page cache: use xa_lock

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.

[[e-mail]: fix nds32, fs/dax.c]
Link: http://lkml.kernel.org/r/[e-mail]: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Matthew Wilcox <[e-mail]>
Acked-by: Jeff Layton <[e-mail]>
Cc: Darrick J. Wong <[e-mail]>
Cc: Dave Chinner <[e-mail]>
Cc: Ryusuke Konishi <[e-mail]>
Cc: Will Deacon <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/cgroup-v1/memory.txt

···
 2.6 Locking
 
    lock_page_cgroup()/unlock_page_cgroup() should not be called under
-   mapping->tree_lock.
+   the i_pages lock.
 
    Other lock order is following:
    PG_locked.

Documentation/vm/page_migration

···
 
 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.
···
    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.
···
 
 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.

arch/arm/include/asm/cacheflush.h

···
 #define ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
 extern void flush_kernel_dcache_page(struct page *);
 
-#define flush_dcache_mmap_lock(mapping) \
-	spin_lock_irq(&(mapping)->tree_lock)
-#define flush_dcache_mmap_unlock(mapping) \
-	spin_unlock_irq(&(mapping)->tree_lock)
+#define flush_dcache_mmap_lock(mapping)		xa_lock_irq(&mapping->i_pages)
+#define flush_dcache_mmap_unlock(mapping)	xa_unlock_irq(&mapping->i_pages)
 
 #define flush_icache_user_range(vma,page,addr,len) \
 	flush_dcache_page(page)

arch/nds32/include/asm/cacheflush.h

···
 void flush_kernel_dcache_page(struct page *page);
 void flush_icache_range(unsigned long start, unsigned long end);
 void flush_icache_page(struct vm_area_struct *vma, struct page *page);
-#define flush_dcache_mmap_lock(mapping)   spin_lock_irq(&(mapping)->tree_lock)
-#define flush_dcache_mmap_unlock(mapping) spin_unlock_irq(&(mapping)->tree_lock)
+#define flush_dcache_mmap_lock(mapping)   xa_lock_irq(&(mapping)->i_pages)
+#define flush_dcache_mmap_unlock(mapping) xa_unlock_irq(&(mapping)->i_pages)
 
 #else
 #include <asm-generic/cacheflush.h>

arch/nios2/include/asm/cacheflush.h

···
 extern void flush_dcache_range(unsigned long start, unsigned long end);
 extern void invalidate_dcache_range(unsigned long start, unsigned long end);
 
-#define flush_dcache_mmap_lock(mapping) \
-	spin_lock_irq(&(mapping)->tree_lock)
-#define flush_dcache_mmap_unlock(mapping) \
-	spin_unlock_irq(&(mapping)->tree_lock)
+#define flush_dcache_mmap_lock(mapping)		xa_lock_irq(&mapping->i_pages)
+#define flush_dcache_mmap_unlock(mapping)	xa_unlock_irq(&mapping->i_pages)
 
 #endif /* _ASM_NIOS2_CACHEFLUSH_H */

arch/parisc/include/asm/cacheflush.h

···
 #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1
 extern void flush_dcache_page(struct page *page);
 
-#define flush_dcache_mmap_lock(mapping) \
-	spin_lock_irq(&(mapping)->tree_lock)
-#define flush_dcache_mmap_unlock(mapping) \
-	spin_unlock_irq(&(mapping)->tree_lock)
+#define flush_dcache_mmap_lock(mapping)		xa_lock_irq(&mapping->i_pages)
+#define flush_dcache_mmap_unlock(mapping)	xa_unlock_irq(&mapping->i_pages)
 
 #define flush_icache_page(vma,page)	do { 		\
 	flush_kernel_dcache_page(page);			\

drivers/staging/lustre/lustre/llite/glimpse.c

···
 	void	      *results[1];
 
 	if (inode->i_mapping)
-		cnt += radix_tree_gang_lookup_tag(&inode->i_mapping->page_tree,
+		cnt += radix_tree_gang_lookup_tag(&inode->i_mapping->i_pages,
 						  results, 0, 1,
 						  PAGECACHE_TAG_DIRTY);
 	if (cnt == 0 && atomic_read(&vob->vob_mmap_cnt) > 0)

drivers/staging/lustre/lustre/mdc/mdc_request.c

···
 	struct page *page;
 	int found;
 
-	spin_lock_irq(&mapping->tree_lock);
-	found = radix_tree_gang_lookup(&mapping->page_tree,
+	xa_lock_irq(&mapping->i_pages);
+	found = radix_tree_gang_lookup(&mapping->i_pages,
 				       (void **)&page, offset, 1);
 	if (found > 0 && !radix_tree_exceptional_entry(page)) {
 		struct lu_dirpage *dp;
 
 		get_page(page);
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		/*
 		 * In contrast to find_lock_page() we are sure that directory
 		 * page cannot be truncated (while DLM lock is held) and,
···
 			page = ERR_PTR(-EIO);
 		}
 	} else {
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		page = NULL;
 	}
 	return page;

fs/afs/write.c

···
 
 		_debug("wback %lx", page->index);
 
-		/* at this point we hold neither mapping->tree_lock nor lock on
-		 * the page itself: the page may be truncated or invalidated
-		 * (changing page->mapping to NULL), or even swizzled back from
-		 * swapper_space to tmpfs file mapping
+		/*
+		 * at this point we hold neither the i_pages lock nor the
+		 * page lock: the page may be truncated or invalidated
+		 * (changing page->mapping to NULL), or even swizzled
+		 * back from swapper_space to tmpfs file mapping
 		 */
 		ret = lock_page_killable(page);
 		if (ret < 0) {

fs/btrfs/compression.c

···
 			break;
 
 		rcu_read_lock();
-		page = radix_tree_lookup(&mapping->page_tree, pg_index);
+		page = radix_tree_lookup(&mapping->i_pages, pg_index);
 		rcu_read_unlock();
 		if (page && !radix_tree_exceptional_entry(page)) {
 			misses++;

fs/btrfs/extent_io.c

···
 
 			done_index = page->index;
 			/*
-			 * At this point we hold neither mapping->tree_lock nor
-			 * lock on the page itself: the page may be truncated or
-			 * invalidated (changing page->mapping to NULL), or even
-			 * swizzled back from swapper_space to tmpfs file
-			 * mapping
+			 * At this point we hold neither the i_pages lock nor
+			 * the page lock: the page may be truncated or
+			 * invalidated (changing page->mapping to NULL),
+			 * or even swizzled back from swapper_space to
+			 * tmpfs file mapping
 			 */
 			if (!trylock_page(page)) {
 				flush_write_bio(epd);
···
 		WARN_ON(!PagePrivate(page));
 
 		clear_page_dirty_for_io(page);
-		spin_lock_irq(&page->mapping->tree_lock);
+		xa_lock_irq(&page->mapping->i_pages);
 		if (!PageDirty(page)) {
-			radix_tree_tag_clear(&page->mapping->page_tree,
+			radix_tree_tag_clear(&page->mapping->i_pages,
 						page_index(page),
 						PAGECACHE_TAG_DIRTY);
 		}
-		spin_unlock_irq(&page->mapping->tree_lock);
+		xa_unlock_irq(&page->mapping->i_pages);
 		ClearPageError(page);
 		unlock_page(page);
 	}

fs/buffer.c

···
  * we get exclusion from try_to_free_buffers with the blockdev mapping's
  * private_lock.
  *
- * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
+ * Hack idea: for the blockdev mapping, private_lock contention
  * may be quite high.  This code could TryLock the page, and if that
- * succeeds, there is no need to take private_lock. (But if
- * private_lock is contended then so is mapping->tree_lock).
+ * succeeds, there is no need to take private_lock.
  */
 static struct buffer_head *
 __find_get_block_slow(struct block_device *bdev, sector_t block)
···
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&mapping->tree_lock, flags);
+	xa_lock_irqsave(&mapping->i_pages, flags);
 	if (page->mapping) {	/* Race with truncate? */
 		WARN_ON_ONCE(warn && !PageUptodate(page));
 		account_page_dirtied(page, mapping);
-		radix_tree_tag_set(&mapping->page_tree,
+		radix_tree_tag_set(&mapping->i_pages,
 				page_index(page), PAGECACHE_TAG_DIRTY);
 	}
-	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	xa_unlock_irqrestore(&mapping->i_pages, flags);
 }
 EXPORT_SYMBOL_GPL(__set_page_dirty);
 
···
  * inode list.
  *
  * mark_buffer_dirty() is atomic.  It takes bh->b_page->mapping->private_lock,
- * mapping->tree_lock and mapping->host->i_lock.
+ * i_pages lock and mapping->host->i_lock.
  */
 void mark_buffer_dirty(struct buffer_head *bh)
 {

fs/cifs/file.c

···
 	for (i = 0; i < found_pages; i++) {
 		page = wdata->pages[i];
 		/*
-		 * At this point we hold neither mapping->tree_lock nor
-		 * lock on the page itself: the page may be truncated or
-		 * invalidated (changing page->mapping to NULL), or even
-		 * swizzled back from swapper_space to tmpfs file
-		 * mapping
+		 * At this point we hold neither the i_pages lock nor the
+		 * page lock: the page may be truncated or invalidated
+		 * (changing page->mapping to NULL), or even swizzled
+		 * back from swapper_space to tmpfs file mapping
 		 */
 
 		if (nr_pages == 0)

fs/dax.c

···
 }
 
 /*
- * We do not necessarily hold the mapping->tree_lock when we call this
- * function so it is possible that 'entry' is no longer a valid item in the
- * radix tree.  This is okay because all we really need to do is to find the
- * correct waitqueue where tasks might be waiting for that old 'entry' and
- * wake them.
+ * @entry may no longer be the entry at the index in the mapping.
+ * The important information it's conveying is whether the entry at
+ * this index used to be a PMD entry.
  */
 static void dax_wake_mapping_entry_waiter(struct address_space *mapping,
 		pgoff_t index, void *entry, bool wake_all)
···
 
