It will be used to check whether the folio is mapped to specific
VMA and whether the mapping address of folio is in the range.
Also a helper function folio_within_vma() to check whether folio
is in the range of vma based on folio_in_range().
Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
---
mm/internal.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/mm/internal.h b/mm/internal.h
index 346d82260964..9e2a5b32c659 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -587,6 +587,56 @@ extern long faultin_vma_page_range(struct vm_area_struct *vma,
bool write, int *locked);
extern bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
unsigned long bytes);
+
+/*
+ * NOTE: This function can't tell whether the folio is "fully mapped" in the
+ * range.
+ * "fully mapped" means all the pages of folio is associated with the page
+ * table of range while this function just check whether the folio range is
+ * within the range [start, end). Funcation caller nees to do page table
+ * check if it cares about the page table association.
+ *
+ * Typical usage (like mlock or madvise) is:
+ * Caller knows at least 1 page of folio is associated with page table of VMA
+ * and the range [start, end) is intersect with the VMA range. Caller wants
+ * to know whether the folio is fully associated with the range. It calls
+ * this function to check whether the folio is in the range first. Then checks
+ * the page table to know whether the folio is fully mapped to the range.
+ */
+static inline bool
+folio_within_range(struct folio *folio, struct vm_area_struct *vma,
+ unsigned long start, unsigned long end)
+{
+ pgoff_t pgoff, addr;
+ unsigned long vma_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+
+ VM_WARN_ON_FOLIO(folio_test_ksm(folio), folio);
+ if (start > end)
+ return false;
+
+ if (start < vma->vm_start)
+ start = vma->vm_start;
+
+ if (end > vma->vm_end)
+ end = vma->vm_end;
+
+ pgoff = folio_pgoff(folio);
+
+ /* if folio start address is not in vma range */
+ if (!in_range(pgoff, vma->vm_pgoff, vma_pglen))
+ return false;
+
+ addr = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
+
+ return !(addr < start || end - addr < folio_size(folio));
+}
+
+static inline bool
+folio_within_vma(struct folio *folio, struct vm_area_struct *vma)
+{
+ return folio_within_range(folio, vma, vma->vm_start, vma->vm_end);
+}
+
/*
* mlock_vma_folio() and munlock_vma_folio():
* should be called with vma's mmap_lock held for read or write,
--
2.39.2
