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page cache: use xa_lock

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Remove the address_space ->tree_lock and use the xa_lock newly added to
the radix_tree_root.  Rename the address_space ->page_tree to ->i_pages,
since we don't really care that it's a tree.

[willy@infradead.org: fix nds32, fs/dax.c]
  Link: http://lkml.kernel.org/r/20180406145415.GB20605@bombadil.infradead.orgLink: http://lkml.kernel.org/r/20180313132639.17387-9-willy@infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox
2018-04-10 16:36:56 -07:00
committed by Linus Torvalds
parent f6bb2a2c0b
commit b93b016313
39 changed files with 345 additions and 366 deletions
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14
Documentation/vm/page_migration
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@@ -90,7 +90,7 @@ Steps:
1. Lock the page to be migrated
2. Insure that writeback is complete.
2. Ensure that writeback is complete.
3. Lock the new page that we want to move to. It is locked so that accesses to
this (not yet uptodate) page immediately lock while the move is in progress.
@@ -100,8 +100,8 @@ Steps:
mapcount is not zero then we do not migrate the page. All user space
processes that attempt to access the page will now wait on the page lock.
5. The radix tree lock is taken. This will cause all processes trying
to access the page via the mapping to block on the radix tree spinlock.
5. The i_pages lock is taken. This will cause all processes trying
to access the page via the mapping to block on the spinlock.
6. The refcount of the page is examined and we back out if references remain
otherwise we know that we are the only one referencing this page.
@@ -114,12 +114,12 @@ Steps:
9. The radix tree is changed to point to the new page.
10. The reference count of the old page is dropped because the radix tree
10. The reference count of the old page is dropped because the address space
reference is gone. A reference to the new page is established because
the new page is referenced to by the radix tree.
the new page is referenced by the address space.
11. The radix tree lock is dropped. With that lookups in the mapping
become possible again. Processes will move from spinning on the tree_lock
11. The i_pages lock is dropped. With that lookups in the mapping
become possible again. Processes will move from spinning on the lock
to sleeping on the locked new page.
12. The page contents are copied to the new page.