small sunrpc cleanups

small sunrpc cleanups

[Christoph Hellwig]

Hi all,

just a few small cleanups done while looking at the code.

Diffstat:
 fs/nfsd/nfs3proc.c         |    2 
 fs/nfsd/nfsproc.c          |    2 
 include/linux/sunrpc/xdr.h |    3 
 net/sunrpc/socklib.c       |  144 +++++++++++++++------------------------------
 net/sunrpc/xdr.c           |   11 +--
 5 files changed, 57 insertions(+), 105 deletions(-)

[PATCH 1/3] sunrpc: simplify xdr_init_encode_pages

[Christoph Hellwig]

The rqst argument to xdr_init_encode_pages is set to NULL by all callers,
and pages is always set to buf->pages.  Remove the two arguments and
hardcode the assignments.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/nfsd/nfs3proc.c         |  2 +-
 fs/nfsd/nfsproc.c          |  2 +-
 include/linux/sunrpc/xdr.h |  3 +--
 net/sunrpc/xdr.c           | 11 ++++-------
 4 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 8902fae8c62d..6c94042b03fa 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -562,7 +562,7 @@ static void nfsd3_init_dirlist_pages(struct svc_rqst *rqstp,
 	buf->pages = rqstp->rq_next_page;
 	rqstp->rq_next_page += (buf->buflen + PAGE_SIZE - 1) >> PAGE_SHIFT;
 
-	xdr_init_encode_pages(xdr, buf, buf->pages,  NULL);
+	xdr_init_encode_pages(xdr, buf);
 }
 
 /*
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index 7c573d792252..f1c2c096804b 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -577,7 +577,7 @@ static void nfsd_init_dirlist_pages(struct svc_rqst *rqstp,
 	buf->pages = rqstp->rq_next_page;
 	rqstp->rq_next_page++;
 
-	xdr_init_encode_pages(xdr, buf, buf->pages,  NULL);
+	xdr_init_encode_pages(xdr, buf);
 }
 
 /*
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index a2ab813a9800..29d3a7659727 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -242,8 +242,7 @@ typedef int	(*kxdrdproc_t)(struct rpc_rqst *rqstp, struct xdr_stream *xdr,
 
 extern void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf,
 			    __be32 *p, struct rpc_rqst *rqst);
-extern void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
-			   struct page **pages, struct rpc_rqst *rqst);
+void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf);
 extern __be32 *xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes);
 extern int xdr_reserve_space_vec(struct xdr_stream *xdr, size_t nbytes);
 extern void __xdr_commit_encode(struct xdr_stream *xdr);
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 4e003cb516fe..1ab973d3e324 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -992,21 +992,18 @@ EXPORT_SYMBOL_GPL(xdr_init_encode);
  * xdr_init_encode_pages - Initialize an xdr_stream for encoding into pages
  * @xdr: pointer to xdr_stream struct
  * @buf: pointer to XDR buffer into which to encode data
- * @pages: list of pages to decode into
- * @rqst: pointer to controlling rpc_rqst, for debugging
  *
  */
-void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
-			   struct page **pages, struct rpc_rqst *rqst)
+void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf)
 {
 	xdr_reset_scratch_buffer(xdr);
 
 	xdr->buf = buf;
-	xdr->page_ptr = pages;
+	xdr->page_ptr = buf->pages;
 	xdr->iov = NULL;
-	xdr->p = page_address(*pages);
+	xdr->p = page_address(*xdr->page_ptr);
 	xdr->end = (void *)xdr->p + min_t(u32, buf->buflen, PAGE_SIZE);
-	xdr->rqst = rqst;
+	xdr->rqst = NULL;
 }
 EXPORT_SYMBOL_GPL(xdr_init_encode_pages);
 
-- 
2.47.2

[PATCH 2/3] sunrpc: simplify xdr_partial_copy_from_skb

[Christoph Hellwig]

csum_partial_copy_to_xdr can handle a checksumming and non-checksumming
case and implements this using a callback, which leads to a lot of
boilerplate code and indirect calls in the fast path.

Switch to storing a no_checksum flag in struct xdr_skb_reader instead
to remove the indirect call and simplify the code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 net/sunrpc/socklib.c | 143 +++++++++++++++----------------------------
 1 file changed, 50 insertions(+), 93 deletions(-)

diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
index 1b2b84feeec6..7196e7042e0f 100644
--- a/net/sunrpc/socklib.c
+++ b/net/sunrpc/socklib.c
@@ -27,97 +27,60 @@
 struct xdr_skb_reader {
 	struct sk_buff	*skb;
 	unsigned int	offset;
+	bool		no_checksum;
 	size_t		count;
 	__wsum		csum;
 };
 