 	/*
 	 * Checking for locked entry and prepare_to_wait_exclusive() happens
-	 * under mapping->tree_lock, ditto for entry handling in our callers.
+	 * under the i_pages lock, ditto for entry handling in our callers.
 	 * So at this point all tasks that could have seen our entry locked
 	 * must be in the waitqueue and the following check will see them.
 	 */
···
 }
 
 /*
- * Check whether the given slot is locked. The function must be called with
- * mapping->tree_lock held
+ * Check whether the given slot is locked.  Must be called with the i_pages
+ * lock held.
  */
 static inline int slot_locked(struct address_space *mapping, void **slot)
 {
 	unsigned long entry = (unsigned long)
-		radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
+		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
 	return entry & RADIX_DAX_ENTRY_LOCK;
 }
 
 /*
- * Mark the given slot is locked. The function must be called with
- * mapping->tree_lock held
+ * Mark the given slot as locked.  Must be called with the i_pages lock held.
  */
 static inline void *lock_slot(struct address_space *mapping, void **slot)
 {
 	unsigned long entry = (unsigned long)
-		radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
+		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
 
 	entry |= RADIX_DAX_ENTRY_LOCK;
-	radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry);
+	radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry);
 	return (void *)entry;
 }
 
 /*
- * Mark the given slot is unlocked. The function must be called with
- * mapping->tree_lock held
+ * Mark the given slot as unlocked.  Must be called with the i_pages lock held.
  */
 static inline void *unlock_slot(struct address_space *mapping, void **slot)
 {
 	unsigned long entry = (unsigned long)
-		radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
+		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
 
 	entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK;
-	radix_tree_replace_slot(&mapping->page_tree, slot, (void *)entry);
+	radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry);
 	return (void *)entry;
 }
 
···
  * put_locked_mapping_entry() when he locked the entry and now wants to
  * unlock it.
  *
- * The function must be called with mapping->tree_lock held.
+ * Must be called with the i_pages lock held.
  */
 static void *get_unlocked_mapping_entry(struct address_space *mapping,
 					pgoff_t index, void ***slotp)
···
 	ewait.wait.func = wake_exceptional_entry_func;
 
 	for (;;) {
-		entry = __radix_tree_lookup(&mapping->page_tree, index, NULL,
+		entry = __radix_tree_lookup(&mapping->i_pages, index, NULL,
 					  &slot);
 		if (!entry ||
 		    WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)) ||
···
 		wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
 		prepare_to_wait_exclusive(wq, &ewait.wait,
 					  TASK_UNINTERRUPTIBLE);
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		schedule();
 		finish_wait(wq, &ewait.wait);
-		spin_lock_irq(&mapping->tree_lock);
+		xa_lock_irq(&mapping->i_pages);
 	}
 }
 
···
 {
 	void *entry, **slot;
 
-	spin_lock_irq(&mapping->tree_lock);
-	entry = __radix_tree_lookup(&mapping->page_tree, index, NULL, &slot);
+	xa_lock_irq(&mapping->i_pages);
+	entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, &slot);
 	if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) ||
 			 !slot_locked(mapping, slot))) {
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		return;
 	}
 	unlock_slot(mapping, slot);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 	dax_wake_mapping_entry_waiter(mapping, index, entry, false);
 }
 
···
 	void *entry, **slot;
 
 restart:
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 	entry = get_unlocked_mapping_entry(mapping, index, &slot);
 
 	if (WARN_ON_ONCE(entry && !radix_tree_exceptional_entry(entry))) {
···
 		if (pmd_downgrade) {
 			/*
 			 * Make sure 'entry' remains valid while we drop
-			 * mapping->tree_lock.
+			 * the i_pages lock.
 			 */
 			entry = lock_slot(mapping, slot);
 		}
 
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		/*
 		 * Besides huge zero pages the only other thing that gets
 		 * downgraded are empty entries which don't need to be
···
 				put_locked_mapping_entry(mapping, index);
 			return ERR_PTR(err);
 		}
-		spin_lock_irq(&mapping->tree_lock);
+		xa_lock_irq(&mapping->i_pages);
 
 		if (!entry) {
 			/*
-			 * We needed to drop the page_tree lock while calling
+			 * We needed to drop the i_pages lock while calling
 			 * radix_tree_preload() and we didn't have an entry to
 			 * lock.  See if another thread inserted an entry at
 			 * our index during this time.
 			 */
-			entry = __radix_tree_lookup(&mapping->page_tree, index,
+			entry = __radix_tree_lookup(&mapping->i_pages, index,
 					NULL, &slot);
 			if (entry) {
 				radix_tree_preload_end();
-				spin_unlock_irq(&mapping->tree_lock);
+				xa_unlock_irq(&mapping->i_pages);
 				goto restart;
 			}
 		}
 
 		if (pmd_downgrade) {
 			dax_disassociate_entry(entry, mapping, false);
-			radix_tree_delete(&mapping->page_tree, index);
+			radix_tree_delete(&mapping->i_pages, index);
 			mapping->nrexceptional--;
 			dax_wake_mapping_entry_waiter(mapping, index, entry,
 					true);
···
 
 		entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY);
 
-		err = __radix_tree_insert(&mapping->page_tree, index,
+		err = __radix_tree_insert(&mapping->i_pages, index,
 				dax_radix_order(entry), entry);
 		radix_tree_preload_end();
 		if (err) {
-			spin_unlock_irq(&mapping->tree_lock);
+			xa_unlock_irq(&mapping->i_pages);
 			/*
 			 * Our insertion of a DAX entry failed, most likely
 			 * because we were inserting a PMD entry and it
···
 		}
 		/* Good, we have inserted empty locked entry into the tree. */
 		mapping->nrexceptional++;
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		return entry;
 	}
 	entry = lock_slot(mapping, slot);
  out_unlock:
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 	return entry;
 }
 
···
 {
 	int ret = 0;
 	void *entry;
-	struct radix_tree_root *page_tree = &mapping->page_tree;
+	struct radix_tree_root *pages = &mapping->i_pages;
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(pages);
 	entry = get_unlocked_mapping_entry(mapping, index, NULL);
 	if (!entry || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)))
 		goto out;
 	if (!trunc &&
-	    (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
-	     radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)))
+	    (radix_tree_tag_get(pages, index, PAGECACHE_TAG_DIRTY) ||
+	     radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE)))
 		goto out;
 	dax_disassociate_entry(entry, mapping, trunc);
-	radix_tree_delete(page_tree, index);
+	radix_tree_delete(pages, index);
 	mapping->nrexceptional--;
 	ret = 1;
 out:
 	put_unlocked_mapping_entry(mapping, index, entry);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(pages);
 	return ret;
 }
 /*
···
 				      void *entry, pfn_t pfn_t,
 				      unsigned long flags, bool dirty)
 {
-	struct radix_tree_root *page_tree = &mapping->page_tree;
+	struct radix_tree_root *pages = &mapping->i_pages;
 	unsigned long pfn = pfn_t_to_pfn(pfn_t);
 	pgoff_t index = vmf->pgoff;
 	void *new_entry;
···
 			unmap_mapping_pages(mapping, vmf->pgoff, 1, false);
 	}
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(pages);
 	new_entry = dax_radix_locked_entry(pfn, flags);
 	if (dax_entry_size(entry) != dax_entry_size(new_entry)) {
 		dax_disassociate_entry(entry, mapping, false);
···
 		void **slot;
 		void *ret;
 
-		ret = __radix_tree_lookup(page_tree, index, &node, &slot);
+		ret = __radix_tree_lookup(pages, index, &node, &slot);
 		WARN_ON_ONCE(ret != entry);
-		__radix_tree_replace(page_tree, node, slot,
+		__radix_tree_replace(pages, node, slot,
 				     new_entry, NULL);
 		entry = new_entry;
 	}
 
 	if (dirty)
-		radix_tree_tag_set(page_tree, index, PAGECACHE_TAG_DIRTY);
+		radix_tree_tag_set(pages, index, PAGECACHE_TAG_DIRTY);
 
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(pages);
 	return entry;
 }
 
···
 static int dax_writeback_one(struct dax_device *dax_dev,
 		struct address_space *mapping, pgoff_t index, void *entry)
 {
-	struct radix_tree_root *page_tree = &mapping->page_tree;
+	struct radix_tree_root *pages = &mapping->i_pages;
 	void *entry2, **slot;
 	unsigned long pfn;
 	long ret = 0;
···
 	if (WARN_ON(!radix_tree_exceptional_entry(entry)))
 		return -EIO;
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(pages);
 	entry2 = get_unlocked_mapping_entry(mapping, index, &slot);
 	/* Entry got punched out / reallocated? */
 	if (!entry2 || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry2)))
···
 	}
 
 	/* Another fsync thread may have already written back this entry */
-	if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
+	if (!radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE))
 		goto put_unlocked;
 	/* Lock the entry to serialize with page faults */
 	entry = lock_slot(mapping, slot);
···
 	 * We can clear the tag now but we have to be careful so that concurrent
 	 * dax_writeback_one() calls for the same index cannot finish before we
 	 * actually flush the caches. This is achieved as the calls will look
-	 * at the entry only under tree_lock and once they do that they will
-	 * see the entry locked and wait for it to unlock.
+	 * at the entry only under the i_pages lock and once they do that
+	 * they will see the entry locked and wait for it to unlock.
 	 */
-	radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE);
-	spin_unlock_irq(&mapping->tree_lock);
+	radix_tree_tag_clear(pages, index, PAGECACHE_TAG_TOWRITE);
+	xa_unlock_irq(pages);
 
