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mm: Convert truncate to XArray

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This is essentially xa_cmpxchg() with the locking handled above us,
and it doesn't have to handle replacing a NULL entry.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2017-11-25 22:52:46 -05:00
parent a97e7904c0
commit 69b6c1319b
1 changed files with 6 additions and 9 deletions
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15
mm/truncate.c
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@ -33,15 +33,12 @@
static inline void __clear_shadow_entry(struct address_space *mapping,
pgoff_t index, void *entry)
{
struct radix_tree_node *node;
void **slot;
XA_STATE(xas, &mapping->i_pages, index);
if (!__radix_tree_lookup(&mapping->i_pages, index, &node, &slot))
xas_set_update(&xas, workingset_update_node);
if (xas_load(&xas) != entry)
return;
if (*slot != entry)
return;
__radix_tree_replace(&mapping->i_pages, node, slot, NULL,
workingset_update_node);
xas_store(&xas, NULL);
mapping->nrexceptional--;
}
@ -738,10 +735,10 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
index++;
}
/*
* For DAX we invalidate page tables after invalidating radix tree. We
* For DAX we invalidate page tables after invalidating page cache. We
* could invalidate page tables while invalidating each entry however
* that would be expensive. And doing range unmapping before doesn't
* work as we have no cheap way to find whether radix tree entry didn't
* work as we have no cheap way to find whether page cache entry didn't
* get remapped later.
*/
if (dax_mapping(mapping)) {