Re: [PATCH Version 4 07/10] NFS probe pseudo-fs for replicas

[Anna Schumaker <Anna.Schumaker@netapp.com>]

Hi Andy,

On 05/11/2016 03:08 PM, andros@netapp.com wrote:
> From: Andy Adamson <andros@netapp.com>
> 
> Probe an NFSv4 Pseudo-fs for fs_locations replicas. Replicas on a Pseudo-fs
> returns multipath addresses for the server which will be tested
> for session trunking.
> 
> Signed-off-by: Andy Adamson <andros@netapp.com>
> ---
>  fs/nfs/internal.h       |  2 ++
>  fs/nfs/nfs4getroot.c    |  3 ++
>  fs/nfs/nfs4proc.c       | 84 +++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/nfs/nfs4xdr.c        | 14 ++++++++-
>  include/linux/nfs_xdr.h |  4 +--
>  5 files changed, 104 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> index f1d1d2c..4a65288 100644
> --- a/fs/nfs/internal.h
> +++ b/fs/nfs/internal.h
> @@ -528,6 +528,8 @@ extern int nfs40_walk_client_list(struct nfs_client *clp,
>  extern int nfs41_walk_client_list(struct nfs_client *clp,
>  				struct nfs_client **result,
>  				struct rpc_cred *cred);
> +extern void nfs4_get_pseudofs_replicas(struct nfs_server *server,
> +				struct nfs_fh *mntfh);
>  
>  static inline struct inode *nfs_igrab_and_active(struct inode *inode)
>  {
> diff --git a/fs/nfs/nfs4getroot.c b/fs/nfs/nfs4getroot.c
> index 039b3eb..4c1f5e4 100644
> --- a/fs/nfs/nfs4getroot.c
> +++ b/fs/nfs/nfs4getroot.c
> @@ -36,6 +36,9 @@ int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool auth_p
>  	}
>  
>  	memcpy(&server->fsid, &fsinfo.fattr->fsid, sizeof(server->fsid));
> +
> +	nfs4_get_pseudofs_replicas(server, mntfh);
> +
>  out:
>  	nfs_free_fattr(fsinfo.fattr);
>  	dprintk("<-- nfs4_get_rootfh() = %d\n", ret);
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 70537f0..8263ee8 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -3253,6 +3253,90 @@ static int nfs4_do_find_root_sec(struct nfs_server *server,
>  	return nfs_v4_minor_ops[mv]->find_root_sec(server, fhandle, info);
>  }
>  
> +static int _nfs4_proc_fs_locations_probe(struct nfs_server *server,
> +					 struct nfs_fh *fhandle,
> +					 struct nfs4_fs_locations *fs_locations,
> +					 struct page *page)
> +{
> +	u32 bitmask[3] = {
> +		[0] = FATTR4_WORD0_FS_LOCATIONS,
> +	};
> +	struct nfs4_fs_locations_arg args = {
> +		.fh = fhandle,
> +		.page = page,
> +		.bitmask = bitmask,
> +		.replicas = 1,
> +	};
> +	struct nfs4_fs_locations_res res = {
> +		.fs_locations = fs_locations,
> +		.replicas = 1,
> +	};
> +	struct rpc_message msg = {
> +		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_FS_LOCATIONS],
> +		.rpc_argp = &args,
> +		.rpc_resp = &res,
> +	};
> +	struct rpc_clnt *clnt = server->nfs_client->cl_rpcclient;
> +	int status = 0;
> +
> +	nfs_fattr_init(&fs_locations->fattr);
> +	fs_locations->nlocations = 0;
> +	fs_locations->server = server;
> +	status = nfs4_call_sync(clnt, server, &msg, &args.seq_args,
> +				&res.seq_res, 0);
> +	return status;
> +}

I don't think we need the status variable here.  Let's just directly return the result of nfs4_call_sync().


