linux-kernel - [PATCH v2 6/6] iomap: reduce unnecessary state_lock when setting ifs uptodate and dirty bits

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Message-Id: <20240812121159.3775074-7-yi.zhang@huaweicloud.com>
Date: Mon, 12 Aug 2024 20:11:59 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	djwong@...nel.org,
	hch@...radead.org,
	brauner@...nel.org,
	david@...morbit.com,
	jack@...e.cz,
	willy@...radead.org,
	yi.zhang@...wei.com,
	yi.zhang@...weicloud.com,
	chengzhihao1@...wei.com,
	yukuai3@...wei.com
Subject: [PATCH v2 6/6] iomap: reduce unnecessary state_lock when setting ifs uptodate and dirty bits

From: Zhang Yi <yi.zhang@...wei.com>

When doing buffered write, we set uptodate and drity bits of the written
range separately, it holds the ifs->state_lock twice when blocksize <
folio size, which is redundant. After large folio is supported, the
spinlock could affect more about the performance, merge them could
reduce some unnecessary locking overhead and gets some performance gain.

Suggested-by: Dave Chinner <david@...morbit.com>
Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/iomap/buffered-io.c | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 96600405dbb5..67d7c1c22c98 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -182,6 +182,37 @@ static void iomap_set_range_dirty(struct folio *folio, size_t off, size_t len)
 		ifs_set_range_dirty(folio, ifs, off, len);
 }
 
+static void ifs_set_range_dirty_uptodate(struct folio *folio,
+		struct iomap_folio_state *ifs, size_t off, size_t len)
+{
+	struct inode *inode = folio->mapping->host;
+	unsigned int blks_per_folio = i_blocks_per_folio(inode, folio);
+	unsigned int first_blk = (off >> inode->i_blkbits);
+	unsigned int last_blk = (off + len - 1) >> inode->i_blkbits;
+	unsigned int nr_blks = last_blk - first_blk + 1;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ifs->state_lock, flags);
+	bitmap_set(ifs->state, first_blk, nr_blks);
+	if (ifs_is_fully_uptodate(folio, ifs))
+		folio_mark_uptodate(folio);
+	bitmap_set(ifs->state, first_blk + blks_per_folio, nr_blks);
+	spin_unlock_irqrestore(&ifs->state_lock, flags);
+}
+
+static void iomap_set_range_dirty_uptodate(struct folio *folio,
+		size_t off, size_t len)
+{
+	struct iomap_folio_state *ifs = folio->private;
+
+	if (ifs)
+		ifs_set_range_dirty_uptodate(folio, ifs, off, len);
+	else
+		folio_mark_uptodate(folio);
+
+	filemap_dirty_folio(folio->mapping, folio);
+}
+
 static struct iomap_folio_state *ifs_alloc(struct inode *inode,
 		struct folio *folio, unsigned int flags)
 {
@@ -851,6 +882,8 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
 static bool __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
 		size_t copied, struct folio *folio)
 {
+	size_t from = offset_in_folio(folio, pos);
+
 	flush_dcache_folio(folio);
 
 	/*
@@ -866,9 +899,8 @@ static bool __iomap_write_end(struct inode *inode, loff_t pos, size_t len,
 	 */
 	if (unlikely(copied < len && !folio_test_uptodate(folio)))
 		return false;
-	iomap_set_range_uptodate(folio, offset_in_folio(folio, pos), len);
-	iomap_set_range_dirty(folio, offset_in_folio(folio, pos), copied);
-	filemap_dirty_folio(inode->i_mapping, folio);
+
+	iomap_set_range_dirty_uptodate(folio, from, copied);
 	return true;
 }
 
-- 
2.39.2