bdi: reimplement bdev_inode_switch_bdi()
A block_device may be attached to different gendisks and thus
different bdis over time. bdev_inode_switch_bdi() is used to switch
the associated bdi. The function assumes that the inode could be
dirty and transfers it between bdis if so. This is a bit nasty in
that it reaches into bdi internals.
This patch reimplements the function so that it writes out the inode
if dirty. This is a lot simpler and can be implemented without
exposing bdi internals.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fs/block_dev.c b/fs/block_dev.c
index d3251ec..cc8d68a 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -50,32 +50,22 @@
EXPORT_SYMBOL(I_BDEV);
/*
- * Move the inode from its current bdi to a new bdi. If the inode is dirty we
- * need to move it onto the dirty list of @dst so that the inode is always on
- * the right list.
+ * Move the inode from its current bdi to a new bdi. Make sure the inode
+ * is clean before moving so that it doesn't linger on the old bdi.
*/
static void bdev_inode_switch_bdi(struct inode *inode,
struct backing_dev_info *dst)
{
- struct backing_dev_info *old = inode->i_data.backing_dev_info;
- bool wakeup_bdi = false;
-
- if (unlikely(dst == old)) /* deadlock avoidance */
- return;
- bdi_lock_two(&old->wb, &dst->wb);
- spin_lock(&inode->i_lock);
- inode->i_data.backing_dev_info = dst;
- if (inode->i_state & I_DIRTY) {
- if (bdi_cap_writeback_dirty(dst) && !wb_has_dirty_io(&dst->wb))
- wakeup_bdi = true;
- list_move(&inode->i_wb_list, &dst->wb.b_dirty);
+ while (true) {
+ spin_lock(&inode->i_lock);
+ if (!(inode->i_state & I_DIRTY)) {
+ inode->i_data.backing_dev_info = dst;
+ spin_unlock(&inode->i_lock);
+ return;
+ }
+ spin_unlock(&inode->i_lock);
+ WARN_ON_ONCE(write_inode_now(inode, true));
}
- spin_unlock(&inode->i_lock);
- spin_unlock(&old->wb.list_lock);
- spin_unlock(&dst->wb.list_lock);
-
- if (wakeup_bdi)
- bdi_wakeup_thread_delayed(dst);
}
/* Kill _all_ buffers and pagecache , dirty or not.. */