> +
> +static int nfs4_proc_fs_locations_probe(struct nfs_server *server,
> +					struct nfs_fh *fhandle,
> +					struct nfs4_fs_locations *fs_locations,
> +					struct page *page)
> +{
> +	struct nfs4_exception exception = { };
> +	int err;
> +
> +	do {
> +		err = _nfs4_proc_fs_locations_probe(server, fhandle,
> +						fs_locations, page);
> +		err = nfs4_handle_exception(server, err, &exception);
> +	} while (exception.retry);
> +	return err;
> +}
> +
> +
> +/**
> + * Probe the pseudo filesystem for an fs_locations replicas list.
> + * Note: The replicas list on a pseudofs is a list of multipath
> + * addresses
> + */
> +void nfs4_get_pseudofs_replicas(struct nfs_server *server,
> +				       struct nfs_fh *mntfh)
> +{
> +	struct page *page = NULL;
> +	struct nfs4_fs_locations *locations = NULL;
> +	int status;
> +
> +	if (server->nfs_client->cl_minorversion == 0)
> +		return;
> +
> +	page = alloc_page(GFP_KERNEL);
> +	if (page == NULL)
> +		goto out;
> +	locations = kmalloc(sizeof(struct nfs4_fs_locations), GFP_KERNEL);
> +	if (locations == NULL)
> +		goto out;
> +
> +	status = nfs4_proc_fs_locations_probe(server, mntfh, locations, page);
> +	if (status != 0)
> +		goto out;
> +
> +	/* test replicas for session trunking here */
> +out:
> +	if (page)
> +		__free_page(page);
> +	kfree(locations);
> +}
> +
>  /**
>   * nfs4_proc_get_rootfh - get file handle for server's pseudoroot
>   * @server: initialized nfs_server handle
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index 88474a4..4dfd136 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -2685,7 +2685,11 @@ static void nfs4_xdr_enc_fs_locations(struct rpc_rqst *req,
>  
>  	encode_compound_hdr(xdr, req, &hdr);
>  	encode_sequence(xdr, &args->seq_args, &hdr);
> -	if (args->migration) {
> +	if (args->replicas) {
> +		encode_putfh(xdr, args->fh, &hdr);
> +		replen = hdr.replen;
> +		encode_fs_locations(xdr, args->bitmask, &hdr);
> +	} else if (args->migration) {

I really don't like the amount of duplicated code going into this if/else block.  Maybe it can be cleaned up like this? (untested and uncompiled)

@@ -2685,22 +2685,15 @@ static void nfs4_xdr_enc_fs_locations(struct rpc_rqst *req,
 
        encode_compound_hdr(xdr, req, &hdr);
        encode_sequence(xdr, &args->seq_args, &hdr);
-       if (args->replicas) {
+       if (args->replicas || args->migration)
                encode_putfh(xdr, args->fh, &hdr);
-               replen = hdr.replen;
-               encode_fs_locations(xdr, args->bitmask, &hdr);
-       } else if (args->migration) {
-               encode_putfh(xdr, args->fh, &hdr);
-               replen = hdr.replen;
-               encode_fs_locations(xdr, args->bitmask, &hdr);
-               if (args->renew)
-                       encode_renew(xdr, args->clientid, &hdr);
-       } else {
+       else
                encode_putfh(xdr, args->dir_fh, &hdr);
-               encode_lookup(xdr, args->name, &hdr);
-               replen = hdr.replen;
-               encode_fs_locations(xdr, args->bitmask, &hdr);
-       }
+       replen = hdr.replen;
+       encode_fs_locations(xdr, args->bitmask, &hdr);
+
+       if (args->migration && args->renew)
+               encode_renew(xdr, args->clientid, &hdr);
 
        /* Set up reply kvec to capture returned fs_locations array. */


Thanks,
Anna

>  		encode_putfh(xdr, args->fh, &hdr);
>  		replen = hdr.replen;
>  		encode_fs_locations(xdr, args->bitmask, &hdr);
> @@ -6916,6 +6920,14 @@ static int nfs4_xdr_dec_fs_locations(struct rpc_rqst *req,
>  	status = decode_putfh(xdr);
>  	if (status)
>  		goto out;
> +	if (res->replicas) {
> +		xdr_enter_page(xdr, PAGE_SIZE);
> +		status = decode_getfattr_generic(xdr,
> +					&res->fs_locations->fattr,
> +					 NULL, res->fs_locations,
> +					 NULL, res->fs_locations->server);
> +		goto out;
> +	}
>  	if (res->migration) {
>  		xdr_enter_page(xdr, PAGE_SIZE);
>  		status = decode_getfattr_generic(xdr,
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index d320906..ab9a08a2 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -1120,13 +1120,13 @@ struct nfs4_fs_locations_arg {
>  	struct page *page;
>  	const u32 *bitmask;
>  	clientid4 clientid;
> -	unsigned char migration:1, renew:1;
> +	unsigned char migration:1, renew:1, replicas:1;
>  };
>  
>  struct nfs4_fs_locations_res {
>  	struct nfs4_sequence_res	seq_res;
>  	struct nfs4_fs_locations       *fs_locations;
> -	unsigned char			migration:1, renew:1;
> +	unsigned char			migration:1, renew:1, replicas:1;
>  };
>  
>  struct nfs4_secinfo4 {
>