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Add scoutfs_btree_parent_range

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Add a btree helper for finding the range of keys which are found in
leaves referenced by the last parent block when searching for a given
key.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2020-12-08 15:31:14 -08:00
parent 65c39e5f97
commit d7f8896fac
2 changed files with 41 additions and 1 deletions
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36
kmod/src/btree.c
View File

@@ -83,6 +83,7 @@ enum btree_walk_flags {
BTW_ALLOC = (1 << 3), /* allocate a new block for 0 ref, requires dirty */
BTW_INSERT = (1 << 4), /* walking to insert, try splitting */
BTW_DELETE = (1 << 5), /* walking to delete, try joining */
BTW_PAR_RNG = (1 << 6), /* return range through final parent */
};
/* total length of the value payload */
@@ -1098,7 +1099,8 @@ static int btree_walk(struct super_block *sb,
unsigned int nr;
int ret;
if (WARN_ON_ONCE((flags & BTW_DIRTY) && (!alloc || !wri)))
if (WARN_ON_ONCE((flags & BTW_DIRTY) && (!alloc || !wri)) ||
WARN_ON_ONCE((flags & BTW_PAR_RNG) && !kr))
return -EINVAL;
/* all ops come through walk and walk calls all reads */
@@ -1144,6 +1146,12 @@ restart:
trace_scoutfs_btree_walk(sb, root, key, flags, level, ref);
/* par range set by ref to last parent block */
if (level < 2 && (flags & BTW_PAR_RNG)) {
ret = 0;
break;
}
ret = get_ref_block(sb, alloc, wri, flags, ref, &bl);
if (ret)
break;
@@ -1742,3 +1750,29 @@ int scoutfs_btree_insert_list(struct super_block *sb,
out:
return ret;
}
/*
* Descend towards the leaf that would contain the key. As we arrive at
* the last parent block, set start and end to the range of keys that
* could be found through traversal of that last parent.
*
* If the tree is too short for parent blocks then the max key range
* is returned.
*/
int scoutfs_btree_parent_range(struct super_block *sb,
struct scoutfs_btree_root *root,
struct scoutfs_key *key,
struct scoutfs_key *start,
struct scoutfs_key *end)
{
struct btree_walk_key_range kr;
int ret;
ret = btree_walk(sb, NULL, NULL, root, BTW_PAR_RNG, key, 0, NULL, &kr);
if (ret == -ENOENT)
ret = 0;
*start = kr.start;
*end = kr.end;
return ret;
}

6
kmod/src/btree.h
View File

@@ -82,6 +82,12 @@ int scoutfs_btree_insert_list(struct super_block *sb,
struct scoutfs_btree_root *root,
struct scoutfs_btree_item_list *lst);
int scoutfs_btree_parent_range(struct super_block *sb,
struct scoutfs_btree_root *root,
struct scoutfs_key *key,
struct scoutfs_key *start,
struct scoutfs_key *end);
void scoutfs_btree_put_iref(struct scoutfs_btree_item_ref *iref);
#endif