[PATCH] knfsd: Replace two page lists in struct svc_rqst with one

We are planning to increase RPCSVC_MAXPAGES from about 8 to about 256. This means we need to be a bit careful about arrays of size RPCSVC_MAXPAGES. struct svc_rqst contains two such arrays. However the there are never more that RPCSVC_MAXPAGES pages in the two arrays together, so only one array is needed. The two arrays are for the pages holding the request, and the pages holding the reply. Instead of two arrays, we can simply keep an index into where the first reply page is. This patch also removes a number of small inline functions that probably server to obscure what is going on rather than clarify it, and opencode the needed functionality. Also remove the 'rq_restailpage' variable as it is *always* 0. i.e. if the response 'xdr' structure has a non-empty tail it is always in the same pages as the head. check counters are initilised and incr properly check for consistant usage of ++ etc maybe extra some inlines for common approach general review Signed-off-by: Neil Brown <[email protected]> Cc: Magnus Maatta <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
adn770 · Oct 4, 2006 · 4452435 · 4452435
1 parent 5680c44
commit 4452435
Show file tree

Hide file tree

Showing 10 changed files with 77 additions and 141 deletions.
diff --git a/fs/nfsd/nfs2acl.c b/fs/nfsd/nfs2acl.c
@@ -241,7 +241,7 @@ static int nfsaclsvc_encode_getaclres(struct svc_rqst *rqstp, u32 *p,
 
 	rqstp->rq_res.page_len = w;
 	while (w > 0) {
-		if (!svc_take_res_page(rqstp))
+		if (!rqstp->rq_respages[rqstp->rq_resused++])
 			return 0;
 		w -= PAGE_SIZE;
 	}

diff --git a/fs/nfsd/nfs3acl.c b/fs/nfsd/nfs3acl.c
@@ -185,7 +185,7 @@ static int nfs3svc_encode_getaclres(struct svc_rqst *rqstp, u32 *p,
 
 		rqstp->rq_res.page_len = w;
 		while (w > 0) {
-			if (!svc_take_res_page(rqstp))
+			if (!rqstp->rq_respages[rqstp->rq_resused++])
 				return 0;
 			w -= PAGE_SIZE;
 		}

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
@@ -343,8 +343,7 @@ nfs3svc_decode_readargs(struct svc_rqst *rqstp, u32 *p,
 	/* set up the kvec */
 	v=0;
 	while (len > 0) {
-		pn = rqstp->rq_resused;
-		svc_take_page(rqstp);
+		pn = rqstp->rq_resused++;
 		args->vec[v].iov_base = page_address(rqstp->rq_respages[pn]);
 		args->vec[v].iov_len = len < PAGE_SIZE? len : PAGE_SIZE;
 		len -= args->vec[v].iov_len;
@@ -382,7 +381,7 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, u32 *p,
 	while (len > args->vec[v].iov_len) {
 		len -= args->vec[v].iov_len;
 		v++;
-		args->vec[v].iov_base = page_address(rqstp->rq_argpages[v]);
+		args->vec[v].iov_base = page_address(rqstp->rq_pages[v]);
 		args->vec[v].iov_len = PAGE_SIZE;
 	}
 	args->vec[v].iov_len = len;
@@ -446,11 +445,11 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, u32 *p,
 	 * This page appears in the rq_res.pages list, but as pages_len is always
 	 * 0, it won't get in the way
 	 */
-	svc_take_page(rqstp);
 	len = ntohl(*p++);
 	if (len == 0 || len > NFS3_MAXPATHLEN || len >= PAGE_SIZE)
 		return 0;
-	args->tname = new = page_address(rqstp->rq_respages[rqstp->rq_resused-1]);
+	args->tname = new =
+		page_address(rqstp->rq_respages[rqstp->rq_resused++]);
 	args->tlen = len;
 	/* first copy and check from the first page */
 	old = (char*)p;
@@ -522,8 +521,8 @@ nfs3svc_decode_readlinkargs(struct svc_rqst *rqstp, u32 *p,
 {
 	if (!(p = decode_fh(p, &args->fh)))
 		return 0;
-	svc_take_page(rqstp);
-	args->buffer = page_address(rqstp->rq_respages[rqstp->rq_resused-1]);
+	args->buffer =
+		page_address(rqstp->rq_respages[rqstp->rq_resused++]);
 
 	return xdr_argsize_check(rqstp, p);
 }
@@ -554,8 +553,8 @@ nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, u32 *p,
 	if (args->count > PAGE_SIZE)
 		args->count = PAGE_SIZE;
 
-	svc_take_page(rqstp);
-	args->buffer = page_address(rqstp->rq_respages[rqstp->rq_resused-1]);
+	args->buffer =
+		page_address(rqstp->rq_respages[rqstp->rq_resused++]);
 
 	return xdr_argsize_check(rqstp, p);
 }
@@ -578,8 +577,7 @@ nfs3svc_decode_readdirplusargs(struct svc_rqst *rqstp, u32 *p,
 	args->count = len;
 
 	while (len > 0) {
-		pn = rqstp->rq_resused;
-		svc_take_page(rqstp);
+		pn = rqstp->rq_resused++;
 		if (!args->buffer)
 			args->buffer = page_address(rqstp->rq_respages[pn]);
 		len -= PAGE_SIZE;
@@ -668,7 +666,6 @@ nfs3svc_encode_readlinkres(struct svc_rqst *rqstp, u32 *p,
 		rqstp->rq_res.page_len = resp->len;
 		if (resp->len & 3) {
 			/* need to pad the tail */
-			rqstp->rq_restailpage = 0;
 			rqstp->rq_res.tail[0].iov_base = p;
 			*p = 0;
 			rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
@@ -693,7 +690,6 @@ nfs3svc_encode_readres(struct svc_rqst *rqstp, u32 *p,
 		rqstp->rq_res.page_len = resp->count;
 		if (resp->count & 3) {
 			/* need to pad the tail */
-			rqstp->rq_restailpage = 0;
 			rqstp->rq_res.tail[0].iov_base = p;
 			*p = 0;
 			rqstp->rq_res.tail[0].iov_len = 4 - (resp->count & 3);
@@ -768,7 +764,6 @@ nfs3svc_encode_readdirres(struct svc_rqst *rqstp, u32 *p,
 		rqstp->rq_res.page_len = (resp->count) << 2;
 
 		/* add the 'tail' to the end of the 'head' page - page 0. */
-		rqstp->rq_restailpage = 0;
 		rqstp->rq_res.tail[0].iov_base = p;
 		*p++ = 0;		/* no more entries */
 		*p++ = htonl(resp->common.err == nfserr_eof);

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
@@ -2039,7 +2039,8 @@ nfsd4_encode_open_downgrade(struct nfsd4_compoundres *resp, int nfserr, struct n
 }
 
 static int
-nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read *read)
+nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr,
+		  struct nfsd4_read *read)
 {
 	u32 eof;
 	int v, pn;
@@ -2061,10 +2062,11 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read
 	len = maxcount;
 	v = 0;
 	while (len > 0) {
-		pn = resp->rqstp->rq_resused;
-		svc_take_page(resp->rqstp);
-		read->rd_iov[v].iov_base = page_address(resp->rqstp->rq_respages[pn]);
-		read->rd_iov[v].iov_len = len < PAGE_SIZE ? len : PAGE_SIZE;
+		pn = resp->rqstp->rq_resused++;
+		read->rd_iov[v].iov_base =
+			page_address(resp->rqstp->rq_respages[pn]);
+		read->rd_iov[v].iov_len =
+			len < PAGE_SIZE ? len : PAGE_SIZE;
 		v++;
 		len -= PAGE_SIZE;
 	}
@@ -2078,7 +2080,8 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read
 		nfserr = nfserr_inval;
 	if (nfserr)
 		return nfserr;
-	eof = (read->rd_offset + maxcount >= read->rd_fhp->fh_dentry->d_inode->i_size);
+	eof = (read->rd_offset + maxcount >=
+	       read->rd_fhp->fh_dentry->d_inode->i_size);
 
 	WRITE32(eof);
 	WRITE32(maxcount);
@@ -2088,7 +2091,6 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read
 	resp->xbuf->page_len = maxcount;
 
 	/* Use rest of head for padding and remaining ops: */
-	resp->rqstp->rq_restailpage = 0;
 	resp->xbuf->tail[0].iov_base = p;
 	resp->xbuf->tail[0].iov_len = 0;
 	if (maxcount&3) {
@@ -2113,8 +2115,7 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_r
 	if (resp->xbuf->page_len)
 		return nfserr_resource;
 
-	svc_take_page(resp->rqstp);
-	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
+	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused++]);
 
 	maxcount = PAGE_SIZE;
 	RESERVE_SPACE(4);
@@ -2138,7 +2139,6 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_r
 	resp->xbuf->page_len = maxcount;
 
 	/* Use rest of head for padding and remaining ops: */
-	resp->rqstp->rq_restailpage = 0;
 	resp->xbuf->tail[0].iov_base = p;
 	resp->xbuf->tail[0].iov_len = 0;
 	if (maxcount&3) {
@@ -2189,8 +2189,7 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_re
 		goto err_no_verf;
 	}
 
-	svc_take_page(resp->rqstp);
-	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
+	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused++]);
 	readdir->common.err = 0;
 	readdir->buflen = maxcount;
 	readdir->buffer = page;
@@ -2215,10 +2214,10 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_re
 	p = readdir->buffer;
 	*p++ = 0;	/* no more entries */
 	*p++ = htonl(readdir->common.err == nfserr_eof);
-	resp->xbuf->page_len = ((char*)p) - (char*)page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
+	resp->xbuf->page_len = ((char*)p) - (char*)page_address(
+		resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
 
 	/* Use rest of head for padding and remaining ops: */
-	resp->rqstp->rq_restailpage = 0;
 	resp->xbuf->tail[0].iov_base = tailbase;
 	resp->xbuf->tail[0].iov_len = 0;
 	resp->p = resp->xbuf->tail[0].iov_base;

diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
@@ -262,8 +262,7 @@ nfssvc_decode_readargs(struct svc_rqst *rqstp, u32 *p,
 	 */
 	v=0;
 	while (len > 0) {
-		pn=rqstp->rq_resused;
-		svc_take_page(rqstp);
+		pn = rqstp->rq_resused++;
 		args->vec[v].iov_base = page_address(rqstp->rq_respages[pn]);
 		args->vec[v].iov_len = len < PAGE_SIZE?len:PAGE_SIZE;
 		len -= args->vec[v].iov_len;
@@ -295,7 +294,7 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, u32 *p,
 	while (len > args->vec[v].iov_len) {
 		len -= args->vec[v].iov_len;
 		v++;
-		args->vec[v].iov_base = page_address(rqstp->rq_argpages[v]);
+		args->vec[v].iov_base = page_address(rqstp->rq_pages[v]);
 		args->vec[v].iov_len = PAGE_SIZE;
 	}
 	args->vec[v].iov_len = len;
@@ -333,8 +332,7 @@ nfssvc_decode_readlinkargs(struct svc_rqst *rqstp, u32 *p, struct nfsd_readlinka
 {
 	if (!(p = decode_fh(p, &args->fh)))
 		return 0;
-	svc_take_page(rqstp);
-	args->buffer = page_address(rqstp->rq_respages[rqstp->rq_resused-1]);
+	args->buffer = page_address(rqstp->rq_respages[rqstp->rq_resused++]);
 
 	return xdr_argsize_check(rqstp, p);
 }
@@ -375,8 +373,7 @@ nfssvc_decode_readdirargs(struct svc_rqst *rqstp, u32 *p,
 	if (args->count > PAGE_SIZE)
 		args->count = PAGE_SIZE;
 
-	svc_take_page(rqstp);
-	args->buffer = page_address(rqstp->rq_respages[rqstp->rq_resused-1]);
+	args->buffer = page_address(rqstp->rq_respages[rqstp->rq_resused++]);
 
 	return xdr_argsize_check(rqstp, p);
 }
@@ -416,7 +413,6 @@ nfssvc_encode_readlinkres(struct svc_rqst *rqstp, u32 *p,
 	rqstp->rq_res.page_len = resp->len;
 	if (resp->len & 3) {
 		/* need to pad the tail */
-		rqstp->rq_restailpage = 0;
 		rqstp->rq_res.tail[0].iov_base = p;
 		*p = 0;
 		rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
@@ -436,7 +432,6 @@ nfssvc_encode_readres(struct svc_rqst *rqstp, u32 *p,
 	rqstp->rq_res.page_len = resp->count;
 	if (resp->count & 3) {
 		/* need to pad the tail */
-		rqstp->rq_restailpage = 0;
 		rqstp->rq_res.tail[0].iov_base = p;
 		*p = 0;
 		rqstp->rq_res.tail[0].iov_len = 4 - (resp->count&3);

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
@@ -791,22 +791,26 @@ nfsd_read_actor(read_descriptor_t *desc, struct page *page, unsigned long offset
 {
 	unsigned long count = desc->count;
 	struct svc_rqst *rqstp = desc->arg.data;
+	struct page **pp = rqstp->rq_respages + rqstp->rq_resused;
 
 	if (size > count)
 		size = count;
 
 	if (rqstp->rq_res.page_len == 0) {
 		get_page(page);
-		rqstp->rq_respages[rqstp->rq_resused++] = page;
+		put_page(*pp);
+		*pp = page;
+		rqstp->rq_resused++;
 		rqstp->rq_res.page_base = offset;
 		rqstp->rq_res.page_len = size;
-	} else if (page != rqstp->rq_respages[rqstp->rq_resused-1]) {
+	} else if (page != pp[-1]) {
 		get_page(page);
-		rqstp->rq_respages[rqstp->rq_resused++] = page;
+		put_page(*pp);
+		*pp = page;
+		rqstp->rq_resused++;
 		rqstp->rq_res.page_len += size;
-	} else {
+	} else
 		rqstp->rq_res.page_len += size;
-	}
 
 	desc->count = count - size;
 	desc->written += size;
@@ -837,7 +841,7 @@ nfsd_vfs_read(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
 		file->f_ra = ra->p_ra;
 
 	if (file->f_op->sendfile && rqstp->rq_sendfile_ok) {
-		svc_pushback_unused_pages(rqstp);
+		rqstp->rq_resused = 1;
 		err = file->f_op->sendfile(file, &offset, *count,
 						 nfsd_read_actor, rqstp);
 	} else {