-typedef size_t (*xdr_skb_read_actor)(struct xdr_skb_reader *desc, void *to,
-				     size_t len);
-
 /**
  * xdr_skb_read_bits - copy some data bits from skb to internal buffer
  * @desc: sk_buff copy helper
  * @to: copy destination
  * @len: number of bytes to copy
  *
- * Possibly called several times to iterate over an sk_buff and copy
- * data out of it.
+ * Possibly called several times to iterate over an sk_buff and copy data out of
+ * it.
  */
 static size_t
 xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
 {
-	if (len > desc->count)
-		len = desc->count;
-	if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
-		return 0;
-	desc->count -= len;
-	desc->offset += len;
-	return len;
-}
+	len = min(len, desc->count);
+
+	if (desc->no_checksum) {
+		if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
+			return 0;
+	} else {
+		__wsum csum;
+
+		csum = skb_copy_and_csum_bits(desc->skb, desc->offset, to, len);
+		desc->csum = csum_block_add(desc->csum, csum, desc->offset);
+	}
 
-/**
- * xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
- * @desc: sk_buff copy helper
- * @to: copy destination
- * @len: number of bytes to copy
- *
- * Same as skb_read_bits, but calculate a checksum at the same time.
- */
-static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
-{
-	unsigned int pos;
-	__wsum csum2;
-
-	if (len > desc->count)
-		len = desc->count;
-	pos = desc->offset;
-	csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len);
-	desc->csum = csum_block_add(desc->csum, csum2, pos);
 	desc->count -= len;
 	desc->offset += len;
 	return len;
 }
 
-/**
- * xdr_partial_copy_from_skb - copy data out of an skb
- * @xdr: target XDR buffer
- * @base: starting offset
- * @desc: sk_buff copy helper
- * @copy_actor: virtual method for copying data
- *
- */
 static ssize_t
-xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
+xdr_partial_copy_from_skb(struct xdr_buf *xdr, struct xdr_skb_reader *desc)
 {
-	struct page	**ppage = xdr->pages;
-	unsigned int	len, pglen = xdr->page_len;
-	ssize_t		copied = 0;
-	size_t		ret;
-
-	len = xdr->head[0].iov_len;
-	if (base < len) {
-		len -= base;
-		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
-		copied += ret;
-		if (ret != len || !desc->count)
-			goto out;
-		base = 0;
-	} else
-		base -= len;
-
-	if (unlikely(pglen == 0))
-		goto copy_tail;
-	if (unlikely(base >= pglen)) {
-		base -= pglen;
-		goto copy_tail;
-	}
-	if (base || xdr->page_base) {
-		pglen -= base;
-		base += xdr->page_base;
-		ppage += base >> PAGE_SHIFT;
-		base &= ~PAGE_MASK;
-	}
-	do {
+	struct page **ppage = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
+	unsigned int poff = xdr->page_base & ~PAGE_MASK;
+	unsigned int pglen = xdr->page_len;
+	ssize_t copied = 0;
+	size_t ret;
+
+	if (xdr->head[0].iov_len == 0)
+		return 0;
+
+	ret = xdr_skb_read_bits(desc, xdr->head[0].iov_base,
+			xdr->head[0].iov_len);
+	if (ret != xdr->head[0].iov_len || !desc->count)
+		return ret;
+	copied += ret;
+
+	while (pglen) {
+		unsigned int len = min(PAGE_SIZE - poff, pglen);
 		char *kaddr;
 
 		/* ACL likes to be lazy in allocating pages - ACLs
@@ -126,36 +89,29 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb
 			*ppage = alloc_page(GFP_NOWAIT | __GFP_NOWARN);
 			if (unlikely(*ppage == NULL)) {
 				if (copied == 0)
-					copied = -ENOMEM;
-				goto out;
+					return -ENOMEM;
+				return copied;
 			}
 		}
 
-		len = PAGE_SIZE;
 		kaddr = kmap_atomic(*ppage);
-		if (base) {
-			len -= base;
-			if (pglen < len)
-				len = pglen;
-			ret = copy_actor(desc, kaddr + base, len);
-			base = 0;
-		} else {
-			if (pglen < len)
-				len = pglen;
-			ret = copy_actor(desc, kaddr, len);
-		}
+		ret = xdr_skb_read_bits(desc, kaddr + poff, len);
 		flush_dcache_page(*ppage);
 		kunmap_atomic(kaddr);
+
 		copied += ret;
 		if (ret != len || !desc->count)
-			goto out;
+			return copied;
 		ppage++;
-	} while ((pglen -= len) != 0);
-copy_tail:
-	len = xdr->tail[0].iov_len;
-	if (base < len)
-		copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
-out:
+		pglen -= len;
+		poff = 0;
+	}
+
+	if (xdr->tail[0].iov_len) {
+		copied += xdr_skb_read_bits(desc, xdr->tail[0].iov_base,
+					xdr->tail[0].iov_len);
+	}
+
 	return copied;
 }
 
@@ -174,12 +130,13 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 	desc.skb = skb;
 	desc.offset = 0;
 	desc.count = skb->len - desc.offset;
+	desc.no_checksum = skb_csum_unnecessary(skb);
 
