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Date: Thu, 9 Feb 2012 17:49:38 +0800
From: Wu Fengguang <fengguang.wu@...el.com>
To: Damien Wyart <damien.wyart@...e.fr>
Cc: Shaohua Li <shaohua.li@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH] block: remove plugging at buffered write time
On Thu, Feb 09, 2012 at 10:40:19AM +0100, Damien Wyart wrote:
> > > Done, thanks! Here is the updated patch with O_SYNC write fix.
>
> > Got these errors with the updated patch on top of 3.3-rc3:
>
> > fs/sync.c: In function 'vfs_fsync_range':
> > fs/sync.c:167:18: error: storage size of 'plug' isn't known
> > fs/sync.c:173:2: error: implicit declaration of function 'blk_start_plug' [-Werror=implicit-function-declaration]
> > fs/sync.c:175:2: error: implicit declaration of function 'blk_finish_plug' [-Werror=implicit-function-declaration]
> > fs/sync.c:167:18: warning: unused variable 'plug' [-Wunused-variable]
>
> Adding a #include <linux/blkdev.h> at the top of fs/sync.c solved the
> problem. Of course, this needs approval of a kernel developper before
> being added to the patch and resubmitted because I know adding #includes
> can have unwanted consequences sometimes or be seen as bloat...
Thank you! This includes the necessary blkdev.h and it compiles here too:
Subject: block: remove plugging at buffered write time
Date: Tue Jan 31 18:25:48 CST 2012
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 to lower layers:
- for direct I/O, from around ->direct_IO() to do_blockdev_direct_IO()
- for O_SYNC writes, to around ->fsync()
CC: Jens Axboe <axboe@...nel.dk>
CC: Li Shaohua <shaohua.li@...el.com>
Signed-off-by: Wu Fengguang <fengguang.wu@...el.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.
--- linux-next.orig/fs/sync.c 2012-02-09 15:59:52.000000000 +0800
+++ linux-next/fs/sync.c 2012-02-09 17:39:02.000000000 +0800
@@ -15,6 +15,7 @@
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/backing-dev.h>
+#include <linux/blkdev.h>
#include "internal.h"
#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \
@@ -164,9 +165,17 @@ SYSCALL_DEFINE1(syncfs, int, fd)
*/
int vfs_fsync_range(struct file *file, loff_t start, loff_t end, int datasync)
{
+ struct blk_plug plug;
+ int ret;
+
if (!file->f_op || !file->f_op->fsync)
return -EINVAL;
- return file->f_op->fsync(file, start, end, datasync);
+
+ blk_start_plug(&plug);
+ ret = file->f_op->fsync(file, start, end, datasync);
+ blk_finish_plug(&plug);
+
+ return ret;
}
EXPORT_SYMBOL(vfs_fsync_range);
--
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