kernel/vm: Implement swap adoption for cut_area middle case.

Rename MovePageRange to Adopt and group it with Resize/Rebase as it
covers the third, middle cut case.

Implement VMAnonymousCache::Adopt() to actually adopt swap pages. This
has to recreate swap blocks instead of taking them over from the source
cache as the cut offset or base offset between the caches may not be
swap block aligned. This means that adoption may fail due to memory
shortage in allocating the swap blocks.

For the middle cut case it is therefore now possible to have the adopt
fail in which case the previous cache restore logic is applied. Since
the readoption of the pages from the second cache can fail for the same
reason, there is a slight chance that we can't restore and lose pages.
For now, just panic in such a case and add a TODO to free memory and
retry.

Change-Id: I9a661f00c8f03bbbea2fe6dee90371c68d7951e6
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2588
Reviewed-by: waddlesplash <[email protected]>

headers/private/kernel/vm/VMCache.h

@@ -113,8 +113,6 @@ public:
 			void				MovePage(vm_page* page, off_t offset);
 			void				MovePage(vm_page* page);
 			void				MoveAllPages(VMCache* fromCache);
-			void				MovePageRange(VMCache* source, off_t offset,
-									off_t size, off_t newOffset);
 
 	inline	page_num_t			WiredPagesCount() const;
 	inline	void				IncrementWiredPagesCount();
@@ -134,6 +132,8 @@ public:
 									int priority);
 	virtual	status_t			Resize(off_t newSize, int priority);
 	virtual	status_t			Rebase(off_t newBase, int priority);
+	virtual	status_t			Adopt(VMCache* source, off_t offset, off_t size,
+									off_t newOffset);
 
 			status_t			FlushAndRemoveAllPages();