Re: [PATCH 03/13] xfs: factor the xfs_iunlink functions

Darrick J. Wong
2020-08-18T23:49:17Z

On Wed, Aug 12, 2020 at 07:25:46PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> Prep work that separates the locking that protects the unlinked list
> from the actual operations being performed. This also helps document
> the fact they are performing list insert and remove operations. No
> functional code change.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>

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

--D

> ---
> fs/xfs/xfs_inode.c | 92 ++++++++++++++++++++++++++++++----------------
> 1 file changed, 60 insertions(+), 32 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 2072bd25989a..f2f502b65691 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -2205,35 +2205,20 @@ xfs_iunlink_update_inode(
> return error;
> }
>
> -/*
> - * This is called when the inode's link count has gone to 0 or we are creating
> - * a tmpfile via O_TMPFILE. The inode @ip must have nlink == 0.
> - *
> - * We place the on-disk inode on a list in the AGI. It will be pulled from this
> - * list when the inode is freed.
> - */
> -STATIC int
> -xfs_iunlink(
> +static int
> +xfs_iunlink_insert_inode(
> struct xfs_trans *tp,
> + struct xfs_buf *agibp,
> struct xfs_inode *ip)
> {
> struct xfs_mount *mp = tp->t_mountp;
> struct xfs_agi *agi;
> - struct xfs_buf *agibp;
> xfs_agino_t next_agino;
> - xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
> xfs_agino_t agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
> + xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
> short bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
> int error;
>
> - ASSERT(VFS_I(ip)->i_nlink == 0);
> - ASSERT(VFS_I(ip)->i_mode != 0);
> - trace_xfs_iunlink(ip);
> -
> - /* Get the agi buffer first. It ensures lock ordering on the list. */
> - error = xfs_read_agi(mp, tp, agno, &agibp);
> - if (error)
> - return error;
> agi = agibp->b_addr;
>
> /*
> @@ -2274,6 +2259,35 @@ xfs_iunlink(
> return xfs_iunlink_update_bucket(tp, agno, agibp, bucket_index, agino);
> }
>
> +/*
> + * This is called when the inode's link count has gone to 0 or we are creating
> + * a tmpfile via O_TMPFILE. The inode @ip must have nlink == 0.
> + *
> + * We place the on-disk inode on a list in the AGI. It will be pulled from this
> + * list when the inode is freed.
> + */
> +STATIC int
> +xfs_iunlink(
> + struct xfs_trans *tp,
> + struct xfs_inode *ip)
> +{
> + struct xfs_mount *mp = tp->t_mountp;
> + struct xfs_buf *agibp;
> + xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
> + int error;
> +
> + ASSERT(VFS_I(ip)->i_nlink == 0);
> + ASSERT(VFS_I(ip)->i_mode != 0);
> + trace_xfs_iunlink(ip);
> +
> + /* Get the agi buffer first. It ensures lock ordering on the list. */
> + error = xfs_read_agi(mp, tp, agno, &agibp);
> + if (error)
> + return error;
> +
> + return xfs_iunlink_insert_inode(tp, agibp, ip);
> +}
> +
> /* Return the imap, dinode pointer, and buffer for an inode. */
> STATIC int
> xfs_iunlink_map_ino(
> @@ -2388,32 +2402,23 @@ xfs_iunlink_map_prev(
> return 0;
> }
>
> -/*
> - * Pull the on-disk inode from the AGI unlinked list.
> - */
> -STATIC int
> -xfs_iunlink_remove(
> +static int
> +xfs_iunlink_remove_inode(
> struct xfs_trans *tp,
> + struct xfs_buf *agibp,
> struct xfs_inode *ip)
> {
> struct xfs_mount *mp = tp->t_mountp;
> struct xfs_agi *agi;
> - struct xfs_buf *agibp;
> struct xfs_buf *last_ibp;
> struct xfs_dinode *last_dip = NULL;
> - xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
> 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 head_agino;
> short bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
> int error;
>
> - trace_xfs_iunlink_remove(ip);
> -
> - /* Get the agi buffer first. It ensures lock ordering on the list. */
> - error = xfs_read_agi(mp, tp, agno, &agibp);
> - if (error)
> - return error;
> agi = agibp->b_addr;
>
> /*
> @@ -2482,6 +2487,29 @@ xfs_iunlink_remove(
> next_agino);
> }
>
> +/*
> + * Pull the on-disk inode from the AGI unlinked list.
> + */
> +STATIC int
> +xfs_iunlink_remove(
> + struct xfs_trans *tp,
> + struct xfs_inode *ip)
> +{
> + struct xfs_mount *mp = tp->t_mountp;
> + struct xfs_buf *agibp;
> + xfs_agnumber_t agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
> + int error;
> +
> + trace_xfs_iunlink_remove(ip);
> +
> + /* Get the agi buffer first. It ensures lock ordering on the list. */
> + error = xfs_read_agi(mp, tp, agno, &agibp);
> + if (error)
> + return error;
> +
> + return xfs_iunlink_remove_inode(tp, agibp, ip);
> +}
> +
> /*
> * Look up the inode number specified and if it is not already marked XFS_ISTALE
> * mark it stale. We should only find clean inodes in this lookup that aren't
> --
> 2.26.2.761.g0e0b3e54be
>