* [PATCH 2/2] NFSD: Replace nfsd_write()'s "stable" argument with "iocb_flags"
2026-07-23 18:20 [PATCH 0/2] NFSD: Decouple the write path from NFSv3 XDR constants Chuck Lever
2026-07-23 18:20 ` [PATCH 1/2] NFS: Move definition of enum nfs3_stable_how Chuck Lever
@ 2026-07-23 18:20 ` Chuck Lever
1 sibling, 0 replies; 3+ messages in thread
From: Chuck Lever @ 2026-07-23 18:20 UTC (permalink / raw)
To: NeilBrown, Jeff Layton, Olga Kornievskaia, Dai Ngo, Tom Talpey; +Cc: linux-nfs
The current nfsd_write() API is not NFS version-agnostic, as it
relies on callers to pass an NFSv3 stable_how value to determine
the persistence of the requested WRITE. NFSv2 does not use a
stable-how value on the wire, and NFSv4 has its own stable_how4
(though stable_how and stable_how4 happen to share the same
numeric values).
To remove the dependence on NFSv3-specific XDR values from NFSD's
generic VFS APIs, replace nfsd_write()'s stable argument with an
argument that passes a set of IOCB flags instead of an XDR-defined
value.
The NFSv4 WRITE and COPY paths had been borrowing the NFSv3
stable_how constants for their own on-the-wire stable values,
relying on the numeric coincidence noted above. Convert those
sites to the stable_how4 enumerators so the v4 code expresses
its own protocol's values directly, with no change in behavior.
While here, bound-check the decoded NFSv3 WRITE stable value, as
the NFSv4 WRITE decoder already does, and make the nfsd3_writeargs
stable field unsigned to suit.
The larger benefit is one less NFSv4 dependency on nfs3.h.
Signed-off-by: Chuck Lever <cel@kernel.org>
---
fs/nfsd/nfs3proc.c | 17 ++++++++++++++++-
fs/nfsd/nfs3xdr.c | 2 ++
fs/nfsd/nfs4proc.c | 18 ++++++++++++++++--
fs/nfsd/nfs4xdr.c | 2 +-
fs/nfsd/nfsproc.c | 2 +-
fs/nfsd/vfs.c | 30 ++++++++++--------------------
fs/nfsd/vfs.h | 6 ++++--
fs/nfsd/xdr3.h | 2 +-
include/linux/nfs4.h | 6 ++++++
9 files changed, 57 insertions(+), 28 deletions(-)
diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 4b3075c05b97..19ab0a713d82 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -49,6 +49,20 @@ static bool nfsd3_time_in_range(const struct iattr *iap)
return true;
}
+static int nfsd3_iocb_flags(enum nfs3_stable_how how)
+{
+ switch (how) {
+ case NFS_FILE_SYNC:
+ /* persist data and timestamps */
+ return IOCB_DSYNC | IOCB_SYNC;
+ case NFS_DATA_SYNC:
+ /* persist data only */
+ return IOCB_DSYNC;
+ default:
+ return 0;
+ }
+}
+
static __be32 nfsd3_map_status(__be32 status)
{
switch (status) {
@@ -261,7 +275,8 @@ nfsd3_proc_write(struct svc_rqst *rqstp)
resp->committed = argp->stable;
resp->status = nfsd_write(rqstp, &resp->fh, argp->offset,
&argp->payload, &cnt,
- resp->committed, resp->verf);
+ nfsd3_iocb_flags(resp->committed),
+ resp->verf);
resp->count = cnt;
resp->status = nfsd3_map_status(resp->status);
return rpc_success;
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 196bcc6edebb..090cea8e545d 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -557,6 +557,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
