Re: [PATCH 16/21] xfs: improve detection of lost xfile contents

Matthew Wilcox
2024-01-26T16:33:43Z

On Fri, Jan 26, 2024 at 02:28:58PM +0100, Christoph Hellwig wrote:
> +/* Has this file lost any of the data stored in it? */
> +static inline bool
> +xfile_has_lost_data(
> + struct inode *inode,
> + struct folio *folio)
> +{
> + struct address_space *mapping = inode->i_mapping;
> +
> + /* This folio itself has been poisoned. */
> + if (folio_test_hwpoison(folio))
> + return true;
> +
> + /* A base page under this large folio has been poisoned. */
> + if (folio_test_large(folio) && folio_test_has_hwpoisoned(folio))
> + return true;
> +
> + /* Data loss has occurred anywhere in this shmem file. */
> + if (test_bit(AS_EIO, &mapping->flags))
> + return true;
> + if (filemap_check_wb_err(mapping, 0))
> + return true;
> +
> + return false;
> +}

This is too much. filemap_check_wb_err() will do just fine for your
needs unless you really want to get fine-grained and perhaps try to
reconstruct the contents of the file.