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 fa5ca304148e7b4756bf2e52cd6afde1dba2b5c3..2b0952974cb9835cd44f0a81f85d8069a3a7552d 100644 (file)
--- 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;
 }