linux-kernel - Re: [PATCH RFC v2 2/3] pidfs: remove 32bit inode number handling

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Message-ID: <20241202151827.tmdvf6hyliyksz6o@quack3>
Date: Mon, 2 Dec 2024 16:18:27 +0100
From: Jan Kara <jack@...e.cz>
To: Christian Brauner <brauner@...nel.org>
Cc: Erin Shepherd <erin.shepherd@....eu>,
	Amir Goldstein <amir73il@...il.com>,
	Jeff Layton <jlayton@...nel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
	Chuck Lever <chuck.lever@...cle.com>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org
Subject: Re: [PATCH RFC v2 2/3] pidfs: remove 32bit inode number handling

On Fri 29-11-24 14:02:24, Christian Brauner wrote:
> Now that we have a unified inode number handling model remove the custom
> ida-based allocation for 32bit.
> 
> Signed-off-by: Christian Brauner <brauner@...nel.org>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/pidfs.c | 46 +++++-----------------------------------------
>  1 file changed, 5 insertions(+), 41 deletions(-)
> 
> diff --git a/fs/pidfs.c b/fs/pidfs.c
> index 0bdd9c525b80895d33f2eae5e8e375788580072f..ff4f25078f3d983bce630e597adbb12262e5d727 100644
> --- a/fs/pidfs.c
> +++ b/fs/pidfs.c
> @@ -371,40 +371,6 @@ struct pid *pidfd_pid(const struct file *file)
>  
>  static struct vfsmount *pidfs_mnt __ro_after_init;
>  
> -#if BITS_PER_LONG == 32
> -/*
> - * Provide a fallback mechanism for 32-bit systems so processes remain
> - * reliably comparable by inode number even on those systems.
> - */
> -static DEFINE_IDA(pidfd_inum_ida);
> -
> -static int pidfs_inum(struct pid *pid, unsigned long *ino)
> -{
> -	int ret;
> -
> -	ret = ida_alloc_range(&pidfd_inum_ida, RESERVED_PIDS + 1,
> -			      UINT_MAX, GFP_ATOMIC);
> -	if (ret < 0)
> -		return -ENOSPC;
> -
> -	*ino = ret;
> -	return 0;
> -}
> -
> -static inline void pidfs_free_inum(unsigned long ino)
> -{
> -	if (ino > 0)
> -		ida_free(&pidfd_inum_ida, ino);
> -}
> -#else
> -static inline int pidfs_inum(struct pid *pid, unsigned long *ino)
> -{
> -	*ino = pid->ino;
> -	return 0;
> -}
> -#define pidfs_free_inum(ino) ((void)(ino))
> -#endif
> -
>  /*
>   * The vfs falls back to simple_setattr() if i_op->setattr() isn't
>   * implemented. Let's reject it completely until we have a clean
> @@ -456,7 +422,6 @@ static void pidfs_evict_inode(struct inode *inode)
>  
>  	clear_inode(inode);
>  	put_pid(pid);
> -	pidfs_free_inum(inode->i_ino);
>  }
>  
>  static const struct super_operations pidfs_sops = {
> @@ -482,17 +447,16 @@ static const struct dentry_operations pidfs_dentry_operations = {
>  
>  static int pidfs_init_inode(struct inode *inode, void *data)
>  {
> +	struct pid *pid = data;
> +
>  	inode->i_private = data;
>  	inode->i_flags |= S_PRIVATE;
>  	inode->i_mode |= S_IRWXU;
>  	inode->i_op = &pidfs_inode_operations;
>  	inode->i_fop = &pidfs_file_operations;
> -	/*
> -	 * Inode numbering for pidfs start at RESERVED_PIDS + 1. This
> -	 * avoids collisions with the root inode which is 1 for pseudo
> -	 * filesystems.
> -	 */
> -	return pidfs_inum(data, &inode->i_ino);
> +	inode->i_ino = pidfs_ino(pid->ino);
> +	inode->i_generation = pidfs_gen(pid->ino);
> +	return 0;
>  }
>  
>  static void pidfs_put_data(void *data)
> 
> -- 
> 2.45.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR