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NFSD: Remove the cap on number of operations per NFSv4 COMPOUND

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This limit has always been a sanity check; in nearly all cases a
large COMPOUND is a sign of a malfunctioning client. The only real
limit on COMPOUND size and complexity is the size of NFSD's send
and receive buffers.

However, there are a few cases where a large COMPOUND is sane. For
example, when a client implementation wants to walk down a long file
pathname in a single round trip.

A small risk is that now a client can construct a COMPOUND request
that can keep a single nfsd thread busy for quite some time.

Suggested-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever
2025-06-10 12:05:09 -04:00
parent a2d61427fb
commit 48aab1606f
5 changed files with 3 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
fs/nfsd/nfs4proc.c
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@@ -2842,20 +2842,10 @@ nfsd4_proc_compound(struct svc_rqst *rqstp)
rqstp->rq_lease_breaker = (void **)&cstate->clp;
trace_nfsd_compound(rqstp, args->tag, args->taglen, args->client_opcnt);
trace_nfsd_compound(rqstp, args->tag, args->taglen, args->opcnt);
while (!status && resp->opcnt < args->opcnt) {
op = &args->ops[resp->opcnt++];
if (unlikely(resp->opcnt == NFSD_MAX_OPS_PER_COMPOUND)) {
/* If there are still more operations to process,
* stop here and report NFS4ERR_RESOURCE. */
if (cstate->minorversion == 0 &&
args->client_opcnt > resp->opcnt) {
op->status = nfserr_resource;
goto encode_op;
}
}
/*
* The XDR decode routines may have pre-set op->status;
* for example, if there is a miscellaneous XDR error
@@ -2932,7 +2922,7 @@ encode_op:
status = op->status;
}
trace_nfsd_compound_status(args->client_opcnt, resp->opcnt,
trace_nfsd_compound_status(args->opcnt, resp->opcnt,
status, nfsd4_op_name(op->opnum));
nfsd4_cstate_clear_replay(cstate);

1
fs/nfsd/nfs4state.c
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@@ -3865,7 +3865,6 @@ static __be32 check_forechannel_attrs(struct nfsd4_channel_attrs *ca, struct nfs
ca->headerpadsz = 0;
ca->maxreq_sz = min_t(u32, ca->maxreq_sz, maxrpc);
ca->maxresp_sz = min_t(u32, ca->maxresp_sz, maxrpc);
ca->maxops = min_t(u32, ca->maxops, NFSD_MAX_OPS_PER_COMPOUND);
ca->maxresp_cached = min_t(u32, ca->maxresp_cached,
NFSD_SLOT_CACHE_SIZE + NFSD_MIN_HDR_SEQ_SZ);
ca->maxreqs = min_t(u32, ca->maxreqs, NFSD_MAX_SLOTS_PER_SESSION);

4
fs/nfsd/nfs4xdr.c
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@@ -2500,10 +2500,8 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
if (xdr_stream_decode_u32(argp->xdr, &argp->minorversion) < 0)
return false;
if (xdr_stream_decode_u32(argp->xdr, &argp->client_opcnt) < 0)
if (xdr_stream_decode_u32(argp->xdr, &argp->opcnt) < 0)
return false;
argp->opcnt = min_t(u32, argp->client_opcnt,
NFSD_MAX_OPS_PER_COMPOUND);
if (argp->opcnt > ARRAY_SIZE(argp->iops)) {
argp->ops = vcalloc(argp->opcnt, sizeof(*argp->ops));

3
fs/nfsd/nfsd.h
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@@ -57,9 +57,6 @@ struct readdir_cd {
__be32 err; /* 0, nfserr, or nfserr_eof */
};
/* Maximum number of operations per session compound */
#define NFSD_MAX_OPS_PER_COMPOUND 50
struct nfsd_genl_rqstp {
struct sockaddr rq_daddr;
struct sockaddr rq_saddr;

1
fs/nfsd/xdr4.h
View File

@@ -870,7 +870,6 @@ struct nfsd4_compoundargs {
char * tag;
u32 taglen;
u32 minorversion;
u32 client_opcnt;
u32 opcnt;
bool splice_ok;
struct nfsd4_op *ops;