On Thu, Jan 31, 2019 at 03:18:27PM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> There's a loop that searches an unlinked bucket list to find the inode
> that points to a given inode. Hoist this into a separate function;
> later we'll use our iunlink backref cache to bypass the slow list
> operation. No functional changes.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_inode.c | 136 ++++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 99 insertions(+), 37 deletions(-)
>
>
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index ea38b66fbc59..d5b3f8fdac7e 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -2084,6 +2084,100 @@ xfs_iunlink(
> return error;
> }
>
> +/* Return the imap, dinode pointer, and buffer for an inode. */
> +STATIC int
> +xfs_iunlink_map_ino(
> + struct xfs_trans *tp,
> + xfs_ino_t next_ino,
Might be good to clean up some of these variable names as this code gets
factored out. E.g., "next_ino" doesn't mean much more than "ino" in the
context of this helper.
> + struct xfs_imap *imap,
> + struct xfs_dinode **dipp,
> + struct xfs_buf **bpp)
> +{
> + struct xfs_mount *mp = tp->t_mountp;
> + int error;
> +
> + imap->im_blkno = 0;
> + error = xfs_imap(mp, tp, next_ino, imap, 0);
> + if (error) {
> + xfs_warn(mp, "%s: xfs_imap returned error %d.",
> + __func__, error);
> + return error;
> + }
> +
> + error = xfs_imap_to_bp(mp, tp, imap, dipp, bpp, 0, 0);
> + if (error) {
> + xfs_warn(mp, "%s: xfs_imap_to_bp returned error %d.",
> + __func__, error);
> + return error;
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * Walk the unlinked chain from @head_agino until we find the inode that
> + * points to @target_ino. Return the inode number, map, dinode pointer,
> + * and inode cluster buffer of that inode as @ino, @imap, @dipp, and @bpp.
> + *
> + * Do not call this function if @target_agino is the head of the list.
> + */
> +STATIC int
> +xfs_iunlink_map_prev(
> + struct xfs_trans *tp,
> + struct xfs_perag *pag,
> + xfs_agino_t head_agino,
> + xfs_agino_t target_agino,
> + xfs_ino_t *ino,
> + struct xfs_imap *imap,
> + struct xfs_dinode **dipp,
> + struct xfs_buf **bpp)
> +{
It would also be nice to have some oneline comments next to the params
of some of these functions.
> + struct xfs_imap last_imap;
> + struct xfs_mount *mp = tp->t_mountp;
> + struct xfs_buf *last_ibp = NULL;
> + struct xfs_dinode *last_dip;
> + xfs_ino_t next_ino = NULLFSINO;
> + xfs_agino_t next_agino;
> + int error;
> +
> + ASSERT(head_agino != target_agino);
> +
> + next_agino = head_agino;
> + while (next_agino != target_agino) {
> + xfs_agino_t unlinked_agino;
> +
> + if (last_ibp)
> + xfs_trans_brelse(tp, last_ibp);
> +
> + next_ino = XFS_AGINO_TO_INO(mp, pag->pag_agno, next_agino);
> + error = xfs_iunlink_map_ino(tp, next_ino, &last_imap,
> + &last_dip, &last_ibp);
> + if (error)
> + return error;
> +
> + unlinked_agino = be32_to_cpu(last_dip->di_next_unlinked);
> + if (!xfs_verify_agino(mp, pag->pag_agno, next_agino) ||
Should the next_agino above be unlinked_agino? Also is the == check
below a loop check (comment pls)?
> + next_agino == unlinked_agino) {
> + XFS_CORRUPTION_ERROR(__func__,
> + XFS_ERRLEVEL_LOW, mp,
> + last_dip, sizeof(*last_dip));
> + error = -EFSCORRUPTED;
> + return error;
> + }
> + next_agino = unlinked_agino;
> + }
> +
> + /* Should never happen, but don't return garbage. */
> + if (next_ino == NULLFSINO)
> + return -EFSCORRUPTED;
> +
> + *ino = next_ino;
> + memcpy(imap, &last_imap, sizeof(last_imap));
> + *dipp = last_dip;
> + *bpp = last_ibp;
> + return 0;
> +}
> +
> /*
> * Pull the on-disk inode from the AGI unlinked list.
> */
> @@ -2153,43 +2247,11 @@ xfs_iunlink_remove(
> } else {
> struct xfs_imap imap;
>
> - /*
> - * We need to search the list for the inode being freed.
> - */
> - last_ibp = NULL;
> - while (next_agino != agino) {
> - if (last_ibp)
> - xfs_trans_brelse(tp, last_ibp);
> -
> - imap.im_blkno = 0;
> - next_ino = XFS_AGINO_TO_INO(mp, agno, next_agino);
> -
> - error = xfs_imap(mp, tp, next_ino, &imap, 0);
> - if (error) {
> - xfs_warn(mp,
> - "%s: xfs_imap returned error %d.",
> - __func__, error);
> - goto out_unlock;
> - }
> -
> - error = xfs_imap_to_bp(mp, tp, &imap, &last_dip,
> - &last_ibp, 0, 0);
> - if (error) {
> - xfs_warn(mp,
> - "%s: xfs_imap_to_bp returned error %d.",
> - __func__, error);
> - goto out_unlock;
> - }
> -
> - next_agino = be32_to_cpu(last_dip->di_next_unlinked);
> - if (!xfs_verify_agino(mp, agno, next_agino)) {
> - XFS_CORRUPTION_ERROR(__func__,
> - XFS_ERRLEVEL_LOW, mp,
> - last_dip, sizeof(*last_dip));
> - error = -EFSCORRUPTED;
> - goto out_unlock;
> - }
> - }
> + /* We need to search the list for the inode being freed. */
> + error = xfs_iunlink_map_prev(tp, pag, next_agino, agino,
> + &next_ino, &imap, &last_dip, &last_ibp);
Another variable nit... next_ino is kind of confusing here, particularly
where we still use next_agino as well. The former is actually the "prev"
ino output, right?
Brian
> + if (error)
> + goto out_unlock;
>
> /*
> * Now last_ibp points to the buffer previous to us on the
>
