mirrors/scoutfs
1
0
Fork 0
mirror of https://github.com/versity/scoutfs.git synced 2026-09-06 08:06:56 +00:00
Code Issues Packages Projects Releases Wiki Activity

Add SUBTREE btree walk flag to restrict join/merge

Browse Source 
Add a BTW_SUBTREE flag to btree_walk() to restrict splitting or joining
of the root block.   When clients are merging into the root built from a
reference to the last parent in the fs tree we want to be careful that
we maintain a single root block that can be spliced back into the fs
tree.   We specifically check that the root block remain within the
split/join thresholds.  If it falls out of compliance we return an error
so that it can be spliced back into the fs tree and then split/joined
with its siblings.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2021-06-15 15:25:14 -07:00
parent b6d0a45f6d
commit 3a03a6a20c
1 changed files with 12 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kmod/src/btree.c
+12
View File
@@ -86,6 +86,7 @@ enum btree_walk_flags {
BTW_PAR_RNG = (1 << 6), /* return range through final parent */
BTW_GET_PAR = (1 << 7), /* get reference to final parent */
BTW_SET_PAR = (1 << 8), /* override reference to final parent */
BTW_SUBTREE = (1 << 9), /* root is parent subtree, return -ERANGE if split/join */
};
/* total length of the value payload */
@@ -1209,6 +1210,17 @@ restart:
break;
}
/*
* join/split won't check subtree parent root, let
* caller know when it needs to be split/join.
*/
if ((flags & BTW_SUBTREE) && level == 1 &&
(!total_above_join_low_water(bt) ||
!mid_free_item_room(bt, sizeof(struct scoutfs_block_ref)))) {
ret = -ERANGE;
break;
}
/*
* Splitting and joining can add or remove parents or
* change the parent item we use to reach the child