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
@@ -170,7 +170,6 @@ static inline void svc_putu32(struct kvec *iov, __be32 val)
 /*
  * The context of a single thread, including the request currently being
  * processed.
- * NOTE: First two items must be prev/next.
  */
 struct svc_rqst {
 	struct list_head	rq_list;	/* idle list */
@@ -189,12 +188,9 @@ struct svc_rqst {
 
 	struct xdr_buf		rq_arg;
 	struct xdr_buf		rq_res;
-	struct page *		rq_argpages[RPCSVC_MAXPAGES];
-	struct page *		rq_respages[RPCSVC_MAXPAGES];
-	int			rq_restailpage;
-	short			rq_argused;	/* pages used for argument */
-	short			rq_arghi;	/* pages available in argument page list */
-	short			rq_resused;	/* pages used for result */
+	struct page *		rq_pages[RPCSVC_MAXPAGES];
+	struct page *		*rq_respages;	/* points into rq_pages */
+	int			rq_resused;	/* number of pages used for result */
 
 	__be32			rq_xid;		/* transmission id */
 	u32			rq_prog;	/* program number */
@@ -255,63 +251,18 @@ xdr_ressize_check(struct svc_rqst *rqstp, __be32 *p)
 	return vec->iov_len <= PAGE_SIZE;
 }
 
-static inline struct page *
-svc_take_res_page(struct svc_rqst *rqstp)
+static inline void svc_free_res_pages(struct svc_rqst *rqstp)
 {
-	if (rqstp->rq_arghi <= rqstp->rq_argused)
-		return NULL;
-	rqstp->rq_arghi--;
-	rqstp->rq_respages[rqstp->rq_resused] =
-		rqstp->rq_argpages[rqstp->rq_arghi];
-	return rqstp->rq_respages[rqstp->rq_resused++];
-}
-
-static inline void svc_take_page(struct svc_rqst *rqstp)
-{
-	if (rqstp->rq_arghi <= rqstp->rq_argused) {
-		WARN_ON(1);
-		return;
-	}
-	rqstp->rq_arghi--;
-	rqstp->rq_respages[rqstp->rq_resused] =
-		rqstp->rq_argpages[rqstp->rq_arghi];
-	rqstp->rq_resused++;
-}
-
-static inline void svc_pushback_allpages(struct svc_rqst *rqstp)
-{
-        while (rqstp->rq_resused) {
-		if (rqstp->rq_respages[--rqstp->rq_resused] == NULL)
-			continue;
-		rqstp->rq_argpages[rqstp->rq_arghi++] =
-			rqstp->rq_respages[rqstp->rq_resused];
-		rqstp->rq_respages[rqstp->rq_resused] = NULL;
-	}
-}
-
-static inline void svc_pushback_unused_pages(struct svc_rqst *rqstp)
-{
-	while (rqstp->rq_resused &&
-	       rqstp->rq_res.pages != &rqstp->rq_respages[rqstp->rq_resused]) {
-
-		if (rqstp->rq_respages[--rqstp->rq_resused] != NULL) {
-			rqstp->rq_argpages[rqstp->rq_arghi++] =
-				rqstp->rq_respages[rqstp->rq_resused];
-			rqstp->rq_respages[rqstp->rq_resused] = NULL;
+	while (rqstp->rq_resused) {
+		struct page **pp = (rqstp->rq_respages +
+				    --rqstp->rq_resused);
+		if (*pp) {
+			put_page(*pp);
+			*pp = NULL;
 		}
 	}
 }
 
-static inline void svc_free_allpages(struct svc_rqst *rqstp)
-{
-        while (rqstp->rq_resused) {
-		if (rqstp->rq_respages[--rqstp->rq_resused] == NULL)
-			continue;
-		put_page(rqstp->rq_respages[rqstp->rq_resused]);
-		rqstp->rq_respages[rqstp->rq_resused] = NULL;
-	}
-}
-
 struct svc_deferred_req {
 	u32			prot;	/* protocol (UDP or TCP) */
 	struct sockaddr_in	addr;