[PATCH v3] block: remove plugging at buffered write time

From: Fengguang Wu
Date: Sun May 06 2012 - 05:11:20 EST


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: Jens Axboe <axboe@xxxxxxxxx>
CC: Li Shaohua <shli@xxxxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/direct-io.c | 5 +++++
mm/filemap.c | 7 -------
2 files changed, 5 insertions(+), 7 deletions(-)

--- linux-next.orig/mm/filemap.c 2012-04-25 12:16:57.496149458 +0800
+++ linux-next/mm/filemap.c 2012-04-25 12:17:00.116149521 +0800
@@ -2605,13 +2601,11 @@ ssize_t generic_file_aio_write(struct ki
{
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);

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);

@@ -2622,7 +2616,6 @@ ssize_t generic_file_aio_write(struct ki
if (err < 0 && ret > 0)
ret = err;
}
- blk_finish_plug(&plug);
return ret;
}
EXPORT_SYMBOL(generic_file_aio_write);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/