diff options
| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2023-10-16 21:10:52 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-10-25 16:47:08 -0700 |
| commit | 0217fbb0271a7c78e16629cf45375916ec2eb35f (patch) | |
| tree | 697f73761ea580fc613ad7e46a6cd0d475f9c060 | |
| parent | d4059993674b533798a551859042957bb5578332 (diff) | |
| download | lwn-0217fbb0271a7c78e16629cf45375916ec2eb35f.tar.gz lwn-0217fbb0271a7c78e16629cf45375916ec2eb35f.zip | |
buffer: add get_nth_bh()
Extract this useful helper from nilfs_page_get_nth_block()
Link: https://lkml.kernel.org/r/20231016201114.1928083-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | fs/nilfs2/page.h | 7 | ||||
| -rw-r--r-- | 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 |