return false;
if (xdr_stream_decode_u32(xdr, &args->stable) < 0)
return false;
+ if (args->stable > NFS_FILE_SYNC)
+ return false;
/* opaque data */
if (xdr_stream_decode_u32(xdr, &args->len) < 0)
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index a39880208761..a2ff1c8f415b 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -72,6 +72,20 @@ MODULE_PARM_DESC(nfsd4_ssc_umount_timeout,
#define NFSDDBG_FACILITY NFSDDBG_PROC
+static int nfsd4_iocb_flags(enum stable_how4 how)
+{
+ switch (how) {
+ case FILE_SYNC4:
+ /* persist data and timestamps */
+ return IOCB_DSYNC | IOCB_SYNC;
+ case DATA_SYNC4:
+ /* persist data only */
+ return IOCB_DSYNC;
+ default:
+ return 0;
+ }
+}
+
static u32 nfsd_attrmask[] = {
NFSD_WRITEABLE_ATTRS_WORD0,
NFSD_WRITEABLE_ATTRS_WORD1,
@@ -1417,7 +1431,7 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
write->wr_how_written = write->wr_stable_how;
status = nfsd_vfs_write(rqstp, &cstate->current_fh, nf,
write->wr_offset, &write->wr_payload,
- &cnt, write->wr_how_written,
+ &cnt, nfsd4_iocb_flags(write->wr_how_written),
(__be32 *)write->wr_verifier.data);
nfsd_file_put(nf);
@@ -2001,7 +2015,7 @@ static void nfsd4_init_copy_res(struct nfsd4_copy *copy, bool sync)
{
copy->cp_res.wr_stable_how =
test_bit(NFSD4_COPY_F_COMMITTED, ©->cp_flags) ?
- NFS_FILE_SYNC : NFS_UNSTABLE;
+ FILE_SYNC4 : UNSTABLE4;
nfsd4_copy_set_sync(copy, sync);
}
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 7ccc7c897b00..a47eb544b99f 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1607,7 +1607,7 @@ nfsd4_decode_write(struct nfsd4_compoundargs *argp, union nfsd4_op_u *u)
return nfserr_bad_xdr;
if (xdr_stream_decode_u32(argp->xdr, &write->wr_stable_how) < 0)
return nfserr_bad_xdr;
- if (write->wr_stable_how > NFS_FILE_SYNC)
+ if (write->wr_stable_how > FILE_SYNC4)
return nfserr_bad_xdr;
if (xdr_stream_decode_u32(argp->xdr, &write->wr_buflen) < 0)
return nfserr_bad_xdr;
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index 919acfba356a..48541ef7644f 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -266,7 +266,7 @@ nfsd_proc_write(struct svc_rqst *rqstp)
fh_copy(&resp->fh, &argp->fh);
resp->status = nfsd_write(rqstp, &resp->fh, argp->offset,
- &argp->payload, &cnt, NFS_DATA_SYNC, NULL);
+ &argp->payload, &cnt, IOCB_DSYNC, NULL);
if (resp->status == nfs_ok)
resp->status = fh_getattr(&resp->fh, &resp->stat);
else if (resp->status == nfserr_jukebox)
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index fdfcd95971db..edb08c006a23 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1433,7 +1433,7 @@ nfsd_direct_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
* @offset: Byte offset of start
* @payload: xdr_buf containing the write payload
* @cnt: IN: number of bytes to write, OUT: number of bytes actually written
- * @stable: An NFS stable_how value
+ * @iocb_flags: VFS IOCB_* flags expressing the requested write stability
* @verf: NFS WRITE verifier
*
* Upon return, caller must invoke fh_put on @fhp.
