linux-kernel - [PATCH 17/25] ext4: support large block size in ext4_block_write

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Message-Id: <20251025032221.2905818-18-libaokun@huaweicloud.com>
Date: Sat, 25 Oct 2025 11:22:13 +0800
From: libaokun@...weicloud.com
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	kernel@...kajraghav.com,
	mcgrof@...nel.org,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	chengzhihao1@...wei.com,
	libaokun1@...wei.com,
	libaokun@...weicloud.com
Subject: [PATCH 17/25] ext4: support large block size in ext4_block_write_begin()

From: Baokun Li <libaokun1@...wei.com>

Use the EXT4_P_TO_LBLK() macro to convert folio indexes to blocks to avoid
negative left shifts after supporting blocksize greater than PAGE_SIZE.

Signed-off-by: Baokun Li <libaokun1@...wei.com>
Reviewed-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/inode.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 73c1da90b604..d97ce88d6e0a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1162,8 +1162,7 @@ int ext4_block_write_begin(handle_t *handle, struct folio *folio,
 	unsigned block_start, block_end;
 	sector_t block;
 	int err = 0;
-	unsigned blocksize = inode->i_sb->s_blocksize;
-	unsigned bbits;
+	unsigned int blocksize = i_blocksize(inode);
 	struct buffer_head *bh, *head, *wait[2];
 	int nr_wait = 0;
 	int i;
@@ -1172,12 +1171,12 @@ int ext4_block_write_begin(handle_t *handle, struct folio *folio,
 	BUG_ON(!folio_test_locked(folio));
 	BUG_ON(to > folio_size(folio));
 	BUG_ON(from > to);
+	WARN_ON_ONCE(blocksize > folio_size(folio));
 
 	head = folio_buffers(folio);
 	if (!head)
 		head = create_empty_buffers(folio, blocksize, 0);
-	bbits = ilog2(blocksize);
-	block = (sector_t)folio->index << (PAGE_SHIFT - bbits);
+	block = EXT4_P_TO_LBLK(inode, folio->index);
 
 	for (bh = head, block_start = 0; bh != head || !block_start;
 	    block++, block_start = block_end, bh = bh->b_this_page) {
-- 
2.46.1