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, 52 insertions, 4 deletions

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 73770a2a2311..36e9cc74ac11 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -98,11 +98,16 @@ struct afs_call {
 	struct afs_cb_interest	*cbi;		/* Callback interest for server used */
 	void			*request;	/* request data (first part) */
 	struct address_space	*mapping;	/* Pages being written from */
+	struct iov_iter		iter;		/* Buffer iterator */
+	struct iov_iter		*_iter;		/* Iterator currently in use */
+	union {	/* Convenience for ->iter */
+		struct kvec	kvec[1];
+		struct bio_vec	bvec[1];
+	};
 	void			*buffer;	/* reply receive buffer */
 	void			*reply[4];	/* Where to put the reply */
 	pgoff_t			first;		/* first page in mapping to deal with */
 	pgoff_t			last;		/* last page in mapping to deal with */
-	size_t			offset;		/* offset into received data store */
 	atomic_t		usage;
 	enum afs_call_state	state;
 	spinlock_t		state_lock;
@@ -127,7 +132,13 @@ struct afs_call {
 	unsigned int		debug_id;	/* Trace ID */
 	u32			operation_ID;	/* operation ID for an incoming call */
 	u32			count;		/* count for use in unmarshalling */
-	__be32			tmp;		/* place to extract temporary data */
+	union {					/* place to extract temporary data */
+		struct {
+			__be32	tmp_u;
+			__be32	tmp;
+		} __attribute__((packed));
+		__be64		tmp64;
+	};
 	afs_dataversion_t	expected_version; /* Updated version expected from store */
 	afs_dataversion_t	expected_version_2; /* 2nd updated version expected from store */
 };
@@ -185,6 +196,7 @@ struct afs_read {
 	refcount_t		usage;
 	unsigned int		index;		/* Which page we're reading into */
 	unsigned int		nr_pages;
+	unsigned int		offset;		/* offset into current page */
 	void (*page_done)(struct afs_call *, struct afs_read *);
 	struct page		**pages;
 	struct page		*array[];
@@ -550,6 +562,15 @@ struct afs_vnode {
 	afs_callback_type_t	cb_type;	/* type of callback */
 };
 
+static inline struct fscache_cookie *afs_vnode_cache(struct afs_vnode *vnode)
+{
+#ifdef CONFIG_AFS_FSCACHE
+	return vnode->cache;
+#else
+	return NULL;
+#endif
+}
+
 /*
  * cached security record for one user's attempt to access a vnode
  */
@@ -930,12 +951,39 @@ extern struct afs_call *afs_alloc_flat_call(struct afs_net *,
 extern void afs_flat_call_destructor(struct afs_call *);
 extern void afs_send_empty_reply(struct afs_call *);
 extern void afs_send_simple_reply(struct afs_call *, const void *, size_t);
-extern int afs_extract_data(struct afs_call *, void *, size_t, bool);
+extern int afs_extract_data(struct afs_call *, bool);
 extern int afs_protocol_error(struct afs_call *, int, enum afs_eproto_cause);
 
+static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t size)
+{
+	call->kvec[0].iov_base = buf;
+	call->kvec[0].iov_len = size;
+	iov_iter_kvec(&call->iter, READ, call->kvec, 1, size);
+}
+
+static inline void afs_extract_to_tmp(struct afs_call *call)
+{
+	afs_extract_begin(call, &call->tmp, sizeof(call->tmp));
+}
+
+static inline void afs_extract_to_tmp64(struct afs_call *call)
+{
+	afs_extract_begin(call, &call->tmp64, sizeof(call->tmp64));
+}
+
+static inline void afs_extract_discard(struct afs_call *call, size_t size)
+{
+	iov_iter_discard(&call->iter, READ, size);
+}
+
+static inline void afs_extract_to_buf(struct afs_call *call, size_t size)
+{
+	afs_extract_begin(call, call->buffer, size);
+}
+
 static inline int afs_transfer_reply(struct afs_call *call)
 {
-	return afs_extract_data(call, call->buffer, call->reply_max, false);
+	return afs_extract_data(call, false);
 }
 
 static inline bool afs_check_call_state(struct afs_call *call,