btrfs: extent_io: Handle errors better in btree_write_cache_pages()

In btree_write_cache_pages(), we can only get @ret <= 0.
Add an ASSERT() for it just in case.

Then instead of submitting the write bio even we got some error, check
the return value first.
If we have already hit some error, just clean up the corrupted or
half-baked bio, and return error.

If there is no error so far, then call flush_write_bio() and return the
result.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 9d52f3b7873237b558b7f948c40cececac72ccd1..8399fc4b27aebc94f9a4188cf967e40948ce37da 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3748,7 +3748,6 @@ int btree_write_cache_pages(struct address_space *mapping,
                .sync_io = wbc->sync_mode == WB_SYNC_ALL,
        };
        int ret = 0;
-       int flush_ret;
        int done = 0;
        int nr_to_write_done = 0;
        struct pagevec pvec;
@@ -3848,8 +3847,12 @@ retry:
                index = 0;
                goto retry;
        }
-       flush_ret = flush_write_bio(&epd);
-       BUG_ON(flush_ret < 0);
+       ASSERT(ret <= 0);
+       if (ret < 0) {
+               end_write_bio(&epd, ret);
+               return ret;
+       }
+       ret = flush_write_bio(&epd);
        return ret;
 }