1 files changed, 35 insertions, 0 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
index 2b7cf0400a21..ae0ae3ea299a 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -140,6 +140,36 @@ static long madvise_dontneed(struct vm_area_struct * vma,
         return 0;
 }
 
+/*
+ * Application wants to free up the pages and associated backing store.
+ * This is effectively punching a hole into the middle of a file.
+ *
+ * NOTE: Currently, only shmfs/tmpfs is supported for this operation.
+ * Other filesystems return -ENOSYS.
+ */
+static long madvise_remove(struct vm_area_struct *vma,
+                                unsigned long start, unsigned long end)
+{
+        struct address_space *mapping;
+        loff_t offset, endoff;
+
+        if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB))
+                return -EINVAL;
+
+        if (!vma->vm_file || !vma->vm_file->f_mapping
+                || !vma->vm_file->f_mapping->host) {
+                        return -EINVAL;
+        }
+
+        mapping = vma->vm_file->f_mapping;
+
+        offset = (loff_t)(start - vma->vm_start)
+                        + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
+        endoff = (loff_t)(end - vma->vm_start - 1)
+                        + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
+        return  vmtruncate_range(mapping->host, offset, endoff);
+}
+
 static long
 madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
                 unsigned long start, unsigned long end, int behavior)
@@ -152,6 +182,9 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
         case MADV_RANDOM:
                 error = madvise_behavior(vma, prev, start, end, behavior);
                 break;
+        case MADV_REMOVE:
+                error = madvise_remove(vma, start, end);
+                break;
 
         case MADV_WILLNEED:
                 error = madvise_willneed(vma, prev, start, end);
@@ -190,6 +223,8 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
  *              some pages ahead.
  *  MADV_DONTNEED - the application is finished with the given range,
  *              so the kernel can free resources associated with it.
+ *  MADV_REMOVE - the application wants to free up the given range of
+ *              pages and associated backing store.
  *
  * return values:
  *  zero    - success