On Wed, Jan 31, 2018 at 11:13 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> Now we want to support midlayer metacopy dentry as well. To support that
> we need to find out lowest data dentry and keep track of that too so that
> later it can be used for data copy up.
>
> Introduce logic to traverse through metacopies and find and install the
> lowest data ovl_path in stack.
>
> This patch does it only for upper dentry at this point of time. Next patch
> will introduce this logic for the cases when upper does not exist.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
I kinda liked better the version that change ovl_check_origin(),
but I guess we are not taking the ORIGIN chain approach anymore.
> ---
> fs/overlayfs/namei.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 77 insertions(+), 3 deletions(-)
>
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index ddb73b5a06d4..e26c0bdf0381 100644
> --- a/fs/overlayfs/namei.c
> +++ b/fs/overlayfs/namei.c
> @@ -205,7 +205,7 @@ static int ovl_check_metacopy_xattr(struct dentry *dentry)
> }
>
> static int ovl_check_metacopy(struct ovl_fs *ofs, struct dentry *dentry,
> - unsigned int ctr)
> + unsigned int numlower, bool is_upper)
> {
> int metacopy;
>
> @@ -213,7 +213,7 @@ static int ovl_check_metacopy(struct ovl_fs *ofs, struct dentry *dentry,
> if (metacopy <= 0 )
> return metacopy;
>
> - if (!ctr) {
> + if (is_upper && !numlower) {
> /*
> * Found a upper dentry with metacopy set but at the same
> * time there is no corresponding origin dentry. Something
> @@ -236,6 +236,77 @@ static int ovl_check_metacopy(struct ovl_fs *ofs, struct dentry *dentry,
> return metacopy;
> }
>
> +/*
> + * Returns < 0 upon error, 0 if dentry does not have metacopy xattr, 1 if
> + * dentry has metacopy xattr.
> + */
> +static int ovl_get_metacopy_chain(struct ovl_fs *ofs,
> + struct dentry *upperdentry,
> + struct ovl_path *lower, unsigned int numlower,
> + struct ovl_path *stackp, unsigned int *ctrp)
> +{
> + int metacopy = 0, i, err;
> + struct dentry *origin = NULL, *parent;
> + struct vfsmount *mnt;
> +
> + if (upperdentry) {
> + metacopy = ovl_check_metacopy(ofs, upperdentry, *ctrp, true);
> + if (metacopy <= 0 )
> + return metacopy;
> + }
> +
> + /*
> + * Expecting one dentry in stackp[0] and lowest data will be installed
> + * at stackp[1], if appropriate./
> + */
> + BUG_ON(*ctrp != 1);
> + err = ovl_check_metacopy(ofs, stackp[0].dentry, *ctrp, false);
> + if (err < 0)
> + return err;
> +
> + if (!err)
> + return metacopy;
> +
> + parent = stackp[0].dentry;
> + dget(parent);
> +
> + /* Get the data dentry corresponding to metacopy dentry */
> + for (i = 0; i < numlower; i++) {
> + mnt = lower[i].layer->mnt;
> + origin = ovl_get_origin(parent, mnt);
> + if (IS_ERR(origin)) {
> + dput(parent);
> + return PTR_ERR(origin);
> + }
> +
> + if (origin) {
> + err = ovl_check_metacopy_xattr(origin);
> + if (err < 0) {
> + dput(parent);
> + dput(origin);
> + return err;
> + }
> +
> + if (err) {
> + dput(parent);
> + parent = origin;
> + origin = NULL;
> + continue;
> + }
> + break;
> + }
> + }
> +
> + dput(parent);
> + if (!origin)
> + return -ESTALE;
> +
> + stackp[1].dentry = origin;
> + stackp[1].layer = lower[i].layer;
> + *ctrp += 1;
> + return 1;
> +}
> +
> static bool ovl_is_opaquedir(struct dentry *dentry)
> {
> return ovl_check_dir_xattr(dentry, OVL_XATTR_OPAQUE);
> @@ -699,7 +770,10 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
> if (err)
> goto out_put_upper;
>
> - err = ovl_check_metacopy(ofs, upperdentry, ctr);
> + err = ovl_get_metacopy_chain(ofs, upperdentry,
> + roe->lowerstack,
> + roe->numlower, stack,
> + &ctr);
> metacopy = err;
> if (err < 0)
> goto out_put_upper;
> --
> 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
--
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
