Allow read using write delegation stateid granted on OPENs with
OPEN4_SHARE_ACCESS_WRITE only, to accommodate clients whose WRITE
implementation may unavoidably do (e.g., due to buffer cache
constraints).
When this condition is detected in nfsd4_encode_read the access
mode FMODE_READ is temporarily added to the file's f_mode and is
removed when the read is done.
Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
---
fs/nfsd/nfs4proc.c | 15 ++++++++++++++-
fs/nfsd/nfs4xdr.c | 8 ++++++++
fs/nfsd/xdr4.h | 1 +
3 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index f6e06c779d09..be43627bbf78 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -973,7 +973,18 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
/* check stateid */
status = nfs4_preprocess_stateid_op(rqstp, cstate, &cstate->current_fh,
&read->rd_stateid, RD_STATE,
- &read->rd_nf, NULL);
+ &read->rd_nf, &read->rd_wd_stid);
+ /*
+ * rd_wd_stid is needed for nfsd4_encode_read to allow write
+ * delegation stateid used for read. Its refcount is decremented
+ * by nfsd4_read_release when read is done.
+ */
+ if (!status && read->rd_wd_stid &&
+ (read->rd_wd_stid->sc_type != SC_TYPE_DELEG ||
+ delegstateid(read->rd_wd_stid)->dl_type != NFS4_OPEN_DELEGATE_WRITE)) {
+ nfs4_put_stid(read->rd_wd_stid);
+ read->rd_wd_stid = NULL;
+ }
read->rd_rqstp = rqstp;
read->rd_fhp = &cstate->current_fh;
@@ -984,6 +995,8 @@ nfsd4_read(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
static void
nfsd4_read_release(union nfsd4_op_u *u)
{
+ if (u->read.rd_wd_stid)
+ nfs4_put_stid(u->read.rd_wd_stid);
if (u->read.rd_nf)
nfsd_file_put(u->read.rd_nf);
trace_nfsd_read_done(u->read.rd_rqstp, u->read.rd_fhp,
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index e67420729ecd..3996678bab3f 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4498,6 +4498,7 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
unsigned long maxcount;
__be32 wire_data[2];
struct file *file;
+ bool wronly = false;
if (nfserr)
return nfserr;
@@ -4515,10 +4516,17 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
maxcount = min_t(unsigned long, read->rd_length,
(xdr->buf->buflen - xdr->buf->len));
+ if (!(file->f_mode & FMODE_READ) && read->rd_wd_stid) {
+ /* allow READ using write delegation stateid */
+ wronly = true;
+ file->f_mode |= FMODE_READ;
+ }
if (file->f_op->splice_read && splice_ok)
nfserr = nfsd4_encode_splice_read(resp, read, file, maxcount);
else
nfserr = nfsd4_encode_readv(resp, read, file, maxcount);
+ if (wronly)
+ file->f_mode &= ~FMODE_READ;
if (nfserr) {
xdr_truncate_encode(xdr, eof_offset);
return nfserr;
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index c26ba86dbdfd..2f053beed899 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -426,6 +426,7 @@ struct nfsd4_read {
struct svc_rqst *rd_rqstp; /* response */
struct svc_fh *rd_fhp; /* response */
u32 rd_eof; /* response */
+ struct nfs4_stid *rd_wd_stid; /* internal */
};
struct nfsd4_readdir {
--
2.43.5
