Re: [RFC PATCH] nfs: Add NFS3PROC_UMOUNT procedure.

[Myklebust, Trond]

BIG NACK... We don't do embrace and extend in Linux...


The whole point of the NFS protocol is to be a standard. We can't just go adding new functionality to one implementation of that standard without breaking interoperability with other implementations...

Trond

--
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com

On Jun 23, 2012, at 6:46 AM, Namjae Jeon wrote:

> From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> 
> Without this patch:
> 
> On NFS Client:
> $ mount -t nfs <NFS_SERVER>:/mnt /mnt
> $ umount /mnt
> 
> On NFS Server:
> $ umount /mnt
> umount: can't umount /mnt: Device or resource busy
> 
> If user has to remove storage device user needs to unplug the
> device.
> This may result in file system corruption on attached media.
> 
> This patch tries to add a NFS UMOUNT procedure for NFSv3 for safe
> removal of attached media at NFS Server.
> 
> With this patch:
> 
> On NFS Client:
> $ mount -t nfs <NFS_SERVER>:/mnt /mnt
> $ umount /mnt
> 
> On NFS Server:
> $ umount /mnt --> umount successful
> 
> Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> Signed-off-by: Vivek Trivedi <t.vivek@xxxxxxxxxxx>
> Signed-off-by: Amit Sahrawat <a.sahrawat@xxxxxxxxxxx>
> ---
> fs/nfs/nfs3proc.c       |   29 +++++++++++++++++++++++++++++
> fs/nfs/nfs3xdr.c        |   39 +++++++++++++++++++++++++++++++++++++++
> fs/nfs/super.c          |   10 ++++++++++
> fs/nfsd/nfs3proc.c      |   28 +++++++++++++++++++++++++++-
> fs/nfsd/nfs3xdr.c       |   19 +++++++++++++++++++
> fs/nfsd/nfsctl.c        |   22 ++++++++++++++++++++++
> fs/nfsd/nfsd.h          |    3 +++
> fs/nfsd/nfssvc.c        |    3 +++
> fs/nfsd/xdr3.h          |   14 +++++++++++++-
> include/linux/nfs3.h    |    1 +
> include/linux/nfs_xdr.h |    9 +++++++++
> 11 files changed, 175 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
> index 2292a0f..726227f 100644
> --- a/fs/nfs/nfs3proc.c
> +++ b/fs/nfs/nfs3proc.c
> @@ -877,6 +877,34 @@ nfs3_proc_lock(struct file *filp, int cmd, struct file_lock *fl)
> 	return nlmclnt_proc(NFS_SERVER(inode)->nlm_host, cmd, fl);
> }
> 
> +static int nfs3_proc_umount(struct nfs_server *server)
> +{
> +	/*
> +	 * dummy argument and response are assigned to UMOUNT request
> +	 * to avoid BUG_ON(proc->p_arglen == 0); in net/sunrpc/clnt.c
> +	 */
> +	struct nfs3_umountargs  arg = {
> +		.dummy          = 0,
> +	};
> +	struct nfs3_umountres   res;
> +
> +	struct rpc_message msg = {
> +		.rpc_proc       = &nfs3_procedures[NFS3PROC_UMOUNT],
> +		.rpc_argp       = &arg,
> +		.rpc_resp       = &res,
> +
> +	};
> +	int err;
> +
> +	msg.rpc_cred = authnull_ops.lookup_cred(NULL, NULL, 0);
> +	dprintk("NFS call  umount\n");
> +	err = rpc_call_sync(server->client, &msg,
> +			RPC_TASK_SOFT | RPC_TASK_SOFTCONN);
> +	put_rpccred(msg.rpc_cred);
> +	dprintk("NFS reply umount: %d\n", err);
> +	return err;
> +}
> +
> const struct nfs_rpc_ops nfs_v3_clientops = {
> 	.version	= 3,			/* protocol version */
> 	.dentry_ops	= &nfs_dentry_operations,
> @@ -922,4 +950,5 @@ const struct nfs_rpc_ops nfs_v3_clientops = {
> 	.clear_acl_cache = nfs3_forget_cached_acls,
> 	.close_context	= nfs_close_context,
> 	.init_client	= nfs_init_client,
> +	.umount			= nfs3_proc_umount,
> };
> diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
> index 6cbe894..874b8b2 100644
> --- a/fs/nfs/nfs3xdr.c
> +++ b/fs/nfs/nfs3xdr.c
> @@ -61,6 +61,7 @@
