fs: remove the bh_end_io argument from __block_write_full_folio

All callers are passing end_buffer_async_write as this argument, so we can
hardcode references to it within __block_write_full_folio(). That lets us
make end_buffer_async_write() static.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Reviewed-by: Jens Axboe <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

fs/buffer.c

···
 }
 
 /*
- * Completion handler for block_write_full_folio() - pages which are unlocked
- * during I/O, and which have PageWriteback cleared upon I/O completion.
+ * Completion handler for block_write_full_folio() - folios which are unlocked
+ * during I/O, and which have the writeback flag cleared upon I/O completion.
  */
-void end_buffer_async_write(struct buffer_head *bh, int uptodate)
+static void end_buffer_async_write(struct buffer_head *bh, int uptodate)
 {
 	unsigned long flags;
 	struct buffer_head *first;
···
 	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
 	return;
 }
-EXPORT_SYMBOL(end_buffer_async_write);
 
 /*
  * If a page's buffers are under async readin (end_buffer_async_read
···
  * causes the writes to be flagged as synchronous writes.
  */
 int __block_write_full_folio(struct inode *inode, struct folio *folio,
-			get_block_t *get_block, struct writeback_control *wbc,
-			bh_end_io_t *handler)
+			get_block_t *get_block, struct writeback_control *wbc)
 {
 	int err;
 	sector_t block;
···
 			continue;
 		}
 		if (test_clear_buffer_dirty(bh)) {
-			mark_buffer_async_write_endio(bh, handler);
+			mark_buffer_async_write_endio(bh,
+				end_buffer_async_write);
 		} else {
 			unlock_buffer(bh);
 		}
···
 		if (buffer_mapped(bh) && buffer_dirty(bh) &&
 		    !buffer_delay(bh)) {
 			lock_buffer(bh);
-			mark_buffer_async_write_endio(bh, handler);
+			mark_buffer_async_write_endio(bh,
+				end_buffer_async_write);
 		} else {
 			/*
 			 * The buffer may have been set dirty during
···
 
 	/* Is the folio fully inside i_size? */
 	if (folio_pos(folio) + folio_size(folio) <= i_size)
-		return __block_write_full_folio(inode, folio, get_block, wbc,
-					       end_buffer_async_write);
+		return __block_write_full_folio(inode, folio, get_block, wbc);
 
 	/* Is the folio fully outside i_size? (truncate in progress) */
 	if (folio_pos(folio) >= i_size) {
···
 	 */
 	folio_zero_segment(folio, offset_in_folio(folio, i_size),
 			folio_size(folio));
-	return __block_write_full_folio(inode, folio, get_block, wbc,
-			end_buffer_async_write);
+	return __block_write_full_folio(inode, folio, get_block, wbc);
 }
 
 sector_t generic_block_bmap(struct address_space *mapping, sector_t block,

fs/gfs2/aops.c

···
 				folio_size(folio));
 
 	return __block_write_full_folio(inode, folio, gfs2_get_block_noalloc,
-			wbc, end_buffer_async_write);
+			wbc);
 }
 
 /**

include/linux/buffer_head.h

···
 		unsigned long blocksize, unsigned long b_state);
 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
-void end_buffer_async_write(struct buffer_head *bh, int uptodate);
 
 /* Things to do with buffers at mapping->private_list */
 void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode);
···
 int block_write_full_folio(struct folio *folio, struct writeback_control *wbc,
 		void *get_block);
 int __block_write_full_folio(struct inode *inode, struct folio *folio,
-			get_block_t *get_block, struct writeback_control *wbc,
-			bh_end_io_t *handler);
+		get_block_t *get_block, struct writeback_control *wbc);
 int block_read_full_folio(struct folio *, get_block_t *);
 bool block_is_partially_uptodate(struct folio *, size_t from, size_t count);
 int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,