missing bits of "splice: fix racy pipe->buffers uses"

that commit has fixed only the parts of that mess in fs/splice.c itself;
there had been more in several other ->splice_read() instances...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

kernel/relay.c

@@ -1251,7 +1251,7 @@ static ssize_t subbuf_splice_actor(struct file *in,
 	subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
 	pidx = (read_start / PAGE_SIZE) % subbuf_pages;
 	poff = read_start & ~PAGE_MASK;
-	nr_pages = min_t(unsigned int, subbuf_pages, pipe->buffers);
+	nr_pages = min_t(unsigned int, subbuf_pages, spd.nr_pages_max);
 
 	for (total_len = 0; spd.nr_pages < nr_pages; spd.nr_pages++) {
 		unsigned int this_len, this_end, private;

kernel/trace/trace.c

@@ -4410,7 +4410,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 	trace_access_lock(iter->cpu_file);
 
 	/* Fill as many pages as possible. */
-	for (i = 0, rem = len; i < pipe->buffers && rem; i++) {
+	for (i = 0, rem = len; i < spd.nr_pages_max && rem; i++) {
 		spd.pages[i] = alloc_page(GFP_KERNEL);
 		if (!spd.pages[i])
 			break;
@@ -5267,7 +5267,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 	trace_access_lock(iter->cpu_file);
 	entries = ring_buffer_entries_cpu(iter->trace_buffer->buffer, iter->cpu_file);
 
-	for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
+	for (i = 0; i < spd.nr_pages_max && len && entries; i++, len -= PAGE_SIZE) {
 		struct page *page;
 		int r;
 

mm/shmem.c

@@ -1613,7 +1613,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
 	index = *ppos >> PAGE_CACHE_SHIFT;
 	loff = *ppos & ~PAGE_CACHE_MASK;
 	req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-	nr_pages = min(req_pages, pipe->buffers);
+	nr_pages = min(req_pages, spd.nr_pages_max);
 
 	spd.nr_pages = find_get_pages_contig(mapping, index,
 						nr_pages, spd.pages);