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From: Stefan Roesch <[email protected]>
To: <[email protected]>, <[email protected]>,
	<[email protected]>, <[email protected]>,
	<[email protected]>
Cc: <[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>
Subject: [RFC PATCH v4 03/17] mm: Prepare balance_dirty_pages() for async buffered writes
Date: Fri, 20 May 2022 11:36:32 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

From: Jan Kara <[email protected]>

If balance_dirty_pages() gets called for async buffered write, we don't
want to wait. Instead we need to indicate to the caller that throttling
is needed so that it can stop writing and offload the rest of the write
to a context that can block.

Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Stefan Roesch <[email protected]>
---
 include/linux/writeback.h |  4 ++++
 mm/page-writeback.c       | 12 +++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index fec248ab1fec..a9114c5090e9 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -372,6 +372,10 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
 unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);
 
 void wb_update_bandwidth(struct bdi_writeback *wb);
+
+/* Invoke balance dirty pages in async mode. */
+#define BDP_ASYNC 0x0001
+
 void balance_dirty_pages_ratelimited(struct address_space *mapping);
 bool wb_over_bg_thresh(struct bdi_writeback *wb);
 
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 89dcc7d8395a..7a320fd2ad33 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1545,8 +1545,8 @@ static inline void wb_dirty_limits(struct dirty_throttle_control *dtc)
  * If we're over `background_thresh' then the writeback threads are woken to
  * perform some writeout.
  */
-static void balance_dirty_pages(struct bdi_writeback *wb,
-				unsigned long pages_dirtied)
+static int balance_dirty_pages(struct bdi_writeback *wb,
+			       unsigned long pages_dirtied, unsigned int flags)
 {
 	struct dirty_throttle_control gdtc_stor = { GDTC_INIT(wb) };
 	struct dirty_throttle_control mdtc_stor = { MDTC_INIT(wb, &gdtc_stor) };
@@ -1566,6 +1566,7 @@ static void balance_dirty_pages(struct bdi_writeback *wb,
 	struct backing_dev_info *bdi = wb->bdi;
 	bool strictlimit = bdi->capabilities & BDI_CAP_STRICTLIMIT;
 	unsigned long start_time = jiffies;
+	int ret = 0;
 
 	for (;;) {
 		unsigned long now = jiffies;
@@ -1794,6 +1795,10 @@ static void balance_dirty_pages(struct bdi_writeback *wb,
 					  period,
 					  pause,
 					  start_time);
+		if (flags & BDP_ASYNC) {
+			ret = -EAGAIN;
+			break;
+		}
 		__set_current_state(TASK_KILLABLE);
 		wb->dirty_sleep = now;
 		io_schedule_timeout(pause);
@@ -1825,6 +1830,7 @@ static void balance_dirty_pages(struct bdi_writeback *wb,
 		if (fatal_signal_pending(current))
 			break;
 	}
+	return ret;
 }
 
 static DEFINE_PER_CPU(int, bdp_ratelimits);
@@ -1906,7 +1912,7 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping)
 	preempt_enable();
 
 	if (unlikely(current->nr_dirtied >= ratelimit))
-		balance_dirty_pages(wb, current->nr_dirtied);
+		balance_dirty_pages(wb, current->nr_dirtied, 0);
 
 	wb_put(wb);
 }
-- 
2.30.2


  parent reply	other threads:[~2022-05-20 18:37 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-20 18:36 [RFC PATCH v4 00/17] io-uring/xfs: support async buffered writes Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 01/17] mm: Move starting of background writeback into the main balancing loop Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 02/17] mm: Move updates of dirty_exceeded into one place Stefan Roesch
2022-05-20 18:36 ` Stefan Roesch [this message]
2022-05-22  7:17   ` [RFC PATCH v4 03/17] mm: Prepare balance_dirty_pages() for async buffered writes Christoph Hellwig
2022-05-25 21:30     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 04/17] mm: Add balance_dirty_pages_ratelimited_flags() function Stefan Roesch
2022-05-23 10:40   ` Jan Kara
2022-05-20 18:36 ` [RFC PATCH v4 05/17] iomap: Add gfp parameter to iomap_page_create() Stefan Roesch
2022-05-22  7:21   ` Christoph Hellwig
2022-05-25 21:29     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 06/17] iomap: Add async buffered write support Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 07/17] iomap: Use balance_dirty_pages_ratelimited_flags in iomap_write_iter Stefan Roesch
2022-05-22  7:19   ` Christoph Hellwig
2022-05-25 21:32     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 08/17] fs: Add check for async buffered writes to generic_write_checks Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 09/17] fs: Split off remove_needs_file_privs() __remove_file_privs() Stefan Roesch
2022-05-22  7:32   ` Christoph Hellwig
2022-05-25 21:34     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 10/17] fs: Split off file_needs_update_time and __file_update_time Stefan Roesch
2022-05-22  7:29   ` Christoph Hellwig
2022-05-25 22:32     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 11/17] fs: Add async write file modification handling Stefan Roesch
2022-05-22  7:24   ` Christoph Hellwig
2022-05-25 21:39     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 12/17] fs: Optimization for concurrent file time updates Stefan Roesch
2022-05-23 10:51   ` Jan Kara
2022-05-25 21:46     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 13/17] io_uring: Add support for async buffered writes Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 14/17] io_uring: Add tracepoint for short writes Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 15/17] xfs: Add iomap async buffered write support Stefan Roesch
2022-05-22  7:33   ` Christoph Hellwig
2022-05-25 21:40     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 16/17] xfs: Add " Stefan Roesch
2022-05-22  7:34   ` Christoph Hellwig
2022-05-25 21:41     ` Stefan Roesch
2022-05-22 15:35   ` Darrick J. Wong
2022-05-25 21:44     ` Stefan Roesch
2022-05-20 18:36 ` [RFC PATCH v4 17/17] xfs: Enable " Stefan Roesch

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