Btrfs: fix remap_file_pages error

when we use remap_file_pages() to remap a file, remap_file_pages always return
error. It is because btrfs didn't set VM_CAN_NONLINEAR for vma.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index abcb91867b56..ce0cd29efa9e 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1189,8 +1189,15 @@ static const struct vm_operations_struct btrfs_file_vm_ops = {
 
 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
 {
-        vma->vm_ops = &btrfs_file_vm_ops;
+        struct address_space *mapping = filp->f_mapping;
+
+        if (!mapping->a_ops->readpage)
+                return -ENOEXEC;
+
         file_accessed(filp);
+        vma->vm_ops = &btrfs_file_vm_ops;
+        vma->vm_flags |= VM_CAN_NONLINEAR;
+
         return 0;
 }