afs: Set up the iov_iter before calling afs_extract_data()

afs_extract_data sets up a temporary iov_iter and passes it to AF_RXRPC
each time it is called to describe the remaining buffer to be filled.

Instead:

 (1) Put an iterator in the afs_call struct.

 (2) Set the iterator for each marshalling stage to load data into the
     appropriate places.  A number of convenience functions are provided to
     this end (eg. afs_extract_to_buf()).

     This iterator is then passed to afs_extract_data().

 (3) Use the new ITER_DISCARD iterator to discard any excess data provided
     by FetchData.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 46 insertions, 58 deletions

diff --git a/fs/afs/vlclient.c b/fs/afs/vlclient.c
index d0f95c4ab05e..e18c51742daa 100644
--- a/fs/afs/vlclient.c
+++ b/fs/afs/vlclient.c
@@ -187,19 +187,18 @@ static int afs_deliver_vl_get_addrs_u(struct afs_call *call)
 	u32 uniquifier, nentries, count;
 	int i, ret;
 
-	_enter("{%u,%zu/%u}", call->unmarshall, call->offset, call->count);
+	_enter("{%u,%zu/%u}",
+	       call->unmarshall, iov_iter_count(call->_iter), call->count);
 
-again:
 	switch (call->unmarshall) {
 	case 0:
-		call->offset = 0;
+		afs_extract_to_buf(call,
+				   sizeof(struct afs_uuid__xdr) + 3 * sizeof(__be32));
 		call->unmarshall++;
 
 		/* Extract the returned uuid, uniquifier, nentries and blkaddrs size */
 	case 1:
-		ret = afs_extract_data(call, call->buffer,
-				       sizeof(struct afs_uuid__xdr) + 3 * sizeof(__be32),
-				       true);
+		ret = afs_extract_data(call, true);
 		if (ret < 0)
 			return ret;
 
@@ -216,28 +215,28 @@ again:
 		call->reply[0] = alist;
 		call->count = count;
 		call->count2 = nentries;
-		call->offset = 0;
 		call->unmarshall++;
 
+	more_entries:
+		count = min(call->count, 4U);
+		afs_extract_to_buf(call, count * sizeof(__be32));
+
 		/* Extract entries */
 	case 2:
-		count = min(call->count, 4U);
-		ret = afs_extract_data(call, call->buffer,
-				       count * sizeof(__be32),
-				       call->count > 4);
+		ret = afs_extract_data(call, call->count > 4);
 		if (ret < 0)
 			return ret;
 
 		alist = call->reply[0];
 		bp = call->buffer;
+		count = min(call->count, 4U);
 		for (i = 0; i < count; i++)
 			if (alist->nr_addrs < call->count2)
 				afs_merge_fs_addr4(alist, *bp++, AFS_FS_PORT);
 
 		call->count -= count;
 		if (call->count > 0)
-			goto again;
-		call->offset = 0;
+			goto more_entries;
 		call->unmarshall++;
 		break;
 	}
@@ -318,44 +317,35 @@ static int afs_deliver_vl_get_capabilities(struct afs_call *call)
 	u32 count;
 	int ret;
 
-	_enter("{%u,%zu/%u}", call->unmarshall, call->offset, call->count);
+	_enter("{%u,%zu/%u}",
+	       call->unmarshall, iov_iter_count(call->_iter), call->count);
 
-again:
 	switch (call->unmarshall) {
 	case 0:
-		call->offset = 0;
+		afs_extract_to_tmp(call);
 		call->unmarshall++;
 
 		/* Extract the capabilities word count */
 	case 1:
-		ret = afs_extract_data(call, &call->tmp,
-				       1 * sizeof(__be32),
-				       true);
+		ret = afs_extract_data(call, true);
 		if (ret < 0)
 			return ret;
 
 		count = ntohl(call->tmp);
-
 		call->count = count;
 		call->count2 = count;
-		call->offset = 0;
+
 		call->unmarshall++;
+		afs_extract_discard(call, count * sizeof(__be32));
 
 		/* Extract capabilities words */
 	case 2:
-		count = min(call->count, 16U);
-		ret = afs_extract_data(call, call->buffer,
-				       count * sizeof(__be32),
-				       call->count > 16);
+		ret = afs_extract_data(call, false);
 		if (ret < 0)
 			return ret;
 
 		/* TODO: Examine capabilities */
 
-		call->count -= count;
-		if (call->count > 0)
-			goto again;
-		call->offset = 0;
 		call->unmarshall++;
 		break;
 	}
@@ -426,22 +416,19 @@ static int afs_deliver_yfsvl_get_endpoints(struct afs_call *call)
 	u32 uniquifier, size;
 	int ret;
 