 	/*
 	 * Even if dax_writeback_mapping_range() was given a wbc->range_start
···
 	 * the pfn mappings are writeprotected and fault waits for mapping
 	 * entry lock.
 	 */
-	spin_lock_irq(&mapping->tree_lock);
-	radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_lock_irq(pages);
+	radix_tree_tag_clear(pages, index, PAGECACHE_TAG_DIRTY);
+	xa_unlock_irq(pages);
 	trace_dax_writeback_one(mapping->host, index, size >> PAGE_SHIFT);
 	put_locked_mapping_entry(mapping, index);
 	return ret;
 
  put_unlocked:
 	put_unlocked_mapping_entry(mapping, index, entry2);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(pages);
 	return ret;
 }
 
···
 	pgoff_t index = vmf->pgoff;
 	int vmf_ret, error;
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 	entry = get_unlocked_mapping_entry(mapping, index, &slot);
 	/* Did we race with someone splitting entry or so? */
 	if (!entry ||
 	    (pe_size == PE_SIZE_PTE && !dax_is_pte_entry(entry)) ||
 	    (pe_size == PE_SIZE_PMD && !dax_is_pmd_entry(entry))) {
 		put_unlocked_mapping_entry(mapping, index, entry);
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
 						      VM_FAULT_NOPAGE);
 		return VM_FAULT_NOPAGE;
 	}
-	radix_tree_tag_set(&mapping->page_tree, index, PAGECACHE_TAG_DIRTY);
+	radix_tree_tag_set(&mapping->i_pages, index, PAGECACHE_TAG_DIRTY);
 	entry = lock_slot(mapping, slot);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 	switch (pe_size) {
 	case PE_SIZE_PTE:
 		error = vm_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);

fs/f2fs/data.c

···
 	SetPageDirty(page);
 	spin_unlock(&mapping->private_lock);
 
-	spin_lock_irqsave(&mapping->tree_lock, flags);
+	xa_lock_irqsave(&mapping->i_pages, flags);
 	WARN_ON_ONCE(!PageUptodate(page));
 	account_page_dirtied(page, mapping);
-	radix_tree_tag_set(&mapping->page_tree,
+	radix_tree_tag_set(&mapping->i_pages,
 			page_index(page), PAGECACHE_TAG_DIRTY);
-	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	xa_unlock_irqrestore(&mapping->i_pages, flags);
 	unlock_page_memcg(page);
 
 	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);

fs/f2fs/dir.c

···
 
 	if (bit_pos == NR_DENTRY_IN_BLOCK &&
 			!truncate_hole(dir, page->index, page->index + 1)) {
-		spin_lock_irqsave(&mapping->tree_lock, flags);
-		radix_tree_tag_clear(&mapping->page_tree, page_index(page),
+		xa_lock_irqsave(&mapping->i_pages, flags);
+		radix_tree_tag_clear(&mapping->i_pages, page_index(page),
 				     PAGECACHE_TAG_DIRTY);
-		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		xa_unlock_irqrestore(&mapping->i_pages, flags);
 
 		clear_page_dirty_for_io(page);
 		ClearPagePrivate(page);

fs/f2fs/inline.c

···
 	kunmap_atomic(src_addr);
 	set_page_dirty(dn.inode_page);
 
-	spin_lock_irqsave(&mapping->tree_lock, flags);
-	radix_tree_tag_clear(&mapping->page_tree, page_index(page),
+	xa_lock_irqsave(&mapping->i_pages, flags);
+	radix_tree_tag_clear(&mapping->i_pages, page_index(page),
 			     PAGECACHE_TAG_DIRTY);
-	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	xa_unlock_irqrestore(&mapping->i_pages, flags);
 
 	set_inode_flag(inode, FI_APPEND_WRITE);
 	set_inode_flag(inode, FI_DATA_EXIST);

fs/f2fs/node.c

···
 	unsigned int long flags;
 
 	if (PageDirty(page)) {
-		spin_lock_irqsave(&mapping->tree_lock, flags);
-		radix_tree_tag_clear(&mapping->page_tree,
+		xa_lock_irqsave(&mapping->i_pages, flags);
+		radix_tree_tag_clear(&mapping->i_pages,
 				page_index(page),
 				PAGECACHE_TAG_DIRTY);
-		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		xa_unlock_irqrestore(&mapping->i_pages, flags);
 
 		clear_page_dirty_for_io(page);
 		dec_page_count(F2FS_M_SB(mapping), F2FS_DIRTY_NODES);
···
 	f2fs_bug_on(sbi, check_nid_range(sbi, nid));
 
 	rcu_read_lock();
-	apage = radix_tree_lookup(&NODE_MAPPING(sbi)->page_tree, nid);
+	apage = radix_tree_lookup(&NODE_MAPPING(sbi)->i_pages, nid);
 	rcu_read_unlock();
 	if (apage)
 		return;

fs/fs-writeback.c

···
 	 * By the time control reaches here, RCU grace period has passed
 	 * since I_WB_SWITCH assertion and all wb stat update transactions
 	 * between unlocked_inode_to_wb_begin/end() are guaranteed to be
-	 * synchronizing against mapping->tree_lock.
+	 * synchronizing against the i_pages lock.
 	 *
-	 * Grabbing old_wb->list_lock, inode->i_lock and mapping->tree_lock
+	 * Grabbing old_wb->list_lock, inode->i_lock and the i_pages lock
 	 * gives us exclusion against all wb related operations on @inode
 	 * including IO list manipulations and stat updates.
 	 */
···
 		spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING);
 	}
 	spin_lock(&inode->i_lock);
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 
 	/*
 	 * Once I_FREEING is visible under i_lock, the eviction path owns
···
 	/*
 	 * Count and transfer stats.  Note that PAGECACHE_TAG_DIRTY points
 	 * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to
-	 * pages actually under underwriteback.
+	 * pages actually under writeback.
 	 */
-	radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0,
+	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, 0,
 				   PAGECACHE_TAG_DIRTY) {
 		struct page *page = radix_tree_deref_slot_protected(slot,
-							&mapping->tree_lock);
+						&mapping->i_pages.xa_lock);
 		if (likely(page) && PageDirty(page)) {
 			dec_wb_stat(old_wb, WB_RECLAIMABLE);
 			inc_wb_stat(new_wb, WB_RECLAIMABLE);
 		}
 	}
 
-	radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0,
+	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, 0,
 				   PAGECACHE_TAG_WRITEBACK) {
 		struct page *page = radix_tree_deref_slot_protected(slot,
-							&mapping->tree_lock);
+						&mapping->i_pages.xa_lock);
 		if (likely(page)) {
 			WARN_ON_ONCE(!PageWriteback(page));
 			dec_wb_stat(old_wb, WB_WRITEBACK);
···
 	 */
 	smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH);
 
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 	spin_unlock(&inode->i_lock);
 	spin_unlock(&new_wb->list_lock);
 	spin_unlock(&old_wb->list_lock);
···
 
 	/*
 	 * In addition to synchronizing among switchers, I_WB_SWITCH tells
-	 * the RCU protected stat update paths to grab the mapping's
-	 * tree_lock so that stat transfer can synchronize against them.
+	 * the RCU protected stat update paths to grab the i_page
+	 * lock so that stat transfer can synchronize against them.
 	 * Let's continue after I_WB_SWITCH is guaranteed to be visible.
 	 */
 	call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn);

fs/inode.c

···
 
 static void __address_space_init_once(struct address_space *mapping)
 {
-	INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC | __GFP_ACCOUNT);
-	spin_lock_init(&mapping->tree_lock);
+	INIT_RADIX_TREE(&mapping->i_pages, GFP_ATOMIC | __GFP_ACCOUNT);
 	init_rwsem(&mapping->i_mmap_rwsem);
 	INIT_LIST_HEAD(&mapping->private_list);
 	spin_lock_init(&mapping->private_lock);
···
 void clear_inode(struct inode *inode)
 {
 	/*
-	 * We have to cycle tree_lock here because reclaim can be still in the
+	 * We have to cycle the i_pages lock here because reclaim can be in the
 	 * process of removing the last page (in __delete_from_page_cache())
-	 * and we must not free mapping under it.
+	 * and we must not free the mapping under it.
 	 */
-	spin_lock_irq(&inode->i_data.tree_lock);
+	xa_lock_irq(&inode->i_data.i_pages);
 	BUG_ON(inode->i_data.nrpages);
 	BUG_ON(inode->i_data.nrexceptional);
-	spin_unlock_irq(&inode->i_data.tree_lock);
+	xa_unlock_irq(&inode->i_data.i_pages);
 	BUG_ON(!list_empty(&inode->i_data.private_list));
 	BUG_ON(!(inode->i_state & I_FREEING));
 	BUG_ON(inode->i_state & I_CLEAR);

fs/nilfs2/btnode.c

···
 				       (unsigned long long)oldkey,
 				       (unsigned long long)newkey);
 
-		spin_lock_irq(&btnc->tree_lock);
-		err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
-		spin_unlock_irq(&btnc->tree_lock);
+		xa_lock_irq(&btnc->i_pages);
+		err = radix_tree_insert(&btnc->i_pages, newkey, obh->b_page);
+		xa_unlock_irq(&btnc->i_pages);
 		/*
 		 * Note: page->index will not change to newkey until
 		 * nilfs_btnode_commit_change_key() will be called.
···
 				       (unsigned long long)newkey);
 		mark_buffer_dirty(obh);
 
