Re: [PATCH 02/23] xfs: prepare for moving perag definitions and support to libxfs

Brian Foster
2021-05-26T12:33:52Z

On Wed, May 19, 2021 at 11:20:41AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> The perag structures really need to be defined with the rest of the
> AG support infrastructure. The struct xfs_perag and init/teardown
> has been placed in xfs_mount.[ch] because there are differences in
> the structure between kernel and userspace. Mainly that userspace
> doesn't have a lot of the internal stuff that the kernel has for
> caches and discard and other such structures.
>
> However, it makes more sense to move this to libxfs than to keep
> this separation because we are now moving to use struct perags
> everywhere in the code instead of passing raw agnumber_t values
> about. Hence we shoudl really move the support infrastructure to
> libxfs/xfs_ag.[ch].
>
> To do this without breaking userspace, first we need to rearrange
> the structures and code so that all the kernel specific code is
> located together. This makes it simple for userspace to ifdef out
> the all the parts it does not need, minimising the code differences
> between kernel and userspace. The next commit will do the move...
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

> fs/xfs/xfs_mount.c | 56 ++++++++++++++++++++++++++--------------------
> fs/xfs/xfs_mount.h | 19 ++++++++--------
> 2 files changed, 42 insertions(+), 33 deletions(-)
>
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 21c630dde476..6966d7b12a13 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -148,9 +148,11 @@ xfs_free_perag(
> spin_unlock(&mp->m_perag_lock);
> ASSERT(pag);
> ASSERT(atomic_read(&pag->pag_ref) == 0);
> +
> cancel_delayed_work_sync(&pag->pag_blockgc_work);
> xfs_iunlink_destroy(pag);
> xfs_buf_hash_destroy(pag);
> +
> call_rcu(&pag->rcu_head, __xfs_free_perag);
> }
> }
> @@ -175,14 +177,14 @@ xfs_sb_validate_fsb_count(
>
> int
> xfs_initialize_perag(
> - xfs_mount_t *mp,
> - xfs_agnumber_t agcount,
> - xfs_agnumber_t *maxagi)
> + struct xfs_mount *mp,
> + xfs_agnumber_t agcount,
> + xfs_agnumber_t *maxagi)
> {
> - xfs_agnumber_t index;
> - xfs_agnumber_t first_initialised = NULLAGNUMBER;
> - xfs_perag_t *pag;
> - int error = -ENOMEM;
> + struct xfs_perag *pag;
> + xfs_agnumber_t index;
> + xfs_agnumber_t first_initialised = NULLAGNUMBER;
> + int error;
>
> /*
> * Walk the current per-ag tree so we don't try to initialise AGs
> @@ -203,21 +205,10 @@ xfs_initialize_perag(
> }
> pag->pag_agno = index;
> pag->pag_mount = mp;
> - spin_lock_init(&pag->pag_ici_lock);
> - INIT_DELAYED_WORK(&pag->pag_blockgc_work, xfs_blockgc_worker);
> - INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
> -
> - error = xfs_buf_hash_init(pag);
> - if (error)
> - goto out_free_pag;
> - init_waitqueue_head(&pag->pagb_wait);
> - spin_lock_init(&pag->pagb_lock);
> - pag->pagb_count = 0;
> - pag->pagb_tree = RB_ROOT;
>
> error = radix_tree_preload(GFP_NOFS);
> if (error)
> - goto out_hash_destroy;
> + goto out_free_pag;
>
> spin_lock(&mp->m_perag_lock);
> if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
> @@ -225,17 +216,32 @@ xfs_initialize_perag(
> spin_unlock(&mp->m_perag_lock);
> radix_tree_preload_end();
> error = -EEXIST;
> - goto out_hash_destroy;
> + goto out_free_pag;
> }
> spin_unlock(&mp->m_perag_lock);
> radix_tree_preload_end();
> - /* first new pag is fully initialized */
> - if (first_initialised == NULLAGNUMBER)
> - first_initialised = index;
> +
> + /* Place kernel structure only init below this point. */
> + spin_lock_init(&pag->pag_ici_lock);
> + spin_lock_init(&pag->pagb_lock);
> + spin_lock_init(&pag->pag_state_lock);
> + INIT_DELAYED_WORK(&pag->pag_blockgc_work, xfs_blockgc_worker);
> + INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
> + init_waitqueue_head(&pag->pagb_wait);
> + pag->pagb_count = 0;
> + pag->pagb_tree = RB_ROOT;
> +
> + error = xfs_buf_hash_init(pag);
> + if (error)
> + goto out_remove_pag;
> +
> error = xfs_iunlink_init(pag);
> if (error)
> goto out_hash_destroy;
> - spin_lock_init(&pag->pag_state_lock);
> +
> + /* first new pag is fully initialized */
> + if (first_initialised == NULLAGNUMBER)
> + first_initialised = index;
> }
>
> index = xfs_set_inode_alloc(mp, agcount);
> @@ -248,6 +254,8 @@ xfs_initialize_perag(
>
> out_hash_destroy:
> xfs_buf_hash_destroy(pag);
> +out_remove_pag:
> + radix_tree_delete(&mp->m_perag_tree, index);
> out_free_pag:
> kmem_free(pag);
> out_unwind_new_pags:
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index bb67274ee23f..6e534be5eea8 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -338,6 +338,16 @@ typedef struct xfs_perag {
> xfs_agino_t pagl_leftrec;
> xfs_agino_t pagl_rightrec;
>
> + int pagb_count; /* pagb slots in use */
> + uint8_t pagf_refcount_level; /* recount btree height */
> +
> + /* Blocks reserved for all kinds of metadata. */
> + struct xfs_ag_resv pag_meta_resv;
> + /* Blocks reserved for the reverse mapping btree. */
> + struct xfs_ag_resv pag_rmapbt_resv;
> +
> + /* -- kernel only structures below this line -- */
> +
> /*
> * Bitsets of per-ag metadata that have been checked and/or are sick.
> * Callers should hold pag_state_lock before accessing this field.
> @@ -364,19 +374,10 @@ typedef struct xfs_perag {
>
> /* for rcu-safe freeing */
> struct rcu_head rcu_head;
> - int pagb_count; /* pagb slots in use */
> -
> - /* Blocks reserved for all kinds of metadata. */
> - struct xfs_ag_resv pag_meta_resv;
> - /* Blocks reserved for the reverse mapping btree. */
> - struct xfs_ag_resv pag_rmapbt_resv;
>
> /* background prealloc block trimming */
> struct delayed_work pag_blockgc_work;
>
> - /* reference count */
> - uint8_t pagf_refcount_level;
> -
> /*
> * Unlinked inode information. This incore information reflects
> * data stored in the AGI, so callers must hold the AGI buffer lock
> --
> 2.31.1
>