Re: [PATCH 4/7] ovl: factor out ovl_free_entry() and ovl_stack_*() helpers

[Alexander Larsson <alexl@redhat.com>]

On Sat, 2023-04-08 at 19:42 +0300, Amir Goldstein wrote:
> In preparation for moving lowerstack into ovl_inode.
> 
> Note that in ovl_lookup() the temp stack dentry refs are now cloned
> into the final ovl_lowerstack instead of being transfered, so cleanup
> always needs to call ovl_stack_free(stack).
> 
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>

Reviewed-by: Alexander Larsson <alexl@redhat.com>

> ---
>  fs/overlayfs/namei.c     | 13 +++++--------
>  fs/overlayfs/overlayfs.h |  5 +++++
>  fs/overlayfs/ovl_entry.h |  2 --
>  fs/overlayfs/super.c     | 14 ++------------
>  fs/overlayfs/util.c      | 34 ++++++++++++++++++++++++++++++++++
>  5 files changed, 46 insertions(+), 22 deletions(-)
> 
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index 31f889d27083..c237c8dbff09 100644
> --- a/fs/overlayfs/namei.c
> +++ b/fs/overlayfs/namei.c
> @@ -907,8 +907,7 @@ struct dentry *ovl_lookup(struct inode *dir,
> struct dentry *dentry,
>  
>         if (!d.stop && ovl_numlower(poe)) {
>                 err = -ENOMEM;
> -               stack = kcalloc(ofs->numlayer - 1, sizeof(struct
> ovl_path),
> -                               GFP_KERNEL);
> +               stack = ovl_stack_alloc(ofs->numlayer - 1);

I realize this is not really related to your patch, but why is this
using ofs->numlayer - 1, rather than ovl_numlower(poe)? The later is
what we iterate over below, and is potentially smaller than numlayers.