> #define NFS3_readdirargs_sz	(NFS3_fh_sz+NFS3_cookieverf_sz+3)
> #define NFS3_readdirplusargs_sz	(NFS3_fh_sz+NFS3_cookieverf_sz+4)
> #define NFS3_commitargs_sz	(NFS3_fh_sz+3)
> +#define NFS3_umountargs_sz	(1)
> 
> #define NFS3_getattrres_sz	(1+NFS3_fattr_sz)
> #define NFS3_setattrres_sz	(1+NFS3_wcc_data_sz)
> @@ -78,6 +79,7 @@
> #define NFS3_fsinfores_sz	(1+NFS3_post_op_attr_sz+12)
> #define NFS3_pathconfres_sz	(1+NFS3_post_op_attr_sz+6)
> #define NFS3_commitres_sz	(1+NFS3_wcc_data_sz+2)
> +#define NFS3_umountres_sz	(1 + 1)
> 
> #define ACL3_getaclargs_sz	(NFS3_fh_sz+1)
> #define ACL3_setaclargs_sz	(NFS3_fh_sz+1+ \
> @@ -1306,6 +1308,22 @@ static void nfs3_xdr_enc_commit3args(struct rpc_rqst *req,
> 	encode_commit3args(xdr, args);
> }
> 
> +/*
> + *   UMOUNT3args
> + */
> +static void encode_umount3args(struct xdr_stream *xdr,
> +		const struct nfs3_umountargs *args)
> +{
> +	encode_uint32(xdr, args->dummy);
> +}
> +
> +static void nfs3_xdr_enc_umount3args(struct rpc_rqst *req,
> +		struct xdr_stream *xdr,
> +		const struct nfs3_umountargs *args)
> +{
> +	encode_umount3args(xdr, args);
> +}
> +
> #ifdef CONFIG_NFS_V3_ACL
> 
> static void nfs3_xdr_enc_getacl3args(struct rpc_rqst *req,
> @@ -1429,6 +1447,26 @@ out_status:
> }
> 
> /*
> + *   UMOUNT3res
> + */
> +static int nfs3_xdr_dec_umount3res(struct rpc_rqst *req,
> +		struct xdr_stream *xdr,
> +		struct nfs3_umountres *result)
> +{
> +	enum nfs_stat status;
> +	int error;
> +
> +	error = decode_nfsstat3(xdr, &status);
> +	if (unlikely(error))
> +		goto out;
> +	if (status != NFS3_OK)
> +		return nfs3_stat_to_errno(status);
> +	error = decode_uint32(xdr, &result->dummy);
> +out:
> +	return error;
> +}
> +
> +/*
>  * 3.3.3  LOOKUP3res
>  *
>  *	struct LOOKUP3resok {
> @@ -2508,6 +2546,7 @@ struct rpc_procinfo	nfs3_procedures[] = {
> 	PROC(FSINFO,		getattr,	fsinfo,		0),
> 	PROC(PATHCONF,		getattr,	pathconf,	0),
> 	PROC(COMMIT,		commit,		commit,		5),
> +	PROC(UMOUNT,		umount,		umount,		0),
> };
> 
> const struct rpc_version nfs_version3 = {
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index 906f09c..9fa295b 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -2525,6 +2525,16 @@ static void nfs_kill_super(struct super_block *s)
> {
> 	struct nfs_server *server = NFS_SB(s);
> 
> +	int err;
> +
> +	if (server->nfs_client->rpc_ops->umount) {
> +		err = server->nfs_client->rpc_ops->umount(server);
> +		if (err < 0) {
> +			printk(KERN_ERR "%s: nfs_proc3_umount() failed err = %d\n",
> +					__func__, err);
> +		}
> +	}
> +
> 	kill_anon_super(s);
> 	nfs_fscache_release_super_cookie(s);
> 	nfs_free_server(server);
> diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
> index 9095f3c..12ca821 100644
> --- a/fs/nfsd/nfs3proc.c
> +++ b/fs/nfsd/nfs3proc.c
> @@ -8,6 +8,7 @@
> #include <linux/ext2_fs.h>
> #include <linux/magic.h>
> 
> +#include "nfsd.h"
> #include "cache.h"
> #include "xdr3.h"
> #include "vfs.h"
> @@ -63,6 +64,21 @@ nfsd3_proc_getattr(struct svc_rqst *rqstp, struct nfsd_fhandle  *argp,
> }
> 
> /*
> + * UMOUNT call.
> + */
> +static __be32
> +nfsd3_proc_umount(struct svc_rqst *rqstp, struct nfsd3_umountargs *argp,
> +		struct nfsd3_umountres *resp)
> +{
> +	dprintk("nfsd: UMOUNT(3)\n");
> +
> +	if (nfs_umountd_workqueue)
> +		queue_work(nfs_umountd_workqueue, &nfs_umount_work);
> +
> +	return nfs_ok;
> +}
> +
> +/*
>  * Set a file's attributes
>  */
> static __be32
> @@ -671,7 +687,7 @@ struct nfsd3_voidargs { int dummy; };
