Re: [PATCH 08/13] xfs: updating i_next_unlinked doesn't need to return old value

Darrick J. Wong
2020-08-19T00:21:36Z

On Wed, Aug 12, 2020 at 07:25:51PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> We already know what the next inode in the unlinked list is supposed
> to be from the in-memory list, so we do not need to look it up first
> from the current inode to be able to update in memory list
> pointers...
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
> fs/xfs/xfs_inode.c | 63 +++++++++++-----------------------------------
> 1 file changed, 14 insertions(+), 49 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index bacd5ae9f5a7..4dde1970f7cd 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -1998,13 +1998,11 @@ xfs_iunlink_update_inode(
> struct xfs_trans *tp,
> struct xfs_inode *ip,
> xfs_agnumber_t agno,
> - xfs_agino_t next_agino,
> - xfs_agino_t *old_next_agino)
> + xfs_agino_t next_agino)
> {
> struct xfs_mount *mp = tp->t_mountp;
> struct xfs_dinode *dip;
> struct xfs_buf *ibp;
> - xfs_agino_t old_value;
> int error;
>
> ASSERT(xfs_verify_agino_or_null(mp, agno, next_agino));
> @@ -2013,37 +2011,10 @@ xfs_iunlink_update_inode(
> if (error)
> return error;
>
> - /* Make sure the old pointer isn't garbage. */
> - old_value = be32_to_cpu(dip->di_next_unlinked);
> - if (!xfs_verify_agino_or_null(mp, agno, old_value)) {
> - xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__, dip,
> - sizeof(*dip), __this_address);
> - error = -EFSCORRUPTED;
> - goto out;
> - }
> -
> - /*
> - * Since we're updating a linked list, we should never find that the
> - * current pointer is the same as the new value, unless we're
> - * terminating the list.
> - */
> - *old_next_agino = old_value;
> - if (old_value == next_agino) {
> - if (next_agino != NULLAGINO) {
> - xfs_inode_verifier_error(ip, -EFSCORRUPTED, __func__,
> - dip, sizeof(*dip), __this_address);
> - error = -EFSCORRUPTED;
> - }
> - goto out;
> - }
> -
> /* Ok, update the new pointer. */
> xfs_iunlink_update_dinode(tp, agno, XFS_INO_TO_AGINO(mp, ip->i_ino),
> ibp, dip, &ip->i_imap, next_agino);
> return 0;
> -out:
> - xfs_trans_brelse(tp, ibp);
> - return error;
> }
>
> static int
> @@ -2079,19 +2050,15 @@ xfs_iunlink_insert_inode(
> nip = list_first_entry_or_null(&agibp->b_pag->pag_ici_unlink_list,
> struct xfs_inode, i_unlink);
> if (nip) {
> - xfs_agino_t old_agino;
> -
> ASSERT(next_agino == XFS_INO_TO_AGINO(mp, nip->i_ino));
>
> /*
> * There is already another inode in the bucket, so point this
> * inode to the current head of the list.
> */
> - error = xfs_iunlink_update_inode(tp, ip, agno, next_agino,
> - &old_agino);
> + error = xfs_iunlink_update_inode(tp, ip, agno, next_agino);
> if (error)
> return error;
> - ASSERT(old_agino == NULLAGINO);
> } else {
> ASSERT(next_agino == NULLAGINO);
> }
> @@ -2149,7 +2116,7 @@ xfs_iunlink_remove_inode(
> struct xfs_agi *agi;
> xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
> xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
> - xfs_agino_t next_agino;
> + xfs_agino_t next_agino = NULLAGINO;
> xfs_agino_t head_agino;
> int error;
>
> @@ -2169,23 +2136,21 @@ xfs_iunlink_remove_inode(
> }
>
> /*
> - * Set our inode's next_unlinked pointer to NULL and then return
> - * the old pointer value so that we can update whatever was previous
> - * to us in the list to point to whatever was next in the list.
> + * Get the next agino in the list. If we are at the end of the list,
> + * then the previous inode's i_next_unlinked filed will get cleared.

"field"

With that fixed,

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> */
> - error = xfs_iunlink_update_inode(tp, ip, agno, NULLAGINO, &next_agino);
> + if (ip != list_last_entry(&agibp->b_pag->pag_ici_unlink_list,
> + struct xfs_inode, i_unlink)) {
> + struct xfs_inode *nip = list_next_entry(ip, i_unlink);
> +
> + next_agino = XFS_INO_TO_AGINO(mp, nip->i_ino);
> + }
> +
> + /* Clear the on disk next unlinked pointer for this inode. */
> + error = xfs_iunlink_update_inode(tp, ip, agno, NULLAGINO);
> if (error)
> return error;
>
> -#ifdef DEBUG
> - {
> - struct xfs_inode *nip = list_next_entry(ip, i_unlink);
> - if (nip)
> - ASSERT(next_agino == XFS_INO_TO_AGINO(mp, nip->i_ino));
> - else
> - ASSERT(next_agino == NULLAGINO);
> - }
> -#endif
>
> if (ip != list_first_entry(&agibp->b_pag->pag_ici_unlink_list,
> struct xfs_inode, i_unlink)) {
> --
> 2.26.2.761.g0e0b3e54be
>