>                 if (!stack)
>                         goto out_put_upper;
>         }
> @@ -1073,7 +1072,7 @@ struct dentry *ovl_lookup(struct inode *dir,
> struct dentry *dentry,
>         if (!oe)
>                 goto out_put;
>  
> -       memcpy(ovl_lowerstack(oe), stack, sizeof(struct ovl_path) *
> ctr);
> +       ovl_stack_cpy(ovl_lowerstack(oe), stack, ctr);
>         dentry->d_fsdata = oe;
>  
>         if (upperopaque)
> @@ -1131,18 +1130,16 @@ struct dentry *ovl_lookup(struct inode *dir,
> struct dentry *dentry,
>                 kfree(origin_path);
>         }
>         dput(index);
> -       kfree(stack);
> +       ovl_stack_free(stack, ctr);
>         kfree(d.redirect);
>         return d_splice_alias(inode, dentry);
>  
>  out_free_oe:
>         dentry->d_fsdata = NULL;
> -       kfree(oe);
> +       ovl_free_entry(oe);
>  out_put:
>         dput(index);
> -       for (i = 0; i < ctr; i++)
> -               dput(stack[i].dentry);
> -       kfree(stack);
> +       ovl_stack_free(stack, ctr);
>  out_put_upper:
>         if (origin_path) {
>                 dput(origin_path->dentry);
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index e100c55bb924..6a50296fef8f 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -373,7 +373,12 @@ int ovl_can_decode_fh(struct super_block *sb);
>  struct dentry *ovl_indexdir(struct super_block *sb);
>  bool ovl_index_all(struct super_block *sb);
>  bool ovl_verify_lower(struct super_block *sb);
> +struct ovl_path *ovl_stack_alloc(unsigned int n);
> +void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src,
> unsigned int n);
> +void ovl_stack_put(struct ovl_path *stack, unsigned int n);
> +void ovl_stack_free(struct ovl_path *stack, unsigned int n);
>  struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
> +void ovl_free_entry(struct ovl_entry *oe);
>  bool ovl_dentry_remote(struct dentry *dentry);
>  void ovl_dentry_update_reval(struct dentry *dentry, struct dentry
> *realdentry);
>  void ovl_dentry_init_reval(struct dentry *dentry, struct dentry
> *upperdentry);
> diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
> index f456a99d6017..754f8ae4ce62 100644
> --- a/fs/overlayfs/ovl_entry.h
> +++ b/fs/overlayfs/ovl_entry.h
> @@ -127,8 +127,6 @@ static inline struct ovl_path
> *ovl_lowerstack(struct ovl_entry *oe)
>         return oe ? oe->__lowerstack : NULL;
>  }
>  
> -struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
> -
>  static inline struct ovl_entry *OVL_E(struct dentry *dentry)
>  {
>         return (struct ovl_entry *) dentry->d_fsdata;
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 89e9843bd2de..d8fe857bd7e1 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -54,15 +54,6 @@ module_param_named(xino_auto, ovl_xino_auto_def,
> bool, 0644);
>  MODULE_PARM_DESC(xino_auto,
>                  "Auto enable xino feature");
>  
> -static void ovl_entry_stack_free(struct ovl_entry *oe)
> -{
> -       struct ovl_path *lowerstack = ovl_lowerstack(oe);
> -       unsigned int i;
> -
> -       for (i = 0; i < ovl_numlower(oe); i++)
> -               dput(lowerstack[i].dentry);
> -}
> -
>  static bool ovl_metacopy_def =
> IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
>  module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
>  MODULE_PARM_DESC(metacopy,
> @@ -73,7 +64,7 @@ static void ovl_dentry_release(struct dentry
> *dentry)
>         struct ovl_entry *oe = dentry->d_fsdata;
>  
>         if (oe) {
> -               ovl_entry_stack_free(oe);
> +               ovl_stack_put(ovl_lowerstack(oe), ovl_numlower(oe));
>                 kfree_rcu(oe, rcu);
>         }
>  }
> @@ -2078,8 +2069,7 @@ static int ovl_fill_super(struct super_block
> *sb, void *data, int silent)
>         return 0;
>  
>  out_free_oe:
> -       ovl_entry_stack_free(oe);
> -       kfree(oe);
> +       ovl_free_entry(oe);
>  out_err:
>         kfree(splitlower);
>         path_put(&upperpath);
> diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> index a139eb581093..1ba6dbea808c 100644
> --- a/fs/overlayfs/util.c
> +++ b/fs/overlayfs/util.c
> @@ -83,6 +83,34 @@ bool ovl_verify_lower(struct super_block *sb)
>         return ofs->config.nfs_export && ofs->config.index;
>  }
>  
> +struct ovl_path *ovl_stack_alloc(unsigned int n)
> +{
> +       return kcalloc(n, sizeof(struct ovl_path), GFP_KERNEL);
> +}
> +
> +void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src,
> unsigned int n)
> +{
> +       unsigned int i;
> +
> +       memcpy(dst, src, sizeof(struct ovl_path) * n);
> +       for (i = 0; i < n; i++)
> +               dget(src[i].dentry);
> +}
> +
> +void ovl_stack_put(struct ovl_path *stack, unsigned int n)
> +{
> +       unsigned int i;
> +
> +       for (i = 0; stack && i < n; i++)
> +               dput(stack[i].dentry);
> +}
> +
> +void ovl_stack_free(struct ovl_path *stack, unsigned int n)
> +{
> +       ovl_stack_put(stack, n);
> +       kfree(stack);
> +}
> +
>  struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
>  {
>         size_t size = offsetof(struct ovl_entry,
> __lowerstack[numlower]);
> @@ -94,6 +122,12 @@ struct ovl_entry *ovl_alloc_entry(unsigned int
> numlower)
>         return oe;
>  }
>  
> +void ovl_free_entry(struct ovl_entry *oe)
> +{
> +       ovl_stack_put(ovl_lowerstack(oe), ovl_numlower(oe));
> +       kfree(oe);
> +}
> +
>  #define OVL_D_REVALIDATE (DCACHE_OP_REVALIDATE |
> DCACHE_OP_WEAK_REVALIDATE)
>  
>  bool ovl_dentry_remote(struct dentry *dentry)

-- 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=-=-=
 Alexander Larsson                                            Red Hat,
Inc 
       alexl@redhat.com            alexander.larsson@gmail.com 
He's an oversexed devious romance novelist who hangs with the wrong 
crowd. She's a radical red-headed doctor prone to fits of savage, 
blood-crazed rage. They fight crime!