[PATCH 17/25] afs: Don't truncate iter during data fetch

David Howells
2021-01-21T02:36:43Z

Don't truncate the iterator to correspond to the actual data size when
fetching the data from the server - rather, pass the length we want to read
to rxrpc.

This will allow the clear-after-read code in future to simply clear the
remaining iterator capacity rather than having to reinitialise the
iterator.

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

fs/afs/fsclient.c | 6 ++++--
fs/afs/internal.h | 6 ++++++
fs/afs/rxrpc.c | 13 +++++++++----
fs/afs/yfsclient.c | 6 ++++--
include/net/af_rxrpc.h | 2 +-
net/rxrpc/recvmsg.c | 9 +++++----
6 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 1d95ed9dd86e..4a57c6c6f12b 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -305,8 +305,9 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
unsigned int size;
int ret;

- _enter("{%u,%zu/%llu}",
- call->unmarshall, iov_iter_count(call->iter), req->actual_len);
+ _enter("{%u,%zu,%zu/%llu}",
+ call->unmarshall, call->iov_len, iov_iter_count(call->iter),
+ req->actual_len);

switch (call->unmarshall) {
case 0:
@@ -343,6 +344,7 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
size = PAGE_SIZE - req->offset;
else
size = req->remain;
+ call->iov_len = size;
call->bvec[0].bv_len = size;
call->bvec[0].bv_offset = req->offset;
call->bvec[0].bv_page = req->pages[req->index];
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 4b255d10f726..1badc7ed0487 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -104,6 +104,7 @@ struct afs_call {
struct afs_server *server; /* The fileserver record if fs op (pins ref) */
struct afs_vlserver *vlserver; /* The vlserver record if vl op */
void *request; /* request data (first part) */
+ size_t iov_len; /* Size of *iter to be used */
struct iov_iter def_iter; /* Default buffer/data iterator */
struct iov_iter *iter; /* Iterator currently in use */
union { /* Convenience for ->def_iter */
@@ -1270,6 +1271,7 @@ static inline void afs_make_op_call(struct afs_operation *op, struct afs_call *c

static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t size)
{
+ call->iov_len = size;
call->kvec[0].iov_base = buf;
call->kvec[0].iov_len = size;
iov_iter_kvec(&call->def_iter, READ, call->kvec, 1, size);
@@ -1277,21 +1279,25 @@ static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t si

static inline void afs_extract_to_tmp(struct afs_call *call)
{
+ call->iov_len = sizeof(call->tmp);
afs_extract_begin(call, &call->tmp, sizeof(call->tmp));
}

static inline void afs_extract_to_tmp64(struct afs_call *call)
{
+ call->iov_len = sizeof(call->tmp64);
afs_extract_begin(call, &call->tmp64, sizeof(call->tmp64));
}

static inline void afs_extract_discard(struct afs_call *call, size_t size)
{
+ call->iov_len = size;
iov_iter_discard(&call->def_iter, READ, size);
}

static inline void afs_extract_to_buf(struct afs_call *call, size_t size)
{
+ call->iov_len = size;
afs_extract_begin(call, call->buffer, size);
}

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 8be709cb8542..0ec38b758f29 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -363,6 +363,7 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
struct rxrpc_call *rxcall;
struct msghdr msg;
struct kvec iov[1];
+ size_t len;
s64 tx_total_len;
int ret;

@@ -466,9 +467,10 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
rxrpc_kernel_abort_call(call->net->socket, rxcall,
RX_USER_ABORT, ret, "KSD");
} else {
+ len = 0;
iov_iter_kvec(&msg.msg_iter, READ, NULL, 0, 0);
rxrpc_kernel_recv_data(call->net->socket, rxcall,
- &msg.msg_iter, false,
+ &msg.msg_iter, &len, false,
&call->abort_code, &call->service_id);
ac->abort_code = call->abort_code;
ac->responded = true;
@@ -504,6 +506,7 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
static void afs_deliver_to_call(struct afs_call *call)
{
enum afs_call_state state;
+ size_t len;
u32 abort_code, remote_abort = 0;
int ret;

