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NFS: Add mount option 'softreval'
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Add a mount option 'softreval' that allows attribute revalidation 'getattr'
calls to time out, and causes them to fall back to using the cached
attributes.
The use case for this option is for ensuring that we can still (slowly)
traverse paths and use cached information even when the server is down.
Once the server comes back up again, the getattr calls start succeeding,
and the caches will revalidate as usual.

The 'softreval' mount option is automatically enabled if you have
specified 'softerr'.  It can be turned off using the options
'nosoftreval', or 'hard'.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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Trond Myklebust authored and Anna Schumaker committed Jan 15, 2020
1 parent 5c965db commit c74dfe9
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Showing 7 changed files with 59 additions and 12 deletions.
14 changes: 12 additions & 2 deletions fs/nfs/fs_context.c
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Original file line number Diff line number Diff line change
Expand Up @@ -73,6 +73,7 @@ enum nfs_param {
Opt_sloppy,
Opt_soft,
Opt_softerr,
Opt_softreval,
Opt_source,
Opt_tcp,
Opt_timeo,
Expand Down Expand Up @@ -128,6 +129,7 @@ static const struct fs_parameter_spec nfs_param_specs[] = {
fsparam_flag ("sloppy", Opt_sloppy),
fsparam_flag ("soft", Opt_soft),
fsparam_flag ("softerr", Opt_softerr),
fsparam_flag ("softreval", Opt_softreval),
fsparam_string("source", Opt_source),
fsparam_flag ("tcp", Opt_tcp),
fsparam_u32 ("timeo", Opt_timeo),
Expand Down Expand Up @@ -460,11 +462,19 @@ static int nfs_fs_context_parse_param(struct fs_context *fc,
ctx->flags &= ~NFS_MOUNT_SOFTERR;
break;
case Opt_softerr:
ctx->flags |= NFS_MOUNT_SOFTERR;
ctx->flags |= NFS_MOUNT_SOFTERR | NFS_MOUNT_SOFTREVAL;
ctx->flags &= ~NFS_MOUNT_SOFT;
break;
case Opt_hard:
ctx->flags &= ~(NFS_MOUNT_SOFT|NFS_MOUNT_SOFTERR);
ctx->flags &= ~(NFS_MOUNT_SOFT |
NFS_MOUNT_SOFTERR |
NFS_MOUNT_SOFTREVAL);
break;
case Opt_softreval:
if (result.negated)
ctx->flags &= ~NFS_MOUNT_SOFTREVAL;
else
ctx->flags &= NFS_MOUNT_SOFTREVAL;
break;
case Opt_posix:
if (result.negated)
Expand Down
8 changes: 7 additions & 1 deletion fs/nfs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1156,7 +1156,13 @@ __nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Lu) getattr failed, error=%d\n",
inode->i_sb->s_id,
(unsigned long long)NFS_FILEID(inode), status);
if (status == -ESTALE) {
switch (status) {
case -ETIMEDOUT:
/* A soft timeout occurred. Use cached information? */
if (server->flags & NFS_MOUNT_SOFTREVAL)
status = 0;
break;
case -ESTALE:
nfs_zap_caches(inode);
if (!S_ISDIR(inode->i_mode))
set_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
Expand Down
7 changes: 6 additions & 1 deletion fs/nfs/nfs3proc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -110,10 +110,15 @@ nfs3_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle,
.rpc_resp = fattr,
};
int status;
unsigned short task_flags = 0;

/* Is this is an attribute revalidation, subject to softreval? */
if (inode && (server->flags & NFS_MOUNT_SOFTREVAL))
task_flags |= RPC_TASK_TIMEOUT;

dprintk("NFS call getattr\n");
nfs_fattr_init(fattr);
status = rpc_call_sync(server->client, &msg, 0);
status = rpc_call_sync(server->client, &msg, task_flags);
dprintk("NFS reply getattr: %d\n", status);
return status;
}
Expand Down
33 changes: 26 additions & 7 deletions fs/nfs/nfs4proc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1097,11 +1097,12 @@ static int nfs4_call_sync_custom(struct rpc_task_setup *task_setup)
return ret;
}

