On Thu, Apr 26, 2018 at 12:10 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> truncate should copy up full file (and not do metacopy only), otherwise
> it will be broken. For example, use truncate to increase size of a file
> so that any read beyong existing size will return null bytes. If we
> don't copy up full file, then we end up opening lower file and read
> from it only reads upto the old size (and not new size after truncate).
> Hence to avoid such situations, copy up data as well when file size
> changes.
>
> So far it was being done by d_real(O_WRONLY) call in truncate()
> path. Now that patch has been reverted. So force full copy up in
> ovl_setattr() if size of file is changing.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/inode.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 19e96d4717bd..0802b67e0776 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -18,7 +18,7 @@
>
> int ovl_setattr(struct dentry *dentry, struct iattr *attr)
> {
> - int err;
> + int err, copy_up_flags = 0;
> struct dentry *upperdentry;
> const struct cred *old_cred;
>
> @@ -45,9 +45,12 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
> err = -ETXTBSY;
> if (atomic_read(&realinode->i_writecount) < 0)
> goto out_drop_write;
> +
> + /* Truncate should trigger data copy up as well */
> + copy_up_flags = O_WRONLY;
> }
>
> - err = ovl_copy_up(dentry);
> + err = ovl_copy_up_flags(dentry, copy_up_flags);
> if (!err) {
> struct inode *winode = NULL;
>
> --
> 2.13.6
>
--
To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
