The extra indentation confused the kernel-doc parser, so remove it.
Fix some other wording while I'm here, and advise the user they need to
call brelse() on this buffer.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/buffer_head.h | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index d78454a4dd1f..7558cd1d3eb3 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -437,14 +437,17 @@ static inline void bh_readahead_batch(int nr, struct buffer_head *bhs[],
 }
 
 /**
- *  __bread() - reads a specified block and returns the bh
- *  @bdev: the block_device to read from
- *  @block: number of block
- *  @size: size (in bytes) to read
+ * __bread() - Read a block.
+ * @bdev: The block device to read from.
+ * @block: Block number in units of block size.
+ * @size: Block size in bytes.
  *
- *  Reads a specified block, and returns buffer head that contains it.
- *  The page cache is allocated from movable area so that it can be migrated.
- *  It returns NULL if the block was unreadable.
+ * Read a specified block, and return the buffer head that refers to it.
+ * The memory is allocated from the movable area so that it can be
+ * migrated.  The buffer head has its refcount elevated and the caller
+ * should call brelse() when it has finished with the buffer.
+ *
+ * Return: NULL if the block was unreadable.
  */
 static inline struct buffer_head *
 __bread(struct block_device *bdev, sector_t block, unsigned size)
-- 
2.43.0

On Thu, Jan 04, 2024 at 04:36:51PM +0000, Matthew Wilcox (Oracle) wrote:
> The extra indentation confused the kernel-doc parser, so remove it.
> Fix some other wording while I'm here, and advise the user they need to
> call brelse() on this buffer.
> 
It looks like __bread_gfp has the same problem:

diff --git a/fs/buffer.c b/fs/buffer.c
index 967f34b70aa8..cfdf45cc290a 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1446,16 +1446,18 @@ void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
 EXPORT_SYMBOL(__breadahead);
 
 /**
- *  __bread_gfp() - reads a specified block and returns the bh
- *  @bdev: the block_device to read from
- *  @block: number of block
- *  @size: size (in bytes) to read
- *  @gfp: page allocation flag
+ * __bread_gfp() - Read a block.
+ * @bdev: The block device to read from.
+ * @block: Block number in units of block size.
+ * @size: Block size in bytes.
  *
- *  Reads a specified block, and returns buffer head that contains it.
- *  The page cache can be allocated from non-movable area
- *  not to prevent page migration if you set gfp to zero.
- *  It returns NULL if the block was unreadable.
+ * Read a specified block, and return the buffer head that refers to it.
+ * The memory can be allocated from a non-movable area to not to prevent
+ * page migration if you set gfp to zero. The buffer head has its
+ * refcount elevated and the caller should call brelse() when it has
+ * finished with the buffer.
+ *
+ * Return: NULL if the block was unreadable.
  */
 struct buffer_head *
 __bread_gfp(struct block_device *bdev, sector_t block,
(END)

Another option is to just change this in __bread_gfp() and add a See
__bread_gfp() in __bread()?

On Mon, Jan 08, 2024 at 03:58:08PM +0100, Pankaj Raghav (Samsung) wrote:
> On Thu, Jan 04, 2024 at 04:36:51PM +0000, Matthew Wilcox (Oracle) wrote:
> > The extra indentation confused the kernel-doc parser, so remove it.
> > Fix some other wording while I'm here, and advise the user they need to
> > call brelse() on this buffer.
> > 
> It looks like __bread_gfp has the same problem:

I'm happy to incorporate this patch, but I'll need your S-o-B on it.