-		spin_lock_irq(&btnc->tree_lock);
-		radix_tree_delete(&btnc->page_tree, oldkey);
-		radix_tree_tag_set(&btnc->page_tree, newkey,
+		xa_lock_irq(&btnc->i_pages);
+		radix_tree_delete(&btnc->i_pages, oldkey);
+		radix_tree_tag_set(&btnc->i_pages, newkey,
 				   PAGECACHE_TAG_DIRTY);
-		spin_unlock_irq(&btnc->tree_lock);
+		xa_unlock_irq(&btnc->i_pages);
 
 		opage->index = obh->b_blocknr = newkey;
 		unlock_page(opage);
···
 		return;
 
 	if (nbh == NULL) {	/* blocksize == pagesize */
-		spin_lock_irq(&btnc->tree_lock);
-		radix_tree_delete(&btnc->page_tree, newkey);
-		spin_unlock_irq(&btnc->tree_lock);
+		xa_lock_irq(&btnc->i_pages);
+		radix_tree_delete(&btnc->i_pages, newkey);
+		xa_unlock_irq(&btnc->i_pages);
 		unlock_page(ctxt->bh->b_page);
 	} else
 		brelse(nbh);

fs/nilfs2/page.c

···
 			struct page *page2;
 
 			/* move the page to the destination cache */
-			spin_lock_irq(&smap->tree_lock);
-			page2 = radix_tree_delete(&smap->page_tree, offset);
+			xa_lock_irq(&smap->i_pages);
+			page2 = radix_tree_delete(&smap->i_pages, offset);
 			WARN_ON(page2 != page);
 
 			smap->nrpages--;
-			spin_unlock_irq(&smap->tree_lock);
+			xa_unlock_irq(&smap->i_pages);
 
-			spin_lock_irq(&dmap->tree_lock);
-			err = radix_tree_insert(&dmap->page_tree, offset, page);
+			xa_lock_irq(&dmap->i_pages);
+			err = radix_tree_insert(&dmap->i_pages, offset, page);
 			if (unlikely(err < 0)) {
 				WARN_ON(err == -EEXIST);
 				page->mapping = NULL;
···
 				page->mapping = dmap;
 				dmap->nrpages++;
 				if (PageDirty(page))
-					radix_tree_tag_set(&dmap->page_tree,
+					radix_tree_tag_set(&dmap->i_pages,
 							   offset,
 							   PAGECACHE_TAG_DIRTY);
 			}
-			spin_unlock_irq(&dmap->tree_lock);
+			xa_unlock_irq(&dmap->i_pages);
 		}
 		unlock_page(page);
 	}
···
 	struct address_space *mapping = page->mapping;
 
 	if (mapping) {
-		spin_lock_irq(&mapping->tree_lock);
+		xa_lock_irq(&mapping->i_pages);
 		if (test_bit(PG_dirty, &page->flags)) {
-			radix_tree_tag_clear(&mapping->page_tree,
+			radix_tree_tag_clear(&mapping->i_pages,
 					     page_index(page),
 					     PAGECACHE_TAG_DIRTY);
-			spin_unlock_irq(&mapping->tree_lock);
+			xa_unlock_irq(&mapping->i_pages);
 			return clear_page_dirty_for_io(page);
 		}
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		return 0;
 	}
 	return TestClearPageDirty(page);

include/linux/backing-dev.h

···
  * @inode: inode of interest
  *
  * Returns the wb @inode is currently associated with.  The caller must be
- * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
+ * holding either @inode->i_lock, the i_pages lock, or the
  * associated wb's list_lock.
  */
 static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
···
 #ifdef CONFIG_LOCKDEP
 	WARN_ON_ONCE(debug_locks &&
 		     (!lockdep_is_held(&inode->i_lock) &&
-		      !lockdep_is_held(&inode->i_mapping->tree_lock) &&
+		      !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&
 		      !lockdep_is_held(&inode->i_wb->list_lock)));
 #endif
 	return inode->i_wb;
···
  * @lockedp: temp bool output param, to be passed to the end function
  *
  * The caller wants to access the wb associated with @inode but isn't
- * holding inode->i_lock, mapping->tree_lock or wb->list_lock.  This
+ * holding inode->i_lock, the i_pages lock or wb->list_lock.  This
  * function determines the wb associated with @inode and ensures that the
  * association doesn't change until the transaction is finished with
  * unlocked_inode_to_wb_end().
···
 	*lockedp = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
 
 	if (unlikely(*lockedp))
-		spin_lock_irq(&inode->i_mapping->tree_lock);
+		xa_lock_irq(&inode->i_mapping->i_pages);
 
 	/*
-	 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
-	 * inode_to_wb() will bark.  Deref directly.
+	 * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages
+	 * lock.  inode_to_wb() will bark.  Deref directly.
 	 */
 	return inode->i_wb;
 }
···
 static inline void unlocked_inode_to_wb_end(struct inode *inode, bool locked)
 {
 	if (unlikely(locked))
-		spin_unlock_irq(&inode->i_mapping->tree_lock);
+		xa_unlock_irq(&inode->i_mapping->i_pages);
 
 	rcu_read_unlock();
 }

include/linux/fs.h

···
 #include <linux/list_lru.h>
 #include <linux/llist.h>
 #include <linux/radix-tree.h>
+#include <linux/xarray.h>
 #include <linux/rbtree.h>
 #include <linux/init.h>
 #include <linux/pid.h>
···
 
 struct address_space {
 	struct inode		*host;		/* owner: inode, block_device */
-	struct radix_tree_root	page_tree;	/* radix tree of all pages */
-	spinlock_t		tree_lock;	/* and lock protecting it */
+	struct radix_tree_root	i_pages;	/* cached pages */
 	atomic_t		i_mmap_writable;/* count VM_SHARED mappings */
 	struct rb_root_cached	i_mmap;		/* tree of private and shared mappings */
 	struct rw_semaphore	i_mmap_rwsem;	/* protect tree, count, list */
-	/* Protected by tree_lock together with the radix tree */
+	/* Protected by the i_pages lock */
 	unsigned long		nrpages;	/* number of total pages */
 	/* number of shadow or DAX exceptional entries */
 	unsigned long		nrexceptional;
···
  *
  * I_WB_SWITCH		Cgroup bdi_writeback switching in progress.  Used to
  *			synchronize competing switching instances and to tell
- *			wb stat updates to grab mapping->tree_lock.  See
+ *			wb stat updates to grab the i_pages lock.  See
  *			inode_switch_wb_work_fn() for details.
  *
  * I_OVL_INUSE		Used by overlayfs to get exclusive ownership on upper

include/linux/mm.h

···
  * refcount. The each user mapping also has a reference to the page.
  *
  * The pagecache pages are stored in a per-mapping radix tree, which is
- * rooted at mapping->page_tree, and indexed by offset.
+ * rooted at mapping->i_pages, and indexed by offset.
  * Where 2.4 and early 2.6 kernels kept dirty/clean pages in per-address_space
  * lists, we instead now tag pages as dirty/writeback in the radix tree.
  *

include/linux/pagemap.h

···
  * 3. check the page is still in pagecache (if no, goto 1)
  *
  * Remove-side that cares about stability of _refcount (eg. reclaim) has the
- * following (with tree_lock held for write):
+ * following (with the i_pages lock held):
  * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
  * B. remove page from pagecache
  * C. free the page
···
  *
  * It is possible that between 1 and 2, the page is removed then the exact same
  * page is inserted into the same position in pagecache. That's OK: the
- * old find_get_page using tree_lock could equally have run before or after
+ * old find_get_page using a lock could equally have run before or after
  * such a re-insertion, depending on order that locks are granted.
  *
  * Lookups racing against pagecache insertion isn't a big problem: either 1

mm/filemap.c

···
  *  ->i_mmap_rwsem		(truncate_pagecache)
  *    ->private_lock		(__free_pte->__set_page_dirty_buffers)
  *      ->swap_lock		(exclusive_swap_page, others)
- *        ->mapping->tree_lock
+ *        ->i_pages lock
  *
  *  ->i_mutex
  *    ->i_mmap_rwsem		(truncate->unmap_mapping_range)
···
  *  ->mmap_sem
  *    ->i_mmap_rwsem
  *      ->page_table_lock or pte_lock	(various, mainly in memory.c)
- *        ->mapping->tree_lock	(arch-dependent flush_dcache_mmap_lock)
+ *        ->i_pages lock	(arch-dependent flush_dcache_mmap_lock)
  *
  *  ->mmap_sem
  *    ->lock_page		(access_process_vm)
···
  *
  *  bdi->wb.list_lock
  *    sb_lock			(fs/fs-writeback.c)
- *    ->mapping->tree_lock	(__sync_single_inode)
+ *    ->i_pages lock		(__sync_single_inode)
  *
  *  ->i_mmap_rwsem
  *    ->anon_vma.lock		(vma_adjust)
···
  *  ->page_table_lock or pte_lock
  *    ->swap_lock		(try_to_unmap_one)
  *    ->private_lock		(try_to_unmap_one)
- *    ->tree_lock		(try_to_unmap_one)
+ *    ->i_pages lock		(try_to_unmap_one)
  *    ->zone_lru_lock(zone)	(follow_page->mark_page_accessed)
  *    ->zone_lru_lock(zone)	(check_pte_range->isolate_lru_page)
  *    ->private_lock		(page_remove_rmap->set_page_dirty)
- *    ->tree_lock		(page_remove_rmap->set_page_dirty)
+ *    ->i_pages lock		(page_remove_rmap->set_page_dirty)
  *    bdi.wb->list_lock		(page_remove_rmap->set_page_dirty)
  *    ->inode->i_lock		(page_remove_rmap->set_page_dirty)
  *    ->memcg->move_lock	(page_remove_rmap->lock_page_memcg)
···
 	void **slot;
 	int error;
 
-	error = __radix_tree_create(&mapping->page_tree, page->index, 0,
+	error = __radix_tree_create(&mapping->i_pages, page->index, 0,
 				    &node, &slot);
 	if (error)
 		return error;
 	if (*slot) {
 		void *p;
 
-		p = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
+		p = radix_tree_deref_slot_protected(slot,
+						    &mapping->i_pages.xa_lock);
 		if (!radix_tree_exceptional_entry(p))
 			return -EEXIST;
 
