Re: [PATCH v3 1/4] xfs: track active state of allocation btree cursors

Darrick J. Wong
2019-08-17T00:52:04Z

On Thu, Aug 15, 2019 at 08:55:35AM -0400, Brian Foster wrote:
> The upcoming allocation algorithm update searches multiple
> allocation btree cursors concurrently. As such, it requires an
> active state to track when a particular cursor should continue
> searching. While active state will be modified based on higher level
> logic, we can define base functionality based on the result of
> allocation btree lookups.
>
> Define an active flag in the private area of the btree cursor.
> Update it based on the result of lookups in the existing allocation
> btree helpers. Finally, provide a new helper to query the current
> state.
>
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> ---
> fs/xfs/libxfs/xfs_alloc.c | 24 +++++++++++++++++++++---
> fs/xfs/libxfs/xfs_alloc_btree.c | 1 +
> fs/xfs/libxfs/xfs_btree.h | 3 +++
> 3 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 372ad55631fc..6340f59ac3f4 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -146,9 +146,13 @@ xfs_alloc_lookup_eq(
> xfs_extlen_t len, /* length of extent */
> int *stat) /* success/failure */
> {
> + int error;
> +
> cur->bc_rec.a.ar_startblock = bno;
> cur->bc_rec.a.ar_blockcount = len;
> - return xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
> + error = xfs_btree_lookup(cur, XFS_LOOKUP_EQ, stat);
> + cur->bc_private.a.priv.abt.active = *stat;

<urk> Not really a fan of mixing types (even if they are bool and int),
how hard would it be to convert some of these *stat to bool?

Does abt.active have a use outside of the struct xfs_alloc_cur in the
next patch?

--D

> + return error;
> }
>
> /*
> @@ -162,9 +166,13 @@ xfs_alloc_lookup_ge(
> xfs_extlen_t len, /* length of extent */
> int *stat) /* success/failure */
> {
> + int error;
> +
> cur->bc_rec.a.ar_startblock = bno;
> cur->bc_rec.a.ar_blockcount = len;
> - return xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
> + error = xfs_btree_lookup(cur, XFS_LOOKUP_GE, stat);
> + cur->bc_private.a.priv.abt.active = *stat;
> + return error;
> }
>
> /*
> @@ -178,9 +186,19 @@ xfs_alloc_lookup_le(
> xfs_extlen_t len, /* length of extent */
> int *stat) /* success/failure */
> {
> + int error;
> cur->bc_rec.a.ar_startblock = bno;
> cur->bc_rec.a.ar_blockcount = len;
> - return xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
> + error = xfs_btree_lookup(cur, XFS_LOOKUP_LE, stat);
> + cur->bc_private.a.priv.abt.active = *stat;
> + return error;
> +}
> +
> +static inline bool
> +xfs_alloc_cur_active(
> + struct xfs_btree_cur *cur)
> +{
> + return cur && cur->bc_private.a.priv.abt.active;
> }
>
> /*
> diff --git a/fs/xfs/libxfs/xfs_alloc_btree.c b/fs/xfs/libxfs/xfs_alloc_btree.c
> index 2a94543857a1..279694d73e4e 100644
> --- a/fs/xfs/libxfs/xfs_alloc_btree.c
> +++ b/fs/xfs/libxfs/xfs_alloc_btree.c
> @@ -507,6 +507,7 @@ xfs_allocbt_init_cursor(
>
> cur->bc_private.a.agbp = agbp;
> cur->bc_private.a.agno = agno;
> + cur->bc_private.a.priv.abt.active = false;
>
> if (xfs_sb_version_hascrc(&mp->m_sb))
> cur->bc_flags |= XFS_BTREE_CRC_BLOCKS;
> diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
> index fa3cd8ab9aba..a66063c356cc 100644
> --- a/fs/xfs/libxfs/xfs_btree.h
> +++ b/fs/xfs/libxfs/xfs_btree.h
> @@ -183,6 +183,9 @@ union xfs_btree_cur_private {
> unsigned long nr_ops; /* # record updates */
> int shape_changes; /* # of extent splits */
> } refc;
> + struct {
> + bool active; /* allocation cursor state */
> + } abt;
> };
>
> /*
> --
> 2.20.1
>