ext4: ext4_inode_info diet

Generic inode has unused i_private pointer which may be used as cur_aio_dio
storage.

TODO: If cur_aio_dio will be passed as an argument to get_block_t this allow
      to have concurent AIO_DIO requests.
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/ext4.h

@@ -912,8 +912,6 @@ struct ext4_inode_info {
 	struct list_head i_completed_io_list;
 	spinlock_t i_completed_io_lock;
 	atomic_t i_ioend_count;	/* Number of outstanding io_end structs */
-	/* current io_end structure for async DIO write*/
-	ext4_io_end_t *cur_aio_dio;
 	atomic_t i_aiodio_unwritten; /* Nr. of inflight conversions pending */
 
 	spinlock_t i_block_reservation_lock;
@@ -1338,6 +1336,16 @@ static inline void ext4_set_io_unwritten_flag(struct inode *inode,
 	}
 }
 
+static inline ext4_io_end_t *ext4_inode_aio(struct inode *inode)
+{
+	return inode->i_private;
+}
+
+static inline void ext4_inode_aio_set(struct inode *inode, ext4_io_end_t *io)
+{
+	inode->i_private = io;
+}
+
 /*
  * Inode dynamic state flags
  */

fs/ext4/extents.c

@@ -3618,7 +3618,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
 {
 	int ret = 0;
 	int err = 0;
-	ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
+	ext4_io_end_t *io = ext4_inode_aio(inode);
 
 	ext_debug("ext4_ext_handle_uninitialized_extents: inode %lu, logical "
 		  "block %llu, max_blocks %u, flags %x, allocated %u\n",
@@ -3876,7 +3876,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 	unsigned int allocated = 0, offset = 0;
 	unsigned int allocated_clusters = 0;
 	struct ext4_allocation_request ar;
-	ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
+	ext4_io_end_t *io = ext4_inode_aio(inode);
 	ext4_lblk_t cluster_offset;
 
 	ext_debug("blocks %u/%u requested for inode %lu\n",

fs/ext4/inode.c

@@ -3056,7 +3056,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 		 * hook to the iocb.
  		 */
 		iocb->private = NULL;
-		EXT4_I(inode)->cur_aio_dio = NULL;
+		ext4_inode_aio_set(inode, NULL);
 		if (!is_sync_kiocb(iocb)) {
 			ext4_io_end_t *io_end =
 				ext4_init_io_end(inode, GFP_NOFS);
@@ -3073,7 +3073,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 			 * is a unwritten extents needs to be converted
 			 * when IO is completed.
 			 */
-			EXT4_I(inode)->cur_aio_dio = iocb->private;
+			ext4_inode_aio_set(inode, io_end);
 		}
 
 		if (overwrite)
@@ -3093,7 +3093,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
 						 NULL,
 						 DIO_LOCKING);
 		if (iocb->private)
-			EXT4_I(inode)->cur_aio_dio = NULL;
+			ext4_inode_aio_set(inode, NULL);
 		/*
 		 * The io_end structure takes a reference to the inode,
 		 * that structure needs to be destroyed and the

fs/ext4/super.c

@@ -965,7 +965,6 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
 	ei->jinode = NULL;
 	INIT_LIST_HEAD(&ei->i_completed_io_list);
 	spin_lock_init(&ei->i_completed_io_lock);
-	ei->cur_aio_dio = NULL;
 	ei->i_sync_tid = 0;
 	ei->i_datasync_tid = 0;
 	atomic_set(&ei->i_ioend_count, 0);