···
 		if (shadowp)
 			*shadowp = p;
 	}
-	__radix_tree_replace(&mapping->page_tree, node, slot, page,
+	__radix_tree_replace(&mapping->i_pages, node, slot, page,
 			     workingset_lookup_update(mapping));
 	mapping->nrpages++;
 	return 0;
···
 		struct radix_tree_node *node;
 		void **slot;
 
-		__radix_tree_lookup(&mapping->page_tree, page->index + i,
+		__radix_tree_lookup(&mapping->i_pages, page->index + i,
 				    &node, &slot);
 
 		VM_BUG_ON_PAGE(!node && nr != 1, page);
 
-		radix_tree_clear_tags(&mapping->page_tree, node, slot);
-		__radix_tree_replace(&mapping->page_tree, node, slot, shadow,
+		radix_tree_clear_tags(&mapping->i_pages, node, slot);
+		__radix_tree_replace(&mapping->i_pages, node, slot, shadow,
 				workingset_lookup_update(mapping));
 	}
 
···
 /*
  * Delete a page from the page cache and free it. Caller has to make
  * sure the page is locked and that nobody else uses it - or that usage
- * is safe.  The caller must hold the mapping's tree_lock.
+ * is safe.  The caller must hold the i_pages lock.
  */
 void __delete_from_page_cache(struct page *page, void *shadow)
 {
···
 	unsigned long flags;
 
 	BUG_ON(!PageLocked(page));
-	spin_lock_irqsave(&mapping->tree_lock, flags);
+	xa_lock_irqsave(&mapping->i_pages, flags);
 	__delete_from_page_cache(page, NULL);
-	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	xa_unlock_irqrestore(&mapping->i_pages, flags);
 
 	page_cache_free_page(mapping, page);
 }
···
  * @mapping: the mapping to which pages belong
  * @pvec: pagevec with pages to delete
  *
- * The function walks over mapping->page_tree and removes pages passed in @pvec
- * from the radix tree. The function expects @pvec to be sorted by page index.
- * It tolerates holes in @pvec (radix tree entries at those indices are not
+ * The function walks over mapping->i_pages and removes pages passed in @pvec
+ * from the mapping. The function expects @pvec to be sorted by page index.
+ * It tolerates holes in @pvec (mapping entries at those indices are not
  * modified). The function expects only THP head pages to be present in the
- * @pvec and takes care to delete all corresponding tail pages from the radix
- * tree as well.
+ * @pvec and takes care to delete all corresponding tail pages from the
+ * mapping as well.
  *
- * The function expects mapping->tree_lock to be held.
+ * The function expects the i_pages lock to be held.
  */
 static void
 page_cache_tree_delete_batch(struct address_space *mapping,
···
 	pgoff_t start;
 
 	start = pvec->pages[0]->index;
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
 		if (i >= pagevec_count(pvec) && !tail_pages)
 			break;
 		page = radix_tree_deref_slot_protected(slot,
-						       &mapping->tree_lock);
+						       &mapping->i_pages.xa_lock);
 		if (radix_tree_exceptional_entry(page))
 			continue;
 		if (!tail_pages) {
···
 		} else {
 			tail_pages--;
 		}
-		radix_tree_clear_tags(&mapping->page_tree, iter.node, slot);
-		__radix_tree_replace(&mapping->page_tree, iter.node, slot, NULL,
+		radix_tree_clear_tags(&mapping->i_pages, iter.node, slot);
+		__radix_tree_replace(&mapping->i_pages, iter.node, slot, NULL,
 				workingset_lookup_update(mapping));
 		total_pages++;
 	}
···
 	if (!pagevec_count(pvec))
 		return;
 
-	spin_lock_irqsave(&mapping->tree_lock, flags);
+	xa_lock_irqsave(&mapping->i_pages, flags);
 	for (i = 0; i < pagevec_count(pvec); i++) {
 		trace_mm_filemap_delete_from_page_cache(pvec->pages[i]);
 
 		unaccount_page_cache_page(mapping, pvec->pages[i]);
 	}
 	page_cache_tree_delete_batch(mapping, pvec);
-	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	xa_unlock_irqrestore(&mapping->i_pages, flags);
 
 	for (i = 0; i < pagevec_count(pvec); i++)
 		page_cache_free_page(mapping, pvec->pages[i]);
···
 		new->mapping = mapping;
 		new->index = offset;
 
-		spin_lock_irqsave(&mapping->tree_lock, flags);
+		xa_lock_irqsave(&mapping->i_pages, flags);
 		__delete_from_page_cache(old, NULL);
 		error = page_cache_tree_insert(mapping, new, NULL);
 		BUG_ON(error);
···
 			__inc_node_page_state(new, NR_FILE_PAGES);
 		if (PageSwapBacked(new))
 			__inc_node_page_state(new, NR_SHMEM);
-		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		xa_unlock_irqrestore(&mapping->i_pages, flags);
 		mem_cgroup_migrate(old, new);
 		radix_tree_preload_end();
 		if (freepage)
···
 	page->mapping = mapping;
 	page->index = offset;
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 	error = page_cache_tree_insert(mapping, page, shadowp);
 	radix_tree_preload_end();
 	if (unlikely(error))
···
 	/* hugetlb pages do not participate in page cache accounting. */
 	if (!huge)
 		__inc_node_page_state(page, NR_FILE_PAGES);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 	if (!huge)
 		mem_cgroup_commit_charge(page, memcg, false, false);
 	trace_mm_filemap_add_to_page_cache(page);
···
 err_insert:
 	page->mapping = NULL;
 	/* Leave page->index set: truncation relies upon it */
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 	if (!huge)
 		mem_cgroup_cancel_charge(page, memcg, false);
 	put_page(page);
···
 	for (i = 0; i < max_scan; i++) {
 		struct page *page;
 
-		page = radix_tree_lookup(&mapping->page_tree, index);
+		page = radix_tree_lookup(&mapping->i_pages, index);
 		if (!page || radix_tree_exceptional_entry(page))
 			break;
 		index++;
···
 	for (i = 0; i < max_scan; i++) {
 		struct page *page;
 
-		page = radix_tree_lookup(&mapping->page_tree, index);
+		page = radix_tree_lookup(&mapping->i_pages, index);
 		if (!page || radix_tree_exceptional_entry(page))
 			break;
 		index--;
···
 	rcu_read_lock();
 repeat:
 	page = NULL;
-	pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
+	pagep = radix_tree_lookup_slot(&mapping->i_pages, offset);
 	if (pagep) {
 		page = radix_tree_deref_slot(pagep);
 		if (unlikely(!page))
···
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
 		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
···
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, *start) {
+	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, *start) {
 		struct page *head, *page;
 
 		if (iter.index > end)
···
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_contig(slot, &mapping->page_tree, &iter, index) {
+	radix_tree_for_each_contig(slot, &mapping->i_pages, &iter, index) {
 		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
···
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_tagged(slot, &mapping->page_tree,
-				   &iter, *index, tag) {
+	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, *index, tag) {
 		struct page *head, *page;
 
 		if (iter.index > end)
···
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_tagged(slot, &mapping->page_tree,
-				   &iter, start, tag) {
+	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, start, tag) {
 		struct page *head, *page;
 repeat:
 		page = radix_tree_deref_slot(slot);
···
 	struct page *head, *page;
 
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter,
-			start_pgoff) {
+	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start_pgoff) {
 		if (iter.index > end_pgoff)
 			break;
 repeat:

mm/huge_memory.c

···
 	} else {
 		/* Additional pin to radix tree */
 		page_ref_add(head, 2);
-		spin_unlock(&head->mapping->tree_lock);
+		xa_unlock(&head->mapping->i_pages);
 	}
 
 	spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
···
 	if (mapping) {
 		void **pslot;
 
-		spin_lock(&mapping->tree_lock);
-		pslot = radix_tree_lookup_slot(&mapping->page_tree,
+		xa_lock(&mapping->i_pages);
+		pslot = radix_tree_lookup_slot(&mapping->i_pages,
 				page_index(head));
 		/*
 		 * Check if the head page is present in radix tree.
 		 * We assume all tail are present too, if head is there.
 		 */
 		if (radix_tree_deref_slot_protected(pslot,
-					&mapping->tree_lock) != head)
+					&mapping->i_pages.xa_lock) != head)
 			goto fail;
 	}
 
···
 		}
 		spin_unlock(&pgdata->split_queue_lock);
 fail:		if (mapping)
-			spin_unlock(&mapping->tree_lock);
+			xa_unlock(&mapping->i_pages);
 		spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
 		unfreeze_page(head);
 		ret = -EBUSY;

mm/khugepaged.c

···
 	 */
 
 	index = start;
-	spin_lock_irq(&mapping->tree_lock);
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+	xa_lock_irq(&mapping->i_pages);
+	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
 		int n = min(iter.index, end) - index;
 
 		/*
···
 		}
 		nr_none += n;
 		for (; index < min(iter.index, end); index++) {
-			radix_tree_insert(&mapping->page_tree, index,
+			radix_tree_insert(&mapping->i_pages, index,
 					new_page + (index % HPAGE_PMD_NR));
 		}
 
···
 			break;
 
 		page = radix_tree_deref_slot_protected(slot,
-				&mapping->tree_lock);
+				&mapping->i_pages.xa_lock);
 		if (radix_tree_exceptional_entry(page) || !PageUptodate(page)) {
-			spin_unlock_irq(&mapping->tree_lock);
+			xa_unlock_irq(&mapping->i_pages);
 			/* swap in or instantiate fallocated page */
 			if (shmem_getpage(mapping->host, index, &page,
 						SGP_NOHUGE)) {
 				result = SCAN_FAIL;
 				goto tree_unlocked;
 			}
-			spin_lock_irq(&mapping->tree_lock);
+			xa_lock_irq(&mapping->i_pages);
 		} else if (trylock_page(page)) {
 			get_page(page);
 		} else {
···
 		}
 
