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Date: Thu, 4 Jan 2024 09:21:13 -0500
From: Chuck Lever <chuck.lever@oracle.com>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Jeff Layton <jlayton@kernel.org>, Chuck Lever <cel@kernel.org>,
        linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
        trondmy@hammerspace.com, viro@zeniv.linux.org.uk, brauner@kernel.org
Subject: Re: [PATCH v2 2/2] fs: Create a generic is_dot_dotdot() utility
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On Thu, Jan 04, 2024 at 09:46:07AM +0200, Amir Goldstein wrote:
> On Wed, Jan 3, 2024 at 9:08 PM Jeff Layton <jlayton@kernel.org> wrote:
> >
> > On Wed, 2024-01-03 at 10:19 -0500, Chuck Lever wrote:
> > > From: Chuck Lever <chuck.lever@oracle.com>
> > >
> > > De-duplicate the same functionality in several places by hoisting
> > > the is_dot_dotdot() function into linux/fs.h.
> > >
> > > Suggested-by: Amir Goldstein <amir73il@gmail.com>
> > > Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> > > ---
> > >  fs/crypto/fname.c    |    8 +-------
> > >  fs/ecryptfs/crypto.c |   10 ----------
> > >  fs/exportfs/expfs.c  |    4 +---
> > >  fs/f2fs/f2fs.h       |   11 -----------
> > >  include/linux/fs.h   |    9 +++++++++
> > >  5 files changed, 11 insertions(+), 31 deletions(-)
> > >
> > > diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
> > > index 7b3fc189593a..0ad52fbe51c9 100644
> > > --- a/fs/crypto/fname.c
> > > +++ b/fs/crypto/fname.c
> > > @@ -74,13 +74,7 @@ struct fscrypt_nokey_name {
> > >
> > >  static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
> > >  {
> > > -     if (str->len == 1 && str->name[0] == '.')
> > > -             return true;
> > > -
> > > -     if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.')
> > > -             return true;
> > > -
> > > -     return false;
> > > +     return is_dot_dotdot(str->name, str->len);
> > >  }
> > >
> > >  /**
> > > diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
> > > index 03bd55069d86..2fe0f3af1a08 100644
> > > --- a/fs/ecryptfs/crypto.c
> > > +++ b/fs/ecryptfs/crypto.c
> > > @@ -1949,16 +1949,6 @@ int ecryptfs_encrypt_and_encode_filename(
> > >       return rc;
> > >  }
> > >
> > > -static bool is_dot_dotdot(const char *name, size_t name_size)
> > > -{
> > > -     if (name_size == 1 && name[0] == '.')
> > > -             return true;
> > > -     else if (name_size == 2 && name[0] == '.' && name[1] == '.')
> > > -             return true;
> > > -
> > > -     return false;
> > > -}
> > > -
> > >  /**
> > >   * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
> > >   * @plaintext_name: The plaintext name
> > > diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
> > > index 84af58eaf2ca..07ea3d62b298 100644
> > > --- a/fs/exportfs/expfs.c
> > > +++ b/fs/exportfs/expfs.c
> > > @@ -255,9 +255,7 @@ static bool filldir_one(struct dir_context *ctx, const char *name, int len,
> > >               container_of(ctx, struct getdents_callback, ctx);
> > >
> > >       buf->sequence++;
> > > -     /* Ignore the '.' and '..' entries */
> > > -     if ((len > 2 || name[0] != '.' || (len == 2 && name[1] != '.')) &&
> > > -         buf->ino == ino && len <= NAME_MAX) {
> > > +     if (buf->ino == ino && len <= NAME_MAX && !is_dot_dotdot(name, len)) {
> > >               memcpy(buf->name, name, len);
> > >               buf->name[len] = '\0';
> > >               buf->found = 1;
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > index 9043cedfa12b..322a3b8a3533 100644
> > > --- a/fs/f2fs/f2fs.h
> > > +++ b/fs/f2fs/f2fs.h
> > > @@ -3368,17 +3368,6 @@ static inline bool f2fs_cp_error(struct f2fs_sb_info *sbi)
> > >       return is_set_ckpt_flags(sbi, CP_ERROR_FLAG);
> > >  }
> > >
> > > -static inline bool is_dot_dotdot(const u8 *name, size_t len)
> > > -{
> > > -     if (len == 1 && name[0] == '.')
> > > -             return true;
> > > -
> > > -     if (len == 2 && name[0] == '.' && name[1] == '.')
> > > -             return true;
> > > -
> > > -     return false;
> > > -}
> > > -
> > >  static inline void *f2fs_kmalloc(struct f2fs_sb_info *sbi,
> > >                                       size_t size, gfp_t flags)
> > >  {
> > > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > > index 98b7a7a8c42e..179eea797c22 100644
> > > --- a/include/linux/fs.h
> > > +++ b/include/linux/fs.h
> > > @@ -2846,6 +2846,15 @@ extern bool path_is_under(const struct path *, const struct path *);
> > >
> > >  extern char *file_path(struct file *, char *, int);
> > >
> > > +static inline bool is_dot_dotdot(const char *name, size_t len)
> > > +{
> > > +     if (len == 1 && name[0] == '.')
> > > +             return true;
> > > +     if (len == 2 && name[0] == '.' && name[1] == '.')
> > > +             return true;
> > > +     return false;
> > > +}
> > > +
> > >  #include <linux/err.h>
> > >
> > >  /* needed for stackable file system support */
> > >
> > >
> >
> > Looks good to me. I took a quick look to see if there were other open-
> > coded versions, but I didn't see any.
> >
> 
> The outstanding open-coded version that wasn't deduped is in
> lookup_one_common(), which is the version that Trond used and
> mentioned in his patch.
> 
> It is also a slightly more "efficient" version, but I have no idea if
> that really matters.

It probably matters in lookup_one_common(), but not in any of the
other callers.


> In any case, having lookup_one_common() and get_name() use
> the same helper is clearly prefered, because the check in lookup_one()
> is the declared reason for the get_name() patch.

I will send a v3.

-- 
Chuck Lever