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* [RESEND][PATCH v2] block: remove plugging at buffered write time
@ 2012-04-08  1:06 Wu Fengguang
  2012-04-09 14:34 ` Jeff Moyer
  0 siblings, 1 reply; 16+ messages in thread
From: Wu Fengguang @ 2012-04-08  1:06 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Jens Axboe, linux-fsdevel, LKML, Dave Chinner, Christoph Hellwig,
	Jan Kara, Chris Mason, Shaohua Li

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

Also moves unplugging for direct I/O from around ->direct_IO() down to
do_blockdev_direct_IO().

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. Otherwise the plugging code here will turn the
low level plugging into no-ops.

CC: Jens Axboe <axboe@kernel.dk>
CC: Shaohua Li <shli@fusionio.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
 fs/direct-io.c |    5 +++++
 fs/sync.c      |   11 ++++++++++-
 mm/filemap.c   |    7 -------
 3 files changed, 15 insertions(+), 8 deletions(-)

--- linux-next.orig/mm/filemap.c	2012-02-08 19:33:29.000000000 +0800
+++ linux-next/mm/filemap.c	2012-02-09 15:59:47.000000000 +0800
@@ -1421,12 +1421,8 @@ generic_file_aio_read(struct kiocb *iocb
 			retval = filemap_write_and_wait_range(mapping, pos,
 					pos + iov_length(iov, nr_segs) - 1);
 			if (!retval) {
-				struct blk_plug plug;
-
-				blk_start_plug(&plug);
 				retval = mapping->a_ops->direct_IO(READ, iocb,
 							iov, pos, nr_segs);
-				blk_finish_plug(&plug);
 			}
 			if (retval > 0) {
 				*ppos = pos + retval;
@@ -2610,13 +2606,11 @@ 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);
 
@@ -2627,7 +2621,6 @@ 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);
--- linux-next.orig/fs/direct-io.c	2012-02-08 19:33:29.000000000 +0800
+++ linux-next/fs/direct-io.c	2012-02-09 16:03:04.000000000 +0800
@@ -1106,6 +1106,7 @@ do_blockdev_direct_IO(int rw, struct kio
 	unsigned long user_addr;
 	size_t bytes;
 	struct buffer_head map_bh = { 0, };
+	struct blk_plug plug;
 
 	if (rw & WRITE)
 		rw = WRITE_ODIRECT;
@@ -1221,6 +1222,8 @@ do_blockdev_direct_IO(int rw, struct kio
 				PAGE_SIZE - user_addr / PAGE_SIZE);
 	}
 
+	blk_start_plug(&plug);
+
 	for (seg = 0; seg < nr_segs; seg++) {
 		user_addr = (unsigned long)iov[seg].iov_base;
 		sdio.size += bytes = iov[seg].iov_len;
@@ -1279,6 +1282,8 @@ do_blockdev_direct_IO(int rw, struct kio
 	if (sdio.bio)
 		dio_bio_submit(dio, &sdio);
 
+	blk_finish_plug(&plug);
+
 	/*
 	 * It is possible that, we return short IO due to end of file.
 	 * In that case, we need to release all the pages we got hold on.

^ permalink raw reply	[flat|nested] 16+ messages in thread
end of thread, other threads:[~2012-05-06  9:58 UTC | newest]

Thread overview: 16+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-04-08  1:06 [RESEND][PATCH v2] block: remove plugging at buffered write time Wu Fengguang
2012-04-09 14:34 ` Jeff Moyer
2012-04-11 23:13   ` Andrew Morton
2012-04-12  1:32     ` Fengguang Wu
2012-04-12  2:20       ` Fengguang Wu
2012-04-12 14:26         ` Jan Kara
2012-04-13  1:40           ` Fengguang Wu
2012-05-03  3:43             ` [PATCH] btrfs: lower metadata writeback threshold on low dirty threshold Fengguang Wu
2012-05-03  3:53               ` [PATCH] writeback: initialize global_dirty_limit Fengguang Wu
2012-05-03  9:25               ` [PATCH] btrfs: lower metadata writeback threshold on low dirty threshold Jan Kara
2012-05-03 10:02                 ` Fengguang Wu
2012-05-03 12:31                 ` Chris Mason
2012-05-03 13:30                 ` Josef Bacik
2012-05-03 14:08               ` Fengguang Wu
2012-05-06  6:01           ` [RESEND][PATCH v2] block: remove plugging at buffered write time Fengguang Wu
2012-05-06  9:58       ` Fengguang Wu

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