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    SubjectRe: [RFC v2 16/83] Initialize block map and free lists in nova_init().
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    On 10.03.2018 20:17, Andiry Xu wrote:
    > From: Andiry Xu <jix024@cs.ucsd.edu>
    >
    > NOVA divides the pmem range equally among per-CPU free lists,
    > and format the red-black trees by inserting the initial free range.
    >
    > Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
    > ---
    > fs/nova/balloc.c | 161 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
    > fs/nova/balloc.h | 13 ++++-
    > fs/nova/super.c | 2 +
    > 3 files changed, 175 insertions(+), 1 deletion(-)
    >
    > diff --git a/fs/nova/balloc.c b/fs/nova/balloc.c
    > index 450c942..cb627db 100644
    > --- a/fs/nova/balloc.c
    > +++ b/fs/nova/balloc.c
    > @@ -55,4 +55,165 @@ void nova_delete_free_lists(struct super_block *sb)
    > sbi->free_lists = NULL;
    > }
    >
    > +// Initialize a free list. Each CPU gets an equal share of the block space to
    > +// manage.
    > +static void nova_init_free_list(struct super_block *sb,
    > + struct free_list *free_list, int index)
    > +{
    > + struct nova_sb_info *sbi = NOVA_SB(sb);
    > + unsigned long per_list_blocks;
    > +
    > + per_list_blocks = sbi->num_blocks / sbi->cpus;

    nit: You've already initialised per_list_blocks in nova_init_blockmap,
    which calls this function. So just reference it, rather than performing
    the the divison every time

    > +
    > + free_list->block_start = per_list_blocks * index;
    > + free_list->block_end = free_list->block_start +
    > + per_list_blocks - 1;
    > + if (index == 0)
    > + free_list->block_start += sbi->head_reserved_blocks;
    > + if (index == sbi->cpus - 1)
    > + free_list->block_end -= sbi->tail_reserved_blocks;
    > +}
    > +
    > +inline struct nova_range_node *nova_alloc_blocknode(struct super_block *sb)
    > +{
    > + return nova_alloc_range_node(sb);
    > +}
    > +
    > +inline void nova_free_blocknode(struct super_block *sb,
    > + struct nova_range_node *node)
    > +{
    > + nova_free_range_node(node);
    > +}
    > +
    > +void nova_init_blockmap(struct super_block *sb, int recovery)
    > +{
    > + struct nova_sb_info *sbi = NOVA_SB(sb);
    > + struct rb_root *tree;
    > + struct nova_range_node *blknode;
    > + struct free_list *free_list;
    > + int i;
    > + int ret;
    > +
    > + /* Divide the block range among per-CPU free lists */
    > + sbi->per_list_blocks = sbi->num_blocks / sbi->cpus;
    > + for (i = 0; i < sbi->cpus; i++) {
    > + free_list = nova_get_free_list(sb, i);
    > + tree = &(free_list->block_free_tree);
    > + nova_init_free_list(sb, free_list, i);
    > +
    > + /* For recovery, update these fields later */
    > + if (recovery == 0) {
    > + free_list->num_free_blocks = free_list->block_end -
    > + free_list->block_start + 1;
    > +
    > + blknode = nova_alloc_blocknode(sb);
    > + if (blknode == NULL)
    > + return;
    > + blknode->range_low = free_list->block_start;
    > + blknode->range_high = free_list->block_end;
    > + ret = nova_insert_blocktree(sbi, tree, blknode);
    > + if (ret) {
    > + nova_err(sb, "%s failed\n", __func__);
    > + nova_free_blocknode(sb, blknode);
    > + return;
    > + }
    > + free_list->first_node = blknode;
    > + free_list->last_node = blknode;
    > + free_list->num_blocknode = 1;
    > + }
    > +
    > + nova_dbgv("%s: free list %d: block start %lu, end %lu, %lu free blocks\n",
    > + __func__, i,
    > + free_list->block_start,
    > + free_list->block_end,
    > + free_list->num_free_blocks);
    > + }
    > +}
    > +
    > +static inline int nova_rbtree_compare_rangenode(struct nova_range_node *curr,
    > + unsigned long range_low)
    > +{
    > + if (range_low < curr->range_low)
    > + return -1;
    > + if (range_low > curr->range_high)
    > + return 1;
    >
    > + return 0;
    > +}
    > +
    > +int nova_find_range_node(struct nova_sb_info *sbi,
    > + struct rb_root *tree, unsigned long range_low,
    > + struct nova_range_node **ret_node)