> #define pAT (1+AT)	/* post attributes - conditional */
> #define WC (7+pAT)	/* WCC attributes */
> 
> -static struct svc_procedure		nfsd_procedures3[22] = {
> +static struct svc_procedure		nfsd_procedures3[23] = {
> 	[NFS3PROC_NULL] = {
> 		.pc_func = (svc_procfunc) nfsd3_proc_null,
> 		.pc_encode = (kxdrproc_t) nfs3svc_encode_voidres,
> @@ -885,11 +901,21 @@ static struct svc_procedure		nfsd_procedures3[22] = {
> 		.pc_cachetype = RC_NOCACHE,
> 		.pc_xdrressize = ST+WC+2,
> 	},
> +	[NFS3PROC_UMOUNT] = {
> +		.pc_func = (svc_procfunc) nfsd3_proc_umount,
> +		.pc_decode = (kxdrproc_t) nfs3svc_decode_umountargs,
> +		.pc_encode = (kxdrproc_t) nfs3svc_encode_umountres,
> +		.pc_argsize = sizeof(struct nfsd3_umountargs),
> +		.pc_ressize = sizeof(struct nfsd3_umountres),
> +		.pc_cachetype = RC_NOCACHE,
> +		.pc_xdrressize = ST+1,
> +	},
> };
> 
> struct svc_version	nfsd_version3 = {
> 		.vs_vers	= 3,
> 		.vs_nproc	= 22,
> +		.vs_nproc	= 23,
> 		.vs_proc	= nfsd_procedures3,
> 		.vs_dispatch	= nfsd_dispatch,
> 		.vs_xdrsize	= NFS3_SVC_XDRSIZE,
> diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
> index 43f46cd..8610282 100644
> --- a/fs/nfsd/nfs3xdr.c
> +++ b/fs/nfsd/nfs3xdr.c
> @@ -611,6 +611,15 @@ nfs3svc_decode_commitargs(struct svc_rqst *rqstp, __be32 *p,
> 	return xdr_argsize_check(rqstp, p);
> }
> 
> +int
> +nfs3svc_decode_umountargs(struct svc_rqst *rqstp, __be32 *p,
> +		struct nfsd3_umountargs *args)
> +{
> +	args->dummy = ntohl(*p++);
> +
> +	return xdr_argsize_check(rqstp, p);
> +}
> +
> /*
>  * XDR encode functions
>  */
> @@ -1091,6 +1100,16 @@ nfs3svc_encode_commitres(struct svc_rqst *rqstp, __be32 *p,
> 	return xdr_ressize_check(rqstp, p);
> }
> 
> +/* UMOUNT */
> +int
> +nfs3svc_encode_umountres(struct svc_rqst *rqstp, __be32 *p,
> +		struct nfsd3_umountres *resp)
> +{
> +	if (resp->status == 0)
> +		*p++ = htonl(resp->dummy);
> +	return xdr_ressize_check(rqstp, p);
> +}
> +
> /*
>  * XDR release functions
>  */
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index c55298e..53748ac 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -50,6 +50,9 @@ enum {
> #endif
> };
> 
> +struct workqueue_struct *nfs_umountd_workqueue;
> +struct work_struct nfs_umount_work;
> +
> /*
>  * write() for these nodes.
>  */
> @@ -1175,6 +1178,17 @@ static struct pernet_operations nfsd_net_ops = {
> 	.size = sizeof(struct nfsd_net),
> };
> 
> +static void nfs_umountd_fn(struct work_struct *unused)
> +{
> +	nfsd_export_flush(&init_net);
> +}
> +
> +static void nfsd_umount_destroy(void)
> +{
> +	if (nfs_umountd_workqueue)
> +		destroy_workqueue(nfs_umountd_workqueue);
> +}
> +
> static int __init init_nfsd(void)
> {
> 	int retval;
> @@ -1204,6 +1218,13 @@ static int __init init_nfsd(void)
> 	retval = register_filesystem(&nfsd_fs_type);
> 	if (retval)
> 		goto out_free_all;
> +
> +	nfs_umountd_workqueue = create_singlethread_workqueue("nfs.umountd");
> +	if (!nfs_umountd_workqueue)
> +		printk(KERN_ERR "nfsd: Failed to create nfs.umountd workqueue\n");
> +	else
> +		INIT_WORK(&nfs_umount_work, nfs_umountd_fn);
> +
> 	return 0;
> out_free_all:
> 	remove_proc_entry("fs/nfs/exports", NULL);
> @@ -1225,6 +1246,7 @@ out_unregister_notifier:
> 
> static void __exit exit_nfsd(void)
> {
> +	nfsd_umount_destroy();
> 	nfsd_reply_cache_shutdown();
> 	remove_proc_entry("fs/nfs/exports", NULL);
> 	remove_proc_entry("fs/nfs", NULL);
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index 1671429..691450a 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -20,6 +20,7 @@
