2012/6/24, Chuck Lever <chuck.lever@xxxxxxxxxx>:
>
> On Jun 23, 2012, at 11:52 AM, Myklebust, Trond wrote:
>
>> The other objection is that NFSv3 already has a way to do this via the
>> MOUNT protocol. We already call MOUNTPROC3_UMNT/MOUNTPROC_UMNT on unmount
>> of a filesystem.
>>
>> The problem with this approach is that if the NFS client crashes before it
>> can call this function, then the server never gets notified. That is a
>> problem that your patch has too...
>
> Indeed. That could be addressed, however, by having the server scrub its
> rmtab when it receives an SM_NOTIFY after a client reboots. The client will
> only send an SM_NOTIFY, however, if it held NLM locks on that server.
>
> There is also a UMNTALL procedure in the MOUNT protocol that a client could
> send to servers on reboot if clients kept track on permanent storage of
> servers they mounted.
>
> None of these approaches is terribly reliable, though, and the issue is
> addressed in NFSv4, which is lease-based. You should probably focus on
> addressing this on the server itself.
Okay, I will check about your advice.
Thanks.
>
>> --
>> Trond Myklebust
>> Linux NFS client maintainer
>>
>> NetApp
>> Trond.Myklebust@xxxxxxxxxx
>> www.netapp.com
>>
>> On Jun 23, 2012, at 11:07 AM, Myklebust, Trond wrote:
>>
>>> 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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>
> --
> Chuck Lever
> chuck[dot]lever[at]oracle[dot]com
>
>
>
>
>
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