diff options
Diffstat (limited to 'fs/xfs/libxfs/xfs_btree.c')
| -rw-r--r-- | fs/xfs/libxfs/xfs_btree.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c index a222f5de2a09..64b47e81f6f3 100644 --- a/fs/xfs/libxfs/xfs_btree.c +++ b/fs/xfs/libxfs/xfs_btree.c @@ -4535,6 +4535,40 @@ xfs_btree_compute_maxlevels( } /* + * Compute the maximum height of a btree that is allowed to consume up to the + * given number of blocks. + */ +unsigned int +xfs_btree_compute_maxlevels_size( + unsigned long long max_btblocks, + unsigned int leaf_mnr) +{ + unsigned long long leaf_blocks = leaf_mnr; + unsigned long long blocks_left; + unsigned int maxlevels; + + if (max_btblocks < 1) + return 0; + + /* + * The loop increments maxlevels as long as there would be enough + * blocks left in the reservation to handle each node block at the + * current level pointing to the minimum possible number of leaf blocks + * at the next level down. We start the loop assuming a single-level + * btree consuming one block. + */ + maxlevels = 1; + blocks_left = max_btblocks - 1; + while (leaf_blocks < blocks_left) { + maxlevels++; + blocks_left -= leaf_blocks; + leaf_blocks *= leaf_mnr; + } + + return maxlevels; +} + +/* * Query a regular btree for all records overlapping a given interval. * Start with a LE lookup of the key of low_rec and return all records * until we find a record with a key greater than the key of high_rec. |