xfs: Use struct xfs_bmdr_block instead of struct xfs_btree_block to calculate root node size

The incore data fork of an inode stores the bmap btree root node as 'struct
xfs_btree_block'. However, the ondisk version of the inode stores the bmap
btree root node as a 'struct xfs_bmdr_block'.

xfs_bmap_add_attrfork_btree() checks if the btree root node fits inside the
data fork of the inode. However, it incorrectly uses 'struct xfs_btree_block'
to compute the size of the bmap btree root node. Since size of 'struct
xfs_btree_block' is larger than that of 'struct xfs_bmdr_block',
xfs_bmap_add_attrfork_btree() could end up unnecessarily demoting the current
root node as the child of newly allocated root node.

This commit optimizes space usage by modifying xfs_bmap_add_attrfork_btree()
to use 'struct xfs_bmdr_block' to check if the bmap btree root node fits
inside the data fork of the inode.

Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Chandan Babu R <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Signed-off-by: Darrick J. Wong <[email protected]>

0 files changed, 0 insertions, 0 deletions