Re: [PATCH 1/3] xfs: use i_prev_unlinked to distinguish inodes that are not on the unlinked list

[Dave Chinner <david@fromorbit.com>]

On Sun, Sep 03, 2023 at 09:15:53AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Alter the definition of i_prev_unlinked slightly to make it more obvious
> when an inode with 0 link count is not part of the iunlink bucket lists
> rooted in the AGI.  This distinction is necessary because it is not
> sufficient to check inode.i_nlink to decide if an inode is on the
> unlinked list.  Updates to i_nlink can happen while holding only
> ILOCK_EXCL, but updates to an inode's position in the AGI unlinked list
> (which happen after the nlink update) requires both ILOCK_EXCL and the
> AGI buffer lock.
> 
> The next few patches will make it possible to reload an entire unlinked
> bucket list when we're walking the inode table or performing handle
> operations and need more than the ability to iget the last inode in the
> chain.
> 
> The upcoming directory repair code also needs to be able to make this
> distinction to decide if a zero link count directory should be moved to
> the orphanage or allowed to inactivate.  An upcoming enhancement to the
> online AGI fsck code will need this distinction to check and rebuild the
> AGI unlinked buckets.
> 
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  fs/xfs/xfs_icache.c |    2 +-
>  fs/xfs/xfs_inode.c  |    3 ++-
>  fs/xfs/xfs_inode.h  |   20 +++++++++++++++++++-
>  3 files changed, 22 insertions(+), 3 deletions(-)

Looks ok.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
-- 
Dave Chinner
david@fromorbit.com