Re: [PATCH 015/119] xfs: refactor btree owner change into a separate visit-blocks function

Brian Foster
2016-06-23T17:20:16Z

On Thu, Jun 16, 2016 at 06:19:28PM -0700, Darrick J. Wong wrote:
> Refactor the btree_change_owner function into a more generic apparatus
> which visits all blocks in a btree. We'll use this in a subsequent
> patch for counting btree blocks for AG reservations.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

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

> fs/xfs/libxfs/xfs_btree.c | 141 +++++++++++++++++++++++++++++----------------
> fs/xfs/libxfs/xfs_btree.h | 5 ++
> 2 files changed, 96 insertions(+), 50 deletions(-)
>
>
> diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
> index 5f5cf23..eac876a 100644
> --- a/fs/xfs/libxfs/xfs_btree.c
> +++ b/fs/xfs/libxfs/xfs_btree.c
> @@ -4289,6 +4289,81 @@ xfs_btree_get_rec(
> return 0;
> }
>
> +/* Visit a block in a btree. */
> +STATIC int
> +xfs_btree_visit_block(
> + struct xfs_btree_cur *cur,
> + int level,
> + xfs_btree_visit_blocks_fn fn,
> + void *data)
> +{
> + struct xfs_btree_block *block;
> + struct xfs_buf *bp;
> + union xfs_btree_ptr rptr;
> + int error;
> +
> + /* do right sibling readahead */
> + xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
> + block = xfs_btree_get_block(cur, level, &bp);
> +
> + /* process the block */
> + error = fn(cur, level, data);
> + if (error)
> + return error;
> +
> + /* now read rh sibling block for next iteration */
> + xfs_btree_get_sibling(cur, block, &rptr, XFS_BB_RIGHTSIB);
> + if (xfs_btree_ptr_is_null(cur, &rptr))
> + return -ENOENT;
> +
> + return xfs_btree_lookup_get_block(cur, level, &rptr, &block);
> +}
> +
> +
> +/* Visit every block in a btree. */
> +int
> +xfs_btree_visit_blocks(
> + struct xfs_btree_cur *cur,
> + xfs_btree_visit_blocks_fn fn,
> + void *data)
> +{
> + union xfs_btree_ptr lptr;
> + int level;
> + struct xfs_btree_block *block = NULL;
> + int error = 0;
> +
> + cur->bc_ops->init_ptr_from_cur(cur, &lptr);
> +
> + /* for each level */
> + for (level = cur->bc_nlevels - 1; level >= 0; level--) {
> + /* grab the left hand block */
> + error = xfs_btree_lookup_get_block(cur, level, &lptr, &block);
> + if (error)
> + return error;
> +
> + /* readahead the left most block for the next level down */
> + if (level > 0) {
> + union xfs_btree_ptr *ptr;
> +
> + ptr = xfs_btree_ptr_addr(cur, 1, block);
> + xfs_btree_readahead_ptr(cur, ptr, 1);
> +
> + /* save for the next iteration of the loop */
> + lptr = *ptr;
> + }
> +
> + /* for each buffer in the level */
> + do {
> + error = xfs_btree_visit_block(cur, level, fn, data);
> + } while (!error);
> +
> + if (error != -ENOENT)
> + return error;
> + }
> +
> + return 0;
> +}
> +
> /*
> * Change the owner of a btree.
> *
> @@ -4313,26 +4388,27 @@ xfs_btree_get_rec(
> * just queue the modified buffer as delayed write buffer so the transaction
> * recovery completion writes the changes to disk.
> */
> +struct xfs_btree_block_change_owner_info {
> + __uint64_t new_owner;
> + struct list_head *buffer_list;
> +};
> +
> static int
> xfs_btree_block_change_owner(
> struct xfs_btree_cur *cur,
> int level,
> - __uint64_t new_owner,
> - struct list_head *buffer_list)