@@ -1445,7 +1445,7 @@ __be32
nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct nfsd_file *nf, loff_t offset,
const struct xdr_buf *payload, unsigned long *cnt,
- int stable, __be32 *verf)
+ int iocb_flags, __be32 *verf)
{
struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
struct file *file = nf->nf_file;
@@ -1482,21 +1482,11 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
exp = fhp->fh_export;
if (!EX_ISSYNC(exp))
- stable = NFS_UNSTABLE;
+ iocb_flags = 0;
init_sync_kiocb(&kiocb, file);
kiocb.ki_pos = offset;
- if (likely(!fhp->fh_use_wgather)) {
- switch (stable) {
- case NFS_FILE_SYNC:
- /* persist data and timestamps */
- kiocb.ki_flags |= IOCB_DSYNC | IOCB_SYNC;
- break;
- case NFS_DATA_SYNC:
- /* persist data only */
- kiocb.ki_flags |= IOCB_DSYNC;
- break;
- }
- }
+ if (likely(!fhp->fh_use_wgather))
+ kiocb.ki_flags |= iocb_flags;
nvecs = xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, payload);
if (nvecs < 0) {
@@ -1537,7 +1527,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
goto out_nfserr;
}
- if (stable && fhp->fh_use_wgather) {
+ if (iocb_flags && fhp->fh_use_wgather) {
host_err = wait_for_concurrent_writes(file);
if (host_err < 0)
commit_reset_write_verifier(nn, rqstp, host_err);
@@ -1628,7 +1618,7 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
* @offset: Byte offset of start
* @payload: xdr_buf containing the write payload
* @cnt: IN: number of bytes to write, OUT: number of bytes actually written
- * @stable: An NFS stable_how value
+ * @iocb_flags: VFS IOCB_* flags expressing the requested write stability
* @verf: NFS WRITE verifier
*
* Upon return, caller must invoke fh_put on @fhp.
@@ -1638,8 +1628,8 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
*/
__be32
nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
- const struct xdr_buf *payload, unsigned long *cnt, int stable,
- __be32 *verf)
+ const struct xdr_buf *payload, unsigned long *cnt,
+ int iocb_flags, __be32 *verf)
{
struct nfsd_file *nf;
__be32 err;
@@ -1651,7 +1641,7 @@ nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, loff_t offset,
goto out;
err = nfsd_vfs_write(rqstp, fhp, nf, offset, payload, cnt,
- stable, verf);
+ iocb_flags, verf);
nfsd_file_put(nf);
out:
trace_nfsd_write_done(rqstp, fhp, offset, *cnt);
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index 5554878781f4..aa7679d4c54a 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -135,11 +135,13 @@ __be32 nfsd_read(struct svc_rqst *rqstp, struct svc_fh *fhp,
u32 *eof);
__be32 nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
loff_t offset, const struct xdr_buf *payload,
- unsigned long *cnt, int stable, __be32 *verf);
+ unsigned long *cnt, int iocb_flags,
+ __be32 *verf);
__be32 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp,
struct nfsd_file *nf, loff_t offset,
const struct xdr_buf *payload,
- unsigned long *cnt, int stable, __be32 *verf);
+ unsigned long *cnt, int iocb_flags,
+ __be32 *verf);
__be32 nfsd_readlink(struct svc_rqst *, struct svc_fh *,
char *, int *);
__be32 nfsd_symlink(struct svc_rqst *, struct svc_fh *,
diff --git a/fs/nfsd/xdr3.h b/fs/nfsd/xdr3.h
index 344203874b4c..cad875d14231 100644
--- a/fs/nfsd/xdr3.h
+++ b/fs/nfsd/xdr3.h
@@ -39,7 +39,7 @@ struct nfsd3_writeargs {
svc_fh fh;
__u64 offset;
__u32 count;
- int stable;
+ __u32 stable;
__u32 len;
struct xdr_buf payload;
};
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index 44e5e9fa12e1..9333f2716b4d 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -263,6 +263,12 @@ enum why_no_delegation4 { /* new to v4.1 */
WND4_IS_DIR = 8,
};
+enum stable_how4 {
+ UNSTABLE4 = 0,
+ DATA_SYNC4 = 1,
+ FILE_SYNC4 = 2,
+};
+
enum lock_type4 {
NFS4_UNLOCK_LT = 0,
NFS4_READ_LT = 1,
--
2.54.0
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