On Sun, Dec 22, 2019 at 9:08 AM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>
> Rename lower_layers[] array to layers[], extend its size by one
> and initialize layers[0] with upper layer values.
> Lower layers are now addressed with index 1..numlower.
> layers[0] is reserved even with lower only overlay.
>
> This gets rid of special casing upper layer in ovl_iterate_real().
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/export.c | 6 ++----
> fs/overlayfs/inode.c | 4 ++--
> fs/overlayfs/namei.c | 10 +++++-----
> fs/overlayfs/overlayfs.h | 2 +-
> fs/overlayfs/ovl_entry.h | 2 +-
> fs/overlayfs/readdir.c | 7 +++----
> fs/overlayfs/super.c | 43 ++++++++++++++++++++++------------------
> fs/overlayfs/util.c | 6 ++++--
> 8 files changed, 42 insertions(+), 38 deletions(-)
>
> diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
> index 70e55588aedc..9128cbb3b198 100644
> --- a/fs/overlayfs/export.c
> +++ b/fs/overlayfs/export.c
> @@ -424,7 +424,6 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
> struct ovl_layer *layer)
> {
> struct ovl_fs *ofs = sb->s_fs_info;
> - struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
> struct dentry *index = NULL;
> struct dentry *this = NULL;
> struct inode *inode;
> @@ -466,7 +465,7 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
> * recursive call walks back from indexed upper to the topmost
> * connected/hashed upper parent (or up to root).
> */
> - this = ovl_lookup_real(sb, upper, &upper_layer);
> + this = ovl_lookup_real(sb, upper, &ofs->layers[0]);
> dput(upper);
> }
>
> @@ -646,8 +645,7 @@ static struct dentry *ovl_get_dentry(struct super_block *sb,
> struct dentry *index)
> {
> struct ovl_fs *ofs = sb->s_fs_info;
> - struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
> - struct ovl_layer *layer = upper ? &upper_layer : lowerpath->layer;
> + struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;
> struct dentry *real = upper ?: (index ?: lowerpath->dentry);
>
> /*
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 481a19965dd1..35712f54fdf9 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -170,7 +170,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
> */
> if (!is_dir || samefs || ovl_xino_bits(dentry->d_sb)) {
> if (!OVL_TYPE_UPPER(type)) {
> - lower_layer = ovl_layer_lower(dentry);
> + lower_layer = ovl_dentry_layer(dentry);
> } else if (OVL_TYPE_ORIGIN(type)) {
> struct kstat lowerstat;
> u32 lowermask = STATX_INO | STATX_BLOCKS |
> @@ -200,7 +200,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
> if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
> (!ovl_verify_lower(dentry->d_sb) &&
> (is_dir || lowerstat.nlink == 1))) {
> - lower_layer = ovl_layer_lower(dentry);
> + lower_layer = ovl_dentry_layer(dentry);
I find this confusing. I expected ovl_dentry_layer() to be an
analogue of ovl_dentry_real(), but it's not: it will return upper
layer if there's no lower layer, not the other way round.
How about keeping the ovl_layer_lower() helper and open code the new
behavior at the single point where it would be used? I can make that
change if you ACK that I didn't miss anything.
> /*
> * Cannot use origin st_dev;st_ino because
> * origin inode content may differ from overlay
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index 76ff66339173..ff67d897f790 100644
> --- a/fs/overlayfs/namei.c
> +++ b/fs/overlayfs/namei.c
> @@ -322,16 +322,16 @@ int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
> struct dentry *origin = NULL;
> int i;
>
> - for (i = 0; i < ofs->numlower; i++) {
> + for (i = 1; i <= ofs->numlower; i++) {
> /*
> * If lower fs uuid is not unique among lower fs we cannot match
> * fh->uuid to layer.
