[PATCH] fs: Add function declaration of simple_dname

[PATCH] fs: Add function declaration of simple_dname

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

The simple_dname() is declared in internal header file as extern
and this generates the following GCC warning.

fs/d_path.c:311:7: warning: no previous prototype for 'simple_dname' [-Wmissing-prototypes]
  311 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
      |       ^~~~~~~~~~~~

Instead of that extern, reuse the fact that internal.h file is internal to fs/* and
declare simple_dname() like any other function.

Fixes: 7e5f7bb08b8c ("unexport simple_dname()")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 fs/d_path.c   | 2 ++
 fs/internal.h | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/d_path.c b/fs/d_path.c
index 0f1fc1743302..4b89448cc78e 100644
--- a/fs/d_path.c
+++ b/fs/d_path.c
@@ -8,6 +8,8 @@
 #include <linux/prefetch.h>
 #include "mount.h"

+#include "internal.h"
+
 static int prepend(char **buffer, int *buflen, const char *str, int namelen)
 {
 	*buflen -= namelen;
diff --git a/fs/internal.h b/fs/internal.h
index 10517ece4516..2def264272f4 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -164,7 +164,7 @@ extern int d_set_mounted(struct dentry *dentry);
 extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
 extern struct dentry *d_alloc_cursor(struct dentry *);
 extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
-extern char *simple_dname(struct dentry *, char *, int);
+char *simple_dname(struct dentry *d, char *buf, int len);
 extern void dput_to_list(struct dentry *, struct list_head *);
 extern void shrink_dentry_list(struct list_head *);

--
2.26.2

Re: [PATCH] fs: Add function declaration of simple_dname

[Matthew Wilcox]

On Wed, Aug 19, 2020 at 11:32:59AM +0300, Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@nvidia.com>
> 
> The simple_dname() is declared in internal header file as extern
> and this generates the following GCC warning.

The fact that it's declared as extern doesn't matter.  You don't need
the change to internal.h at all.  The use of 'extern' on a function
declaration is purely decorative:

  5 If the declaration of an identifier for a function has no
  storage-class specifier, its linkage is determined exactly as if it
  were declared with the storage-class specifier extern.

I'd drop the change to internal.h and fix the changelog.

> fs/d_path.c:311:7: warning: no previous prototype for 'simple_dname' [-Wmissing-prototypes]
>   311 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
>       |       ^~~~~~~~~~~~
> 
> Instead of that extern, reuse the fact that internal.h file is internal to fs/* and
> declare simple_dname() like any other function.
> 
> Fixes: 7e5f7bb08b8c ("unexport simple_dname()")
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
>  fs/d_path.c   | 2 ++
>  fs/internal.h | 2 +-
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/d_path.c b/fs/d_path.c
> index 0f1fc1743302..4b89448cc78e 100644
> --- a/fs/d_path.c
> +++ b/fs/d_path.c
> @@ -8,6 +8,8 @@
>  #include <linux/prefetch.h>
>  #include "mount.h"
> 
> +#include "internal.h"
> +
>  static int prepend(char **buffer, int *buflen, const char *str, int namelen)
>  {
>  	*buflen -= namelen;
> diff --git a/fs/internal.h b/fs/internal.h
> index 10517ece4516..2def264272f4 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -164,7 +164,7 @@ extern int d_set_mounted(struct dentry *dentry);
>  extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
>  extern struct dentry *d_alloc_cursor(struct dentry *);
>  extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
> -extern char *simple_dname(struct dentry *, char *, int);
> +char *simple_dname(struct dentry *d, char *buf, int len);
>  extern void dput_to_list(struct dentry *, struct list_head *);
>  extern void shrink_dentry_list(struct list_head *);
> 
> --
> 2.26.2
> 

Re: [PATCH] fs: Add function declaration of simple_dname

[Leon Romanovsky]

On Wed, Aug 19, 2020 at 12:34:24PM +0100, Matthew Wilcox wrote:
> On Wed, Aug 19, 2020 at 11:32:59AM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
> >
> > The simple_dname() is declared in internal header file as extern
> > and this generates the following GCC warning.
>
> The fact that it's declared as extern doesn't matter.  You don't need
> the change to internal.h at all.  The use of 'extern' on a function
> declaration is purely decorative:
>
>   5 If the declaration of an identifier for a function has no
>   storage-class specifier, its linkage is determined exactly as if it
>   were declared with the storage-class specifier extern.