-	if (skb_csum_unnecessary(skb))
+	if (desc.no_checksum)
 		goto no_checksum;
 
 	desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
-	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
+	if (xdr_partial_copy_from_skb(xdr, &desc) < 0)
 		return -1;
 	if (desc.offset != skb->len) {
 		__wsum csum2;
@@ -195,7 +152,7 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 		netdev_rx_csum_fault(skb->dev, skb);
 	return 0;
 no_checksum:
-	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
+	if (xdr_partial_copy_from_skb(xdr, &desc) < 0)
 		return -1;
 	if (desc.count)
 		return -1;
-- 
2.47.2

[PATCH 3/3] sunrpc: unexport csum_partial_copy_to_xdr

[Christoph Hellwig]

csum_partial_copy_to_xdr is only used inside the sunrpc module, so
remove the export.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 net/sunrpc/socklib.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
index 7196e7042e0f..68b16f2ba686 100644
--- a/net/sunrpc/socklib.c
+++ b/net/sunrpc/socklib.c
@@ -158,7 +158,6 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 		return -1;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
 
 static inline int xprt_sendmsg(struct socket *sock, struct msghdr *msg,
 			       size_t seek)
-- 
2.47.2

Re: [PATCH 2/3] sunrpc: simplify xdr_partial_copy_from_skb

[Jeff Layton]

On Tue, 2025-05-13 at 10:57 +0200, Christoph Hellwig wrote:
> csum_partial_copy_to_xdr can handle a checksumming and non-checksumming
> case and implements this using a callback, which leads to a lot of
> boilerplate code and indirect calls in the fast path.
> 
> Switch to storing a no_checksum flag in struct xdr_skb_reader instead
> to remove the indirect call and simplify the code.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  net/sunrpc/socklib.c | 143 +++++++++++++++----------------------------
>  1 file changed, 50 insertions(+), 93 deletions(-)
> 
> diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
> index 1b2b84feeec6..7196e7042e0f 100644
> --- a/net/sunrpc/socklib.c
> +++ b/net/sunrpc/socklib.c
> @@ -27,97 +27,60 @@
>  struct xdr_skb_reader {
>  	struct sk_buff	*skb;
>  	unsigned int	offset;
> +	bool		no_checksum;

The change is reasonable overall, but I'm not a fan of having a
negative boolean like this (i.e. one that starts with no_*). Can we
reverse the sense of this and call it "must_checksum" or something?

