Re: [RFC][PATCH 3/4] ovl: fold ovl_copy_up_truncate() into ovl_copy_up()

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On Sat, Nov 12, 2016 at 9:36 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> This removes code duplication and is prep work
> for fixing up copy up locking.
>

Miklos,

Please consider applying this prep patch even though
you NACKed the concurrent copy up patch.

It is net code deduplication and its also a good prep work
to any other locking scheme change for concurrent copy up.

Amir.

> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
>  fs/overlayfs/copy_up.c   | 19 ++++++++++++++++---
>  fs/overlayfs/inode.c     | 33 +--------------------------------
>  fs/overlayfs/overlayfs.h |  3 +--
>  3 files changed, 18 insertions(+), 37 deletions(-)
>
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index 7e67512..a16127b 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -336,8 +336,8 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
>   * d_parent it is possible that the copy up will lock the old parent.  At
>   * that point the file will have already been copied up anyway.
>   */
> -int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
> -                   struct path *lowerpath, struct kstat *stat)
> +static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
> +                          struct path *lowerpath, struct kstat *stat)
>  {
>         DEFINE_DELAYED_CALL(done);
>         struct dentry *workdir = ovl_workdir(dentry);
> @@ -391,7 +391,7 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
>         return err;
>  }
>
> -int ovl_copy_up(struct dentry *dentry)
> +static int __ovl_copy_up(struct dentry *dentry, int flags)
>  {
>         int err = 0;
>         const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
> @@ -419,6 +419,9 @@ int ovl_copy_up(struct dentry *dentry)
>
>                 ovl_path_lower(next, &lowerpath);
>                 err = vfs_getattr(&lowerpath, &stat);
> +               /* maybe truncate regular file. this has no effect on dirs */
> +               if (flags & O_TRUNC)
> +                       stat.size = 0;
>                 if (!err)
>                         err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
>
> @@ -429,3 +432,13 @@ int ovl_copy_up(struct dentry *dentry)
>
>         return err;
>  }
> +
> +int ovl_copy_up(struct dentry *dentry)
> +{
> +       return __ovl_copy_up(dentry, 0);
> +}
> +
> +int ovl_copy_up_open(struct dentry *dentry, int flags)
> +{
> +       return __ovl_copy_up(dentry, flags);
> +}
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index a10e948..7abae00 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -13,34 +13,6 @@
>  #include <linux/posix_acl.h>
>  #include "overlayfs.h"
>
> -static int ovl_copy_up_truncate(struct dentry *dentry)
> -{
> -       int err;
> -       struct dentry *parent;
> -       struct kstat stat;
> -       struct path lowerpath;
> -       const struct cred *old_cred;
> -
> -       parent = dget_parent(dentry);
> -       err = ovl_copy_up(parent);
> -       if (err)
> -               goto out_dput_parent;
> -
> -       ovl_path_lower(dentry, &lowerpath);
> -
> -       old_cred = ovl_override_creds(dentry->d_sb);
> -       err = vfs_getattr(&lowerpath, &stat);
> -       if (!err) {
> -               stat.size = 0;
> -               err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
> -       }
> -       revert_creds(old_cred);
> -
> -out_dput_parent:
> -       dput(parent);
> -       return err;
> -}
> -
>  int ovl_setattr(struct dentry *dentry, struct iattr *attr)
>  {
>         int err;
> @@ -281,10 +253,7 @@ int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
>         if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
>                 err = ovl_want_write(dentry);
>                 if (!err) {
> -                       if (file_flags & O_TRUNC)
> -                               err = ovl_copy_up_truncate(dentry);
> -                       else
> -                               err = ovl_copy_up(dentry);
> +                       err = ovl_copy_up_open(dentry, file_flags);
>                         ovl_drop_write(dentry);
>                 }
>         }
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index 421fd50..1a2f9a5 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -215,7 +215,6 @@ void ovl_cleanup(struct inode *dir, struct dentry *dentry);
>
>  /* copy_up.c */
>  int ovl_copy_up(struct dentry *dentry);
> -int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
> -                   struct path *lowerpath, struct kstat *stat);
> +int ovl_copy_up_open(struct dentry *dentry, int flags);
>  int ovl_copy_xattr(struct dentry *old, struct dentry *new);
>  int ovl_set_attr(struct dentry *upper, struct kstat *stat);
> --
> 2.7.4
>
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