So why do we need to keep extern keyword if we use intenral.h directly?

>
> I'd drop the change to internal.h and fix the changelog.

Thanks

>
> > fs/d_path.c:311:7: warning: no previous prototype for 'simple_dname' [-Wmissing-prototypes]
> >   311 | char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
> >       |       ^~~~~~~~~~~~
> >
> > Instead of that extern, reuse the fact that internal.h file is internal to fs/* and
> > declare simple_dname() like any other function.
> >
> > Fixes: 7e5f7bb08b8c ("unexport simple_dname()")
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> > ---
> >  fs/d_path.c   | 2 ++
> >  fs/internal.h | 2 +-
> >  2 files changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/d_path.c b/fs/d_path.c
> > index 0f1fc1743302..4b89448cc78e 100644
> > --- a/fs/d_path.c
> > +++ b/fs/d_path.c
> > @@ -8,6 +8,8 @@
> >  #include <linux/prefetch.h>
> >  #include "mount.h"
> >
> > +#include "internal.h"
> > +
> >  static int prepend(char **buffer, int *buflen, const char *str, int namelen)
> >  {
> >  	*buflen -= namelen;
> > diff --git a/fs/internal.h b/fs/internal.h
> > index 10517ece4516..2def264272f4 100644
> > --- a/fs/internal.h
> > +++ b/fs/internal.h
> > @@ -164,7 +164,7 @@ extern int d_set_mounted(struct dentry *dentry);
> >  extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
> >  extern struct dentry *d_alloc_cursor(struct dentry *);
> >  extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
> > -extern char *simple_dname(struct dentry *, char *, int);
> > +char *simple_dname(struct dentry *d, char *buf, int len);
> >  extern void dput_to_list(struct dentry *, struct list_head *);
> >  extern void shrink_dentry_list(struct list_head *);
> >
> > --
> > 2.26.2
> >

Re: [PATCH] fs: Add function declaration of simple_dname

[Matthew Wilcox]

On Wed, Aug 19, 2020 at 02:40:01PM +0300, Leon Romanovsky wrote:
> On Wed, Aug 19, 2020 at 12:34:24PM +0100, Matthew Wilcox wrote:
> > On Wed, Aug 19, 2020 at 11:32:59AM +0300, Leon Romanovsky wrote:
> > > From: Leon Romanovsky <leonro@nvidia.com>
> > >
> > > The simple_dname() is declared in internal header file as extern
> > > and this generates the following GCC warning.
> >
> > The fact that it's declared as extern doesn't matter.  You don't need
> > the change to internal.h at all.  The use of 'extern' on a function
> > declaration is purely decorative:
> >
> >   5 If the declaration of an identifier for a function has no
> >   storage-class specifier, its linkage is determined exactly as if it
> >   were declared with the storage-class specifier extern.
> 
> So why do we need to keep extern keyword if we use intenral.h directly?

We don't.  It's just personal preference.  I don't use extern keywords
on function declarations anywhere, but Al does and it's rude to change it.

Re: [PATCH] fs: Add function declaration of simple_dname

[Leon Romanovsky]

On Wed, Aug 19, 2020 at 12:47:55PM +0100, Matthew Wilcox wrote:
> On Wed, Aug 19, 2020 at 02:40:01PM +0300, Leon Romanovsky wrote:
> > On Wed, Aug 19, 2020 at 12:34:24PM +0100, Matthew Wilcox wrote:
> > > On Wed, Aug 19, 2020 at 11:32:59AM +0300, Leon Romanovsky wrote:
> > > > From: Leon Romanovsky <leonro@nvidia.com>
> > > >
> > > > The simple_dname() is declared in internal header file as extern
> > > > and this generates the following GCC warning.
> > >
> > > The fact that it's declared as extern doesn't matter.  You don't need
> > > the change to internal.h at all.  The use of 'extern' on a function
> > > declaration is purely decorative:
> > >
> > >   5 If the declaration of an identifier for a function has no
> > >   storage-class specifier, its linkage is determined exactly as if it
> > >   were declared with the storage-class specifier extern.
> >
> > So why do we need to keep extern keyword if we use intenral.h directly?
>
> We don't.  It's just personal preference.  I don't use extern keywords
> on function declarations anywhere, but Al does and it's rude to change it.

I didn't have any intention to be rude, just like you, I don't use extern keyword.

I'll resend to make a progress.

Thanks

>