On Mon, Oct 2, 2017 at 4:40 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> Presence of OVL_XATTR_METACOPY reflects that file has been copied up
> with metadata only and data needs to be copied up later from lower.
> So this xattr is set when a metadata copy takes place and cleared when
> data copy takes place.
>
> We also use a bit in ovl_inode->flags to cache OVL_METACOPY which reflects
> whether ovl inode has only metadata copied up.
>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> ---
> fs/overlayfs/copy_up.c | 42 ++++++++++++++++++++++++++++++++++++++++--
> fs/overlayfs/inode.c | 3 ++-
> fs/overlayfs/overlayfs.h | 5 ++++-
> fs/overlayfs/util.c | 21 +++++++++++++++++++--
> 4 files changed, 65 insertions(+), 6 deletions(-)
>
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index b2d9ed81e9ff..d76a4272b43e 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -439,6 +439,26 @@ static int ovl_get_tmpfile(struct ovl_copy_up_ctx *c, struct dentry **tempp)
> goto out;
> }
>
> +static int ovl_copy_up_data_inode(struct ovl_copy_up_ctx *c)
> +{
> + struct path upperpath;
> + int err;
> +
> + ovl_path_upper(c->dentry, &upperpath);
> + BUG_ON(upperpath.dentry == NULL);
> +
> + err = ovl_copy_up_data(&c->lowerpath, &upperpath, c->stat.size);
> + if (err)
> + return err;
> +
> + err= vfs_removexattr(upperpath.dentry, OVL_XATTR_METACOPY);
> + if (err)
> + return err;
> +
> + ovl_clear_flag(OVL_METACOPY, d_inode(c->dentry));
> + return err;
> +}
> +
> static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
> {
> int err;
> @@ -482,6 +502,13 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
> return err;
> }
>
> + if (c->metadata_only) {
> + err = ovl_check_setxattr(c->dentry, temp, OVL_XATTR_METACOPY,
> + NULL, 0, -EOPNOTSUPP);
> + if (err)
> + return err;
> + }
> +
> return 0;
> }
>
> @@ -511,6 +538,9 @@ static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
> goto out_cleanup;
>
> ovl_inode_update(d_inode(c->dentry), newdentry);
> + if (c->metadata_only) {
> + ovl_set_flag(OVL_METACOPY, d_inode(c->dentry));
> + }
> out:
> dput(temp);
> return err;
> @@ -638,7 +668,7 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
> }
> ovl_do_check_copy_up(ctx.lowerpath.dentry);
>
> - err = ovl_copy_up_start(dentry);
> + err = ovl_copy_up_start(dentry, flags);
> /* err < 0: interrupted, err > 0: raced with another copy-up */
> if (unlikely(err)) {
> if (err > 0)
> @@ -648,6 +678,8 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
> err = ovl_do_copy_up(&ctx);
> if (!err && !ovl_dentry_has_upper_alias(dentry))
> err = ovl_link_up(&ctx);
> + if (!err && ovl_dentry_needs_data_copy_up(dentry, flags))
> + err = ovl_copy_up_data_inode(&ctx);
I think it would simplify life cycle of copy up if ovl_copy_up_data_inode()
is always before ovl_link_up() and that ovl_dentry_has_upper_alias()
means "has a concrete upper alias with data".
index feature already supports an upper index without any upper aliases
(a property that I use in the ro-copyup patches).
Amir.
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