-	_enter("{%u,%zu/%u,%u}", call->unmarshall, call->offset, call->count, call->count2);
+	_enter("{%u,%zu,%u}",
+	       call->unmarshall, iov_iter_count(call->_iter), call->count2);
 
-again:
 	switch (call->unmarshall) {
 	case 0:
-		call->offset = 0;
+		afs_extract_to_buf(call, sizeof(uuid_t) + 3 * sizeof(__be32));
 		call->unmarshall = 1;
 
 		/* Extract the returned uuid, uniquifier, fsEndpoints count and
 		 * either the first fsEndpoint type or the volEndpoints
 		 * count if there are no fsEndpoints. */
 	case 1:
-		ret = afs_extract_data(call, call->buffer,
-				       sizeof(uuid_t) +
-				       3 * sizeof(__be32),
-				       true);
+		ret = afs_extract_data(call, true);
 		if (ret < 0)
 			return ret;
 
@@ -459,15 +446,11 @@ again:
 			return -ENOMEM;
 		alist->version = uniquifier;
 		call->reply[0] = alist;
-		call->offset = 0;
 
 		if (call->count == 0)
 			goto extract_volendpoints;
 
-		call->unmarshall = 2;
-
-		/* Extract fsEndpoints[] entries */
-	case 2:
+	next_fsendpoint:
 		switch (call->count2) {
 		case YFS_ENDPOINT_IPV4:
 			size = sizeof(__be32) * (1 + 1 + 1);
@@ -481,7 +464,12 @@ again:
 		}
 
 		size += sizeof(__be32);
-		ret = afs_extract_data(call, call->buffer, size, true);
+		afs_extract_to_buf(call, size);
+		call->unmarshall = 2;
+
+		/* Extract fsEndpoints[] entries */
+	case 2:
+		ret = afs_extract_data(call, true);
 		if (ret < 0)
 			return ret;
 
@@ -512,10 +500,9 @@ again:
 		 */
 		call->count2 = ntohl(*bp++);
 
-		call->offset = 0;
 		call->count--;
 		if (call->count > 0)
-			goto again;
+			goto next_fsendpoint;
 
 	extract_volendpoints:
 		/* Extract the list of volEndpoints. */
@@ -526,6 +513,7 @@ again:
 			return afs_protocol_error(call, -EBADMSG,
 						  afs_eproto_yvl_vlendpt_type);
 
+		afs_extract_to_buf(call, 1 * sizeof(__be32));
 		call->unmarshall = 3;
 
 		/* Extract the type of volEndpoints[0].  Normally we would
@@ -533,17 +521,14 @@ again:
 		 * data of the current one, but this is the first...
 		 */
 	case 3:
-		ret = afs_extract_data(call, call->buffer, sizeof(__be32), true);
+		ret = afs_extract_data(call, true);
 		if (ret < 0)
 			return ret;
 
 		bp = call->buffer;
-		call->count2 = ntohl(*bp++);
-		call->offset = 0;
-		call->unmarshall = 4;
 
-		/* Extract volEndpoints[] entries */
-	case 4:
+	next_volendpoint:
+		call->count2 = ntohl(*bp++);
 		switch (call->count2) {
 		case YFS_ENDPOINT_IPV4:
 			size = sizeof(__be32) * (1 + 1 + 1);
@@ -557,8 +542,13 @@ again:
 		}
 
 		if (call->count > 1)
-			size += sizeof(__be32);
-		ret = afs_extract_data(call, call->buffer, size, true);
+			size += sizeof(__be32); /* Get next type too */
+		afs_extract_to_buf(call, size);
+		call->unmarshall = 4;
+
+		/* Extract volEndpoints[] entries */
+	case 4:
+		ret = afs_extract_data(call, true);
 		if (ret < 0)
 			return ret;
 
@@ -584,19 +574,17 @@ again:
 		/* Got either the type of the next entry or the count of
 		 * volEndpoints if no more fsEndpoints.
 		 */
-		call->offset = 0;
 		call->count--;
-		if (call->count > 0) {
-			call->count2 = ntohl(*bp++);
-			goto again;
-		}
+		if (call->count > 0)
+			goto next_volendpoint;
 
 	end:
+		afs_extract_discard(call, 0);
 		call->unmarshall = 5;
 
 		/* Done */
 	case 5:
-		ret = afs_extract_data(call, call->buffer, 0, false);
+		ret = afs_extract_data(call, false);
 		if (ret < 0)
 			return ret;
 		call->unmarshall = 6;