writeback: check for registered bdi in flusher add and inode dirty

Also a debugging aid. We want to catch dirty inodes being added to
backing devices that don't do writeback.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 2e601ce581c9..da86ef58e427 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1046,6 +1046,14 @@ void __mark_inode_dirty(struct inode *inode, int flags)
                  */
                 if (!was_dirty) {
                         struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
+                        struct backing_dev_info *bdi = wb->bdi;
+
+                        if (bdi_cap_writeback_dirty(bdi) &&
+                            !test_bit(BDI_registered, &bdi->state)) {
+                                WARN_ON(1);
+                                printk(KERN_ERR "bdi-%s not registered\n",
+                                                                bdi->name);
+                        }
 
                         inode->dirtied_when = jiffies;
                         list_move(&inode->i_list, &wb->b_dirty);