linux-ext4 - [PATCH 2/7] fs/buffer: introduce sleeping flavors for pagecache lookups

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Message-Id: <20250418015921.132400-3-dave@stgolabs.net>
Date: Thu, 17 Apr 2025 18:59:16 -0700
From: Davidlohr Bueso <dave@...olabs.net>
To: jack@...e.cz,
	tytso@....edu,
	adilger.kernel@...ger.ca,
	brauner@...nel.org
Cc: mcgrof@...nel.org,
	willy@...radead.org,
	hare@...e.de,
	djwong@...nel.org,
	linux-ext4@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	Davidlohr Bueso <dave@...olabs.net>
Subject: [PATCH 2/7] fs/buffer: introduce sleeping flavors for pagecache lookups

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>
---
 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 f8fcffdbe5d9..5b1d74c818e9 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1414,6 +1414,15 @@ __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 f0a4ad7839b6..c791aa9a08da 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -222,6 +222,8 @@ 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 *);
@@ -397,6 +399,12 @@ 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