Test generic/020 fails for ext4 with 64K blocksize. This adds changes in common/attr for MAX_ATTRS calculations for ext2|ext3|ext4 along with comments explaining the calculations. Suggested-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> --- common/attr | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/common/attr b/common/attr index d3902346..35682d7c 100644 --- a/common/attr +++ b/common/attr @@ -256,6 +256,45 @@ case "$FSTYP" in xfs|udf|pvfs2|9p|ceph|nfs) MAX_ATTRS=1000 ;; +ext2|ext3|ext4) + # For 4k blocksizes, most of the attributes have an attr_name of + # "attribute_NN" which is 12, and "value_NN" which is 8. + # But for larger block sizes, we start having extended attributes of the + # form "attribute_NNN" or "attribute_NNNN", and "value_NNN" and + # "value_NNNN", which causes the round(len(..), 4) to jump up by 4 + # bytes. So round_up(len(attr_name, 4)) becomes 16 instead of 12, and + # round_up(len(value, 4)) becomes 12 instead of 8. + # + # For 64K blocksize the calculation becomes + # max_attrs = (block_size - 32) / (16 + 12 + 16) + # or + # max_attrs = (block_size - 32) / 44 + # + # For 4K blocksize:- + # max_attrs = (block_size - 32) / (16 + 8 + 12) + # or + # max_attrs = (block_size - 32) / 36 + # + # Note (for 4K bs) above are exact calculations for attrs of type + # attribute_NN with values of type value_NN. + # With above calculations, for 4k blocksize max_attrs becomes 112. + # This means we can have few attrs of type attribute_NNN with values of + # type value_NNN. To avoid/handle this we need to add extra 4 bytes of + # headroom. + # + # So for 4K, the calculations becomes:- + # max_attrs = (block_size - 32) / (16 + 8 + 12 + 4) + # or + # max_attrs = (block_size - 32) / 40 + # + # Assume max ~1 block of attrs + BLOCK_SIZE=`_get_block_size $TEST_DIR` + if [ $BLOCK_SIZE -le 4096 ]; then + let MAX_ATTRS=$((($BLOCK_SIZE - 32) / (16 + 8 + 12 + 4))) + else + let MAX_ATTRS=$((($BLOCK_SIZE - 32) / (16 + 12 + 16 ))) + fi + ;; *) # Assume max ~1 block of attrs BLOCK_SIZE=`_get_block_size $TEST_DIR` -- 2.31.1
