mm/hmm: improve and rename hmm_vma_get_pfns() to hmm_range_snapshot()

[linux-2.6-microblaze.git] / mm / hmm.c

diff --git a/mm/hmm.c b/mm/hmm.c
index 84e0577..bd957a9 100644 (file)
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -702,23 +702,25 @@ static void hmm_pfns_special(struct hmm_range *range)
 }
 
 /*
- * hmm_vma_get_pfns() - snapshot CPU page table for a range of virtual addresses
- * @range: range being snapshotted
- * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid
- *          vma permission, 0 success
+ * hmm_range_snapshot() - snapshot CPU page table for a range
+ * @range: range
+ * Returns: number of valid pages in range->pfns[] (from range start
+ *          address). This may be zero. If the return value is negative,
+ *          then one of the following values may be returned:
+ *
+ *           -EINVAL  invalid arguments or mm or virtual address are in an
+ *                    invalid vma (ie either hugetlbfs or device file vma).
+ *           -EPERM   For example, asking for write, when the range is
+ *                    read-only
+ *           -EAGAIN  Caller needs to retry
+ *           -EFAULT  Either no valid vma exists for this range, or it is
+ *                    illegal to access the range
  *
  * This snapshots the CPU page table for a range of virtual addresses. Snapshot
  * validity is tracked by range struct. See hmm_vma_range_done() for further
  * information.
- *
- * The range struct is initialized here. It tracks the CPU page table, but only
- * if the function returns success (0), in which case the caller must then call
- * hmm_vma_range_done() to stop CPU page table update tracking on this range.
- *
- * NOT CALLING hmm_vma_range_done() IF FUNCTION RETURNS 0 WILL LEAD TO SERIOUS
- * MEMORY CORRUPTION ! YOU HAVE BEEN WARNED !
  */
-int hmm_vma_get_pfns(struct hmm_range *range)
+long hmm_range_snapshot(struct hmm_range *range)
 {
        struct vm_area_struct *vma = range->vma;
        struct hmm_vma_walk hmm_vma_walk;
@@ -772,6 +774,7 @@ int hmm_vma_get_pfns(struct hmm_range *range)
        hmm_vma_walk.fault = false;
        hmm_vma_walk.range = range;
        mm_walk.private = &hmm_vma_walk;
+       hmm_vma_walk.last = range->start;
 
        mm_walk.vma = vma;
        mm_walk.mm = vma->vm_mm;
@@ -788,9 +791,9 @@ int hmm_vma_get_pfns(struct hmm_range *range)
         * function return 0).
         */
        range->hmm = hmm;
-       return 0;
+       return (hmm_vma_walk.last - range->start) >> PAGE_SHIFT;
 }
-EXPORT_SYMBOL(hmm_vma_get_pfns);
+EXPORT_SYMBOL(hmm_range_snapshot);
 
 /*
  * hmm_vma_range_done() - stop tracking change to CPU page table over a range