btrfs: do not reset extent map members for inline extents read
Currently for inline extents read inside btrfs_get_extent(), we will
reset several extent map members:
- em->start
Reset to extent_start, which is completely unnecessary.
The extent_start and em->start should have already be zero, ensured by
tree-checker already.
- em->len
Reset the round_up(copy_size, fs_info->sectorsize), which is again
unnecessary.
- em->orig_block_len
Reset to em->len (sectorsize), while it is originally unset from
btrfs_extent_item_to_extent_map().
This makes no difference, as all extent map handling paths will
ignore the orig_block_len if they found it's an inlined extent.
Such inline extent orig_block_len ignoring examples can be found in
btrfs_drop_extent_cache().
- em->orig_start
Reset to em->start (0), while it is originally set to EXTENT_MAP_HOLE.
This makes no difference either, as all extent map handling paths will
ignore the em->orig_start if they found it's an inline extent.
Thus all these em members resetting are unnecessary.
Replace them with ASSERT()s checking the only two members (block_start
and length) that make sense.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>