> */
> - if (ofs->lower_layers[i].fsid &&
> - ofs->lower_layers[i].fs->bad_uuid)
> + if (ofs->layers[i].fsid &&
> + ofs->layers[i].fs->bad_uuid)
> continue;
>
> - origin = ovl_decode_real_fh(fh, ofs->lower_layers[i].mnt,
> + origin = ovl_decode_real_fh(fh, ofs->layers[i].mnt,
> connected);
> if (origin)
> break;
> @@ -354,7 +354,7 @@ int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
> }
> **stackp = (struct ovl_path){
> .dentry = origin,
> - .layer = &ofs->lower_layers[i]
> + .layer = &ofs->layers[i]
> };
>
> return 0;
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index f283b1d69a9e..50d41a314308 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -237,7 +237,7 @@ enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
> struct dentry *ovl_dentry_upper(struct dentry *dentry);
> struct dentry *ovl_dentry_lower(struct dentry *dentry);
> struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
> -struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
> +struct ovl_layer *ovl_dentry_layer(struct dentry *dentry);
> struct dentry *ovl_dentry_real(struct dentry *dentry);
> struct dentry *ovl_i_dentry_upper(struct inode *inode);
> struct inode *ovl_inode_upper(struct inode *inode);
> diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
> index 28348c44ea5b..ffaf7376f4ab 100644
> --- a/fs/overlayfs/ovl_entry.h
> +++ b/fs/overlayfs/ovl_entry.h
> @@ -48,7 +48,7 @@ struct ovl_fs {
> unsigned int numlower;
> /* Number of unique lower sb that differ from upper sb */
> unsigned int numlowerfs;
> - struct ovl_layer *lower_layers;
> + struct ovl_layer *layers;
> struct ovl_sb *lower_fs;
> /* workbasedir is the path at workdir= mount option */
> struct dentry *workbasedir;
> diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
> index 47a91c9733a5..32a7f8a38091 100644
> --- a/fs/overlayfs/readdir.c
> +++ b/fs/overlayfs/readdir.c
> @@ -508,7 +508,7 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
> ino = stat.ino;
> } else if (xinobits && !OVL_TYPE_UPPER(type)) {
> ino = ovl_remap_lower_ino(ino, xinobits,
> - ovl_layer_lower(this)->fsid,
> + ovl_dentry_layer(this)->fsid,
> p->name, p->len);
> }
>
> @@ -685,15 +685,14 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
> int err;
> struct ovl_dir_file *od = file->private_data;
> struct dentry *dir = file->f_path.dentry;
> - struct ovl_layer *lower_layer = ovl_layer_lower(dir);
> struct ovl_readdir_translate rdt = {
> .ctx.actor = ovl_fill_real,
> .orig_ctx = ctx,
> .xinobits = ovl_xino_bits(dir->d_sb),
> };
>
> - if (rdt.xinobits && lower_layer)
> - rdt.fsid = lower_layer->fsid;
> + if (rdt.xinobits)
> + rdt.fsid = ovl_dentry_layer(dir)->fsid;
>
> if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {
> struct kstat stat;
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 7621ff176d15..84f96f64bbb8 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -224,13 +224,13 @@ static void ovl_free_fs(struct ovl_fs *ofs)
> if (ofs->upperdir_locked)
> ovl_inuse_unlock(ofs->upper_mnt->mnt_root);
> mntput(ofs->upper_mnt);
> - for (i = 0; i < ofs->numlower; i++) {
> - iput(ofs->lower_layers[i].trap);
> - mntput(ofs->lower_layers[i].mnt);
> + for (i = 1; i <= ofs->numlower; i++) {
> + iput(ofs->layers[i].trap);
> + mntput(ofs->layers[i].mnt);
> }
> for (i = 0; i < ofs->numlowerfs; i++)
> free_anon_bdev(ofs->lower_fs[i].pseudo_dev);
> - kfree(ofs->lower_layers);
> + kfree(ofs->layers);
> kfree(ofs->lower_fs);
>
> kfree(ofs->config.lowerdir);