 		/*
-		 * The page must be locked, so we can drop the tree_lock
+		 * The page must be locked, so we can drop the i_pages lock
 		 * without racing with truncate.
 		 */
 		VM_BUG_ON_PAGE(!PageLocked(page), page);
···
 			result = SCAN_TRUNCATED;
 			goto out_unlock;
 		}
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 
 		if (isolate_lru_page(page)) {
 			result = SCAN_DEL_PAGE_LRU;
···
 		if (page_mapped(page))
 			unmap_mapping_pages(mapping, index, 1, false);
 
-		spin_lock_irq(&mapping->tree_lock);
+		xa_lock_irq(&mapping->i_pages);
 
-		slot = radix_tree_lookup_slot(&mapping->page_tree, index);
+		slot = radix_tree_lookup_slot(&mapping->i_pages, index);
 		VM_BUG_ON_PAGE(page != radix_tree_deref_slot_protected(slot,
-					&mapping->tree_lock), page);
+					&mapping->i_pages.xa_lock), page);
 		VM_BUG_ON_PAGE(page_mapped(page), page);
 
 		/*
···
 		list_add_tail(&page->lru, &pagelist);
 
 		/* Finally, replace with the new page. */
-		radix_tree_replace_slot(&mapping->page_tree, slot,
+		radix_tree_replace_slot(&mapping->i_pages, slot,
 				new_page + (index % HPAGE_PMD_NR));
 
 		slot = radix_tree_iter_resume(slot, &iter);
 		index++;
 		continue;
 out_lru:
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		putback_lru_page(page);
 out_isolate_failed:
 		unlock_page(page);
···
 		}
 
 		for (; index < end; index++) {
-			radix_tree_insert(&mapping->page_tree, index,
+			radix_tree_insert(&mapping->i_pages, index,
 					new_page + (index % HPAGE_PMD_NR));
 		}
 		nr_none += n;
 	}
 
 tree_locked:
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 tree_unlocked:
 
 	if (result == SCAN_SUCCEED) {
···
 	} else {
 		/* Something went wrong: rollback changes to the radix-tree */
 		shmem_uncharge(mapping->host, nr_none);
-		spin_lock_irq(&mapping->tree_lock);
-		radix_tree_for_each_slot(slot, &mapping->page_tree, &iter,
-				start) {
+		xa_lock_irq(&mapping->i_pages);
+		radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
 			if (iter.index >= end)
 				break;
 			page = list_first_entry_or_null(&pagelist,
···
 					break;
 				nr_none--;
 				/* Put holes back where they were */
-				radix_tree_delete(&mapping->page_tree,
-						  iter.index);
+				radix_tree_delete(&mapping->i_pages, iter.index);
 				continue;
 			}
 
···
 			/* Unfreeze the page. */
 			list_del(&page->lru);
 			page_ref_unfreeze(page, 2);
-			radix_tree_replace_slot(&mapping->page_tree,
-						slot, page);
+			radix_tree_replace_slot(&mapping->i_pages, slot, page);
 			slot = radix_tree_iter_resume(slot, &iter);
-			spin_unlock_irq(&mapping->tree_lock);
+			xa_unlock_irq(&mapping->i_pages);
 			putback_lru_page(page);
 			unlock_page(page);
-			spin_lock_irq(&mapping->tree_lock);
+			xa_lock_irq(&mapping->i_pages);
 		}
 		VM_BUG_ON(nr_none);
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 
 		/* Unfreeze new_page, caller would take care about freeing it */
 		page_ref_unfreeze(new_page, 1);
···
 	swap = 0;
 	memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
 		if (iter.index >= start + HPAGE_PMD_NR)
 			break;
 

mm/memcontrol.c

···
 
 	/*
 	 * Interrupts should be disabled here because the caller holds the
-	 * mapping->tree_lock lock which is taken with interrupts-off. It is
+	 * i_pages lock which is taken with interrupts-off. It is
 	 * important here to have the interrupts disabled because it is the
-	 * only synchronisation we have for udpating the per-CPU variables.
+	 * only synchronisation we have for updating the per-CPU variables.
 	 */
 	VM_BUG_ON(!irqs_disabled());
 	mem_cgroup_charge_statistics(memcg, page, PageTransHuge(page),

mm/migrate.c

···
 	oldzone = page_zone(page);
 	newzone = page_zone(newpage);
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 
-	pslot = radix_tree_lookup_slot(&mapping->page_tree,
+	pslot = radix_tree_lookup_slot(&mapping->i_pages,
  					page_index(page));
 
 	expected_count += 1 + page_has_private(page);
 	if (page_count(page) != expected_count ||
-		radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
-		spin_unlock_irq(&mapping->tree_lock);
+		radix_tree_deref_slot_protected(pslot,
+					&mapping->i_pages.xa_lock) != page) {
+		xa_unlock_irq(&mapping->i_pages);
 		return -EAGAIN;
 	}
 
 	if (!page_ref_freeze(page, expected_count)) {
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		return -EAGAIN;
 	}
 
···
 	if (mode == MIGRATE_ASYNC && head &&
 			!buffer_migrate_lock_buffers(head, mode)) {
 		page_ref_unfreeze(page, expected_count);
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		return -EAGAIN;
 	}
 
···
 		SetPageDirty(newpage);
 	}
 
-	radix_tree_replace_slot(&mapping->page_tree, pslot, newpage);
+	radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);
 
 	/*
 	 * Drop cache reference from old page by unfreezing
···
 	 */
 	page_ref_unfreeze(page, expected_count - 1);
 
-	spin_unlock(&mapping->tree_lock);
+	xa_unlock(&mapping->i_pages);
 	/* Leave irq disabled to prevent preemption while updating stats */
 
 	/*
···
 	int expected_count;
 	void **pslot;
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 
-	pslot = radix_tree_lookup_slot(&mapping->page_tree,
-					page_index(page));
+	pslot = radix_tree_lookup_slot(&mapping->i_pages, page_index(page));
 
 	expected_count = 2 + page_has_private(page);
 	if (page_count(page) != expected_count ||
-		radix_tree_deref_slot_protected(pslot, &mapping->tree_lock) != page) {
-		spin_unlock_irq(&mapping->tree_lock);
+		radix_tree_deref_slot_protected(pslot, &mapping->i_pages.xa_lock) != page) {
+		xa_unlock_irq(&mapping->i_pages);
 		return -EAGAIN;
 	}
 
 	if (!page_ref_freeze(page, expected_count)) {
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		return -EAGAIN;
 	}
 
···
 
 	get_page(newpage);
 
-	radix_tree_replace_slot(&mapping->page_tree, pslot, newpage);
+	radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);
 
 	page_ref_unfreeze(page, expected_count - 1);
 
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 
 	return MIGRATEPAGE_SUCCESS;
 }

mm/page-writeback.c

···
  * so that it can tag pages faster than a dirtying process can create them).
  */
 /*
- * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce tree_lock latency.
+ * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce the i_pages lock
+ * latency.
  */
 void tag_pages_for_writeback(struct address_space *mapping,
 			     pgoff_t start, pgoff_t end)
···
 	struct radix_tree_iter iter;
 	void **slot;
 
-	spin_lock_irq(&mapping->tree_lock);
-	radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, start,
+	xa_lock_irq(&mapping->i_pages);
+	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, start,
 							PAGECACHE_TAG_DIRTY) {
 		if (iter.index > end)
 			break;
-		radix_tree_iter_tag_set(&mapping->page_tree, &iter,
+		radix_tree_iter_tag_set(&mapping->i_pages, &iter,
 							PAGECACHE_TAG_TOWRITE);
 		tagged++;
 		if ((tagged % WRITEBACK_TAG_BATCH) != 0)
 			continue;
 		slot = radix_tree_iter_resume(slot, &iter);
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		cond_resched();
-		spin_lock_irq(&mapping->tree_lock);
+		xa_lock_irq(&mapping->i_pages);
 	}
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 }
 EXPORT_SYMBOL(tag_pages_for_writeback);
 
···
 			return 1;
 		}
 
-		spin_lock_irqsave(&mapping->tree_lock, flags);
+		xa_lock_irqsave(&mapping->i_pages, flags);
 		BUG_ON(page_mapping(page) != mapping);
 		WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
 		account_page_dirtied(page, mapping);
-		radix_tree_tag_set(&mapping->page_tree, page_index(page),
+		radix_tree_tag_set(&mapping->i_pages, page_index(page),
 				   PAGECACHE_TAG_DIRTY);
-		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		xa_unlock_irqrestore(&mapping->i_pages, flags);
 		unlock_page_memcg(page);
 
 		if (mapping->host) {
···
 		struct backing_dev_info *bdi = inode_to_bdi(inode);
 		unsigned long flags;
 
-		spin_lock_irqsave(&mapping->tree_lock, flags);
+		xa_lock_irqsave(&mapping->i_pages, flags);
 		ret = TestClearPageWriteback(page);
 		if (ret) {
-			radix_tree_tag_clear(&mapping->page_tree,
-						page_index(page),
+			radix_tree_tag_clear(&mapping->i_pages, page_index(page),
 						PAGECACHE_TAG_WRITEBACK);
 			if (bdi_cap_account_writeback(bdi)) {
 				struct bdi_writeback *wb = inode_to_wb(inode);
···
 						     PAGECACHE_TAG_WRITEBACK))
 			sb_clear_inode_writeback(mapping->host);
 
-		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		xa_unlock_irqrestore(&mapping->i_pages, flags);
 	} else {
 		ret = TestClearPageWriteback(page);
 	}
···
 		struct backing_dev_info *bdi = inode_to_bdi(inode);
 		unsigned long flags;
 
-		spin_lock_irqsave(&mapping->tree_lock, flags);
+		xa_lock_irqsave(&mapping->i_pages, flags);
 		ret = TestSetPageWriteback(page);
 		if (!ret) {
 			bool on_wblist;
···
 			on_wblist = mapping_tagged(mapping,
 						   PAGECACHE_TAG_WRITEBACK);
 
