iov_iter: advancing variants of iov_iter_get_pages{,_alloc}()

Most of the users immediately follow successful iov_iter_get_pages()
with advancing by the amount it had returned.

Provide inline wrappers doing that, convert trivial open-coded
uses of those.

BTW, iov_iter_get_pages() never returns more than it had been asked
to; such checks in cifs ought to be removed someday...
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/vhost/scsi.c

@@ -643,14 +643,12 @@ vhost_scsi_map_to_sgl(struct vhost_scsi_cmd *cmd,
 	size_t offset;
 	unsigned int npages = 0;
 
-	bytes = iov_iter_get_pages(iter, pages, LONG_MAX,
+	bytes = iov_iter_get_pages2(iter, pages, LONG_MAX,
 				VHOST_SCSI_PREALLOC_UPAGES, &offset);
 	/* No pages were pinned */
 	if (bytes <= 0)
 		return bytes < 0 ? bytes : -EFAULT;
 
-	iov_iter_advance(iter, bytes);
-
 	while (bytes) {
 		unsigned n = min_t(unsigned, PAGE_SIZE - offset, bytes);
 		sg_set_page(sg++, pages[npages++], n, offset);

fs/ceph/file.c

@@ -95,12 +95,11 @@ static ssize_t __iter_get_bvecs(struct iov_iter *iter, size_t maxsize,
 		size_t start;
 		int idx = 0;
 
-		bytes = iov_iter_get_pages(iter, pages, maxsize - size,
+		bytes = iov_iter_get_pages2(iter, pages, maxsize - size,
 					   ITER_GET_BVECS_PAGES, &start);
 		if (bytes < 0)
 			return size ?: bytes;
 
-		iov_iter_advance(iter, bytes);
 		size += bytes;
 
 		for ( ; bytes; idx++, bvec_idx++) {

fs/cifs/file.c

@@ -3022,7 +3022,7 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 		if (ctx->direct_io) {
 			ssize_t result;
 
-			result = iov_iter_get_pages_alloc(
+			result = iov_iter_get_pages_alloc2(
 				from, &pagevec, cur_len, &start);
 			if (result < 0) {
 				cifs_dbg(VFS,
@@ -3036,7 +3036,6 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 				break;
 			}
 			cur_len = (size_t)result;
-			iov_iter_advance(from, cur_len);
 
 			nr_pages =
 				(cur_len + start + PAGE_SIZE - 1) / PAGE_SIZE;
@@ -3758,7 +3757,7 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 		if (ctx->direct_io) {
 			ssize_t result;
 
-			result = iov_iter_get_pages_alloc(
+			result = iov_iter_get_pages_alloc2(
 					&direct_iov, &pagevec,
 					cur_len, &start);
 			if (result < 0) {
@@ -3774,7 +3773,6 @@ cifs_send_async_read(loff_t offset, size_t len, struct cifsFileInfo *open_file,
 				break;
 			}
 			cur_len = (size_t)result;
-			iov_iter_advance(&direct_iov, cur_len);
 
 			rdata = cifs_readdata_direct_alloc(
 					pagevec, cifs_uncached_readv_complete);

fs/cifs/misc.c

@@ -1029,7 +1029,7 @@ setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 	saved_len = count;
 
 	while (count && npages < max_pages) {
-		rc = iov_iter_get_pages(iter, pages, count, max_pages, &start);
+		rc = iov_iter_get_pages2(iter, pages, count, max_pages, &start);
 		if (rc < 0) {
 			cifs_dbg(VFS, "Couldn't get user pages (rc=%zd)\n", rc);
 			break;
@@ -1041,7 +1041,6 @@ setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw)
 			break;
 		}
 
-		iov_iter_advance(iter, rc);
 		count -= rc;
 		rc += start;
 		cur_npages = DIV_ROUND_UP(rc, PAGE_SIZE);

fs/direct-io.c

@@ -169,7 +169,7 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
 	const enum req_op dio_op = dio->opf & REQ_OP_MASK;
 	ssize_t ret;
 
-	ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES,
+	ret = iov_iter_get_pages2(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES,
 				&sdio->from);
 
 	if (ret < 0 && sdio->blocks_available && dio_op == REQ_OP_WRITE) {
@@ -191,7 +191,6 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
 	}
 
 	if (ret >= 0) {
-		iov_iter_advance(sdio->iter, ret);
 		ret += sdio->from;
 		sdio->head = 0;
 		sdio->tail = (ret + PAGE_SIZE - 1) / PAGE_SIZE;

fs/fuse/dev.c

@@ -730,14 +730,13 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
 		}
 	} else {
 		size_t off;
-		err = iov_iter_get_pages(cs->iter, &page, PAGE_SIZE, 1, &off);
+		err = iov_iter_get_pages2(cs->iter, &page, PAGE_SIZE, 1, &off);
 		if (err < 0)
 			return err;
 		BUG_ON(!err);
 		cs->len = err;
 		cs->offset = off;
 		cs->pg = page;
-		iov_iter_advance(cs->iter, err);
 	}
 
 	return lock_request(cs->req);

fs/fuse/file.c

@@ -1401,14 +1401,13 @@ static int fuse_get_user_pages(struct fuse_args_pages *ap, struct iov_iter *ii,
 	while (nbytes < *nbytesp && ap->num_pages < max_pages) {
 		unsigned npages;
 		size_t start;
-		ret = iov_iter_get_pages(ii, &ap->pages[ap->num_pages],
+		ret = iov_iter_get_pages2(ii, &ap->pages[ap->num_pages],
 					*nbytesp - nbytes,
 					max_pages - ap->num_pages,
 					&start);
 		if (ret < 0)
 			break;
 
