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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: [PATCH v6 03/16] mm: Add balance_dirty_pages_ratelimited_flags() function
Date: Thu, 26 May 2022 10:38:27 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

From: Jan Kara <[email protected]>

This adds the helper function balance_dirty_pages_ratelimited_flags().
It adds the parameter flags to balance_dirty_pages_ratelimited().
The flags parameter is passed to balance_dirty_pages(). For async
buffered writes the flag value will be BDP_ASYNC.

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.

The new helper function is also used by balance_dirty_pages_ratelimited().

Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Stefan Roesch <[email protected]>
---
 include/linux/writeback.h |  7 ++++++
 mm/page-writeback.c       | 48 +++++++++++++++++++++++++--------------
 2 files changed, 38 insertions(+), 17 deletions(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index fec248ab1fec..1bddad86a4f6 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -372,7 +372,14 @@ 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);
+int balance_dirty_pages_ratelimited_flags(struct address_space *mapping,
+		unsigned int flags);
+
 bool wb_over_bg_thresh(struct bdi_writeback *wb);
 
 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 89dcc7d8395a..3701e813d05f 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);
@@ -1845,28 +1851,18 @@ static DEFINE_PER_CPU(int, bdp_ratelimits);
  */
 DEFINE_PER_CPU(int, dirty_throttle_leaks) = 0;
 
-/**
- * balance_dirty_pages_ratelimited - balance dirty memory state
- * @mapping: address_space which was dirtied
- *
- * Processes which are dirtying memory should call in here once for each page
- * which was newly dirtied.  The function will periodically check the system's
- * dirty state and will initiate writeback if needed.
- *
- * Once we're over the dirty memory limit we decrease the ratelimiting
- * by a lot, to prevent individual processes from overshooting the limit
- * by (ratelimit_pages) each.
- */
-void balance_dirty_pages_ratelimited(struct address_space *mapping)
+int balance_dirty_pages_ratelimited_flags(struct address_space *mapping,
+					unsigned int flags)
 {
 	struct inode *inode = mapping->host;
 	struct backing_dev_info *bdi = inode_to_bdi(inode);
 	struct bdi_writeback *wb = NULL;
 	int ratelimit;
+	int ret = 0;
 	int *p;
 
 	if (!(bdi->capabilities & BDI_CAP_WRITEBACK))
-		return;
+		return ret;
 
 	if (inode_cgwb_enabled(inode))
 		wb = wb_get_create_current(bdi, GFP_KERNEL);
@@ -1906,9 +1902,27 @@ 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, flags);
 
 	wb_put(wb);
+	return ret;
+}
+
+/**
+ * balance_dirty_pages_ratelimited - balance dirty memory state
+ * @mapping: address_space which was dirtied
+ *
+ * Processes which are dirtying memory should call in here once for each page
+ * which was newly dirtied.  The function will periodically check the system's
+ * dirty state and will initiate writeback if needed.
+ *
+ * Once we're over the dirty memory limit we decrease the ratelimiting
+ * by a lot, to prevent individual processes from overshooting the limit
+ * by (ratelimit_pages) each.
+ */
+void balance_dirty_pages_ratelimited(struct address_space *mapping)
+{
+	balance_dirty_pages_ratelimited_flags(mapping, 0);
 }
 EXPORT_SYMBOL(balance_dirty_pages_ratelimited);
 
-- 
2.30.2



  parent reply	other threads:[~2022-05-26 17:39 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-26 17:38 [PATCH v6 00/16] io-uring/xfs: support async buffered writes Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 01/16] mm: Move starting of background writeback into the main balancing loop Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 02/16] mm: Move updates of dirty_exceeded into one place Stefan Roesch
2022-05-26 17:38 ` Stefan Roesch [this message]
2022-05-31  6:52   ` [PATCH v6 03/16] mm: Add balance_dirty_pages_ratelimited_flags() function Christoph Hellwig
2022-05-26 17:38 ` [PATCH v6 04/16] iomap: Add flags parameter to iomap_page_create() Stefan Roesch
2022-05-26 18:25   ` Darrick J. Wong
2022-05-26 18:43     ` Stefan Roesch
     [not found]   ` <[email protected]>
2022-05-31 18:12     ` Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 05/16] iomap: Add async buffered write support Stefan Roesch
2022-05-26 18:42   ` Darrick J. Wong
2022-05-26 22:37   ` Dave Chinner
2022-05-27  8:42     ` Jan Kara
2022-05-27 22:52       ` Dave Chinner
2022-05-31  7:55         ` Jan Kara
2022-05-26 17:38 ` [PATCH v6 06/16] fs: Add check for async buffered writes to generic_write_checks Stefan Roesch
2022-05-31  6:59   ` Christoph Hellwig
2022-05-26 17:38 ` [PATCH v6 07/16] fs: add __remove_file_privs() with flags parameter Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 08/16] fs: Split off inode_needs_update_time and __file_update_time Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 09/16] fs: Add async write file modification handling Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 10/16] fs: Optimization for concurrent file time updates Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 11/16] io_uring: Add support for async buffered writes Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 12/16] io_uring: Add tracepoint for short writes Stefan Roesch
2022-05-26 17:38 ` [PATCH v6 13/16] xfs: Specify lockmode when calling xfs_ilock_for_iomap() Stefan Roesch
2022-05-31  7:03   ` Christoph Hellwig
2022-05-26 17:38 ` [PATCH v6 14/16] xfs: Change function signature of xfs_ilock_iocb() Stefan Roesch
2022-05-31  7:04   ` Christoph Hellwig
2022-05-26 17:38 ` [PATCH v6 15/16] xfs: Add async buffered write support Stefan Roesch
2022-05-31  7:05   ` Christoph Hellwig
2022-05-26 17:38 ` [PATCH v6 16/16] xfs: Enable " Stefan Roesch

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