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Subject[PATCH v9 47/61] shmem: Convert shmem_alloc_hugepage to XArray
Date
From: Matthew Wilcox <mawilcox@microsoft.com>

xa_find() is a slightly easier API to use than
radix_tree_gang_lookup_slot() because it contains its own RCU locking.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
mm/shmem.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index fb06fb3e644a..a0a354a87f3b 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1416,23 +1416,17 @@ static struct page *shmem_alloc_hugepage(gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
struct vm_area_struct pvma;
- struct inode *inode = &info->vfs_inode;
- struct address_space *mapping = inode->i_mapping;
- pgoff_t idx, hindex;
- void __rcu **results;
+ struct address_space *mapping = info->vfs_inode.i_mapping;
+ pgoff_t hindex;
struct page *page;

if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
return NULL;

hindex = round_down(index, HPAGE_PMD_NR);
- rcu_read_lock();
- if (radix_tree_gang_lookup_slot(&mapping->i_pages, &results, &idx,
- hindex, 1) && idx < hindex + HPAGE_PMD_NR) {
- rcu_read_unlock();
+ if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
+ XA_PRESENT))
return NULL;
- }
- rcu_read_unlock();

shmem_pseudo_vma_init(&pvma, info, hindex);
page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
--
2.16.1
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