btrfs: subpage: only call btrfs_alloc_subpage() when sectorsize is smaller than PAGE_SIZE
There are two call sites of btrfs_alloc_subpage():
- btrfs_attach_subpage()
We have ensured sectorsize is smaller than PAGE_SIZE
- alloc_extent_buffer()
We call btrfs_alloc_subpage() unconditionally.
The alloc_extent_buffer() forces us to check the sectorsize size against
page size inside btrfs_alloc_subpage().
Since the function name, btrfs_alloc_subpage(), already indicates it
should only get called for subpage cases, do the check in
alloc_extent_buffer() and add an ASSERT() in btrfs_alloc_subpage().
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>