[PATCH 0/6] Simplifications around submit_bio_hook

[Nikolay Borisov <nborisov@suse.com>]

I've been taking a look at the submit_bio_hook et al  and I saw some
opportunities for improvement. First I begin by simplifying the definition of 
submit_bio_hook callback and making one of its arguments explicit. 

Patch 3 removes a redundant extent_io_tree argument that was passed through 
several layers of functions and ultimately made it somewhat cumbersome to reason
what extent_io_tree is being used. 

Patch 4 and 5 hardcode a 0 being passed  for the bio_offset parameter to
btrfs_submit_bio_start/btree_submit_bio_start since it only matters for DIO. 

Patch 6 finally does away with the bio_offset parameter of submit_bio_hook. 

Here is the output of bloat-o-meter for posterity:

add/remove: 0/0 grow/shrink: 4/7 up/down: 48/-319 (-271)
Function                                     old     new   delta
read_extent_buffer_pages                     784     822     +38
btrfs_add_ordered_sum                        100     104      +4
btrfs_submit_bio_hook                        364     367      +3
btree_submit_bio_hook                        175     178      +3
end_bio_extent_readpage                     2119    2116      -3
btrfs_reloc_clone_csums                      272     262     -10
btrfs_csum_one_bio                          1358    1348     -10
btree_read_extent_buffer_pages               282     272     -10
readahead_tree_block                          73      55     -18
reada_tree_block_flagged                     194     165     -29
submit_one_bio                               313      74    -239
Total: Before=1072719, After=1072448, chg -0.03%

Nikolay Borisov (6):
  btrfs: Define submit_bio_hook's type directly
  btrfs: Change submit_bio_hook to taking an inode directly
  btrfs: Remove 'tree' argument from read_extent_buffer_pages
  btrfs: Pass 0 for bio_offset to btrfs_wq_submit_bio
  btrfs: Always pass 0 bio_offset for btree_submit_bio_start
  btrfs: Remove bio_offset argument from submit_bio_hook

 fs/btrfs/disk-io.c   | 22 +++++++---------------
 fs/btrfs/extent_io.c | 10 ++++------
 fs/btrfs/extent_io.h |  9 +++------
 fs/btrfs/inode.c     | 11 +++++------
 4 files changed, 19 insertions(+), 33 deletions(-)

-- 
2.17.1