[PATCH 0/4] btrfs: reduce btrfs_get_extent() calls for buffered write path

[Qu Wenruo <wqu@suse.com>]

Although btrfs has bs < ps support for a long time, and the larger data
folios support is also going to be graduate from experimental features
soon, the write path is still iterating each fs block and call
btrfs_get_extent() on each fs block.

What makes the situation worse is that, for the write path we do not
have any cached extent map, meaning even with large folios and we got a
continuous range that can be submitted in one go, we still call
btrfs_get_extent() many times and get the same range extent map again
and again.

This series will reduce the duplicated btrfs_get_extent() calls by only
call it once for each range, other than for each fs block.

The first 3 patches are just minor cleanups/refactors, the last patch
is the real optimization.

I don't expect there will be much difference in the real world though.

Qu Wenruo (4):
  btrfs: integrate the error handling of submit_one_sector()
  btrfs: use bitmap_set() to replace set_bit() in a loop
  btrfs: extract the io finishing code into a helper
  btrfs: reduce extent map lookup during writes

 fs/btrfs/extent_io.c | 243 ++++++++++++++++++++++++-------------------
 1 file changed, 134 insertions(+), 109 deletions(-)

-- 
2.52.0