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nfsd4: allow encoding across page boundaries

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After this we can handle for example getattr of very large ACLs.

Read, readdir, readlink are still special cases with their own limits.

Also we can't handle a new operation starting close to the end of a
page.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields 2013-08-26 16:04:46 -04:00
parent a8095f7e80
commit 2825a7f907
6 changed files with 126 additions and 19 deletions
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4
fs/nfsd/nfs4proc.c
View File

@ -1264,6 +1264,10 @@ static void svcxdr_init_encode(struct svc_rqst *rqstp,
xdr->end = head->iov_base + PAGE_SIZE - 2 * RPC_MAX_AUTH_SIZE;
/* Tail and page_len should be zero at this point: */
buf->len = buf->head[0].iov_len;
xdr->scratch.iov_len = 0;
xdr->page_ptr = buf->pages;
buf->buflen = PAGE_SIZE * (1 + rqstp->rq_page_end - buf->pages)
- 2 * RPC_MAX_AUTH_SIZE;
}
/*

60
fs/nfsd/nfs4xdr.c
View File

@ -1624,6 +1624,7 @@ static int nfsd4_max_reply(u32 opnum)
* the head and tail in another page:
*/
return 2 * PAGE_SIZE;
case OP_GETATTR:
case OP_READ:
return INT_MAX;
default:
@ -2560,21 +2561,31 @@ out_resource:
goto out;
}
static void svcxdr_init_encode_from_buffer(struct xdr_stream *xdr,
struct xdr_buf *buf, __be32 *p, int bytes)
{
xdr->scratch.iov_len = 0;
memset(buf, 0, sizeof(struct xdr_buf));
buf->head[0].iov_base = p;
buf->head[0].iov_len = 0;
buf->len = 0;
xdr->buf = buf;
xdr->iov = buf->head;
xdr->p = p;
xdr->end = (void *)p + bytes;
buf->buflen = bytes;
}
__be32 nfsd4_encode_fattr_to_buf(__be32 **p, int words,
struct svc_fh *fhp, struct svc_export *exp,
struct dentry *dentry, u32 *bmval,
struct svc_rqst *rqstp, int ignore_crossmnt)
{
struct xdr_buf dummy = {
.head[0] = {
.iov_base = *p,
},
.buflen = words << 2,
};
struct xdr_buf dummy;
struct xdr_stream xdr;
__be32 ret;
xdr_init_encode(&xdr, &dummy, NULL);
svcxdr_init_encode_from_buffer(&xdr, &dummy, *p, words << 2);
ret = nfsd4_encode_fattr(&xdr, fhp, exp, dentry, bmval, rqstp,
ignore_crossmnt);
*p = xdr.p;
@ -3064,8 +3075,6 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
if (nfserr)
return nfserr;
if (resp->xdr.buf->page_len)
return nfserr_resource;
p = xdr_reserve_space(xdr, 8); /* eof flag and byte count */
if (!p)
@ -3075,6 +3084,9 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
if (xdr->end - xdr->p < 1)
return nfserr_resource;
if (resp->xdr.buf->page_len)
return nfserr_resource;
maxcount = svc_max_payload(resp->rqstp);
if (maxcount > read->rd_length)
maxcount = read->rd_length;
@ -3119,6 +3131,8 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr,
- (char *)resp->xdr.buf->head[0].iov_base);
resp->xdr.buf->page_len = maxcount;
xdr->buf->len += maxcount;
xdr->page_ptr += v;
xdr->buf->buflen = maxcount + PAGE_SIZE - 2 * RPC_MAX_AUTH_SIZE;
xdr->iov = xdr->buf->tail;
/* Use rest of head for padding and remaining ops: */
@ -3145,6 +3159,11 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
if (nfserr)
return nfserr;
p = xdr_reserve_space(xdr, 4);
if (!p)
return nfserr_resource;
if (resp->xdr.buf->page_len)
return nfserr_resource;
if (!*resp->rqstp->rq_next_page)
@ -3154,10 +3173,6 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
maxcount = PAGE_SIZE;
p = xdr_reserve_space(xdr, 4);
if (!p)
return nfserr_resource;
if (xdr->end - xdr->p < 1)
return nfserr_resource;
@ -3180,6 +3195,8 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
- (char *)resp->xdr.buf->head[0].iov_base;
resp->xdr.buf->page_len = maxcount;
xdr->buf->len += maxcount;
xdr->page_ptr += 1;
xdr->buf->buflen -= PAGE_SIZE;
xdr->iov = xdr->buf->tail;
/* Use rest of head for padding and remaining ops: */
@ -3206,15 +3223,16 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
if (nfserr)
return nfserr;
if (resp->xdr.buf->page_len)
return nfserr_resource;
if (!*resp->rqstp->rq_next_page)
return nfserr_resource;
p = xdr_reserve_space(xdr, NFS4_VERIFIER_SIZE);
if (!p)
return nfserr_resource;
if (resp->xdr.buf->page_len)
return nfserr_resource;
if (!*resp->rqstp->rq_next_page)
return nfserr_resource;
/* XXX: Following NFSv3, we ignore the READDIR verifier for now. */
WRITE32(0);
WRITE32(0);
@ -3266,6 +3284,10 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
xdr->iov = xdr->buf->tail;
xdr->page_ptr++;
xdr->buf->buflen -= PAGE_SIZE;
xdr->iov = xdr->buf->tail;
/* Use rest of head for padding and remaining ops: */
resp->xdr.buf->tail[0].iov_base = tailbase;
resp->xdr.buf->tail[0].iov_len = 0;
@ -3800,6 +3822,8 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
!nfsd4_enc_ops[op->opnum]);
encoder = nfsd4_enc_ops[op->opnum];
op->status = encoder(resp, op->status, &op->u);
xdr_commit_encode(xdr);
/* nfsd4_check_resp_size guarantees enough room for error status */
if (!op->status) {
int space_needed = 0;
@ -3919,6 +3943,8 @@ nfs4svc_encode_compoundres(struct svc_rqst *rqstp, __be32 *p, struct nfsd4_compo
WARN_ON_ONCE(buf->len != buf->head[0].iov_len + buf->page_len +
buf->tail[0].iov_len);
rqstp->rq_next_page = resp->xdr.page_ptr + 1;
p = resp->tagp;
*p++ = htonl(resp->taglen);
memcpy(p, resp->tag, resp->taglen);