    Instead of having a **ret_node pointer as an argument, just make the
    function return struct nova_range *node and have callers check for null:

    struct nova_range_node *node = nova_find_range_node(sbi, tree, range);

    if (ret) {
    //do stuff with *node
    }

    > +{
    > + struct nova_range_node *curr = NULL;
    > + struct rb_node *temp;
    > + int compVal;
    > + int ret = 0;
    > +
    > + temp = tree->rb_node;
    > +
    > + while (temp) {
    > + curr = container_of(temp, struct nova_range_node, node);
    > + compVal = nova_rbtree_compare_rangenode(curr, range_low);
    > +
    > + if (compVal == -1) {
    > + temp = temp->rb_left;
    > + } else if (compVal == 1) {
    > + temp = temp->rb_right;
    > + } else {
    > + ret = 1;
    > + break;
    > + }
    > + }
    > +
    > + *ret_node = curr;
    > + return ret;
    > +}
    > +
    > +
    > +int nova_insert_range_node(struct rb_root *tree,
    > + struct nova_range_node *new_node)
    > +{
    > + struct nova_range_node *curr;
    > + struct rb_node **temp, *parent;
    > + int compVal;
    > +
    > + temp = &(tree->rb_node);
    > + parent = NULL;
    > +
    > + while (*temp) {
    > + curr = container_of(*temp, struct nova_range_node, node);
    > + compVal = nova_rbtree_compare_rangenode(curr,
    > + new_node->range_low);
    > + parent = *temp;
    > +
    > + if (compVal == -1) {
    > + temp = &((*temp)->rb_left);
    > + } else if (compVal == 1) {
    > + temp = &((*temp)->rb_right);
    > + } else {
    > + nova_dbg("%s: entry %lu - %lu already exists: %lu - %lu\n",
    > + __func__, new_node->range_low,
    > + new_node->range_high, curr->range_low,
    > + curr->range_high);
    > + return -EINVAL;
    > + }
    > + }
    > +
    > + rb_link_node(&new_node->node, parent, temp);
    > + rb_insert_color(&new_node->node, tree);
    > +
    > + return 0;
    > +}
    > +
    > +inline int nova_insert_blocktree(struct nova_sb_info *sbi,
    > + struct rb_root *tree, struct nova_range_node *new_node)
    > +{
    > + int ret;
    > +
    > + ret = nova_insert_range_node(tree, new_node);
    > + if (ret)
    > + nova_dbg("ERROR: %s failed %d\n", __func__, ret);
    > +
    > + return ret;
    > +}
    > diff --git a/fs/nova/balloc.h b/fs/nova/balloc.h
    > index e7c7a1d..57a93e4 100644
    > --- a/fs/nova/balloc.h
    > +++ b/fs/nova/balloc.h
    > @@ -62,5 +62,16 @@ enum alloc_type {
    >
    > int nova_alloc_block_free_lists(struct super_block *sb);
    > void nova_delete_free_lists(struct super_block *sb);
    > -
    > +inline struct nova_range_node *nova_alloc_blocknode(struct super_block *sb);
    > +inline void nova_free_blocknode(struct super_block *sb,
    > + struct nova_range_node *bnode);
    > +extern void nova_init_blockmap(struct super_block *sb, int recovery);
    > +inline int nova_insert_blocktree(struct nova_sb_info *sbi,
    > + struct rb_root *tree, struct nova_range_node *new_node);
    > +
    > +extern int nova_insert_range_node(struct rb_root *tree,
    > + struct nova_range_node *new_node);
    > +extern int nova_find_range_node(struct nova_sb_info *sbi,
    > + struct rb_root *tree, unsigned long range_low,
    > + struct nova_range_node **ret_node);
    > #endif
    > diff --git a/fs/nova/super.c b/fs/nova/super.c
    > index 43b24a7..9762f26 100644
    > --- a/fs/nova/super.c
    > +++ b/fs/nova/super.c
    > @@ -376,6 +376,8 @@ static struct nova_inode *nova_init(struct super_block *sb,
    > pi->nova_ino = NOVA_BLOCKNODE_INO;
    > nova_flush_buffer(pi, CACHELINE_SIZE, 1);
    >
    > + nova_init_blockmap(sb, 0);
    > +
    > sbi->nova_sb->s_size = cpu_to_le64(size);
    > sbi->nova_sb->s_blocksize = cpu_to_le32(blocksize);
    > sbi->nova_sb->s_magic = cpu_to_le32(NOVA_SUPER_MAGIC);
    >

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