btrfs: subpage: introduce helpers to handle subpage delalloc locking
Three new helpers are introduced for the incoming subpage delalloc locking
change.
- btrfs_folio_set_writer_lock()
This is to mark specified range with subpage specific writer lock.
After calling this, the subpage range can be proper unlocked by
btrfs_folio_end_writer_lock()
- btrfs_subpage_find_writer_locked()
This is to find the writer locked subpage range in a page.
With the help of btrfs_folio_set_writer_lock(), it can allow us to
record and find previously locked subpage range without extra memory
allocation.
- btrfs_folio_end_all_writers()
This is for the locked_page of __extent_writepage(), as there may be
multiple subpage delalloc ranges locked.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2 files changed