-		iov_iter_advance(ii, ret);
 		nbytes += ret;
 
 		ret += start;

fs/nfs/direct.c

@@ -364,13 +364,12 @@ static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
 		size_t pgbase;
 		unsigned npages, i;
 
-		result = iov_iter_get_pages_alloc(iter, &pagevec, 
+		result = iov_iter_get_pages_alloc2(iter, &pagevec,
 						  rsize, &pgbase);
 		if (result < 0)
 			break;
 	
 		bytes = result;
-		iov_iter_advance(iter, bytes);
 		npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
 		for (i = 0; i < npages; i++) {
 			struct nfs_page *req;
@@ -812,13 +811,12 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 		size_t pgbase;
 		unsigned npages, i;
 
-		result = iov_iter_get_pages_alloc(iter, &pagevec, 
+		result = iov_iter_get_pages_alloc2(iter, &pagevec,
 						  wsize, &pgbase);
 		if (result < 0)
 			break;
 
 		bytes = result;
-		iov_iter_advance(iter, bytes);
 		npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
 		for (i = 0; i < npages; i++) {
 			struct nfs_page *req;

include/linux/uio.h

@@ -351,4 +351,24 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
 	};
 }
 
+static inline ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
+			size_t maxsize, unsigned maxpages, size_t *start)
+{
+	ssize_t res = iov_iter_get_pages(i, pages, maxsize, maxpages, start);
+
+	if (res >= 0)
+		iov_iter_advance(i, res);
+	return res;
+}
+
+static inline ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
+			size_t maxsize, size_t *start)
+{
+	ssize_t res = iov_iter_get_pages_alloc(i, pages, maxsize, start);
+
+	if (res >= 0)
+		iov_iter_advance(i, res);
+	return res;
+}
+
 #endif

net/core/datagram.c

@@ -632,12 +632,11 @@ int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
 		if (frag == MAX_SKB_FRAGS)
 			return -EMSGSIZE;
 
-		copied = iov_iter_get_pages(from, pages, length,
+		copied = iov_iter_get_pages2(from, pages, length,
 					    MAX_SKB_FRAGS - frag, &start);
 		if (copied < 0)
 			return -EFAULT;
 
-		iov_iter_advance(from, copied);
 		length -= copied;
 
 		truesize = PAGE_ALIGN(copied + start);

net/core/skmsg.c

@@ -324,14 +324,13 @@ int sk_msg_zerocopy_from_iter(struct sock *sk, struct iov_iter *from,
 			goto out;
 		}
 
-		copied = iov_iter_get_pages(from, pages, bytes, maxpages,
+		copied = iov_iter_get_pages2(from, pages, bytes, maxpages,
 					    &offset);
 		if (copied <= 0) {
 			ret = -EFAULT;
 			goto out;
 		}
 
-		iov_iter_advance(from, copied);
 		bytes -= copied;
 		msg->sg.size += copied;
 

net/rds/message.c

@@ -391,7 +391,7 @@ static int rds_message_zcopy_from_user(struct rds_message *rm, struct iov_iter *
 		size_t start;
 		ssize_t copied;
 
-		copied = iov_iter_get_pages(from, &pages, PAGE_SIZE,
+		copied = iov_iter_get_pages2(from, &pages, PAGE_SIZE,
 					    1, &start);
 		if (copied < 0) {
 			struct mmpin *mmp;
@@ -405,7 +405,6 @@ static int rds_message_zcopy_from_user(struct rds_message *rm, struct iov_iter *
 			goto err;
 		}
 		total_copied += copied;
-		iov_iter_advance(from, copied);
 		length -= copied;
 		sg_set_page(sg, pages, copied, start);
 		rm->data.op_nents++;

net/tls/tls_sw.c

@@ -1352,7 +1352,7 @@ static int tls_setup_from_iter(struct iov_iter *from,
 			rc = -EFAULT;
 			goto out;
 		}
-		copied = iov_iter_get_pages(from, pages,
+		copied = iov_iter_get_pages2(from, pages,
 					    length,
 					    maxpages, &offset);
 		if (copied <= 0) {
@@ -1360,8 +1360,6 @@ static int tls_setup_from_iter(struct iov_iter *from,
 			goto out;
 		}
 
-		iov_iter_advance(from, copied);
-
 		length -= copied;
 		size += copied;
 		while (copied) {