>  	size_t		count;
>  	__wsum		csum;
>  };
>  
> -typedef size_t (*xdr_skb_read_actor)(struct xdr_skb_reader *desc, void *to,
> -				     size_t len);
> -
>  /**
>   * xdr_skb_read_bits - copy some data bits from skb to internal buffer
>   * @desc: sk_buff copy helper
>   * @to: copy destination
>   * @len: number of bytes to copy
>   *
> - * Possibly called several times to iterate over an sk_buff and copy
> - * data out of it.
> + * Possibly called several times to iterate over an sk_buff and copy data out of
> + * it.
>   */
>  static size_t
>  xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
>  {
> -	if (len > desc->count)
> -		len = desc->count;
> -	if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
> -		return 0;
> -	desc->count -= len;
> -	desc->offset += len;
> -	return len;
> -}
> +	len = min(len, desc->count);
> +
> +	if (desc->no_checksum) {
> +		if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
> +			return 0;
> +	} else {
> +		__wsum csum;
> +
> +		csum = skb_copy_and_csum_bits(desc->skb, desc->offset, to, len);
> +		desc->csum = csum_block_add(desc->csum, csum, desc->offset);
> +	}
>  
> -/**
> - * xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
> - * @desc: sk_buff copy helper
> - * @to: copy destination
> - * @len: number of bytes to copy
> - *
> - * Same as skb_read_bits, but calculate a checksum at the same time.
> - */
> -static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
> -{
> -	unsigned int pos;
> -	__wsum csum2;
> -
> -	if (len > desc->count)
> -		len = desc->count;
> -	pos = desc->offset;
> -	csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len);
> -	desc->csum = csum_block_add(desc->csum, csum2, pos);
>  	desc->count -= len;
>  	desc->offset += len;
>  	return len;
>  }
>  
> -/**
> - * xdr_partial_copy_from_skb - copy data out of an skb
> - * @xdr: target XDR buffer
> - * @base: starting offset
> - * @desc: sk_buff copy helper
> - * @copy_actor: virtual method for copying data
> - *
> - */
>  static ssize_t
> -xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
> +xdr_partial_copy_from_skb(struct xdr_buf *xdr, struct xdr_skb_reader *desc)
>  {
> -	struct page	**ppage = xdr->pages;
> -	unsigned int	len, pglen = xdr->page_len;
> -	ssize_t		copied = 0;
> -	size_t		ret;
> -
> -	len = xdr->head[0].iov_len;
> -	if (base < len) {
> -		len -= base;
> -		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
> -		copied += ret;
> -		if (ret != len || !desc->count)
> -			goto out;
> -		base = 0;
> -	} else
> -		base -= len;
> -
> -	if (unlikely(pglen == 0))
> -		goto copy_tail;
> -	if (unlikely(base >= pglen)) {
> -		base -= pglen;
> -		goto copy_tail;
> -	}
> -	if (base || xdr->page_base) {
> -		pglen -= base;
> -		base += xdr->page_base;
> -		ppage += base >> PAGE_SHIFT;
> -		base &= ~PAGE_MASK;
> -	}
> -	do {
> +	struct page **ppage = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
> +	unsigned int poff = xdr->page_base & ~PAGE_MASK;
> +	unsigned int pglen = xdr->page_len;
> +	ssize_t copied = 0;
> +	size_t ret;
> +
> +	if (xdr->head[0].iov_len == 0)
> +		return 0;
> +
> +	ret = xdr_skb_read_bits(desc, xdr->head[0].iov_base,
> +			xdr->head[0].iov_len);
> +	if (ret != xdr->head[0].iov_len || !desc->count)
> +		return ret;
> +	copied += ret;
> +
> +	while (pglen) {
> +		unsigned int len = min(PAGE_SIZE - poff, pglen);
>  		char *kaddr;
>  
>  		/* ACL likes to be lazy in allocating pages - ACLs
> @@ -126,36 +89,29 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb
>  			*ppage = alloc_page(GFP_NOWAIT | __GFP_NOWARN);
>  			if (unlikely(*ppage == NULL)) {
>  				if (copied == 0)
> -					copied = -ENOMEM;
> -				goto out;
> +					return -ENOMEM;
> +				return copied;
>  			}
>  		}
>  
> -		len = PAGE_SIZE;
>  		kaddr = kmap_atomic(*ppage);
> -		if (base) {
> -			len -= base;
> -			if (pglen < len)
> -				len = pglen;
> -			ret = copy_actor(desc, kaddr + base, len);
> -			base = 0;
> -		} else {
> -			if (pglen < len)
> -				len = pglen;
> -			ret = copy_actor(desc, kaddr, len);
> -		}
> +		ret = xdr_skb_read_bits(desc, kaddr + poff, len);
>  		flush_dcache_page(*ppage);
>  		kunmap_atomic(kaddr);
> +
>  		copied += ret;
>  		if (ret != len || !desc->count)
> -			goto out;
> +			return copied;
>  		ppage++;
> -	} while ((pglen -= len) != 0);
> -copy_tail:
> -	len = xdr->tail[0].iov_len;
> -	if (base < len)
> -		copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
> -out:
> +		pglen -= len;
> +		poff = 0;
> +	}
> +
> +	if (xdr->tail[0].iov_len) {
> +		copied += xdr_skb_read_bits(desc, xdr->tail[0].iov_base,
> +					xdr->tail[0].iov_len);
> +	}
> +
>  	return copied;
>  }
>  
> @@ -174,12 +130,13 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
>  	desc.skb = skb;
>  	desc.offset = 0;
>  	desc.count = skb->len - desc.offset;
> +	desc.no_checksum = skb_csum_unnecessary(skb);
>  
> -	if (skb_csum_unnecessary(skb))
> +	if (desc.no_checksum)
>  		goto no_checksum;
>  
>  	desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
> -	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
> +	if (xdr_partial_copy_from_skb(xdr, &desc) < 0)
>  		return -1;
>  	if (desc.offset != skb->len) {
>  		__wsum csum2;
> @@ -195,7 +152,7 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
>  		netdev_rx_csum_fault(skb->dev, skb);
>  	return 0;
>  no_checksum:
> -	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
> +	if (xdr_partial_copy_from_skb(xdr, &desc) < 0)
>  		return -1;
>  	if (desc.count)
>  		return -1;

-- 
Jeff Layton <jlayton@kernel.org>

Re: [PATCH 1/3] sunrpc: simplify xdr_init_encode_pages

[Jeff Layton]

