[PATCH] do_truncate() call fix in tiny-shmem.c

[linux-2.6] / mm / madvise.c

diff --git a/mm/madvise.c b/mm/madvise.c
index 73180a22877ed24bcbd01fbca9a2be10c799df2f..ae0ae3ea299a7a83b72939236ef4931eb5ac16d0 100644 (file)
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -37,7 +37,7 @@ static long madvise_behavior(struct vm_area_struct * vma,
 
        if (new_flags == vma->vm_flags) {
                *prev = vma;
-               goto success;
+               goto out;
        }
 
        pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
@@ -62,6 +62,7 @@ static long madvise_behavior(struct vm_area_struct * vma,
                        goto out;
        }
 
+success:
        /*
         * vm_flags is protected by the mmap_sem held in write mode.
         */
@@ -70,7 +71,6 @@ static long madvise_behavior(struct vm_area_struct * vma,
 out:
        if (error == -ENOMEM)
                error = -EAGAIN;
-success:
        return error;
 }
 
@@ -126,7 +126,7 @@ static long madvise_dontneed(struct vm_area_struct * vma,
                             unsigned long start, unsigned long end)
 {
        *prev = vma;
-       if ((vma->vm_flags & VM_LOCKED) || is_vm_hugetlb_page(vma))
+       if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
                return -EINVAL;
 
        if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
@@ -140,10 +140,41 @@ static long madvise_dontneed(struct vm_area_struct * vma,
        return 0;
 }
 
-static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
-                       unsigned long start, unsigned long end, int behavior)
+/*
+ * 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)
 {
-       long error = -EBADF;
+       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)
+{
+       long error;
 
        switch (behavior) {
        case MADV_NORMAL:
@@ -151,6 +182,9 @@ static long 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);
@@ -164,7 +198,6 @@ static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev
                error = -EINVAL;
                break;
        }
-               
        return error;
 }
 
@@ -190,6 +223,8 @@ static long 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
@@ -234,8 +269,9 @@ asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior)
         * - different from the way of handling in mlock etc.
         */
        vma = find_vma_prev(current->mm, start, &prev);
-       if (!vma && prev)
-               vma = prev->vm_next;
+       if (vma && start > vma->vm_start)
+               prev = vma;
+
        for (;;) {
                /* Still start < end. */
                error = -ENOMEM;