-			radix_tree_tag_set(&mapping->page_tree,
-						page_index(page),
+			radix_tree_tag_set(&mapping->i_pages, page_index(page),
 						PAGECACHE_TAG_WRITEBACK);
 			if (bdi_cap_account_writeback(bdi))
 				inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK);
···
 				sb_mark_inode_writeback(mapping->host);
 		}
 		if (!PageDirty(page))
-			radix_tree_tag_clear(&mapping->page_tree,
-						page_index(page),
+			radix_tree_tag_clear(&mapping->i_pages, page_index(page),
 						PAGECACHE_TAG_DIRTY);
 		if (!keep_write)
-			radix_tree_tag_clear(&mapping->page_tree,
-						page_index(page),
+			radix_tree_tag_clear(&mapping->i_pages, page_index(page),
 						PAGECACHE_TAG_TOWRITE);
-		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		xa_unlock_irqrestore(&mapping->i_pages, flags);
 	} else {
 		ret = TestSetPageWriteback(page);
 	}
···
  */
 int mapping_tagged(struct address_space *mapping, int tag)
 {
-	return radix_tree_tagged(&mapping->page_tree, tag);
+	return radix_tree_tagged(&mapping->i_pages, tag);
 }
 EXPORT_SYMBOL(mapping_tagged);
 

mm/readahead.c

···
 			break;
 
 		rcu_read_lock();
-		page = radix_tree_lookup(&mapping->page_tree, page_offset);
+		page = radix_tree_lookup(&mapping->i_pages, page_offset);
 		rcu_read_unlock();
 		if (page && !radix_tree_exceptional_entry(page))
 			continue;

mm/rmap.c

···
  *                 mmlist_lock (in mmput, drain_mmlist and others)
  *                 mapping->private_lock (in __set_page_dirty_buffers)
  *                   mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
- *                     mapping->tree_lock (widely used)
+ *                     i_pages lock (widely used)
  *                 inode->i_lock (in set_page_dirty's __mark_inode_dirty)
  *                 bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
  *                   sb_lock (within inode_lock in fs/fs-writeback.c)
- *                   mapping->tree_lock (widely used, in set_page_dirty,
+ *                   i_pages lock (widely used, in set_page_dirty,
  *                             in arch-dependent flush_dcache_mmap_lock,
  *                             within bdi.wb->list_lock in __sync_single_inode)
  *

mm/shmem.c

···
 
 	VM_BUG_ON(!expected);
 	VM_BUG_ON(!replacement);
-	item = __radix_tree_lookup(&mapping->page_tree, index, &node, &pslot);
+	item = __radix_tree_lookup(&mapping->i_pages, index, &node, &pslot);
 	if (!item)
 		return -ENOENT;
 	if (item != expected)
 		return -ENOENT;
-	__radix_tree_replace(&mapping->page_tree, node, pslot,
+	__radix_tree_replace(&mapping->i_pages, node, pslot,
 			     replacement, NULL);
 	return 0;
 }
···
 	void *item;
 
 	rcu_read_lock();
-	item = radix_tree_lookup(&mapping->page_tree, index);
+	item = radix_tree_lookup(&mapping->i_pages, index);
 	rcu_read_unlock();
 	return item == swp_to_radix_entry(swap);
 }
···
 	page->mapping = mapping;
 	page->index = index;
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 	if (PageTransHuge(page)) {
 		void __rcu **results;
 		pgoff_t idx;
 		int i;
 
 		error = 0;
-		if (radix_tree_gang_lookup_slot(&mapping->page_tree,
+		if (radix_tree_gang_lookup_slot(&mapping->i_pages,
 					&results, &idx, index, 1) &&
 				idx < index + HPAGE_PMD_NR) {
 			error = -EEXIST;
···
 
 		if (!error) {
 			for (i = 0; i < HPAGE_PMD_NR; i++) {
-				error = radix_tree_insert(&mapping->page_tree,
+				error = radix_tree_insert(&mapping->i_pages,
 						index + i, page + i);
 				VM_BUG_ON(error);
 			}
 			count_vm_event(THP_FILE_ALLOC);
 		}
 	} else if (!expected) {
-		error = radix_tree_insert(&mapping->page_tree, index, page);
+		error = radix_tree_insert(&mapping->i_pages, index, page);
 	} else {
 		error = shmem_radix_tree_replace(mapping, index, expected,
 								 page);
···
 			__inc_node_page_state(page, NR_SHMEM_THPS);
 		__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
 		__mod_node_page_state(page_pgdat(page), NR_SHMEM, nr);
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 	} else {
 		page->mapping = NULL;
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 		page_ref_sub(page, nr);
 	}
 	return error;
···
 
 	VM_BUG_ON_PAGE(PageCompound(page), page);
 
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 	error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
 	page->mapping = NULL;
 	mapping->nrpages--;
 	__dec_node_page_state(page, NR_FILE_PAGES);
 	__dec_node_page_state(page, NR_SHMEM);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 	put_page(page);
 	BUG_ON(error);
 }
···
 {
 	void *old;
 
-	spin_lock_irq(&mapping->tree_lock);
-	old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
+	old = radix_tree_delete_item(&mapping->i_pages, index, radswap);
+	xa_unlock_irq(&mapping->i_pages);
 	if (old != radswap)
 		return -ENOENT;
 	free_swap_and_cache(radix_to_swp_entry(radswap));
···
  * Determine (in bytes) how many of the shmem object's pages mapped by the
  * given offsets are swapped out.
  *
- * This is safe to call without i_mutex or mapping->tree_lock thanks to RCU,
+ * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
  * as long as the inode doesn't go away and racy results are not a problem.
  */
 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
···
 
 	rcu_read_lock();
 
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
 		if (iter.index >= end)
 			break;
 
···
  * Determine (in bytes) how many of the shmem object's pages mapped by the
  * given vma is swapped out.
  *
- * This is safe to call without i_mutex or mapping->tree_lock thanks to RCU,
+ * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
  * as long as the inode doesn't go away and racy results are not a problem.
  */
 unsigned long shmem_swap_usage(struct vm_area_struct *vma)
···
 	int error = 0;
 
 	radswap = swp_to_radix_entry(swap);
-	index = find_swap_entry(&mapping->page_tree, radswap);
+	index = find_swap_entry(&mapping->i_pages, radswap);
 	if (index == -1)
 		return -EAGAIN;	/* tell shmem_unuse we found nothing */
 
···
 
 	hindex = round_down(index, HPAGE_PMD_NR);
 	rcu_read_lock();
-	if (radix_tree_gang_lookup_slot(&mapping->page_tree, &results, &idx,
+	if (radix_tree_gang_lookup_slot(&mapping->i_pages, &results, &idx,
 				hindex, 1) && idx < hindex + HPAGE_PMD_NR) {
 		rcu_read_unlock();
 		return NULL;
···
 	 * Our caller will very soon move newpage out of swapcache, but it's
 	 * a nice clean interface for us to replace oldpage by newpage there.
 	 */
-	spin_lock_irq(&swap_mapping->tree_lock);
+	xa_lock_irq(&swap_mapping->i_pages);
 	error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
 								   newpage);
 	if (!error) {
 		__inc_node_page_state(newpage, NR_FILE_PAGES);
 		__dec_node_page_state(oldpage, NR_FILE_PAGES);
 	}
-	spin_unlock_irq(&swap_mapping->tree_lock);
+	xa_unlock_irq(&swap_mapping->i_pages);
 
 	if (unlikely(error)) {
 		/*
···
 	start = 0;
 	rcu_read_lock();
 
-	radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
 		page = radix_tree_deref_slot(slot);
 		if (!page || radix_tree_exception(page)) {
 			if (radix_tree_deref_retry(page)) {
···
 				continue;
 			}
 		} else if (page_count(page) - page_mapcount(page) > 1) {
-			spin_lock_irq(&mapping->tree_lock);
-			radix_tree_tag_set(&mapping->page_tree, iter.index,
+			xa_lock_irq(&mapping->i_pages);
+			radix_tree_tag_set(&mapping->i_pages, iter.index,
 					   SHMEM_TAG_PINNED);
-			spin_unlock_irq(&mapping->tree_lock);
+			xa_unlock_irq(&mapping->i_pages);
 		}
 
 		if (need_resched()) {
···
 
 	error = 0;
 	for (scan = 0; scan <= LAST_SCAN; scan++) {
-		if (!radix_tree_tagged(&mapping->page_tree, SHMEM_TAG_PINNED))
+		if (!radix_tree_tagged(&mapping->i_pages, SHMEM_TAG_PINNED))
 			break;
 
 		if (!scan)
···
 
 		start = 0;
 		rcu_read_lock();
-		radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter,
+		radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter,
 					   start, SHMEM_TAG_PINNED) {
 
 			page = radix_tree_deref_slot(slot);
···
 				error = -EBUSY;
 			}
 
-			spin_lock_irq(&mapping->tree_lock);
-			radix_tree_tag_clear(&mapping->page_tree,
+			xa_lock_irq(&mapping->i_pages);
+			radix_tree_tag_clear(&mapping->i_pages,
 					     iter.index, SHMEM_TAG_PINNED);
-			spin_unlock_irq(&mapping->tree_lock);
+			xa_unlock_irq(&mapping->i_pages);
 continue_resched:
 			if (need_resched()) {
 				slot = radix_tree_iter_resume(slot, &iter);

mm/swap_state.c

···
 	SetPageSwapCache(page);
 