On Tue, 2025-05-13 at 10:57 +0200, Christoph Hellwig wrote:
> The rqst argument to xdr_init_encode_pages is set to NULL by all callers,
> and pages is always set to buf->pages.  Remove the two arguments and
> hardcode the assignments.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/nfsd/nfs3proc.c         |  2 +-
>  fs/nfsd/nfsproc.c          |  2 +-
>  include/linux/sunrpc/xdr.h |  3 +--
>  net/sunrpc/xdr.c           | 11 ++++-------
>  4 files changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
> index 8902fae8c62d..6c94042b03fa 100644
> --- a/fs/nfsd/nfs3proc.c
> +++ b/fs/nfsd/nfs3proc.c
> @@ -562,7 +562,7 @@ static void nfsd3_init_dirlist_pages(struct svc_rqst *rqstp,
>  	buf->pages = rqstp->rq_next_page;
>  	rqstp->rq_next_page += (buf->buflen + PAGE_SIZE - 1) >> PAGE_SHIFT;
>  
> -	xdr_init_encode_pages(xdr, buf, buf->pages,  NULL);
> +	xdr_init_encode_pages(xdr, buf);
>  }
>  
>  /*
> diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
> index 7c573d792252..f1c2c096804b 100644
> --- a/fs/nfsd/nfsproc.c
> +++ b/fs/nfsd/nfsproc.c
> @@ -577,7 +577,7 @@ static void nfsd_init_dirlist_pages(struct svc_rqst *rqstp,
>  	buf->pages = rqstp->rq_next_page;
>  	rqstp->rq_next_page++;
>  
> -	xdr_init_encode_pages(xdr, buf, buf->pages,  NULL);
> +	xdr_init_encode_pages(xdr, buf);
>  }
>  
>  /*
> diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
> index a2ab813a9800..29d3a7659727 100644
> --- a/include/linux/sunrpc/xdr.h
> +++ b/include/linux/sunrpc/xdr.h
> @@ -242,8 +242,7 @@ typedef int	(*kxdrdproc_t)(struct rpc_rqst *rqstp, struct xdr_stream *xdr,
>  
>  extern void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf,
>  			    __be32 *p, struct rpc_rqst *rqst);
> -extern void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
> -			   struct page **pages, struct rpc_rqst *rqst);
> +void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf);
>  extern __be32 *xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes);
>  extern int xdr_reserve_space_vec(struct xdr_stream *xdr, size_t nbytes);
>  extern void __xdr_commit_encode(struct xdr_stream *xdr);
> diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
> index 4e003cb516fe..1ab973d3e324 100644
> --- a/net/sunrpc/xdr.c
> +++ b/net/sunrpc/xdr.c
> @@ -992,21 +992,18 @@ EXPORT_SYMBOL_GPL(xdr_init_encode);
>   * xdr_init_encode_pages - Initialize an xdr_stream for encoding into pages
>   * @xdr: pointer to xdr_stream struct
>   * @buf: pointer to XDR buffer into which to encode data
> - * @pages: list of pages to decode into
> - * @rqst: pointer to controlling rpc_rqst, for debugging
>   *
>   */
> -void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
> -			   struct page **pages, struct rpc_rqst *rqst)
> +void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf)
>  {
>  	xdr_reset_scratch_buffer(xdr);
>  
>  	xdr->buf = buf;
> -	xdr->page_ptr = pages;
> +	xdr->page_ptr = buf->pages;
>  	xdr->iov = NULL;
> -	xdr->p = page_address(*pages);
> +	xdr->p = page_address(*xdr->page_ptr);
>  	xdr->end = (void *)xdr->p + min_t(u32, buf->buflen, PAGE_SIZE);
> -	xdr->rqst = rqst;
> +	xdr->rqst = NULL;
>  }
>  EXPORT_SYMBOL_GPL(xdr_init_encode_pages);
>  

Reviewed-by: Jeff Layton <jlayton@kernel.org>

Re: [PATCH 3/3] sunrpc: unexport csum_partial_copy_to_xdr

[Jeff Layton]

On Tue, 2025-05-13 at 10:57 +0200, Christoph Hellwig wrote:
> csum_partial_copy_to_xdr is only used inside the sunrpc module, so
> remove the export.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  net/sunrpc/socklib.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
> index 7196e7042e0f..68b16f2ba686 100644
> --- a/net/sunrpc/socklib.c
> +++ b/net/sunrpc/socklib.c
> @@ -158,7 +158,6 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
>  		return -1;
>  	return 0;
>  }
> -EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
>  
>  static inline int xprt_sendmsg(struct socket *sock, struct msghdr *msg,
>  			       size_t seek)

Reviewed-by: Jeff Layton <jlayton@kernel.org>

Re: [PATCH 2/3] sunrpc: simplify xdr_partial_copy_from_skb

[Christoph Hellwig]

On Tue, May 13, 2025 at 07:15:37AM -0500, Jeff Layton wrote:
> > +	bool		no_checksum;
> 
> The change is reasonable overall, but I'm not a fan of having a
> negative boolean like this (i.e. one that starts with no_*). Can we
> reverse the sense of this and call it "must_checksum" or something?

I can invert it.  It just seems like the normal case should be no-flag
one, but either version will work just fine.

[PATCH 2/3] sunrpc: simplify xdr_partial_copy_from_skb

[Christoph Hellwig]

csum_partial_copy_to_xdr can handle a checksumming and non-checksumming
case and implements this using a callback, which leads to a lot of
boilerplate code and indirect calls in the fast path.

