Btrfs: Do metadata checksums for reads via a workqueue

Before, metadata checksumming was done by the callers of read_tree_block,
which would set EXTENT_CSUM bits in the extent tree to show that a given
range of pages was already checksummed and didn't need to be verified
again.

But, those bits could go away via try_to_releasepage, and the end
result was bogus checksum failures on pages that never left the cache.

The new code validates checksums when the page is read.  It is a little
tricky because metadata blocks can span pages and a single read may
end up going via multiple bios.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 0 insertions, 5 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index c92c6b0ee582..efce173a935c 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -158,9 +158,6 @@ int __btrfs_cow_block(struct btrfs_trans_handle *trans,
         } else {
                 root_gen = 0;
         }
-        if (!(buf->flags & EXTENT_CSUM))
-                WARN_ON(1);
-
         WARN_ON(root->ref_cows && trans->transid !=
                 root->fs_info->running_transaction->transid);
         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
@@ -247,8 +244,6 @@ int btrfs_cow_block(struct btrfs_trans_handle *trans,
                        root->fs_info->generation);
                 WARN_ON(1);
         }
-        if (!(buf->flags & EXTENT_CSUM))
-                WARN_ON(1);
 
         header_trans = btrfs_header_generation(buf);
         spin_lock(&root->fs_info->hash_lock);