file)
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -101,6 +101,7 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
                const char *fmt, ...);
 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
 void bdi_unregister(struct backing_dev_info *bdi);
+int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
 void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
                                long nr_pages);
 int bdi_writeback_task(struct bdi_writeback *wb);

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index f13e067..dbda470 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -11,6 +11,8 @@
 #include <linux/writeback.h>
 #include <linux/device.h>
 
+static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
+
 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
 {
 }
@@ -715,6 +717,33 @@ void bdi_destroy(struct backing_dev_info *bdi)
 }
 EXPORT_SYMBOL(bdi_destroy);
 
+/*
+ * For use from filesystems to quickly init and register a bdi associated
+ * with dirty writeback
+ */
+int bdi_setup_and_register(struct backing_dev_info *bdi, char *name,
+                          unsigned int cap)
+{
+       char tmp[32];
+       int err;
+
+       bdi->name = name;
+       bdi->capabilities = cap;
+       err = bdi_init(bdi);
+       if (err)
+               return err;
+
+       sprintf(tmp, "%.28s%s", name, "-%d");
+       err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq));
+       if (err) {
+               bdi_destroy(bdi);
+               return err;
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL(bdi_setup_and_register);
+
 static wait_queue_head_t congestion_wqh[2] = {
                __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
                __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])