1
include/linux/sunrpc/svc.h
View File

@ -244,6 +244,7 @@ struct svc_rqst {
struct page * rq_pages[RPCSVC_MAXPAGES];
struct page * *rq_respages; /* points into rq_pages */
struct page * *rq_next_page; /* next reply page to use */
struct page * *rq_page_end; /* one past the last page */
struct kvec rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */

1
include/linux/sunrpc/xdr.h
View File

@ -215,6 +215,7 @@ typedef int (*kxdrdproc_t)(void *rqstp, struct xdr_stream *xdr, void *obj);
extern void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p);
extern __be32 *xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes);
extern void xdr_commit_encode(struct xdr_stream *xdr);
extern void xdr_truncate_encode(struct xdr_stream *xdr, size_t len);
extern void xdr_write_pages(struct xdr_stream *xdr, struct page **pages,
unsigned int base, unsigned int len);

1
net/sunrpc/svc_xprt.c
View File

@ -597,6 +597,7 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
}
rqstp->rq_pages[i] = p;
}
rqstp->rq_page_end = &rqstp->rq_pages[i];
rqstp->rq_pages[i++] = NULL; /* this might be seen in nfs_read_actor */
/* Make arg->head point to first page and arg->pages point to rest */

78
net/sunrpc/xdr.c
View File

@ -462,6 +462,7 @@ void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
struct kvec *iov = buf->head;
int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
xdr_set_scratch_buffer(xdr, NULL, 0);
BUG_ON(scratch_len < 0);
xdr->buf = buf;
xdr->iov = iov;
@ -481,6 +482,74 @@ void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
}
EXPORT_SYMBOL_GPL(xdr_init_encode);
/**
* xdr_commit_encode - Ensure all data is written to buffer
* @xdr: pointer to xdr_stream
*
* We handle encoding across page boundaries by giving the caller a
* temporary location to write to, then later copying the data into
* place; xdr_commit_encode does that copying.
*
* Normally the caller doesn't need to call this directly, as the
* following xdr_reserve_space will do it. But an explicit call may be
* required at the end of encoding, or any other time when the xdr_buf
* data might be read.
*/
void xdr_commit_encode(struct xdr_stream *xdr)
{
int shift = xdr->scratch.iov_len;
void *page;
if (shift == 0)
return;
page = page_address(*xdr->page_ptr);
memcpy(xdr->scratch.iov_base, page, shift);
memmove(page, page + shift, (void *)xdr->p - page);
xdr->scratch.iov_len = 0;
}
EXPORT_SYMBOL_GPL(xdr_commit_encode);
__be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr, size_t nbytes)
{
static __be32 *p;
int space_left;
int frag1bytes, frag2bytes;
if (nbytes > PAGE_SIZE)
return NULL; /* Bigger buffers require special handling */
if (xdr->buf->len + nbytes > xdr->buf->buflen)
return NULL; /* Sorry, we're totally out of space */
frag1bytes = (xdr->end - xdr->p) << 2;
frag2bytes = nbytes - frag1bytes;
if (xdr->iov)
xdr->iov->iov_len += frag1bytes;
else {
xdr->buf->page_len += frag1bytes;
xdr->page_ptr++;
}
xdr->iov = NULL;
/*
* If the last encode didn't end exactly on a page boundary, the
* next one will straddle boundaries. Encode into the next
* page, then copy it back later in xdr_commit_encode. We use
* the "scratch" iov to track any temporarily unused fragment of
* space at the end of the previous buffer:
*/
xdr->scratch.iov_base = xdr->p;
xdr->scratch.iov_len = frag1bytes;
p = page_address(*xdr->page_ptr);
/*
* Note this is where the next encode will start after we've
* shifted this one back:
*/
xdr->p = (void *)p + frag2bytes;
space_left = xdr->buf->buflen - xdr->buf->len;
xdr->end = (void *)p + min_t(int, space_left, PAGE_SIZE);
xdr->buf->page_len += frag2bytes;
xdr->buf->len += nbytes;
return p;
}
/**
* xdr_reserve_space - Reserve buffer space for sending
* @xdr: pointer to xdr_stream
@ -495,14 +564,18 @@ __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
__be32 *p = xdr->p;
__be32 *q;
xdr_commit_encode(xdr);
/* align nbytes on the next 32-bit boundary */
nbytes += 3;
nbytes &= ~3;
q = p + (nbytes >> 2);
if (unlikely(q > xdr->end || q < p))
return NULL;
return xdr_get_next_encode_buffer(xdr, nbytes);
xdr->p = q;
xdr->iov->iov_len += nbytes;
if (xdr->iov)
xdr->iov->iov_len += nbytes;
else
xdr->buf->page_len += nbytes;
xdr->buf->len += nbytes;
return p;
}
@ -539,6 +612,7 @@ void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
WARN_ON_ONCE(1);
return;
}
xdr_commit_encode(xdr);
fraglen = min_t(int, buf->len - len, tail->iov_len);
tail->iov_len -= fraglen;