direct-io: Remove unused DIO_SKIP_DIO_COUNT logic

This flag was added by fe0f07d0 ("direct-io: only inc/deci
inode->i_dio_count for file systems") as means to optimise the atomic
modificaiton of the variable for blockdevices. However with the advent
of 542ff7bf ("block: new direct I/O implementation") it became
unused. So let's remove it.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/direct-io.c

@@ -315,7 +315,6 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags)
 			dio_warn_stale_pagecache(dio->iocb->ki_filp);
 	}
 
-	if (!(dio->flags & DIO_SKIP_DIO_COUNT))
 	inode_dio_end(dio->inode);
 
 	if (flags & DIO_COMPLETE_ASYNC) {
@@ -1296,7 +1295,6 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 	/*
 	 * Will be decremented at I/O completion time.
 	 */
-	if (!(dio->flags & DIO_SKIP_DIO_COUNT))
 	inode_dio_begin(inode);
 
 	retval = 0;

include/linux/fs.h

@@ -2976,9 +2976,6 @@ enum {
 
 	/* filesystem does not support filling holes */
 	DIO_SKIP_HOLES	= 0x02,
-
-	/* inode/fs/bdev does not need truncate protection */
-	DIO_SKIP_DIO_COUNT = 0x08,
 };
 
 void dio_end_io(struct bio *bio);