On Wed, Nov 01, 2017 at 10:22:47PM +0200, Amir Goldstein wrote:
> From: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
>
> Generate unique values of st_dev per lower layer for non-samefs
> overlay mount. The unique values are obtained by allocating anonymous
> bdevs for each of the lowerdirs in the overlayfs instance.
Still not sure that why are we allocating anonymous bdev only for
lower and not upper. Until and unless we have a good reason not not
do so, treating them in same way will make it atleast easier to
understand?
Vivek
>
> The anonymous bdev is going to be returned by stat(2) for lowerdir
> non-dir entries in non-samefs case.
>
> [amir: split from ovl_getattr() and re-structure patches]
>
> Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/ovl_entry.h | 1 +
> fs/overlayfs/super.c | 18 ++++++++++++++++--
> 2 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
> index 1e28329b5db8..93eb6a044dd2 100644
> --- a/fs/overlayfs/ovl_entry.h
> +++ b/fs/overlayfs/ovl_entry.h
> @@ -19,6 +19,7 @@ struct ovl_config {
>
> struct ovl_layer {
> struct vfsmount *mnt;
> + dev_t pseudo_dev;
> };
>
> struct ovl_path {
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index e6e13d9588d1..323dfd7a0236 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -219,8 +219,10 @@ static void ovl_put_super(struct super_block *sb)
> if (ufs->upper_mnt && ufs->upperdir_locked)
> ovl_inuse_unlock(ufs->upper_mnt->mnt_root);
> mntput(ufs->upper_mnt);
> - for (i = 0; i < ufs->numlower; i++)
> + for (i = 0; i < ufs->numlower; i++) {
> mntput(ufs->lower_layers[i].mnt);
> + free_anon_bdev(ufs->lower_layers[i].pseudo_dev);
> + }
> kfree(ufs->lower_layers);
>
> kfree(ufs->config.lowerdir);
> @@ -1032,11 +1034,19 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
> goto out_put_workdir;
> for (i = 0; i < numlower; i++) {
> struct vfsmount *mnt;
> + dev_t dev;
> +
> + err = get_anon_bdev(&dev);
> + if (err) {
> + pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
> + goto out_put_lower_layers;
> + }
>
> mnt = clone_private_mount(&stack[i]);
> err = PTR_ERR(mnt);
> if (IS_ERR(mnt)) {
> pr_err("overlayfs: failed to clone lowerpath\n");
> + free_anon_bdev(dev);
> goto out_put_lower_layers;
> }
> /*
> @@ -1046,6 +1056,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
> mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
>
> ufs->lower_layers[ufs->numlower].mnt = mnt;
> + ufs->lower_layers[ufs->numlower].pseudo_dev = dev;
> ufs->numlower++;
>
> /* Check if all lower layers are on same sb */
> @@ -1160,8 +1171,11 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
> out_free_oe:
> kfree(oe);
> out_put_lower_layers:
> - for (i = 0; i < ufs->numlower; i++)
> + for (i = 0; i < ufs->numlower; i++) {
> + if (ufs->lower_layers[i].mnt)
> + free_anon_bdev(ufs->lower_layers[i].pseudo_dev);
> mntput(ufs->lower_layers[i].mnt);
> + }
> kfree(ufs->lower_layers);
> out_put_workdir:
> dput(ufs->workdir);
> --
> 2.7.4
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