static int nfs4_call_sync_sequence(struct rpc_clnt *clnt,
struct nfs_server *server,
struct rpc_message *msg,
struct nfs4_sequence_args *args,
struct nfs4_sequence_res *res)
static int nfs4_do_call_sync(struct rpc_clnt *clnt,
struct nfs_server *server,
struct rpc_message *msg,
struct nfs4_sequence_args *args,
struct nfs4_sequence_res *res,
unsigned short task_flags)
{
struct nfs_client *clp = server->nfs_client;
struct nfs4_call_sync_data data = {
Expand All @@ -1113,12 +1114,23 @@ static int nfs4_call_sync_sequence(struct rpc_clnt *clnt,
.rpc_client = clnt,
.rpc_message = msg,
.callback_ops = clp->cl_mvops->call_sync_ops,
.callback_data = &data
.callback_data = &data,
.flags = task_flags,
};

return nfs4_call_sync_custom(&task_setup);
}

static int nfs4_call_sync_sequence(struct rpc_clnt *clnt,
struct nfs_server *server,
struct rpc_message *msg,
struct nfs4_sequence_args *args,
struct nfs4_sequence_res *res)
{
return nfs4_do_call_sync(clnt, server, msg, args, res, 0);
}


int nfs4_call_sync(struct rpc_clnt *clnt,
struct nfs_server *server,
struct rpc_message *msg,
Expand Down Expand Up @@ -4064,11 +4076,18 @@ static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle,
.rpc_argp = &args,
.rpc_resp = &res,
};
unsigned short task_flags = 0;

/* Is this is an attribute revalidation, subject to softreval? */
if (inode && (server->flags & NFS_MOUNT_SOFTREVAL))
task_flags |= RPC_TASK_TIMEOUT;

nfs4_bitmap_copy_adjust(bitmask, nfs4_bitmask(server, label), inode);

nfs_fattr_init(fattr);
return nfs4_call_sync(server->client, server, &msg, &args.seq_args, &res.seq_res, 0);
nfs4_init_sequence(&args.seq_args, &res.seq_res, 0, 0);
return nfs4_do_call_sync(server->client, server, &msg,
&args.seq_args, &res.seq_res, task_flags);
}

int nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle,
Expand Down
7 changes: 6 additions & 1 deletion fs/nfs/proc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -108,10 +108,15 @@ nfs_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle,
.rpc_resp = fattr,
};
int status;
unsigned short task_flags = 0;

/* Is this is an attribute revalidation, subject to softreval? */
if (inode && (server->flags & NFS_MOUNT_SOFTREVAL))
task_flags |= RPC_TASK_TIMEOUT;

dprintk("NFS call getattr\n");
nfs_fattr_init(fattr);
status = rpc_call_sync(server->client, &msg, 0);
status = rpc_call_sync(server->client, &msg, task_flags);
dprintk("NFS reply getattr: %d\n", status);
return status;
}
Expand Down
1 change: 1 addition & 0 deletions fs/nfs/super.c
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Original file line number Diff line number Diff line change
Expand Up @@ -375,6 +375,7 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
} nfs_info[] = {
{ NFS_MOUNT_SOFT, ",soft", "" },
{ NFS_MOUNT_SOFTERR, ",softerr", "" },
{ NFS_MOUNT_SOFTREVAL, ",softreval", "" },
{ NFS_MOUNT_POSIX, ",posix", "" },
{ NFS_MOUNT_NOCTO, ",nocto", "" },
{ NFS_MOUNT_NOAC, ",noac", "" },
Expand Down
1 change: 1 addition & 0 deletions include/linux/nfs_fs_sb.h
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Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,7 @@ struct nfs_server {
#define NFS_MOUNT_LOCAL_FLOCK 0x100000
#define NFS_MOUNT_LOCAL_FCNTL 0x200000
#define NFS_MOUNT_SOFTERR 0x400000
#define NFS_MOUNT_SOFTREVAL 0x800000

unsigned int caps; /* server capabilities */
unsigned int rsize; /* read size */
Expand Down

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