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NFSD: Cap rsize_bop result based on send buffer size

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Since before the git era, NFSD has conserved the number of pages
held by each nfsd thread by combining the RPC receive and send
buffers into a single array of pages. This works because there are
no cases where an operation needs a large RPC Call message and a
large RPC Reply at the same time.

Once an RPC Call has been received, svc_process() updates
svc_rqst::rq_res to describe the part of rq_pages that can be
used for constructing the Reply. This means that the send buffer
(rq_res) shrinks when the received RPC record containing the RPC
Call is large.

Add an NFSv4 helper that computes the size of the send buffer. It
replaces svc_max_payload() in spots where svc_max_payload() returns
a value that might be larger than the remaining send buffer space.
Callers who need to know the transport's actual maximum payload size
will continue to use svc_max_payload().

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2022-09-01 15:29:55 -04:00
parent 781fde1a2b
commit 76ce4dcec0
1 changed files with 24 additions and 24 deletions
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48
fs/nfsd/nfs4proc.c
View File

@ -2771,6 +2771,22 @@ out:
#define op_encode_channel_attrs_maxsz (6 + 1 + 1)
/*
* The _rsize() helpers are invoked by the NFSv4 COMPOUND decoder, which
* is called before sunrpc sets rq_res.buflen. Thus we have to compute
* the maximum payload size here, based on transport limits and the size
* of the remaining space in the rq_pages array.
*/
static u32 nfsd4_max_payload(const struct svc_rqst *rqstp)
{
u32 buflen;
buflen = (rqstp->rq_page_end - rqstp->rq_next_page) * PAGE_SIZE;
buflen -= rqstp->rq_auth_slack;
buflen -= rqstp->rq_res.head[0].iov_len;
return min_t(u32, buflen, svc_max_payload(rqstp));
}
static u32 nfsd4_only_status_rsize(const struct svc_rqst *rqstp,
const struct nfsd4_op *op)
{
@ -2816,9 +2832,9 @@ static u32 nfsd4_getattr_rsize(const struct svc_rqst *rqstp,
u32 ret = 0;
if (bmap0 & FATTR4_WORD0_ACL)
return svc_max_payload(rqstp);
return nfsd4_max_payload(rqstp);
if (bmap0 & FATTR4_WORD0_FS_LOCATIONS)
return svc_max_payload(rqstp);
return nfsd4_max_payload(rqstp);
if (bmap1 & FATTR4_WORD1_OWNER) {
ret += IDMAP_NAMESZ + 4;
@ -2878,10 +2894,7 @@ static u32 nfsd4_open_rsize(const struct svc_rqst *rqstp,
static u32 nfsd4_read_rsize(const struct svc_rqst *rqstp,
const struct nfsd4_op *op)
{
u32 maxcount = 0, rlen = 0;
maxcount = svc_max_payload(rqstp);
rlen = min(op->u.read.rd_length, maxcount);
u32 rlen = min(op->u.read.rd_length, nfsd4_max_payload(rqstp));
return (op_encode_hdr_size + 2 + XDR_QUADLEN(rlen)) * sizeof(__be32);
}
@ -2889,8 +2902,7 @@ static u32 nfsd4_read_rsize(const struct svc_rqst *rqstp,
static u32 nfsd4_read_plus_rsize(const struct svc_rqst *rqstp,
const struct nfsd4_op *op)
{
u32 maxcount = svc_max_payload(rqstp);
u32 rlen = min(op->u.read.rd_length, maxcount);
u32 rlen = min(op->u.read.rd_length, nfsd4_max_payload(rqstp));
/*
* If we detect that the file changed during hole encoding, then we
* recover by encoding the remaining reply as data. This means we need
@ -2904,10 +2916,7 @@ static u32 nfsd4_read_plus_rsize(const struct svc_rqst *rqstp,
static u32 nfsd4_readdir_rsize(const struct svc_rqst *rqstp,
const struct nfsd4_op *op)
{
u32 maxcount = 0, rlen = 0;
maxcount = svc_max_payload(rqstp);
rlen = min(op->u.readdir.rd_maxcount, maxcount);
u32 rlen = min(op->u.readdir.rd_maxcount, nfsd4_max_payload(rqstp));
return (op_encode_hdr_size + op_encode_verifier_maxsz +
XDR_QUADLEN(rlen)) * sizeof(__be32);
@ -3046,10 +3055,7 @@ static u32 nfsd4_copy_notify_rsize(const struct svc_rqst *rqstp,
static u32 nfsd4_getdeviceinfo_rsize(const struct svc_rqst *rqstp,
const struct nfsd4_op *op)
{
u32 maxcount = 0, rlen = 0;
maxcount = svc_max_payload(rqstp);
rlen = min(op->u.getdeviceinfo.gd_maxcount, maxcount);
u32 rlen = min(op->u.getdeviceinfo.gd_maxcount, nfsd4_max_payload(rqstp));
return (op_encode_hdr_size +
1 /* gd_layout_type*/ +
@ -3099,10 +3105,7 @@ static u32 nfsd4_seek_rsize(const struct svc_rqst *rqstp,
static u32 nfsd4_getxattr_rsize(const struct svc_rqst *rqstp,
const struct nfsd4_op *op)
{
u32 maxcount, rlen;
maxcount = svc_max_payload(rqstp);
rlen = min_t(u32, XATTR_SIZE_MAX, maxcount);
u32 rlen = min_t(u32, XATTR_SIZE_MAX, nfsd4_max_payload(rqstp));
return (op_encode_hdr_size + 1 + XDR_QUADLEN(rlen)) * sizeof(__be32);
}
@ -3116,10 +3119,7 @@ static u32 nfsd4_setxattr_rsize(const struct svc_rqst *rqstp,
static u32 nfsd4_listxattrs_rsize(const struct svc_rqst *rqstp,
const struct nfsd4_op *op)
{
u32 maxcount, rlen;
maxcount = svc_max_payload(rqstp);
rlen = min(op->u.listxattrs.lsxa_maxcount, maxcount);
u32 rlen = min(op->u.listxattrs.lsxa_maxcount, nfsd4_max_payload(rqstp));
return (op_encode_hdr_size + 4 + XDR_QUADLEN(rlen)) * sizeof(__be32);
}