Switch to storing a need_checksum flag in struct xdr_skb_reader instead
to remove the indirect call and simplify the code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 net/sunrpc/socklib.c | 163 ++++++++++++++++---------------------------
 1 file changed, 59 insertions(+), 104 deletions(-)

diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
index 1b2b84feeec6..75e31e3a3ced 100644
--- a/net/sunrpc/socklib.c
+++ b/net/sunrpc/socklib.c
@@ -27,97 +27,60 @@
 struct xdr_skb_reader {
 	struct sk_buff	*skb;
 	unsigned int	offset;
+	bool		need_checksum;
 	size_t		count;
 	__wsum		csum;
 };
 
-typedef size_t (*xdr_skb_read_actor)(struct xdr_skb_reader *desc, void *to,
-				     size_t len);
-
 /**
  * xdr_skb_read_bits - copy some data bits from skb to internal buffer
  * @desc: sk_buff copy helper
  * @to: copy destination
  * @len: number of bytes to copy
  *
- * Possibly called several times to iterate over an sk_buff and copy
- * data out of it.
+ * Possibly called several times to iterate over an sk_buff and copy data out of
+ * it.
  */
 static size_t
 xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
 {
-	if (len > desc->count)
-		len = desc->count;
-	if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
-		return 0;
-	desc->count -= len;
-	desc->offset += len;
-	return len;
-}
+	len = min(len, desc->count);
+
+	if (desc->need_checksum) {
+		__wsum csum;
+
+		csum = skb_copy_and_csum_bits(desc->skb, desc->offset, to, len);
+		desc->csum = csum_block_add(desc->csum, csum, desc->offset);
+	} else {
+		if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
+			return 0;
+	}
 
-/**
- * xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
- * @desc: sk_buff copy helper
- * @to: copy destination
- * @len: number of bytes to copy
- *
- * Same as skb_read_bits, but calculate a checksum at the same time.
- */
-static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
-{
-	unsigned int pos;
-	__wsum csum2;
-
-	if (len > desc->count)
-		len = desc->count;
-	pos = desc->offset;
-	csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len);
-	desc->csum = csum_block_add(desc->csum, csum2, pos);
 	desc->count -= len;
 	desc->offset += len;
 	return len;
 }
 
-/**
- * xdr_partial_copy_from_skb - copy data out of an skb
- * @xdr: target XDR buffer
- * @base: starting offset
- * @desc: sk_buff copy helper
- * @copy_actor: virtual method for copying data
- *
- */
 static ssize_t
-xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
+xdr_partial_copy_from_skb(struct xdr_buf *xdr, struct xdr_skb_reader *desc)
 {
-	struct page	**ppage = xdr->pages;
-	unsigned int	len, pglen = xdr->page_len;
-	ssize_t		copied = 0;
-	size_t		ret;
-
-	len = xdr->head[0].iov_len;
-	if (base < len) {
-		len -= base;
-		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
-		copied += ret;
-		if (ret != len || !desc->count)
-			goto out;
-		base = 0;
-	} else
-		base -= len;
-
-	if (unlikely(pglen == 0))
-		goto copy_tail;
-	if (unlikely(base >= pglen)) {
-		base -= pglen;
-		goto copy_tail;
-	}
-	if (base || xdr->page_base) {
-		pglen -= base;
-		base += xdr->page_base;
-		ppage += base >> PAGE_SHIFT;
-		base &= ~PAGE_MASK;
-	}
-	do {
+	struct page **ppage = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
+	unsigned int poff = xdr->page_base & ~PAGE_MASK;
+	unsigned int pglen = xdr->page_len;
+	ssize_t copied = 0;
+	size_t ret;
+
+	if (xdr->head[0].iov_len == 0)
+		return 0;
+
+	ret = xdr_skb_read_bits(desc, xdr->head[0].iov_base,
+			xdr->head[0].iov_len);
+	if (ret != xdr->head[0].iov_len || !desc->count)
+		return ret;
+	copied += ret;
+
+	while (pglen) {
+		unsigned int len = min(PAGE_SIZE - poff, pglen);
 		char *kaddr;
 
 		/* ACL likes to be lazy in allocating pages - ACLs
@@ -126,36 +89,29 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb
 			*ppage = alloc_page(GFP_NOWAIT | __GFP_NOWARN);
 			if (unlikely(*ppage == NULL)) {
 				if (copied == 0)
-					copied = -ENOMEM;
-				goto out;
+					return -ENOMEM;
+				return copied;
 			}
 		}
 
-		len = PAGE_SIZE;
 		kaddr = kmap_atomic(*ppage);
-		if (base) {
-			len -= base;
-			if (pglen < len)
-				len = pglen;
-			ret = copy_actor(desc, kaddr + base, len);
-			base = 0;
-		} else {
-			if (pglen < len)
-				len = pglen;
-			ret = copy_actor(desc, kaddr, len);
-		}
+		ret = xdr_skb_read_bits(desc, kaddr + poff, len);
 		flush_dcache_page(*ppage);
 		kunmap_atomic(kaddr);
+
 		copied += ret;
 		if (ret != len || !desc->count)
-			goto out;
+			return copied;
 		ppage++;
-	} while ((pglen -= len) != 0);
-copy_tail:
-	len = xdr->tail[0].iov_len;
-	if (base < len)
-		copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
-out:
+		pglen -= len;
+		poff = 0;
+	}
+
+	if (xdr->tail[0].iov_len) {
+		copied += xdr_skb_read_bits(desc, xdr->tail[0].iov_base,
+					xdr->tail[0].iov_len);
+	}
+
 	return copied;
 }
 
