On Wed, Jan 11, 2023 at 09:49:05AM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> The population function creates an XFS btree format directory by
> polling the extent count of the inode and creating new dirents until
> the extent count goes over the limit that pushes it into btree
> format.
>
> It then removes every second dirent to create empty space in the
> directory data to ensure that operations like metadump with
> obfuscation can check that they don't leak stale data from deleted
> dirents.
>
> Whilst this does not result in directory data blocks being freed, it
> does not take into account the fact that the dabtree index has half
> the entries removed from it and that can result in btree nodes
> merging and extents being freed. This causes the extent count to go
> down, and the inode is converted back into extent form. The
> population checks then fail because it should be in btree form.
>
> Fix this by counting the number of directory data extents rather than
> the total number of extents in the data fork. We can do this simply
> by using xfs_bmap and counting the number of extents returned as it
> does not report extents beyond EOF (which is where the dabtree is
> located). As the number of data blocks does not change with the
> dirent removal algorithm used, this will ensure that the inode data
> fork remains in btree format.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
> common/populate | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/common/populate b/common/populate
> index 9b60fa5c1..7b5b16fb8 100644
> --- a/common/populate
> +++ b/common/populate
> @@ -80,8 +80,11 @@ __populate_create_nfiles() {
> continue
> fi
>
> - local nextents="$(_xfs_get_fsxattr nextents $name)"
> - if [ "${nextents}" -gt "${max_nextents}" ]; then
> + # Extent count checks use data blocks only to avoid the removal
> + # step from removing dabtree index blocks and reducing the
> + # number of extents below the required threshold.
> + local nextents="$(xfs_bmap ${name} |grep -v hole | wc -l)"
> + if [ "$((nextents - 1))" -gt "${max_nextents}" ]; then
Pretty much the same patch I had in my tree...
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
--D
> echo ${d}
> break
> fi
> --
> 2.38.1
>
