Re: [RFC PATCH] ceph: add remote object copy counter to fs client

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2021-10-20 at 15:37 +0100, Luís Henriques wrote:
> This counter will keep track of the number of remote object copies done on
> copy_file_range syscalls.  This counter will be filesystem per-client, and
> can be accessed from the client debugfs directory.
> 
> Cc: Patrick Donnelly <pdonnell@redhat.com>
> Signed-off-by: Luís Henriques <lhenriques@suse.de>
> ---
> This is an RFC to reply to Patrick's request in [0].  Note that I'm not
> 100% sure about the usefulness of this patch, or if this is the best way
> to provide the functionality Patrick requested.  Anyway, this is just to
> get some feedback, hence the RFC.
> 
> Cheers,
> --
> Luís
> 
> [0] https://github.com/ceph/ceph/pull/42720
> 

I think this would be better integrated into the stats infrastructure.

Maybe you could add a new set of "copy" stats to struct
ceph_client_metric that tracks the total copy operations done, their
size and latency (similar to read and write ops)?


>  fs/ceph/debugfs.c | 17 ++++++++++++++++-
>  fs/ceph/file.c    |  1 +
>  fs/ceph/super.c   |  1 +
>  fs/ceph/super.h   |  2 ++
>  4 files changed, 20 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ceph/debugfs.c b/fs/ceph/debugfs.c
> index 38b78b45811f..09f4c04ade0e 100644
> --- a/fs/ceph/debugfs.c
> +++ b/fs/ceph/debugfs.c
> @@ -346,13 +346,22 @@ static int status_show(struct seq_file *s, void *p)
>  	return 0;
>  }
>  
> +static int copyfrom_show(struct seq_file *s, void *p)
> +{
> +	struct ceph_fs_client *fsc = s->private;
> +
> +	seq_printf(s, "%llu\n", atomic64_read(&fsc->copyfrom_count));
> +
> +	return 0;
> +}
> +
>  DEFINE_SHOW_ATTRIBUTE(mdsmap);
>  DEFINE_SHOW_ATTRIBUTE(mdsc);
>  DEFINE_SHOW_ATTRIBUTE(caps);
>  DEFINE_SHOW_ATTRIBUTE(mds_sessions);
>  DEFINE_SHOW_ATTRIBUTE(metric);
>  DEFINE_SHOW_ATTRIBUTE(status);
> -
> +DEFINE_SHOW_ATTRIBUTE(copyfrom);
>  
>  /*
>   * debugfs
> @@ -387,6 +396,7 @@ void ceph_fs_debugfs_cleanup(struct ceph_fs_client *fsc)
>  	debugfs_remove(fsc->debugfs_caps);
>  	debugfs_remove(fsc->debugfs_metric);
>  	debugfs_remove(fsc->debugfs_mdsc);
> +	debugfs_remove(fsc->debugfs_copyfrom);
>  }
>  
>  void ceph_fs_debugfs_init(struct ceph_fs_client *fsc)
> @@ -443,6 +453,11 @@ void ceph_fs_debugfs_init(struct ceph_fs_client *fsc)
>  						  fsc->client->debugfs_dir,
>  						  fsc,
>  						  &status_fops);
> +	fsc->debugfs_copyfrom = debugfs_create_file("copyfrom",
> +						    0400,
> +						    fsc->client->debugfs_dir,
> +						    fsc,
> +						    &copyfrom_fops);
>  }
>  
>  
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index d16fd2d5fd42..bbeb437ca4bf 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -2254,6 +2254,7 @@ static ssize_t ceph_do_objects_copy(struct ceph_inode_info *src_ci, u64 *src_off
>  				bytes = ret;
>  			goto out;
>  		}
> +		atomic64_inc(&fsc->copyfrom_count);
>  		len -= object_size;
>  		bytes += object_size;
>  		*src_off += object_size;
> diff --git a/fs/ceph/super.c b/fs/ceph/super.c
> index 9b1b7f4cfdd4..4972554185e3 100644
> --- a/fs/ceph/super.c
> +++ b/fs/ceph/super.c
> @@ -670,6 +670,7 @@ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
>  	fsc->have_copy_from2 = true;
>  
>  	atomic_long_set(&fsc->writeback_count, 0);
> +	atomic64_set(&fsc->copyfrom_count, 0);
>  
>  	err = -ENOMEM;
>  	/*
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index a40eb14c282a..65846beca418 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -119,6 +119,7 @@ struct ceph_fs_client {
>  	struct ceph_mds_client *mdsc;
>  
>  	atomic_long_t writeback_count;
> +	atomic64_t copyfrom_count;
>  
>  	struct workqueue_struct *inode_wq;
>  	struct workqueue_struct *cap_wq;
> @@ -131,6 +132,7 @@ struct ceph_fs_client {
>  	struct dentry *debugfs_metric;
>  	struct dentry *debugfs_status;
>  	struct dentry *debugfs_mds_sessions;
> +	struct dentry *debugfs_copyfrom;
>  #endif
>  
>  #ifdef CONFIG_CEPH_FSCACHE

-- 
Jeff Layton <jlayton@kernel.org>