@@ -169,17 +125,22 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb
  */
 int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 {
-	struct xdr_skb_reader	desc;
-
-	desc.skb = skb;
-	desc.offset = 0;
-	desc.count = skb->len - desc.offset;
+	struct xdr_skb_reader desc = {
+		.skb		= skb,
+		.count		= skb->len - desc.offset,
+	};
 
-	if (skb_csum_unnecessary(skb))
-		goto no_checksum;
+	if (skb_csum_unnecessary(skb)) {
+		if (xdr_partial_copy_from_skb(xdr, &desc) < 0)
+			return -1;
+		if (desc.count)
+			return -1;
+		return 0;
+	}
 
+	desc.need_checksum = true;
 	desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
-	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
+	if (xdr_partial_copy_from_skb(xdr, &desc) < 0)
 		return -1;
 	if (desc.offset != skb->len) {
 		__wsum csum2;
@@ -194,12 +155,6 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 	    !skb->csum_complete_sw)
 		netdev_rx_csum_fault(skb->dev, skb);
 	return 0;
-no_checksum:
-	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
-		return -1;
-	if (desc.count)
-		return -1;
-	return 0;
 }
 EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
 
-- 
2.47.2

Re: [PATCH 2/3] sunrpc: simplify xdr_partial_copy_from_skb

[Jeff Layton]