> + void *data)
> {
> + struct xfs_btree_block_change_owner_info *bbcoi = data;
> struct xfs_btree_block *block;
> struct xfs_buf *bp;
> - union xfs_btree_ptr rptr;
> -
> - /* do right sibling readahead */
> - xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
>
> /* modify the owner */
> block = xfs_btree_get_block(cur, level, &bp);
> if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
> - block->bb_u.l.bb_owner = cpu_to_be64(new_owner);
> + block->bb_u.l.bb_owner = cpu_to_be64(bbcoi->new_owner);
> else
> - block->bb_u.s.bb_owner = cpu_to_be32(new_owner);
> + block->bb_u.s.bb_owner = cpu_to_be32(bbcoi->new_owner);
>
> /*
> * If the block is a root block hosted in an inode, we might not have a
> @@ -4346,19 +4422,14 @@ xfs_btree_block_change_owner(
> xfs_trans_ordered_buf(cur->bc_tp, bp);
> xfs_btree_log_block(cur, bp, XFS_BB_OWNER);
> } else {
> - xfs_buf_delwri_queue(bp, buffer_list);
> + xfs_buf_delwri_queue(bp, bbcoi->buffer_list);
> }
> } else {
> ASSERT(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE);
> ASSERT(level == cur->bc_nlevels - 1);
> }
>
> - /* now read rh sibling block for next iteration */
> - xfs_btree_get_sibling(cur, block, &rptr, XFS_BB_RIGHTSIB);
> - if (xfs_btree_ptr_is_null(cur, &rptr))
> - return -ENOENT;
> -
> - return xfs_btree_lookup_get_block(cur, level, &rptr, &block);
> + return 0;
> }
>
> int
> @@ -4367,43 +4438,13 @@ xfs_btree_change_owner(
> __uint64_t new_owner,
> struct list_head *buffer_list)
> {
> - union xfs_btree_ptr lptr;
> - int level;
> - struct xfs_btree_block *block = NULL;
> - int error = 0;
> + struct xfs_btree_block_change_owner_info bbcoi;
>
> - cur->bc_ops->init_ptr_from_cur(cur, &lptr);
> + bbcoi.new_owner = new_owner;
> + bbcoi.buffer_list = buffer_list;
>
> - /* for each level */
> - for (level = cur->bc_nlevels - 1; level >= 0; level--) {
> - /* grab the left hand block */
> - error = xfs_btree_lookup_get_block(cur, level, &lptr, &block);
> - if (error)
> - return error;
> -
> - /* readahead the left most block for the next level down */
> - if (level > 0) {
> - union xfs_btree_ptr *ptr;
> -
> - ptr = xfs_btree_ptr_addr(cur, 1, block);
> - xfs_btree_readahead_ptr(cur, ptr, 1);
> -
> - /* save for the next iteration of the loop */
> - lptr = *ptr;
> - }
> -
> - /* for each buffer in the level */
> - do {
> - error = xfs_btree_block_change_owner(cur, level,
> - new_owner,
> - buffer_list);
> - } while (!error);
> -
> - if (error != -ENOENT)
> - return error;
> - }
> -
> - return 0;
> + return xfs_btree_visit_blocks(cur, xfs_btree_block_change_owner,
> + &bbcoi);
> }
>
> /**
> diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
> index 898fee5..0ec3055 100644
> --- a/fs/xfs/libxfs/xfs_btree.h
> +++ b/fs/xfs/libxfs/xfs_btree.h
> @@ -506,4 +506,9 @@ int xfs_btree_query_range(struct xfs_btree_cur *cur,
> union xfs_btree_irec *low_rec, union xfs_btree_irec *high_rec,
> xfs_btree_query_range_fn fn, void *priv);
>
> +typedef int (*xfs_btree_visit_blocks_fn)(struct xfs_btree_cur *cur, int level,
> + void *data);
> +int xfs_btree_visit_blocks(struct xfs_btree_cur *cur,
> + xfs_btree_visit_blocks_fn fn, void *data);
> +
> #endif /* __XFS_BTREE_H__ */
>
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