ext4: remove ext4_ioend_wait()

Now that we clear PageWriteback after extent conversion, there's no
need to wait for io_end processing in ext4_evict_inode().  Running
AIO/DIO keeps file reference until aio_complete() is called so
ext4_evict_inode() cannot be called.  For io_end structures resulting
from buffered IO waiting is happening because we wait for
PageWriteback in truncate_inode_pages().
Reviewed-by: NZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ext4.h

@@ -2651,7 +2651,6 @@ extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
 /* page-io.c */
 extern int __init ext4_init_pageio(void);
 extern void ext4_exit_pageio(void);
-extern void ext4_ioend_shutdown(struct inode *);
 extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
 extern ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end);
 extern int ext4_put_io_end(ext4_io_end_t *io_end);

fs/ext4/inode.c

@@ -215,7 +215,8 @@ void ext4_evict_inode(struct inode *inode)
 			filemap_write_and_wait(&inode->i_data);
 		}
 		truncate_inode_pages(&inode->i_data, 0);
-		ext4_ioend_shutdown(inode);
+
+		WARN_ON(atomic_read(&EXT4_I(inode)->i_ioend_count));
 		goto no_delete;
 	}
 
@@ -225,8 +226,8 @@ void ext4_evict_inode(struct inode *inode)
 	if (ext4_should_order_data(inode))
 		ext4_begin_ordered_truncate(inode, 0);
 	truncate_inode_pages(&inode->i_data, 0);
-	ext4_ioend_shutdown(inode);
 
+	WARN_ON(atomic_read(&EXT4_I(inode)->i_ioend_count));
 	if (is_bad_inode(inode))
 		goto no_delete;
 

fs/ext4/page-io.c

@@ -45,25 +45,6 @@ void ext4_exit_pageio(void)
 	kmem_cache_destroy(io_end_cachep);
 }
 
-/*
- * This function is called by ext4_evict_inode() to make sure there is
- * no more pending I/O completion work left to do.
- */
-void ext4_ioend_shutdown(struct inode *inode)
-{
-	wait_queue_head_t *wq = ext4_ioend_wq(inode);
-
-	wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
-	/*
-	 * We need to make sure the work structure is finished being
-	 * used before we let the inode get destroyed.
-	 */
-	if (work_pending(&EXT4_I(inode)->i_rsv_conversion_work))
-		cancel_work_sync(&EXT4_I(inode)->i_rsv_conversion_work);
-	if (work_pending(&EXT4_I(inode)->i_unrsv_conversion_work))
-		cancel_work_sync(&EXT4_I(inode)->i_unrsv_conversion_work);
-}
-
 /*
  * Print an buffer I/O error compatible with the fs/buffer.c.  This
  * provides compatibility with dmesg scrapers that look for a specific