On Thu, 2025-05-15 at 13:48 +0200, Christoph Hellwig wrote:
> csum_partial_copy_to_xdr can handle a checksumming and non-checksumming
> case and implements this using a callback, which leads to a lot of
> boilerplate code and indirect calls in the fast path.
> 
> Switch to storing a need_checksum flag in struct xdr_skb_reader instead
> to remove the indirect call and simplify the code.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  net/sunrpc/socklib.c | 163 ++++++++++++++++---------------------------
>  1 file changed, 59 insertions(+), 104 deletions(-)
> 
> diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
> index 1b2b84feeec6..75e31e3a3ced 100644
> --- a/net/sunrpc/socklib.c
> +++ b/net/sunrpc/socklib.c
> @@ -27,97 +27,60 @@
>  struct xdr_skb_reader {
>  	struct sk_buff	*skb;
>  	unsigned int	offset;
> +	bool		need_checksum;
>  	size_t		count;
>  	__wsum		csum;
>  };
>  
> -typedef size_t (*xdr_skb_read_actor)(struct xdr_skb_reader *desc, void *to,
> -				     size_t len);
> -
>  /**
>   * xdr_skb_read_bits - copy some data bits from skb to internal buffer
>   * @desc: sk_buff copy helper
>   * @to: copy destination
>   * @len: number of bytes to copy
>   *
> - * Possibly called several times to iterate over an sk_buff and copy
> - * data out of it.
> + * Possibly called several times to iterate over an sk_buff and copy data out of
> + * it.
>   */
>  static size_t
>  xdr_skb_read_bits(struct xdr_skb_reader *desc, void *to, size_t len)
>  {
> -	if (len > desc->count)
> -		len = desc->count;
> -	if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
> -		return 0;
> -	desc->count -= len;
> -	desc->offset += len;
> -	return len;
> -}
> +	len = min(len, desc->count);
> +
> +	if (desc->need_checksum) {
> +		__wsum csum;
> +
> +		csum = skb_copy_and_csum_bits(desc->skb, desc->offset, to, len);
> +		desc->csum = csum_block_add(desc->csum, csum, desc->offset);
> +	} else {
> +		if (unlikely(skb_copy_bits(desc->skb, desc->offset, to, len)))
> +			return 0;
> +	}
>  
> -/**
> - * xdr_skb_read_and_csum_bits - copy and checksum from skb to buffer
> - * @desc: sk_buff copy helper
> - * @to: copy destination
> - * @len: number of bytes to copy
> - *
> - * Same as skb_read_bits, but calculate a checksum at the same time.
> - */
> -static size_t xdr_skb_read_and_csum_bits(struct xdr_skb_reader *desc, void *to, size_t len)
> -{
> -	unsigned int pos;
> -	__wsum csum2;
> -
> -	if (len > desc->count)
> -		len = desc->count;
> -	pos = desc->offset;
> -	csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len);
> -	desc->csum = csum_block_add(desc->csum, csum2, pos);
>  	desc->count -= len;
>  	desc->offset += len;
>  	return len;
>  }
>  
> -/**
> - * xdr_partial_copy_from_skb - copy data out of an skb
> - * @xdr: target XDR buffer
> - * @base: starting offset
> - * @desc: sk_buff copy helper
> - * @copy_actor: virtual method for copying data
> - *
> - */
>  static ssize_t
> -xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb_reader *desc, xdr_skb_read_actor copy_actor)
> +xdr_partial_copy_from_skb(struct xdr_buf *xdr, struct xdr_skb_reader *desc)
>  {
> -	struct page	**ppage = xdr->pages;
> -	unsigned int	len, pglen = xdr->page_len;
> -	ssize_t		copied = 0;
> -	size_t		ret;
> -
> -	len = xdr->head[0].iov_len;
> -	if (base < len) {
> -		len -= base;
> -		ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
> -		copied += ret;
> -		if (ret != len || !desc->count)
> -			goto out;
> -		base = 0;
> -	} else
> -		base -= len;
> -
> -	if (unlikely(pglen == 0))
> -		goto copy_tail;
> -	if (unlikely(base >= pglen)) {
> -		base -= pglen;
> -		goto copy_tail;
> -	}
> -	if (base || xdr->page_base) {
> -		pglen -= base;
> -		base += xdr->page_base;
> -		ppage += base >> PAGE_SHIFT;
> -		base &= ~PAGE_MASK;
> -	}
> -	do {
> +	struct page **ppage = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
> +	unsigned int poff = xdr->page_base & ~PAGE_MASK;
> +	unsigned int pglen = xdr->page_len;
> +	ssize_t copied = 0;
> +	size_t ret;
> +
> +	if (xdr->head[0].iov_len == 0)
> +		return 0;
> +
> +	ret = xdr_skb_read_bits(desc, xdr->head[0].iov_base,
> +			xdr->head[0].iov_len);
> +	if (ret != xdr->head[0].iov_len || !desc->count)
> +		return ret;
> +	copied += ret;
> +
> +	while (pglen) {
> +		unsigned int len = min(PAGE_SIZE - poff, pglen);
>  		char *kaddr;
>  
>  		/* ACL likes to be lazy in allocating pages - ACLs
> @@ -126,36 +89,29 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb
>  			*ppage = alloc_page(GFP_NOWAIT | __GFP_NOWARN);
>  			if (unlikely(*ppage == NULL)) {
>  				if (copied == 0)
> -					copied = -ENOMEM;
> -				goto out;
> +					return -ENOMEM;
> +				return copied;
>  			}
>  		}
>  
> -		len = PAGE_SIZE;
>  		kaddr = kmap_atomic(*ppage);
> -		if (base) {
> -			len -= base;
> -			if (pglen < len)
> -				len = pglen;
> -			ret = copy_actor(desc, kaddr + base, len);
> -			base = 0;
> -		} else {
> -			if (pglen < len)
> -				len = pglen;
> -			ret = copy_actor(desc, kaddr, len);
> -		}
> +		ret = xdr_skb_read_bits(desc, kaddr + poff, len);
>  		flush_dcache_page(*ppage);
>  		kunmap_atomic(kaddr);
> +
>  		copied += ret;
>  		if (ret != len || !desc->count)
> -			goto out;
> +			return copied;
>  		ppage++;
> -	} while ((pglen -= len) != 0);
> -copy_tail:
> -	len = xdr->tail[0].iov_len;
> -	if (base < len)
> -		copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
> -out:
> +		pglen -= len;
> +		poff = 0;
> +	}
> +
> +	if (xdr->tail[0].iov_len) {
> +		copied += xdr_skb_read_bits(desc, xdr->tail[0].iov_base,
> +					xdr->tail[0].iov_len);
> +	}
> +
>  	return copied;
>  }
>  
> @@ -169,17 +125,22 @@ xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, struct xdr_skb
>   */
>  int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
>  {
> -	struct xdr_skb_reader	desc;
> -
> -	desc.skb = skb;
> -	desc.offset = 0;
> -	desc.count = skb->len - desc.offset;
> +	struct xdr_skb_reader desc = {
> +		.skb		= skb,
> +		.count		= skb->len - desc.offset,
> +	};
>  
> -	if (skb_csum_unnecessary(skb))
> -		goto no_checksum;
> +	if (skb_csum_unnecessary(skb)) {
> +		if (xdr_partial_copy_from_skb(xdr, &desc) < 0)
> +			return -1;
> +		if (desc.count)
> +			return -1;
> +		return 0;
> +	}
>  
> +	desc.need_checksum = true;
>  	desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
> -	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_and_csum_bits) < 0)
> +	if (xdr_partial_copy_from_skb(xdr, &desc) < 0)
>  		return -1;
>  	if (desc.offset != skb->len) {
>  		__wsum csum2;
> @@ -194,12 +155,6 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
>  	    !skb->csum_complete_sw)
>  		netdev_rx_csum_fault(skb->dev, skb);
>  	return 0;
> -no_checksum:
> -	if (xdr_partial_copy_from_skb(xdr, 0, &desc, xdr_skb_read_bits) < 0)
> -		return -1;
> -	if (desc.count)
> -		return -1;
> -	return 0;
>  }
>  EXPORT_SYMBOL_GPL(csum_partial_copy_to_xdr);
>  

Reviewed-by: Jeff Layton <jlayton@kernel.org>