From: Fengguang Wu <fengguang.wu@intel.com>
Date: Thu, 9 Aug 2012 13:23:07 +0000 (+0200)
Subject: block: remove plugging at buffered write time
X-Git-Tag: firefly_0821_release~3680^2~2156^2~6
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=8430f9772f9ac305211f177b0fa56a312175da11;p=firefly-linux-kernel-4.4.55.git

block: remove plugging at buffered write time

Buffered write(2) is not directly tied to IO, so it's not suitable to
handle plug in generic_file_aio_write().

Note that plugging for O_SYNC writes is also removed. The user may pass
arbitrary @size arguments, which may be much larger than the preferable
I/O size, or may cross extent/device boundaries. Let the lower layers
handle the plugging. The plugging code here actually turns them into
no-ops.

CC: Li Shaohua <shli@fusionio.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/mm/filemap.c b/mm/filemap.c
index fa5ca304148e..2b0952974cb9 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2527,14 +2527,12 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
-	struct blk_plug plug;
 	ssize_t ret;
 
 	BUG_ON(iocb->ki_pos != pos);
 
 	sb_start_write(inode->i_sb);
 	mutex_lock(&inode->i_mutex);
-	blk_start_plug(&plug);
 	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 	mutex_unlock(&inode->i_mutex);
 
@@ -2545,7 +2543,6 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 		if (err < 0 && ret > 0)
 			ret = err;
 	}
-	blk_finish_plug(&plug);
 	sb_end_write(inode->i_sb);
 	return ret;
 }