> @@ -1318,16 +1318,16 @@ static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
> return ofs->numlowerfs;
> }
>
> -static int ovl_get_lower_layers(struct super_block *sb, struct ovl_fs *ofs,
> - struct path *stack, unsigned int numlower)
> +static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
> + struct path *stack, unsigned int numlower)
> {
> int err;
> unsigned int i;
>
> err = -ENOMEM;
> - ofs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer),
> - GFP_KERNEL);
> - if (ofs->lower_layers == NULL)
> + ofs->layers = kcalloc(numlower + 1, sizeof(struct ovl_layer),
> + GFP_KERNEL);
> + if (ofs->layers == NULL)
> goto out;
>
> ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb),
> @@ -1335,6 +1335,11 @@ static int ovl_get_lower_layers(struct super_block *sb, struct ovl_fs *ofs,
> if (ofs->lower_fs == NULL)
> goto out;
>
> + /* idx 0 is reserved for upper fs even with lower only overlay */
> + ofs->layers[0].mnt = ofs->upper_mnt;
> + ofs->layers[0].idx = 0;
> + ofs->layers[0].fsid = 0;
> +
> for (i = 0; i < numlower; i++) {
> struct vfsmount *mnt;
> struct inode *trap;
> @@ -1368,15 +1373,15 @@ static int ovl_get_lower_layers(struct super_block *sb, struct ovl_fs *ofs,
> */
> mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
>
> - ofs->lower_layers[ofs->numlower].trap = trap;
> - ofs->lower_layers[ofs->numlower].mnt = mnt;
> - ofs->lower_layers[ofs->numlower].idx = i + 1;
> - ofs->lower_layers[ofs->numlower].fsid = fsid;
> + ofs->numlower++;
> + ofs->layers[ofs->numlower].trap = trap;
> + ofs->layers[ofs->numlower].mnt = mnt;
> + ofs->layers[ofs->numlower].idx = ofs->numlower;
> + ofs->layers[ofs->numlower].fsid = fsid;
> if (fsid) {
> - ofs->lower_layers[ofs->numlower].fs =
> + ofs->layers[ofs->numlower].fs =
> &ofs->lower_fs[fsid - 1];
> }
> - ofs->numlower++;
> }
>
> /*
> @@ -1463,7 +1468,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
> goto out_err;
> }
>
> - err = ovl_get_lower_layers(sb, ofs, stack, numlower);
> + err = ovl_get_layers(sb, ofs, stack, numlower);
> if (err)
> goto out_err;
>
> @@ -1474,7 +1479,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
>
> for (i = 0; i < numlower; i++) {
> oe->lowerstack[i].dentry = dget(stack[i].dentry);
> - oe->lowerstack[i].layer = &ofs->lower_layers[i];
> + oe->lowerstack[i].layer = &ofs->layers[i+1];
> }
>
> if (remote)
> @@ -1555,9 +1560,9 @@ static int ovl_check_overlapping_layers(struct super_block *sb,
> return err;
> }
>
> - for (i = 0; i < ofs->numlower; i++) {
> + for (i = 1; i <= ofs->numlower; i++) {
> err = ovl_check_layer(sb, ofs,
> - ofs->lower_layers[i].mnt->mnt_root,
> + ofs->layers[i].mnt->mnt_root,
> "lowerdir");
> if (err)
> return err;
> diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> index f5678a3f8350..3fa1ca8ddd48 100644
> --- a/fs/overlayfs/util.c
> +++ b/fs/overlayfs/util.c
> @@ -198,11 +198,13 @@ struct dentry *ovl_dentry_lower(struct dentry *dentry)
> return oe->numlower ? oe->lowerstack[0].dentry : NULL;
> }
>
> -struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
> +/* Either top most lower layer or upper layer for pure upper */
> +struct ovl_layer *ovl_dentry_layer(struct dentry *dentry)
> {
> + struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
> struct ovl_entry *oe = dentry->d_fsdata;
>
> - return oe->numlower ? oe->lowerstack[0].layer : NULL;
> + return oe->numlower ? oe->lowerstack[0].layer : &ofs->layers[0];
> }
>
> /*
> --
> 2.17.1
>