> diff --git a/fs/buffer.c b/fs/buffer.c
> index 967f34b70aa8..cfdf45cc290a 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -1446,16 +1446,18 @@ void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
>  EXPORT_SYMBOL(__breadahead);
>  
>  /**
> - *  __bread_gfp() - reads a specified block and returns the bh
> - *  @bdev: the block_device to read from
> - *  @block: number of block
> - *  @size: size (in bytes) to read
> - *  @gfp: page allocation flag
> + * __bread_gfp() - Read a block.
> + * @bdev: The block device to read from.
> + * @block: Block number in units of block size.
> + * @size: Block size in bytes.
>   *
> - *  Reads a specified block, and returns buffer head that contains it.
> - *  The page cache can be allocated from non-movable area
> - *  not to prevent page migration if you set gfp to zero.
> - *  It returns NULL if the block was unreadable.
> + * Read a specified block, and return the buffer head that refers to it.
> + * The memory can be allocated from a non-movable area to not to prevent
> + * page migration if you set gfp to zero. The buffer head has its
> + * refcount elevated and the caller should call brelse() when it has
> + * finished with the buffer.
> + *
> + * Return: NULL if the block was unreadable.
>   */
>  struct buffer_head *
>  __bread_gfp(struct block_device *bdev, sector_t block,
> (END)
> 
> Another option is to just change this in __bread_gfp() and add a See
> __bread_gfp() in __bread()?

On Mon, Jan 08, 2024 at 04:09:01PM +0000, Matthew Wilcox wrote:
> On Mon, Jan 08, 2024 at 03:58:08PM +0100, Pankaj Raghav (Samsung) wrote:
> > On Thu, Jan 04, 2024 at 04:36:51PM +0000, Matthew Wilcox (Oracle) wrote:
> > > The extra indentation confused the kernel-doc parser, so remove it.
> > > Fix some other wording while I'm here, and advise the user they need to
> > > call brelse() on this buffer.
> > > 
> > It looks like __bread_gfp has the same problem:
> 
> I'm happy to incorporate this patch, but I'll need your S-o-B on it.

Something like this:

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: Mon, 8 Jan 2024 19:37:41 +0100
Subject: [PATCH] buffer: Update __bread() and __bread_gfp kernel-doc

The extra indentation confused the kernel-doc parser, so remove it.
Fix some other wording while I'm here, and advise the user they need to
call brelse() on this buffer.

Instead of duplicating the doc in __bread() and __bread_gfp(), update
__bread_gfp() doc and point to it from __bread().

Signed-off-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 fs/buffer.c                 | 21 ++++++++++++---------
 include/linux/buffer_head.h |  9 +--------
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 967f34b70aa8..ea55fb3fcfae 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1446,16 +1446,19 @@ void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
 EXPORT_SYMBOL(__breadahead);
 
 /**
- *  __bread_gfp() - reads a specified block and returns the bh
- *  @bdev: the block_device to read from
- *  @block: number of block
- *  @size: size (in bytes) to read
- *  @gfp: page allocation flag
+ * __bread_gfp() - Read a block.
+ * @bdev: The block device to read from.
+ * @block: Block number in units of block size.
+ * @size: Block size in bytes.
+ * @gfp: gfp flags.
  *
- *  Reads a specified block, and returns buffer head that contains it.
- *  The page cache can be allocated from non-movable area
- *  not to prevent page migration if you set gfp to zero.
- *  It returns NULL if the block was unreadable.
+ * Read a specified block, and return the buffer head that refers to it.
+ * The memory can be allocated from a non-movable area to not to prevent
+ * page migration if you set gfp to zero. The buffer head has its
+ * refcount elevated and the caller should call brelse() when it has
+ * finished with the buffer.
+ *
+ * Return: NULL if the block was unreadable.
  */
 struct buffer_head *
 __bread_gfp(struct block_device *bdev, sector_t block,
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 5f23ee599889..ac56014b29dd 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -440,14 +440,7 @@ static inline void bh_readahead_batch(int nr, struct buffer_head *bhs[],
 }
 
 /**
- *  __bread() - reads a specified block and returns the bh
- *  @bdev: the block_device to read from
- *  @block: number of block
- *  @size: size (in bytes) to read
- *
- *  Reads a specified block, and returns buffer head that contains it.
- *  The page cache is allocated from movable area so that it can be migrated.
- *  It returns NULL if the block was unreadable.
+ * See __bread_gfp()
  */
 static inline struct buffer_head *
 __bread(struct block_device *bdev, sector_t block, unsigned size)
-- 
2.40.1