[PATCH v4 36/36] mm: Align THP mappings for non-DAX

[Matthew Wilcox]

From: William Kucharski <william.kucharski@xxxxxxxxxx>

When we have the opportunity to use transparent huge pages to map a
file, we want to follow the same rules as DAX.

Signed-off-by: William Kucharski <william.kucharski@xxxxxxxxxx>
[Inline __thp_get_unmapped_area() into thp_get_unmapped_area()]
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 mm/huge_memory.c | 40 +++++++++++++---------------------------
 1 file changed, 13 insertions(+), 27 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 15a86b06befc..e78686b628ae 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -535,30 +535,30 @@ bool is_transparent_hugepage(struct page *page)
 }
 EXPORT_SYMBOL_GPL(is_transparent_hugepage);
 
-static unsigned long __thp_get_unmapped_area(struct file *filp,
-		unsigned long addr, unsigned long len,
-		loff_t off, unsigned long flags, unsigned long size)
+unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags)
 {
+	loff_t off = (loff_t)pgoff << PAGE_SHIFT;
 	loff_t off_end = off + len;
-	loff_t off_align = round_up(off, size);
+	loff_t off_align = round_up(off, PMD_SIZE);
 	unsigned long len_pad, ret;
 
-	if (off_end <= off_align || (off_end - off_align) < size)
-		return 0;
+	if (off_end <= off_align || (off_end - off_align) < PMD_SIZE)
+		goto regular;
 
-	len_pad = len + size;
+	len_pad = len + PMD_SIZE;
 	if (len_pad < len || (off + len_pad) < off)
-		return 0;
+		goto regular;
 
 	ret = current->mm->get_unmapped_area(filp, addr, len_pad,
 					      off >> PAGE_SHIFT, flags);
 
 	/*
-	 * The failure might be due to length padding. The caller will retry
-	 * without the padding.
+	 * The failure might be due to length padding.  Retry without
+	 * the padding.
 	 */
 	if (IS_ERR_VALUE(ret))
-		return 0;
+		goto regular;
 
 	/*
 	 * Do not try to align to THP boundary if allocation at the address
@@ -567,23 +567,9 @@ static unsigned long __thp_get_unmapped_area(struct file *filp,
 	if (ret == addr)
 		return addr;
 
-	ret += (off - ret) & (size - 1);
+	ret += (off - ret) & (PMD_SIZE - 1);
 	return ret;
-}
-
-unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
-		unsigned long len, unsigned long pgoff, unsigned long flags)
-{
-	unsigned long ret;
-	loff_t off = (loff_t)pgoff << PAGE_SHIFT;
-
-	if (!IS_DAX(filp->f_mapping->host) || !IS_ENABLED(CONFIG_FS_DAX_PMD))
-		goto out;
-
-	ret = __thp_get_unmapped_area(filp, addr, len, off, flags, PMD_SIZE);
-	if (ret)
-		return ret;
-out:
+regular:
 	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 }
 EXPORT_SYMBOL_GPL(thp_get_unmapped_area);
-- 
2.26.2