On Thu, Mar 29, 2018 at 10:38 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> Currently we first call vfs_getxattr() to get size of REDIRECT xatttr and
> then make another call vfs_getxattr() to read the xattr in buffer.
>
> This is all part of ovl_lookup() and we do not have ovl_inode->lock. That
> means it is possible that inode got copied up on another cpu and is not
> a metacopy inode anymore. And that also means REDIRECT xattr got removed.
> And that means that while first call to vfs_getxattr() succeeded, second
> call can fail with -ENODATA.
>
> Do not error out if -ENODATA is received from second call. With metacopy
> enabled, it is not an error case anymore.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/namei.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index a7a9588f64b7..a97666245726 100644
> --- a/fs/overlayfs/namei.c
> +++ b/fs/overlayfs/namei.c
> @@ -47,8 +47,15 @@ static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
> goto invalid;
>
> res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
> - if (res < 0)
> + if (res < 0) {
> + /*
> + * Redirect xattr can be removed if a parallel data
> + * copy up took place.
> + */
> + if (res == -ENODATA)
> + goto err_free;
> goto fail;
> + }
> if (res == 0)
> goto invalid;
> if (buf[0] == '/') {
> --
> 2.13.6
>
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