Re: [PATCH] consolidate dt_type() helper definitions

From: Jeff Layton
Date: Wed Mar 29 2023 - 15:59:35 EST

On Wed, 2023-03-29 at 19:29 +0000, Chuck Lever III wrote:
>
> > On Mar 29, 2023, at 3:24 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> >
> > There are 4 functions named dt_type() in the kernel. Consolidate the 3
> > that are basically identical into one helper function in fs.h that
> > takes a umode_t argument. The v9fs helper is renamed to distinguish it
> > from the others.
> >
> > Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
>
> Reviewed-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>
> One (non-blocking) comment below.
>
>
> > ---
> > fs/9p/vfs_dir.c | 6 +++---
> > fs/configfs/dir.c | 8 +-------
> > fs/kernfs/dir.c | 8 +-------
> > fs/libfs.c | 9 ++-------
> > include/linux/fs.h | 6 ++++++
> > 5 files changed, 13 insertions(+), 24 deletions(-)
> >
> > diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c
> > index 3d74b04fe0de..80b331f7f446 100644
> > --- a/fs/9p/vfs_dir.c
> > +++ b/fs/9p/vfs_dir.c
> > @@ -41,12 +41,12 @@ struct p9_rdir {
> > };
> >
> > /**
> > - * dt_type - return file type
> > + * v9fs_dt_type - return file type
> > * @mistat: mistat structure
> > *
> > */
> >
> > -static inline int dt_type(struct p9_wstat *mistat)
> > +static inline int v9fs_dt_type(struct p9_wstat *mistat)
> > {
> > unsigned long perm = mistat->mode;
> > int rettype = DT_REG;
> > @@ -128,7 +128,7 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx)
> > }
> >
> > over = !dir_emit(ctx, st.name, strlen(st.name),
> > - v9fs_qid2ino(&st.qid), dt_type(&st));
> > + v9fs_qid2ino(&st.qid), v9fs_dt_type(&st));
> > p9stat_free(&st);
> > if (over)
> > return 0;
> > diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
> > index 4afcbbe63e68..43863a1696eb 100644
> > --- a/fs/configfs/dir.c
> > +++ b/fs/configfs/dir.c
> > @@ -1599,12 +1599,6 @@ static int configfs_dir_close(struct inode *inode, struct file *file)
> > return 0;
> > }
> >
> > -/* Relationship between s_mode and the DT_xxx types */
> > -static inline unsigned char dt_type(struct configfs_dirent *sd)
> > -{
> > - return (sd->s_mode >> 12) & 15;
> > -}
> > -
> > static int configfs_readdir(struct file *file, struct dir_context *ctx)
> > {
> > struct dentry *dentry = file->f_path.dentry;
> > @@ -1654,7 +1648,7 @@ static int configfs_readdir(struct file *file, struct dir_context *ctx)
> > name = configfs_get_name(next);
> > len = strlen(name);
> >
> > - if (!dir_emit(ctx, name, len, ino, dt_type(next)))
> > + if (!dir_emit(ctx, name, len, ino, dt_type(next->s_mode)))
> > return 0;
> >
> > spin_lock(&configfs_dirent_lock);
> > diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
> > index ef00b5fe8cee..0b7e9b8ee93e 100644
> > --- a/fs/kernfs/dir.c
> > +++ b/fs/kernfs/dir.c
> > @@ -1748,12 +1748,6 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
> > return error;
> > }
> >
> > -/* Relationship between mode and the DT_xxx types */
> > -static inline unsigned char dt_type(struct kernfs_node *kn)
> > -{
> > - return (kn->mode >> 12) & 15;
> > -}
> > -
> > static int kernfs_dir_fop_release(struct inode *inode, struct file *filp)
> > {
> > kernfs_put(filp->private_data);
> > @@ -1831,7 +1825,7 @@ static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
> > pos;
> > pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) {
> > const char *name = pos->name;
> > - unsigned int type = dt_type(pos);
> > + unsigned int type = dt_type(pos->mode);
> > int len = strlen(name);
> > ino_t ino = kernfs_ino(pos);
> >
> > diff --git a/fs/libfs.c b/fs/libfs.c
> > index 4eda519c3002..d0f0cdae9ff7 100644
> > --- a/fs/libfs.c
> > +++ b/fs/libfs.c
> > @@ -174,12 +174,6 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
> > }
> > EXPORT_SYMBOL(dcache_dir_lseek);
> >
> > -/* Relationship between i_mode and the DT_xxx types */
> > -static inline unsigned char dt_type(struct inode *inode)
> > -{
> > - return (inode->i_mode >> 12) & 15;
> > -}
> > -
> > /*
> > * Directory is locked and all positive dentries in it are safe, since
> > * for ramfs-type trees they can't go away without unlink() or rmdir(),
> > @@ -206,7 +200,8 @@ int dcache_readdir(struct file *file, struct dir_context *ctx)
> >
> > while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
> > if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
> > - d_inode(next)->i_ino, dt_type(d_inode(next))))
> > + d_inode(next)->i_ino,
> > + dt_type(d_inode(next)->i_mode)))
> > break;
> > ctx->pos++;
> > p = &next->d_child;
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index c85916e9f7db..777a3641fc5d 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -2885,6 +2885,12 @@ extern void iterate_supers(void (*)(struct super_block *, void *), void *);
> > extern void iterate_supers_type(struct file_system_type *,
> > void (*)(struct super_block *, void *), void *);
> >
> > +/* Relationship between i_mode and the DT_xxx types */
> > +static inline unsigned char dt_type(umode_t mode)
> > +{
> > + return (mode >> 12) & 15;
>
> Was wondering if there are appropriate symbolic constants
> that could be used instead of naked integers? NBD if not.
>

If there is a way to express that with well-known constants, I don't
know it. It looks like Linus added this to libfs.c back in 2002 (from
linux-fullhistory tree):

commit a12662634bf285a5350a2106301e754652875d2f
Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxx>
Date: Tue Jul 2 01:37:41 2002 -0700

Make ramfs/driverfs maintain directory nlink counts.

Make dcache filesystems export directory entry types
to readdir.

Linus, are there symbolic constants that you know of that we could use
here instead?


>
> > +}
> > +
> > extern int dcache_dir_open(struct inode *, struct file *);
> > extern int dcache_dir_close(struct inode *, struct file *);
> > extern loff_t dcache_dir_lseek(struct file *, loff_t, int);
> > --
> > 2.39.2
> >
>
> --
> Chuck Lever
>
>

--
Jeff Layton <jlayton@xxxxxxxxxx>