From 3decb8564eff88a2533f83b01cec2cf9259c3eaf Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Mon, 16 Oct 2023 21:10:49 +0100 Subject: buffer: make folio_create_empty_buffers() return a buffer_head Patch series "Finish the create_empty_buffers() transition", v2. Pankaj recently added folio_create_empty_buffers() as the folio equivalent to create_empty_buffers(). This patch set finishes the conversion by first converting all remaining filesystems to call folio_create_empty_buffers(), then renaming it back to create_empty_buffers(). I took the opportunity to make a few simplifications like making folio_create_empty_buffers() return the head buffer and extracting get_nth_bh() from nilfs2. A few of the patches in this series aren't directly related to create_empty_buffers(), but I saw them while I was working on this and thought they'd be easy enough to add to this series. Compile-tested only, other than ext4. This patch (of 26): Almost all callers want to know the first BH that was allocated for this folio. We already have that handy, so return it. Link: https://lkml.kernel.org/r/20231016201114.1928083-1-willy@infradead.org Link: https://lkml.kernel.org/r/20231016201114.1928083-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Pankaj Raghav Cc: Andreas Gruenbacher Cc: Ryusuke Konishi Signed-off-by: Andrew Morton --- fs/buffer.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) (limited to 'fs') diff --git a/fs/buffer.c b/fs/buffer.c index 86ddfa52c699..bfa7604d1891 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1641,8 +1641,8 @@ EXPORT_SYMBOL(block_invalidate_folio); * block_dirty_folio() via private_lock. try_to_free_buffers * is already excluded via the folio lock. */ -void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize, - unsigned long b_state) +struct buffer_head *folio_create_empty_buffers(struct folio *folio, + unsigned long blocksize, unsigned long b_state) { struct buffer_head *bh, *head, *tail; gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT | __GFP_NOFAIL; @@ -1669,6 +1669,8 @@ void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize, } folio_attach_private(folio, head); spin_unlock(&folio->mapping->private_lock); + + return head; } EXPORT_SYMBOL(folio_create_empty_buffers); @@ -1770,13 +1772,15 @@ static struct buffer_head *folio_create_buffers(struct folio *folio, struct inode *inode, unsigned int b_state) { + struct buffer_head *bh; + BUG_ON(!folio_test_locked(folio)); - if (!folio_buffers(folio)) - folio_create_empty_buffers(folio, - 1 << READ_ONCE(inode->i_blkbits), - b_state); - return folio_buffers(folio); + bh = folio_buffers(folio); + if (!bh) + bh = folio_create_empty_buffers(folio, + 1 << READ_ONCE(inode->i_blkbits), b_state); + return bh; } /* @@ -2676,10 +2680,8 @@ int block_truncate_page(struct address_space *mapping, return PTR_ERR(folio); bh = folio_buffers(folio); - if (!bh) { - folio_create_empty_buffers(folio, blocksize, 0); - bh = folio_buffers(folio); - } + if (!bh) + bh = folio_create_empty_buffers(folio, blocksize, 0); /* Find the buffer that contains "offset" */ offset = offset_in_folio(folio, from); -- cgit v1.2.3