fs/nfs, swapon: check holes in swapfile

swapon over NFS does not go through generic_swapfile_activate
code path when setting up extents. This makes holes in NFS
swapfiles possible which is not expected for swapon.

Signed-off-by: Murphy Zhou <jencce.kernel@gmail.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 8eb731d9be3eae2d7b63308af27edd6dc397ea67..ccd9bc09880675af3d6b38bda680b9155d3dfa19 100644 (file)
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -489,7 +489,19 @@ static int nfs_launder_page(struct page *page)
 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
                                                sector_t *span)
 {
+       unsigned long blocks;
+       long long isize;
        struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
+       struct inode *inode = file->f_mapping->host;
+
+       spin_lock(&inode->i_lock);
+       blocks = inode->i_blocks;
+       isize = inode->i_size;
+       spin_unlock(&inode->i_lock);
+       if (blocks*512 < isize) {
+               pr_warn("swap activate: swapfile has holes\n");
+               return -EINVAL;
+       }
 
        *span = sis->pages;