linux-kernel - [PATCH AUTOSEL 6.12 26/37] fs/buffer: introduce sleeping flavors for pagecache lookups

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Message-Id: <20250429235122.537321-26-sashal@kernel.org>
Date: Tue, 29 Apr 2025 19:51:11 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Davidlohr Bueso <dave@...olabs.net>,
	Jan Kara <jack@...e.cz>,
	kdevops@...ts.linux.dev,
	Luis Chamberlain <mcgrof@...nel.org>,
	Christian Brauner <brauner@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	viro@...iv.linux.org.uk,
	willy@...radead.org,
	akpm@...ux-foundation.org,
	josef@...icpanda.com,
	mhocko@...e.com,
	linux-fsdevel@...r.kernel.org
Subject: [PATCH AUTOSEL 6.12 26/37] fs/buffer: introduce sleeping flavors for pagecache lookups

From: Davidlohr Bueso <dave@...olabs.net>

[ Upstream commit 2814a7d3d2ff5d2cdd22936f641f758fdb971fa0 ]

Add __find_get_block_nonatomic() and sb_find_get_block_nonatomic()
calls for which users will be converted where safe. These versions
will take the folio lock instead of the mapping's private_lock.

Reviewed-by: Jan Kara <jack@...e.cz>
Signed-off-by: Davidlohr Bueso <dave@...olabs.net>
Link: https://kdevops.org/ext4/v6.15-rc2.html # [0]
Link: https://lore.kernel.org/all/aAAEvcrmREWa1SKF@bombadil.infradead.org/ # [1]
Link: https://lore.kernel.org/20250418015921.132400-3-dave@stgolabs.net
Tested-by: kdevops@...ts.linux.dev
Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>
Signed-off-by: Christian Brauner <brauner@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/buffer.c                 | 9 +++++++++
 include/linux/buffer_head.h | 8 ++++++++
 2 files changed, 17 insertions(+)

diff --git a/fs/buffer.c b/fs/buffer.c
index ba464c2002061..b04705eb6cc57 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1420,6 +1420,15 @@ __find_get_block(struct block_device *bdev, sector_t block, unsigned size)
 }
 EXPORT_SYMBOL(__find_get_block);
 
+/* same as __find_get_block() but allows sleeping contexts */
+struct buffer_head *
+__find_get_block_nonatomic(struct block_device *bdev, sector_t block,
+			   unsigned size)
+{
+	return find_get_block_common(bdev, block, size, false);
+}
+EXPORT_SYMBOL(__find_get_block_nonatomic);
+
 /**
  * bdev_getblk - Get a buffer_head in a block device's buffer cache.
  * @bdev: The block device.
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 932139c5d46f5..ffcd76d977703 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -223,6 +223,8 @@ void __wait_on_buffer(struct buffer_head *);
 wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
 struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
 			unsigned size);
+struct buffer_head *__find_get_block_nonatomic(struct block_device *bdev,
+			sector_t block, unsigned size);
 struct buffer_head *bdev_getblk(struct block_device *bdev, sector_t block,
 		unsigned size, gfp_t gfp);
 void __brelse(struct buffer_head *);
@@ -398,6 +400,12 @@ sb_find_get_block(struct super_block *sb, sector_t block)
 	return __find_get_block(sb->s_bdev, block, sb->s_blocksize);
 }
 
+static inline struct buffer_head *
+sb_find_get_block_nonatomic(struct super_block *sb, sector_t block)
+{
+	return __find_get_block_nonatomic(sb->s_bdev, block, sb->s_blocksize);
+}
+
 static inline void
 map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
 {
-- 
2.39.5