Btrfs: don't force pages under writeback to finish when aborting

Dave reported a BUG_ON() that happened in end_page_writeback() after an abort.
This happened because we unconditionally call end_page_writeback() in the endio
case, which is right.  However when we abort the transaction we will call
end_page_writeback() on any writeback pages we find, which is wrong.  We need to
lock the page and wait on page writeback to complete if it is.  There is nothing
unsafe about this since we are discarding the transaction anyway.  Thanks,

Reported-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8a7a366267ec81eb12d356b101a18f7dc72f0701..aab7d89f3ff0aa8aa6f69722f890a86a707aa599 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3763,10 +3763,9 @@ static int btrfs_destroy_marked_extents(struct btrfs_root *root,
                        if (eb)
                                ret = test_and_clear_bit(EXTENT_BUFFER_DIRTY,
                                                         &eb->bflags);
-                       if (PageWriteback(page))
-                               end_page_writeback(page);
-
                        lock_page(page);
+
+                       wait_on_page_writeback(page);
                        if (PageDirty(page)) {
                                clear_page_dirty_for_io(page);
                                spin_lock_irq(&page->mapping->tree_lock);