Re: [PATCH RESEND v2 02/18] xfs: Increase XFS_DEFER_OPS_NR_INODES to 5

Darrick J. Wong
2022-08-09T16:39:05Z

On Thu, Aug 04, 2022 at 12:39:57PM -0700, Allison Henderson wrote:
> Renames that generate parent pointer updates can join up to 5
> inodes locked in sorted order. So we need to increase the
> number of defer ops inodes and relock them in the same way.
>
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
> fs/xfs/libxfs/xfs_defer.c | 28 ++++++++++++++++++++++++++--
> fs/xfs/libxfs/xfs_defer.h | 8 +++++++-
> fs/xfs/xfs_inode.c | 2 +-
> fs/xfs/xfs_inode.h | 1 +
> 4 files changed, 35 insertions(+), 4 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
> index 5a321b783398..c0279b57e51d 100644
> --- a/fs/xfs/libxfs/xfs_defer.c
> +++ b/fs/xfs/libxfs/xfs_defer.c
> @@ -820,13 +820,37 @@ xfs_defer_ops_continue(
> struct xfs_trans *tp,
> struct xfs_defer_resources *dres)
> {
> - unsigned int i;
> + unsigned int i, j;
> + struct xfs_inode *sips[XFS_DEFER_OPS_NR_INODES];
> + struct xfs_inode *temp;
>
> ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
> ASSERT(!(tp->t_flags & XFS_TRANS_DIRTY));
>
> /* Lock the captured resources to the new transaction. */
> - if (dfc->dfc_held.dr_inos == 2)
> + if (dfc->dfc_held.dr_inos > 2) {
> + /*
> + * Renames with parent pointer updates can lock up to 5 inodes,
> + * sorted by their inode number. So we need to make sure they
> + * are relocked in the same way.
> + */
> + memset(sips, 0, sizeof(sips));
> + for (i = 0; i < dfc->dfc_held.dr_inos; i++)
> + sips[i] = dfc->dfc_held.dr_ip[i];
> +
> + /* Bubble sort of at most 5 inodes */
> + for (i = 0; i < dfc->dfc_held.dr_inos; i++) {
> + for (j = 1; j < dfc->dfc_held.dr_inos; j++) {
> + if (sips[j]->i_ino < sips[j-1]->i_ino) {
> + temp = sips[j];
> + sips[j] = sips[j-1];
> + sips[j-1] = temp;
> + }
> + }
> + }

Why not reuse xfs_sort_for_rename?

I also wonder if it's worth the trouble to replace the open-coded
bubblesort with a call to sort_r(), but TBH I suspect the cost of a
retpoline for the compare function isn't worth the overhead.

> +
> + xfs_lock_inodes(sips, dfc->dfc_held.dr_inos, XFS_ILOCK_EXCL);
> + } else if (dfc->dfc_held.dr_inos == 2)
> xfs_lock_two_inodes(dfc->dfc_held.dr_ip[0], XFS_ILOCK_EXCL,
> dfc->dfc_held.dr_ip[1], XFS_ILOCK_EXCL);
> else if (dfc->dfc_held.dr_inos == 1)
> diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
> index 114a3a4930a3..3e4029d2ce41 100644
> --- a/fs/xfs/libxfs/xfs_defer.h
> +++ b/fs/xfs/libxfs/xfs_defer.h
> @@ -70,7 +70,13 @@ extern const struct xfs_defer_op_type xfs_attr_defer_type;
> /*
> * Deferred operation item relogging limits.
> */
> -#define XFS_DEFER_OPS_NR_INODES 2 /* join up to two inodes */
> +
> +/*
> + * Rename w/ parent pointers can require up to 5 inodes with defered ops to
> + * be joined to the transaction: src_dp, target_dp, src_ip, target_ip, and wip.
> + * These inodes are locked in sorted order by their inode numbers

Much inode. Thanks for recording this.

--D

> + */
> +#define XFS_DEFER_OPS_NR_INODES 5
> #define XFS_DEFER_OPS_NR_BUFS 2 /* join up to two buffers */
>
> /* Resources that must be held across a transaction roll. */
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 3022918bf96a..cfdcca95594f 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -447,7 +447,7 @@ xfs_lock_inumorder(
> * lock more than one at a time, lockdep will report false positives saying we
> * have violated locking orders.
> */
> -static void
> +void
> xfs_lock_inodes(
> struct xfs_inode **ips,
> int inodes,
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index 4d626f4321bc..bc06d6e4164a 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -573,5 +573,6 @@ void xfs_end_io(struct work_struct *work);
>
> int xfs_ilock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2);
> void xfs_iunlock2_io_mmap(struct xfs_inode *ip1, struct xfs_inode *ip2);
> +void xfs_lock_inodes(struct xfs_inode **ips, int inodes, uint lock_mode);
>
> #endif /* __XFS_INODE_H__ */
> --
> 2.25.1
>