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NFSv4.1: Ask for no delegation on OPEN if using O_DIRECT 

If we're using NFSv4.1, then we have the ability to let the server know
whether or not we believe that returning a delegation as part of our OPEN
request would be useful.
The feature needs to be used with care, since the client sending the request
doesn't necessarily know how other clients are using that file, and how
they may be affected by the delegation.
For this reason, our initial use of the feature will be to let the server
know when the client believes that handing out a delegation would not be
useful.
The first application for this function is when opening the file using
O_DIRECT.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2015-01-30 14:21:14 -05:00
parent 0e3b137fbf
commit 6ae373394c
3 changed files with 85 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
fs/nfs/nfs4proc.c
View File

@ -940,6 +940,31 @@ static bool nfs4_clear_cap_atomic_open_v1(struct nfs_server *server,
return true;
}
static u32
nfs4_map_atomic_open_share(struct nfs_server *server,
fmode_t fmode, int openflags)
{
u32 res = 0;
switch (fmode & (FMODE_READ | FMODE_WRITE)) {
case FMODE_READ:
res = NFS4_SHARE_ACCESS_READ;
break;
case FMODE_WRITE:
res = NFS4_SHARE_ACCESS_WRITE;
break;
case FMODE_READ|FMODE_WRITE:
res = NFS4_SHARE_ACCESS_BOTH;
}
if (!(server->caps & NFS_CAP_ATOMIC_OPEN_V1))
goto out;
/* Want no delegation if we're using O_DIRECT */
if (openflags & O_DIRECT)
res |= NFS4_SHARE_WANT_NO_DELEG;
out:
return res;
}
static enum open_claim_type4
nfs4_map_atomic_open_claim(struct nfs_server *server,
enum open_claim_type4 claim)
@ -1002,6 +1027,8 @@ static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
atomic_inc(&sp->so_count);
p->o_arg.open_flags = flags;
p->o_arg.fmode = fmode & (FMODE_READ|FMODE_WRITE);
p->o_arg.share_access = nfs4_map_atomic_open_share(server,
fmode, flags);
/* don't put an ACCESS op in OPEN compound if O_EXCL, because ACCESS
* will return permission denied for all bits until close */
if (!(flags & O_EXCL)) {
@ -2695,6 +2722,9 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
goto out_wait;
}
}
calldata->arg.share_access =
nfs4_map_atomic_open_share(NFS_SERVER(inode),
calldata->arg.fmode, 0);
nfs_fattr_init(calldata->res.fattr);
calldata->timestamp = jiffies;

79
fs/nfs/nfs4xdr.c
View File

@ -1351,24 +1351,12 @@ static void encode_lookup(struct xdr_stream *xdr, const struct qstr *name, struc
encode_string(xdr, name->len, name->name);
}
static void encode_share_access(struct xdr_stream *xdr, fmode_t fmode)
static void encode_share_access(struct xdr_stream *xdr, u32 share_access)
{
__be32 *p;
p = reserve_space(xdr, 8);
switch (fmode & (FMODE_READ|FMODE_WRITE)) {
case FMODE_READ:
*p++ = cpu_to_be32(NFS4_SHARE_ACCESS_READ);
break;
case FMODE_WRITE:
*p++ = cpu_to_be32(NFS4_SHARE_ACCESS_WRITE);
break;
case FMODE_READ|FMODE_WRITE:
*p++ = cpu_to_be32(NFS4_SHARE_ACCESS_BOTH);
break;
default:
*p++ = cpu_to_be32(0);
}
*p++ = cpu_to_be32(share_access);
*p = cpu_to_be32(0); /* for linux, share_deny = 0 always */
}
@ -1380,7 +1368,7 @@ static inline void encode_openhdr(struct xdr_stream *xdr, const struct nfs_opena
* owner 4 = 32
*/
encode_nfs4_seqid(xdr, arg->seqid);
encode_share_access(xdr, arg->fmode);
encode_share_access(xdr, arg->share_access);
p = reserve_space(xdr, 36);
p = xdr_encode_hyper(p, arg->clientid);
*p++ = cpu_to_be32(24);
@ -1535,7 +1523,7 @@ static void encode_open_downgrade(struct xdr_stream *xdr, const struct nfs_close
encode_op_hdr(xdr, OP_OPEN_DOWNGRADE, decode_open_downgrade_maxsz, hdr);
encode_nfs4_stateid(xdr, &arg->stateid);
encode_nfs4_seqid(xdr, arg->seqid);
encode_share_access(xdr, arg->fmode);
encode_share_access(xdr, arg->share_access);
}
static void
@ -4935,20 +4923,13 @@ static int decode_space_limit(struct xdr_stream *xdr, u64 *maxsize)
return -EIO;
}
static int decode_delegation(struct xdr_stream *xdr, struct nfs_openres *res)
static int decode_rw_delegation(struct xdr_stream *xdr,
uint32_t delegation_type,
struct nfs_openres *res)
{
__be32 *p;
uint32_t delegation_type;
int status;
p = xdr_inline_decode(xdr, 4);
if (unlikely(!p))
goto out_overflow;
delegation_type = be32_to_cpup(p);
if (delegation_type == NFS4_OPEN_DELEGATE_NONE) {
res->delegation_type = 0;
return 0;
}
status = decode_stateid(xdr, &res->delegation);
if (unlikely(status))
return status;
@ -4972,6 +4953,52 @@ static int decode_delegation(struct xdr_stream *xdr, struct nfs_openres *res)
return -EIO;
}
static int decode_no_delegation(struct xdr_stream *xdr, struct nfs_openres *res)
{
__be32 *p;
uint32_t why_no_delegation;
p = xdr_inline_decode(xdr, 4);
if (unlikely(!p))
goto out_overflow;
why_no_delegation = be32_to_cpup(p);
switch (why_no_delegation) {
case WND4_CONTENTION:
case WND4_RESOURCE:
xdr_inline_decode(xdr, 4);
/* Ignore for now */
}
return 0;
out_overflow:
print_overflow_msg(__func__, xdr);
return -EIO;
}
static int decode_delegation(struct xdr_stream *xdr, struct nfs_openres *res)
{
__be32 *p;
uint32_t delegation_type;
p = xdr_inline_decode(xdr, 4);
if (unlikely(!p))
goto out_overflow;
delegation_type = be32_to_cpup(p);
res->delegation_type = 0;
switch (delegation_type) {
case NFS4_OPEN_DELEGATE_NONE:
return 0;
case NFS4_OPEN_DELEGATE_READ:
case NFS4_OPEN_DELEGATE_WRITE:
return decode_rw_delegation(xdr, delegation_type, res);
case NFS4_OPEN_DELEGATE_NONE_EXT:
return decode_no_delegation(xdr, res);
}
return -EIO;
out_overflow:
print_overflow_msg(__func__, xdr);
return -EIO;
}
static int decode_open(struct xdr_stream *xdr, struct nfs_openres *res)
{
__be32 *p;

2
include/linux/nfs_xdr.h
View File

@ -326,6 +326,7 @@ struct nfs_openargs {
struct nfs_seqid * seqid;
int open_flags;
fmode_t fmode;
u32 share_access;
u32 access;
__u64 clientid;
struct stateowner_id id;
@ -393,6 +394,7 @@ struct nfs_closeargs {
nfs4_stateid stateid;
struct nfs_seqid * seqid;
fmode_t fmode;
u32 share_access;
const u32 * bitmask;
};