> #include <linux/nfsd/debug.h>
> #include <linux/nfsd/export.h>
> #include <linux/nfsd/stats.h>
> +#include <linux/workqueue.h>
> 
> /*
>  * nfsd version
> @@ -61,6 +62,8 @@ extern unsigned int		nfsd_drc_max_mem;
> extern unsigned int		nfsd_drc_mem_used;
> 
> extern const struct seq_operations nfs_exports_op;
> +extern struct workqueue_struct *nfs_umountd_workqueue;
> +extern struct work_struct nfs_umount_work;
> 
> /*
>  * Function prototypes.
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index ee709fc..1fb3598 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -256,6 +256,9 @@ static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
> {
> 	/* When last nfsd thread exits we need to do some clean-up */
> 	nfsd_serv = NULL;
> +	if (nfs_umountd_workqueue)
> +		flush_workqueue(nfs_umountd_workqueue);
> +
> 	nfsd_shutdown();
> 
> 	svc_rpcb_cleanup(serv, net);
> diff --git a/fs/nfsd/xdr3.h b/fs/nfsd/xdr3.h
> index 7df980e..b542c92 100644
> --- a/fs/nfsd/xdr3.h
> +++ b/fs/nfsd/xdr3.h
> @@ -106,6 +106,10 @@ struct nfsd3_commitargs {
> 	__u32			count;
> };
> 
> +struct nfsd3_umountargs {
> +	__u32	dummy;
> +};
> +
> struct nfsd3_getaclargs {
> 	struct svc_fh		fh;
> 	int			mask;
> @@ -219,6 +223,11 @@ struct nfsd3_commitres {
> 	struct svc_fh		fh;
> };
> 
> +struct nfsd3_umountres {
> +	__be32	status;
> +	__u32	dummy;
> +};
> +
> struct nfsd3_getaclres {
> 	__be32			status;
> 	struct svc_fh		fh;
> @@ -295,6 +304,8 @@ int nfs3svc_decode_readdirplusargs(struct svc_rqst *, __be32 *,
> 				struct nfsd3_readdirargs *);
> int nfs3svc_decode_commitargs(struct svc_rqst *, __be32 *,
> 				struct nfsd3_commitargs *);
> +int nfs3svc_decode_umountargs(struct svc_rqst *, __be32 *,
> +				struct nfsd3_umountargs *);
> int nfs3svc_encode_voidres(struct svc_rqst *, __be32 *, void *);
> int nfs3svc_encode_attrstat(struct svc_rqst *, __be32 *,
> 				struct nfsd3_attrstat *);
> @@ -324,7 +335,8 @@ int nfs3svc_encode_pathconfres(struct svc_rqst *, __be32 *,
> 				struct nfsd3_pathconfres *);
> int nfs3svc_encode_commitres(struct svc_rqst *, __be32 *,
> 				struct nfsd3_commitres *);
> -
> +int nfs3svc_encode_umountres(struct svc_rqst *, __be32 *,
> +				struct nfsd3_umountres *);
> int nfs3svc_release_fhandle(struct svc_rqst *, __be32 *,
> 				struct nfsd3_attrstat *);
> int nfs3svc_release_fhandle2(struct svc_rqst *, __be32 *,
> diff --git a/include/linux/nfs3.h b/include/linux/nfs3.h
> index 6ccfe3b..968e2e0 100644
> --- a/include/linux/nfs3.h
> +++ b/include/linux/nfs3.h
> @@ -90,6 +90,7 @@ struct nfs3_fh {
> #define NFS3PROC_FSINFO		19
> #define NFS3PROC_PATHCONF	20
> #define NFS3PROC_COMMIT		21
> +#define NFS3PROC_UMOUNT		22
> 
> #define NFS_MNT3_VERSION	3
> 
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index 5c0014d..da53bd8 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -786,6 +786,14 @@ struct nfs3_readdirargs {
> 	struct page **		pages;
> };
> 
> +struct nfs3_umountargs {
> +	__u32			dummy;
> +};
> +
> +struct nfs3_umountres {
> +	__u32			dummy;
> +};
> +
> struct nfs3_diropres {
> 	struct nfs_fattr *	dir_attr;
> 	struct nfs_fh *		fh;
> @@ -1425,6 +1433,7 @@ struct nfs_rpc_ops {
> 	struct nfs_client *
> 		(*init_client) (struct nfs_client *, const struct rpc_timeout *,
> 				const char *, rpc_authflavor_t);
> +	int	(*umount)(struct nfs_server *);
> };
> 
> /*
> -- 
> 1.7.9.5
> 

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