mm/hugeltb: simplify the return code of __vma_reservation_common()

It's guaranteed that the vma is associated with a resv_map, i.e.  either
VM_MAYSHARE or HPAGE_RESV_OWNER, when the code reaches here or we would
have returned via !resv check above.  So it's unneeded to check whether
HPAGE_RESV_OWNER is set here.  Simplify the return code to make it more
clear.

Link: https://lkml.kernel.org/r/20210410072348.20437-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Feilong Lin <linfeilong@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ce9e18d..d91bd78 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2174,27 +2174,26 @@ static long __vma_reservation_common(struct hstate *h,
 
        if (vma->vm_flags & VM_MAYSHARE)
                return ret;
-       else if (is_vma_resv_set(vma, HPAGE_RESV_OWNER) && ret >= 0) {
-               /*
-                * In most cases, reserves always exist for private mappings.
-                * However, a file associated with mapping could have been
-                * hole punched or truncated after reserves were consumed.
-                * As subsequent fault on such a range will not use reserves.
-                * Subtle - The reserve map for private mappings has the
-                * opposite meaning than that of shared mappings.  If NO
-                * entry is in the reserve map, it means a reservation exists.
-                * If an entry exists in the reserve map, it means the
-                * reservation has already been consumed.  As a result, the
-                * return value of this routine is the opposite of the
-                * value returned from reserve map manipulation routines above.
-                */
-               if (ret)
-                       return 0;
-               else
-                       return 1;
-       }
-       else
-               return ret < 0 ? ret : 0;
+       /*
+        * We know private mapping must have HPAGE_RESV_OWNER set.
+        *
+        * In most cases, reserves always exist for private mappings.
+        * However, a file associated with mapping could have been
+        * hole punched or truncated after reserves were consumed.
+        * As subsequent fault on such a range will not use reserves.
+        * Subtle - The reserve map for private mappings has the
+        * opposite meaning than that of shared mappings.  If NO
+        * entry is in the reserve map, it means a reservation exists.
+        * If an entry exists in the reserve map, it means the
+        * reservation has already been consumed.  As a result, the
+        * return value of this routine is the opposite of the
+        * value returned from reserve map manipulation routines above.
+        */
+       if (ret > 0)
+               return 0;
+       if (ret == 0)
+               return 1;
+       return ret;
 }
 
 static long vma_needs_reservation(struct hstate *h,