[PATCH v2 4/7] nfsd: implement OPEN_ARGS_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION

Jeff Layton
2024-08-26T12:46:44Z

Allow clients to request getting a delegation xor an open stateid if a
delegation isn't available. This allows the client to avoid sending a
final CLOSE for the (useless) open stateid, when it is granted a
delegation.

This is done by moving the increment of the open stateid and unlocking
of the st_mutex until after we acquire a delegation. If we get a
delegation, we zero out the op_stateid field and set the NO_OPEN_STATEID
flag. If the open stateid was brand new, then unhash it too in this case
since it won't be needed.

If we can't get a delegation or the new flag wasn't requested, then just
increment and copy the open stateid as usual.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/nfsd/nfs4state.c | 28 ++++++++++++++++++++++++----
fs/nfsd/nfs4xdr.c | 5 +++--
include/uapi/linux/nfs4.h | 7 +++++--
3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9fe67c412f9b..b544320246bf 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -6029,6 +6029,17 @@ static void nfsd4_deleg_xgrade_none_ext(struct nfsd4_open *open,
*/
}

+/* Are we only returning a delegation stateid? */
+static bool open_xor_delegation(struct nfsd4_open *open)
+{
+ if (!(open->op_deleg_want & OPEN4_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION))
+ return false;
+ if (open->op_delegate_type != NFS4_OPEN_DELEGATE_READ &&
+ open->op_delegate_type != NFS4_OPEN_DELEGATE_WRITE)
+ return false;
+ return true;
+}
+
/**
* nfsd4_process_open2 - finish open processing
* @rqstp: the RPC transaction being executed
@@ -6051,6 +6062,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
struct nfs4_delegation *dp = NULL;
__be32 status;
bool new_stp = false;
+ bool deleg_only = false;

/*
* Lookup file; if found, lookup stateid and check open request,
@@ -6105,9 +6117,6 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
open->op_odstate = NULL;
}

- nfs4_inc_and_copy_stateid(&open->op_stateid, &stp->st_stid);
- mutex_unlock(&stp->st_mutex);
-
if (nfsd4_has_session(&resp->cstate)) {
if (open->op_deleg_want & NFS4_SHARE_WANT_NO_DELEG) {
open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
@@ -6121,7 +6130,18 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
* OPEN succeeds even if we fail.
*/
nfs4_open_delegation(open, stp, &resp->cstate.current_fh);
+ deleg_only = open_xor_delegation(open);
nodeleg:
+ if (deleg_only) {
+ memcpy(&open->op_stateid, &zero_stateid, sizeof(open->op_stateid));
+ open->op_rflags |= OPEN4_RESULT_NO_OPEN_STATEID;
+ if (new_stp)
+ release_open_stateid(stp);
+ } else {
+ nfs4_inc_and_copy_stateid(&open->op_stateid, &stp->st_stid);
+ }
+ mutex_unlock(&stp->st_mutex);
+
status = nfs_ok;
trace_nfsd_open(&stp->st_stid.sc_stateid);
out:
@@ -6137,7 +6157,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
/*
* To finish the open response, we just need to set the rflags.
*/
- open->op_rflags = NFS4_OPEN_RESULT_LOCKTYPE_POSIX;
+ open->op_rflags |= NFS4_OPEN_RESULT_LOCKTYPE_POSIX;
if (nfsd4_has_session(&resp->cstate))
open->op_rflags |= NFS4_OPEN_RESULT_MAY_NOTIFY_LOCK;
else if (!(open->op_openowner->oo_flags & NFS4_OO_CONFIRMED))
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 1c8219ea8af7..8266f910d847 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1066,7 +1066,7 @@ static __be32 nfsd4_decode_share_access(struct nfsd4_compoundargs *argp, u32 *sh
return nfs_ok;
if (!argp->minorversion)
return nfserr_bad_xdr;
- switch (w & NFS4_SHARE_WANT_MASK) {
+ switch (w & NFS4_SHARE_WANT_TYPE_MASK) {
case NFS4_SHARE_WANT_NO_PREFERENCE:
case NFS4_SHARE_WANT_READ_DELEG:
case NFS4_SHARE_WANT_WRITE_DELEG:
@@ -3410,7 +3410,8 @@ static __be32 nfsd4_encode_fattr4_xattr_support(struct xdr_stream *xdr,

#define NFSD_OA_SHARE_ACCESS_WANT (BIT(OPEN_ARGS_SHARE_ACCESS_WANT_ANY_DELEG) | \
BIT(OPEN_ARGS_SHARE_ACCESS_WANT_NO_DELEG) | \
- BIT(OPEN_ARGS_SHARE_ACCESS_WANT_CANCEL))
+ BIT(OPEN_ARGS_SHARE_ACCESS_WANT_CANCEL) | \
+ BIT(OPEN_ARGS_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION))

#define NFSD_OA_OPEN_CLAIM (BIT(OPEN_ARGS_OPEN_CLAIM_NULL) | \
BIT(OPEN_ARGS_OPEN_CLAIM_PREVIOUS) | \
diff --git a/include/uapi/linux/nfs4.h b/include/uapi/linux/nfs4.h
index caf4db2fcbb9..4273e0249fcb 100644
--- a/include/uapi/linux/nfs4.h
+++ b/include/uapi/linux/nfs4.h
@@ -58,7 +58,7 @@
#define NFS4_SHARE_DENY_BOTH 0x0003

/* nfs41 */
-#define NFS4_SHARE_WANT_MASK 0xFF00
+#define NFS4_SHARE_WANT_TYPE_MASK 0xFF00
#define NFS4_SHARE_WANT_NO_PREFERENCE 0x0000
#define NFS4_SHARE_WANT_READ_DELEG 0x0100
#define NFS4_SHARE_WANT_WRITE_DELEG 0x0200
@@ -66,13 +66,16 @@
#define NFS4_SHARE_WANT_NO_DELEG 0x0400
#define NFS4_SHARE_WANT_CANCEL 0x0500

-#define NFS4_SHARE_WHEN_MASK 0xF0000
+#define NFS4_SHARE_WHEN_MASK 0xF0000
#define NFS4_SHARE_SIGNAL_DELEG_WHEN_RESRC_AVAIL 0x10000
#define NFS4_SHARE_PUSH_DELEG_WHEN_UNCONTENDED 0x20000

+#define NFS4_SHARE_WANT_MOD_MASK 0xF00000
#define NFS4_SHARE_WANT_DELEG_TIMESTAMPS 0x100000
#define NFS4_SHARE_WANT_OPEN_XOR_DELEGATION 0x200000

+#define NFS4_SHARE_WANT_MASK (NFS4_SHARE_WANT_TYPE_MASK | NFS4_SHARE_WANT_MOD_MASK)
+
#define NFS4_CDFC4_FORE 0x1
#define NFS4_CDFC4_BACK 0x2
#define NFS4_CDFC4_BOTH 0x3

--
2.46.0