 	address_space = swap_address_space(entry);
-	spin_lock_irq(&address_space->tree_lock);
+	xa_lock_irq(&address_space->i_pages);
 	for (i = 0; i < nr; i++) {
 		set_page_private(page + i, entry.val + i);
-		error = radix_tree_insert(&address_space->page_tree,
+		error = radix_tree_insert(&address_space->i_pages,
 					  idx + i, page + i);
 		if (unlikely(error))
 			break;
···
 		VM_BUG_ON(error == -EEXIST);
 		set_page_private(page + i, 0UL);
 		while (i--) {
-			radix_tree_delete(&address_space->page_tree, idx + i);
+			radix_tree_delete(&address_space->i_pages, idx + i);
 			set_page_private(page + i, 0UL);
 		}
 		ClearPageSwapCache(page);
 		page_ref_sub(page, nr);
 	}
-	spin_unlock_irq(&address_space->tree_lock);
+	xa_unlock_irq(&address_space->i_pages);
 
 	return error;
 }
···
 	address_space = swap_address_space(entry);
 	idx = swp_offset(entry);
 	for (i = 0; i < nr; i++) {
-		radix_tree_delete(&address_space->page_tree, idx + i);
+		radix_tree_delete(&address_space->i_pages, idx + i);
 		set_page_private(page + i, 0);
 	}
 	ClearPageSwapCache(page);
···
 	entry.val = page_private(page);
 
 	address_space = swap_address_space(entry);
-	spin_lock_irq(&address_space->tree_lock);
+	xa_lock_irq(&address_space->i_pages);
 	__delete_from_swap_cache(page);
-	spin_unlock_irq(&address_space->tree_lock);
+	xa_unlock_irq(&address_space->i_pages);
 
 	put_swap_page(page, entry);
 	page_ref_sub(page, hpage_nr_pages(page));
···
 		return -ENOMEM;
 	for (i = 0; i < nr; i++) {
 		space = spaces + i;
-		INIT_RADIX_TREE(&space->page_tree, GFP_ATOMIC|__GFP_NOWARN);
+		INIT_RADIX_TREE(&space->i_pages, GFP_ATOMIC|__GFP_NOWARN);
 		atomic_set(&space->i_mmap_writable, 0);
 		space->a_ops = &swap_aops;
 		/* swap cache doesn't use writeback related tags */
 		mapping_set_no_writeback_tags(space);
-		spin_lock_init(&space->tree_lock);
 	}
 	nr_swapper_spaces[type] = nr;
 	rcu_assign_pointer(swapper_spaces[type], spaces);

mm/truncate.c

···
 	struct radix_tree_node *node;
 	void **slot;
 
-	if (!__radix_tree_lookup(&mapping->page_tree, index, &node, &slot))
+	if (!__radix_tree_lookup(&mapping->i_pages, index, &node, &slot))
 		return;
 	if (*slot != entry)
 		return;
-	__radix_tree_replace(&mapping->page_tree, node, slot, NULL,
+	__radix_tree_replace(&mapping->i_pages, node, slot, NULL,
 			     workingset_update_node);
 	mapping->nrexceptional--;
 }
···
 static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
 			       void *entry)
 {
-	spin_lock_irq(&mapping->tree_lock);
+	xa_lock_irq(&mapping->i_pages);
 	__clear_shadow_entry(mapping, index, entry);
-	spin_unlock_irq(&mapping->tree_lock);
+	xa_unlock_irq(&mapping->i_pages);
 }
 
 /*
···
 	dax = dax_mapping(mapping);
 	lock = !dax && indices[j] < end;
 	if (lock)
-		spin_lock_irq(&mapping->tree_lock);
+		xa_lock_irq(&mapping->i_pages);
 
 	for (i = j; i < pagevec_count(pvec); i++) {
 		struct page *page = pvec->pages[i];
···
 	}
 
 	if (lock)
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_unlock_irq(&mapping->i_pages);
 	pvec->nr = j;
 }
 
···
 		 * modification that does not see AS_EXITING is
 		 * completed before starting the final truncate.
 		 */
-		spin_lock_irq(&mapping->tree_lock);
-		spin_unlock_irq(&mapping->tree_lock);
+		xa_lock_irq(&mapping->i_pages);
+		xa_unlock_irq(&mapping->i_pages);
 
 		truncate_inode_pages(mapping, 0);
 	}
···
 	if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
 		return 0;
 
-	spin_lock_irqsave(&mapping->tree_lock, flags);
+	xa_lock_irqsave(&mapping->i_pages, flags);
 	if (PageDirty(page))
 		goto failed;
 
 	BUG_ON(page_has_private(page));
 	__delete_from_page_cache(page, NULL);
-	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	xa_unlock_irqrestore(&mapping->i_pages, flags);
 
 	if (mapping->a_ops->freepage)
 		mapping->a_ops->freepage(page);
···
 	put_page(page);	/* pagecache ref */
 	return 1;
 failed:
-	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	xa_unlock_irqrestore(&mapping->i_pages, flags);
 	return 0;
 }
 

mm/vmscan.c

···
 	BUG_ON(!PageLocked(page));
 	BUG_ON(mapping != page_mapping(page));
 
-	spin_lock_irqsave(&mapping->tree_lock, flags);
+	xa_lock_irqsave(&mapping->i_pages, flags);
 	/*
 	 * The non racy check for a busy page.
 	 *
···
 	 * load is not satisfied before that of page->_refcount.
 	 *
 	 * Note that if SetPageDirty is always performed via set_page_dirty,
-	 * and thus under tree_lock, then this ordering is not required.
+	 * and thus under the i_pages lock, then this ordering is not required.
 	 */
 	if (unlikely(PageTransHuge(page)) && PageSwapCache(page))
 		refcount = 1 + HPAGE_PMD_NR;
···
 		swp_entry_t swap = { .val = page_private(page) };
 		mem_cgroup_swapout(page, swap);
 		__delete_from_swap_cache(page);
-		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		xa_unlock_irqrestore(&mapping->i_pages, flags);
 		put_swap_page(page, swap);
 	} else {
 		void (*freepage)(struct page *);
···
 		 * only page cache pages found in these are zero pages
 		 * covering holes, and because we don't want to mix DAX
 		 * exceptional entries and shadow exceptional entries in the
-		 * same page_tree.
+		 * same address_space.
 		 */
 		if (reclaimed && page_is_file_cache(page) &&
 		    !mapping_exiting(mapping) && !dax_mapping(mapping))
 			shadow = workingset_eviction(mapping, page);
 		__delete_from_page_cache(page, shadow);
-		spin_unlock_irqrestore(&mapping->tree_lock, flags);
+		xa_unlock_irqrestore(&mapping->i_pages, flags);
 
 		if (freepage != NULL)
 			freepage(page);
···
 	return 1;
 
 cannot_free:
-	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+	xa_unlock_irqrestore(&mapping->i_pages, flags);
 	return 0;
 }
 

mm/workingset.c

···
  * @mapping: address space the page was backing
  * @page: the page being evicted
  *
- * Returns a shadow entry to be stored in @mapping->page_tree in place
+ * Returns a shadow entry to be stored in @mapping->i_pages in place
  * of the evicted @page so that a later refault can be detected.
  */
 void *workingset_eviction(struct address_space *mapping, struct page *page)
···
 	 *
 	 * Avoid acquiring the list_lru lock when the nodes are
 	 * already where they should be. The list_empty() test is safe
-	 * as node->private_list is protected by &mapping->tree_lock.
+	 * as node->private_list is protected by the i_pages lock.
 	 */
 	if (node->count && node->count == node->exceptional) {
 		if (list_empty(&node->private_list))
···
 	unsigned long nodes;
 	unsigned long cache;
 
-	/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
+	/* list_lru lock nests inside the IRQ-safe i_pages lock */
 	local_irq_disable();
 	nodes = list_lru_shrink_count(&shadow_nodes, sc);
 	local_irq_enable();
···
 
 	/*
 	 * Page cache insertions and deletions synchroneously maintain
-	 * the shadow node LRU under the mapping->tree_lock and the
+	 * the shadow node LRU under the i_pages lock and the
 	 * lru_lock.  Because the page cache tree is emptied before
 	 * the inode can be destroyed, holding the lru_lock pins any
 	 * address_space that has radix tree nodes on the LRU.
 	 *
-	 * We can then safely transition to the mapping->tree_lock to
+	 * We can then safely transition to the i_pages lock to
 	 * pin only the address_space of the particular node we want
 	 * to reclaim, take the node off-LRU, and drop the lru_lock.
 	 */
 
 	node = container_of(item, struct radix_tree_node, private_list);
-	mapping = container_of(node->root, struct address_space, page_tree);
+	mapping = container_of(node->root, struct address_space, i_pages);
 
 	/* Coming from the list, invert the lock order */
-	if (!spin_trylock(&mapping->tree_lock)) {
+	if (!xa_trylock(&mapping->i_pages)) {
 		spin_unlock(lru_lock);
 		ret = LRU_RETRY;
 		goto out;
···
 	if (WARN_ON_ONCE(node->exceptional))
 		goto out_invalid;
 	inc_lruvec_page_state(virt_to_page(node), WORKINGSET_NODERECLAIM);
-	__radix_tree_delete_node(&mapping->page_tree, node,
+	__radix_tree_delete_node(&mapping->i_pages, node,
 				 workingset_lookup_update(mapping));
 
 out_invalid:
-	spin_unlock(&mapping->tree_lock);
+	xa_unlock(&mapping->i_pages);
 	ret = LRU_REMOVED_RETRY;
 out:
 	local_irq_enable();
···
 {
 	unsigned long ret;
 
-	/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
+	/* list_lru lock nests inside the IRQ-safe i_pages lock */
 	local_irq_disable();
 	ret = list_lru_shrink_walk(&shadow_nodes, sc, shadow_lru_isolate, NULL);
 	local_irq_enable();
···
 
 /*
  * Our list_lru->lock is IRQ-safe as it nests inside the IRQ-safe
- * mapping->tree_lock.
+ * i_pages lock.
  */
 static struct lock_class_key shadow_nodes_key;