[PATCH v2 0/2] btrfs: unify the read and writer locks for btrfs_subpage

[Qu Wenruo <wqu@suse.com>]

[CHANGELOG]
v2:
- Rename btrfs_subpage::locked to btrfs_subpage::nr_locked

When the handling of sector size < page size is introduced, there are
two types of locking, reader and writer lock.

The main reason for the reader lock is to handle metadata to make sure
the page::private is not released when there is still a metadata being
read.

However since commit d7172f52e993 ("btrfs: use per-buffer locking for
extent_buffer reading"), metadata read no longer relies on
btrfs_subpage::readers.

Making the writer lock as the only utilized subpage locking.

This patchset converts all the existing reader lock usage and rename the
writer lock into a generic lock.

This patchset relies on this patch "btrfs: fix the delalloc range
locking if sector size < page size", as it removes the last user of
btrfs_folio_start_writer_lock().

Qu Wenruo (2):
  btrfs: unify to use writer locks for subpage locking
  btrfs: rename btrfs_folio_(set|start|end)_writer_lock()

 fs/btrfs/compression.c |   3 +-
 fs/btrfs/extent_io.c   |  20 +++-----
 fs/btrfs/subpage.c     | 108 ++++++++++-------------------------------
 fs/btrfs/subpage.h     |  33 +++++--------
 4 files changed, 45 insertions(+), 119 deletions(-)

-- 
2.46.2