[v2,05/27] buffer: Add get_nth_bh()

Message ID	20231016201114.1928083-6-willy@infradead.org
State	Not Applicable
Headers	show Return-Path: <SRS0=cg7c=F6=vger.kernel.org=linux-ext4-owner@ozlabs.org> From: "Matthew Wilcox (Oracle)" <willy@infradead.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>, linux-fsdevel@vger.kernel.org, gfs2@lists.linux.dev, linux-nilfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, ntfs3@lists.linux.dev, ocfs2-devel@lists.linux.dev, reiserfs-devel@vger.kernel.org, linux-ext4@vger.kernel.org, Pankaj Raghav <p.raghav@samsung.com>, Ryusuke Konishi <konishi.ryusuke@gmail.com> Subject: [PATCH v2 05/27] buffer: Add get_nth_bh() Date: Mon, 16 Oct 2023 21:10:52 +0100 Message-Id: <20231016201114.1928083-6-willy@infradead.org> In-Reply-To: <20231016201114.1928083-1-willy@infradead.org> References: <20231016201114.1928083-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	Finish the create_empty_buffers() transition \| expand [v2,00/27] Finish the create_empty_buffers() transition [v2,01/27] buffer: Return bool from grow_dev_folio() [v2,02/27] buffer: Make folio_create_empty_buffers() return a buffer_head [v2,03/27] mpage: Convert map_buffer_to_folio() to folio_create_empty_buffers() [v2,04/27] ext4: Convert to folio_create_empty_buffers [v2,05/27] buffer: Add get_nth_bh() [v2,06/27] gfs2: Convert inode unstuffing to use a folio [v2,07/27] gfs2: Convert gfs2_getbuf() to folios [v2,08/27] gfs2: Convert gfs2_getjdatabuf to use a folio [v2,09/27] gfs2: Convert gfs2_write_buf_to_page() to use a folio [v2,10/27] nilfs2: Convert nilfs_mdt_freeze_buffer to use a folio [v2,11/27] nilfs2: Convert nilfs_grab_buffer() to use a folio [v2,12/27] nilfs2: Convert nilfs_copy_page() to nilfs_copy_folio() [v2,13/27] nilfs2: Convert nilfs_mdt_forget_block() to use a folio [v2,14/27] nilfs2: Convert nilfs_mdt_get_frozen_buffer to use a folio [v2,15/27] nilfs2: Remove nilfs_page_get_nth_block [v2,16/27] nilfs2: Convert nilfs_lookup_dirty_data_buffers to use folio_create_empty_buffers [v2,17/27] ntfs: Convert ntfs_read_block() to use a folio [v2,18/27] ntfs: Convert ntfs_writepage to use a folio [v2,19/27] ntfs: Convert ntfs_prepare_pages_for_non_resident_write() to folios [v2,20/27] ntfs3: Convert ntfs_zero_range() to use a folio [v2,21/27] ocfs2: Convert ocfs2_map_page_blocks to use a folio [v2,22/27] reiserfs: Convert writepage to use a folio [v2,23/27] ufs: Add ufs_get_locked_folio and ufs_put_locked_folio [v2,24/27] ufs: Use ufs_get_locked_folio() in ufs_alloc_lastblock() [v2,25/27] ufs; Convert ufs_change_blocknr() to use folios [v2,26/27] ufs: Remove ufs_get_locked_page() [v2,27/27] buffer: Remove folio_create_empty_buffers()

Message ID

20231016201114.1928083-6-willy@infradead.org

State

Not Applicable

Headers

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        linux-fsdevel@vger.kernel.org, gfs2@lists.linux.dev,
        linux-nilfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net,
        ntfs3@lists.linux.dev, ocfs2-devel@lists.linux.dev,
        reiserfs-devel@vger.kernel.org, linux-ext4@vger.kernel.org,
        Pankaj Raghav <p.raghav@samsung.com>,
        Ryusuke Konishi <konishi.ryusuke@gmail.com>
Subject: [PATCH v2 05/27] buffer: Add get_nth_bh()
Date: Mon, 16 Oct 2023 21:10:52 +0100
Message-Id: <20231016201114.1928083-6-willy@infradead.org>
In-Reply-To: <20231016201114.1928083-1-willy@infradead.org>
References: <20231016201114.1928083-1-willy@infradead.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Series

Finish the create_empty_buffers() transition | expand

Commit Message

Matthew Wilcox Oct. 16, 2023, 8:10 p.m. UTC

Extract this useful helper from nilfs_page_get_nth_block()

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
---
 fs/nilfs2/page.h            |  7 +------
 include/linux/buffer_head.h | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/fs/nilfs2/page.h b/fs/nilfs2/page.h
index 21ddcdd4d63e..344d71942d36 100644
--- a/fs/nilfs2/page.h
+++ b/fs/nilfs2/page.h
@@ -55,12 +55,7 @@  unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
 static inline struct buffer_head *
 nilfs_page_get_nth_block(struct page *page, unsigned int count)
 {
-	struct buffer_head *bh = page_buffers(page);
-
-	while (count-- > 0)
-		bh = bh->b_this_page;
-	get_bh(bh);
-	return bh;
+	return get_nth_bh(page_buffers(page), count);
 }
 
 #endif /* _NILFS_PAGE_H */
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 1001244a8941..3d85a0cf0ca5 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -457,6 +457,28 @@  __bread(struct block_device *bdev, sector_t block, unsigned size)
 	return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
 }
 
+/**
+ * get_nth_bh - Get a reference on the n'th buffer after this one.
+ * @bh: The buffer to start counting from.
+ * @count: How many buffers to skip.
+ *
+ * This is primarily useful for finding the nth buffer in a folio; in
+ * that case you pass the head buffer and the byte offset in the folio
+ * divided by the block size.  It can be used for other purposes, but
+ * it will wrap at the end of the folio rather than returning NULL or
+ * proceeding to the next folio for you.
+ *
+ * Return: The requested buffer with an elevated refcount.
+ */
+static inline __must_check
+struct buffer_head *get_nth_bh(struct buffer_head *bh, unsigned int count)
+{
+	while (count--)
+		bh = bh->b_this_page;
+	get_bh(bh);
+	return bh;
+}
+
 bool block_dirty_folio(struct address_space *mapping, struct folio *folio);
 
 #ifdef CONFIG_BUFFER_HEAD

[v2,05/27] buffer: Add get_nth_bh()

Commit Message

Patch