io_uring/kbuf: remove obsolete buf_nr_pages and update comments

The buf_nr_pages field in io_buffer_list was previously used to
determine whether the buffer list uses ring-provided buffers or classic
provided buffers. This is now determined by checking the IOBL_BUF_RING
flag.

Remove the buf_nr_pages field and update related comments.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: joannekoong

include/linux/io_uring_types.h

@@ -327,8 +327,8 @@ struct io_ring_ctx {
 
 		/*
 		 * Modifications are protected by ->uring_lock and ->mmap_lock.
-		 * The flags, buf_pages and buf_nr_pages fields should be stable
-		 * once published.
+		 * The buffer list's io mapped region should be stable once
+		 * published.
 		 */
 		struct xarray		io_bl_xa;
 

io_uring/kbuf.h

@@ -14,8 +14,8 @@ enum {
 
 struct io_buffer_list {
 	/*
-	 * If ->buf_nr_pages is set, then buf_pages/buf_ring are used. If not,
-	 * then these are classic provided buffers and ->buf_list is used.
+	 * If the IOBL_BUF_RING flag is set, then buf_ring is used. If not, then
+	 * these are classic provided buffers and ->buf_list is used.
 	 */
 	union {
 		struct list_head buf_list;
@@ -27,7 +27,6 @@ struct io_buffer_list {
 	__u16 bgid;
 
 	/* below is for ring provided buffers */
-	__u16 buf_nr_pages;
 	__u16 nr_entries;
 	__u16 head;
 	__u16 mask;