[PATCH] btrfs: extent_io read eb to dirty_metadata_bytes on ioerr

[Dennis Zhou]

Before, if a eb failed to write out, we would end up triggering a
BUG_ON(). As of f4340622e0226 ("btrfs: extent_io: Move the BUG_ON() in
flush_write_bio() one level up"), we no longer BUG_ON(), so we should
make life consistent and add back the unwritten bytes to
dirty_metadata_bytes.

Signed-off-by: Dennis Zhou <den...@kernel.org>
Cc: Filipe Manana <fdman...@kernel.org>
---
 fs/btrfs/extent_io.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 1ff438fd5bc2..b67133a23652 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3728,11 +3728,21 @@ static void end_extent_buffer_writeback(struct 
extent_buffer *eb)
 static void set_btree_ioerr(struct page *page)
 {
        struct extent_buffer *eb = (struct extent_buffer *)page->private;
+       struct btrfs_fs_info *fs_info;
 
        SetPageError(page);
        if (test_and_set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
                return;
 
+       /*
+        * If we error out, we should add back the dirty_metadata_bytes
+        * to make it consistent.
+        */
+       fs_info = eb->fs_info;
+       percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
+                                eb->len,
+                                fs_info->dirty_metadata_batch);
+
        /*
         * If writeback for a btree extent that doesn't belong to a log tree
         * failed, increment the counter transaction->eb_write_errors.
-- 
2.17.1