@@ -131,9 +131,6 @@ static int ovl_open(struct inode *inode, struct file *file)
if (IS_ERR(realfile))
return PTR_ERR(realfile);
- /* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
- file->f_mapping = realfile->f_mapping;
-
file->private_data = realfile;
return 0;
@@ -504,6 +504,11 @@ static const struct inode_operations ovl_special_inode_operations = {
.update_time = ovl_update_time,
};
+const struct address_space_operations ovl_aops = {
+ /* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
+ .direct_IO = noop_direct_IO,
+};
+
/*
* It is possible to stack overlayfs instance on top of another
* overlayfs instance as lower layer. We need to annonate the
@@ -575,6 +580,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
case S_IFREG:
inode->i_op = &ovl_file_inode_operations;
inode->i_fop = &ovl_file_operations;
+ inode->i_mapping->a_ops = &ovl_aops;
break;
case S_IFDIR:
Since overlayfs implements stacked file operations, the underlying filesystems are not supposed to be exposed to the overlayfs file, whose f_inode is an overlayfs inode. Assigning an overlayfs file to swap_file results in an attempt of xfs code to dereference an xfs_inode struct from an ovl_inode pointer: CPU: 0 PID: 2462 Comm: swapon Not tainted 4.18.0-xfstests-12721-g33e17876ea4e #3402 RIP: 0010:xfs_find_bdev_for_inode+0x23/0x2f Call Trace: xfs_iomap_swapfile_activate+0x1f/0x43 __se_sys_swapon+0xb1a/0xee9 Fix this by not assigning the real inode mapping to f_mapping, which will cause swapon() to return an error (-EINVAL). Although it makes sense not to allow setting swpafile on an overlayfs file, some users may depend on it, so we may need to fix this up in the future. Keeping f_mapping pointing to overlay inode mapping will cause O_DIRECT open to fail. Fix this by installing ovl_aops with noop_direct_IO in overlay inode mapping. Keeping f_mapping pointing to overlay inode mapping will cause other a_ops related operations to fail (e.g. readahead()). Those will be fixed by follow up patches. Suggested-by: Miklos Szeredi <mszeredi@redhat.com> Fixes: f7c72396d0de ("ovl: add O_DIRECT support") Signed-off-by: Amir Goldstein <amir73il@gmail.com> --- fs/overlayfs/file.c | 3 --- fs/overlayfs/inode.c | 6 ++++++ 2 files changed, 6 insertions(+), 3 deletions(-)