9p: Fix read/write debug statements to report server reply

[ Upstream commit be3193e ]

Previous conversion to iov missed these debug statements which would now
always print the requested size instead of the actual server reply.

Write also added a loop in a much older commit but we didn't report
these, while reads do report each iteration -- it's more coherent to
keep reporting all requests to server so move that at the same time.

Fixes: 7f02464 ("9p: convert to advancing variant of iov_iter_get_pages_alloc()")
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Message-ID: <20240109-9p-rw-trace-v1-1-327178114257@codewreck.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

net/9p/client.c

@@ -1583,7 +1583,7 @@ p9_client_read_once(struct p9_fid *fid, u64 offset, struct iov_iter *to,
 		received = rsize;
 	}
 
-	p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
+	p9_debug(P9_DEBUG_9P, "<<< RREAD count %d\n", received);
 
 	if (non_zc) {
 		int n = copy_to_iter(dataptr, received, to);
@@ -1609,9 +1609,6 @@ p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err)
 	int total = 0;
 	*err = 0;
 
-	p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %zd\n",
-		 fid->fid, offset, iov_iter_count(from));
-
 	while (iov_iter_count(from)) {
 		int count = iov_iter_count(from);
 		int rsize = fid->iounit;
@@ -1623,6 +1620,9 @@ p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err)
 		if (count < rsize)
 			rsize = count;
 
+		p9_debug(P9_DEBUG_9P, ">>> TWRITE fid %d offset %llu count %d (/%d)\n",
+			 fid->fid, offset, rsize, count);
+
 		/* Don't bother zerocopy for small IO (< 1024) */
 		if (clnt->trans_mod->zc_request && rsize > 1024) {
 			req = p9_client_zc_rpc(clnt, P9_TWRITE, NULL, from, 0,
@@ -1650,7 +1650,7 @@ p9_client_write(struct p9_fid *fid, u64 offset, struct iov_iter *from, int *err)
 			written = rsize;
 		}
 
-		p9_debug(P9_DEBUG_9P, "<<< RWRITE count %d\n", count);
+		p9_debug(P9_DEBUG_9P, "<<< RWRITE count %d\n", written);
 
 		p9_req_put(clnt, req);
 		iov_iter_revert(from, count - written - iov_iter_count(from));