Hi James,
Thanks for persisting with this.
On Tue, 18 Mar 2025 at 20:44, James Bottomley
<James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote:
>
> No functional change. Preparatory to using the internal function to
> iterate a directory with just a dentry not a file.
>
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> ---
> fs/libfs.c | 41 +++++++++++++++++++++++++++++------------
> 1 file changed, 29 insertions(+), 12 deletions(-)
>
> diff --git a/fs/libfs.c b/fs/libfs.c
> index 8444f5cc4064..816bfe6c0430 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -189,28 +189,21 @@ EXPORT_SYMBOL(dcache_dir_lseek);
> * for ramfs-type trees they can't go away without unlink() or rmdir(),
> * both impossible due to the lock on directory.
> */
> -
> -int dcache_readdir(struct file *file, struct dir_context *ctx)
> +static void internal_readdir(struct dentry *dentry, struct dentry *cursor,
It might make sense to make this __always_inline, so that the callback
argument is guaranteed to become a compile time constant when the
caller is dcache_readdir(). Otherwise, the indirect call overhead
might impact its performance.
> + void *data, bool start,
> + bool (*callback)(void *, struct dentry *))
> {
> - struct dentry *dentry = file->f_path.dentry;
> - struct dentry *cursor = file->private_data;
> struct dentry *next = NULL;
> struct hlist_node **p;
>
> - if (!dir_emit_dots(file, ctx))
> - return 0;
> -
> - if (ctx->pos == 2)
> + if (start)
> p = &dentry->d_children.first;
> else
> p = &cursor->d_sib.next;
>
> 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,
> - fs_umode_to_dtype(d_inode(next)->i_mode)))
> + if (!callback(data, next))
> break;
> - ctx->pos++;
> p = &next->d_sib.next;
> }
> spin_lock(&dentry->d_lock);
> @@ -219,6 +212,30 @@ int dcache_readdir(struct file *file, struct dir_context *ctx)
> hlist_add_before(&cursor->d_sib, &next->d_sib);
> spin_unlock(&dentry->d_lock);
> dput(next);
> +}
> +
> +static bool dcache_readdir_callback(void *data, struct dentry *entry)
> +{
> + struct dir_context *ctx = data;
> +
> + if (!dir_emit(ctx, entry->d_name.name, entry->d_name.len,
> + d_inode(entry)->i_ino,
> + fs_umode_to_dtype(d_inode(entry)->i_mode)))
> + return false;
> + ctx->pos++;
> + return true;
> +}
> +
> +int dcache_readdir(struct file *file, struct dir_context *ctx)
> +{
> + struct dentry *dentry = file->f_path.dentry;
> + struct dentry *cursor = file->private_data;
> +
> + if (!dir_emit_dots(file, ctx))
> + return 0;
> +
> + internal_readdir(dentry, cursor, ctx, ctx->pos == 2,
> + dcache_readdir_callback);
>
> return 0;
> }
> --
> 2.43.0
>