@@ -516,10 +519,11 @@ static void afs_deliver_to_call(struct afs_call *call)
state == AFS_CALL_SV_AWAIT_ACK
) {
if (state == AFS_CALL_SV_AWAIT_ACK) {
+ len = 0;
iov_iter_kvec(&call->def_iter, READ, NULL, 0, 0);
ret = rxrpc_kernel_recv_data(call->net->socket,
call->rxcall, &call->def_iter,
- false, &remote_abort,
+ &len, false, &remote_abort,
&call->service_id);
trace_afs_receive_data(call, &call->def_iter, false, ret);

@@ -929,10 +933,11 @@ int afs_extract_data(struct afs_call *call, bool want_more)
u32 remote_abort = 0;
int ret;

- _enter("{%s,%zu},%d", call->type->name, iov_iter_count(iter), want_more);
+ _enter("{%s,%zu,%zu},%d",
+ call->type->name, call->iov_len, iov_iter_count(iter), want_more);

ret = rxrpc_kernel_recv_data(net->socket, call->rxcall, iter,
- want_more, &remote_abort,
+ &call->iov_len, want_more, &remote_abort,
&call->service_id);
if (ret == 0 || ret == -EAGAIN)
return ret;
diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c
index bd787e71a657..6c45d32da13c 100644
--- a/fs/afs/yfsclient.c
+++ b/fs/afs/yfsclient.c
@@ -363,8 +363,9 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
unsigned int size;
int ret;

- _enter("{%u,%zu/%llu}",
- call->unmarshall, iov_iter_count(call->iter), req->actual_len);
+ _enter("{%u,%zu, %zu/%llu}",
+ call->unmarshall, call->iov_len, iov_iter_count(call->iter),
+ req->actual_len);

switch (call->unmarshall) {
case 0:
@@ -396,6 +397,7 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
size = PAGE_SIZE - req->offset;
else
size = req->remain;
+ call->iov_len = size;
call->bvec[0].bv_len = size;
call->bvec[0].bv_offset = req->offset;
call->bvec[0].bv_page = req->pages[req->index];
diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h
index f6abcc0bbd6e..cee5f83c0f11 100644
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -53,7 +53,7 @@ int rxrpc_kernel_send_data(struct socket *, struct rxrpc_call *,
struct msghdr *, size_t,
rxrpc_notify_end_tx_t);
int rxrpc_kernel_recv_data(struct socket *, struct rxrpc_call *,
- struct iov_iter *, bool, u32 *, u16 *);
+ struct iov_iter *, size_t *, bool, u32 *, u16 *);
bool rxrpc_kernel_abort_call(struct socket *, struct rxrpc_call *,
u32, int, const char *);
void rxrpc_kernel_end_call(struct socket *, struct rxrpc_call *);
diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index fef3573fdc8b..eca6dda26c77 100644
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -669,6 +669,7 @@ int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
* @sock: The socket that the call exists on
* @call: The call to send data through
* @iter: The buffer to receive into
+ * @_len: The amount of data we want to receive (decreased on return)
* @want_more: True if more data is expected to be read
* @_abort: Where the abort code is stored if -ECONNABORTED is returned
* @_service: Where to store the actual service ID (may be upgraded)
@@ -684,7 +685,7 @@ int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
* *_abort should also be initialised to 0.
*/
int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
- struct iov_iter *iter,
+ struct iov_iter *iter, size_t *_len,
bool want_more, u32 *_abort, u16 *_service)
{
size_t offset = 0;
@@ -692,7 +693,7 @@ int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,

_enter("{%d,%s},%zu,%d",
call->debug_id, rxrpc_call_states[call->state],
- iov_iter_count(iter), want_more);
+ *_len, want_more);

ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_SECURING);

@@ -703,8 +704,8 @@ int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
case RXRPC_CALL_SERVER_RECV_REQUEST:
case RXRPC_CALL_SERVER_ACK_REQUEST:
ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
- iov_iter_count(iter), 0,
- &offset);
+ *_len, 0, &offset);
+ *_len -= offset;
if (ret < 0)
goto out;