erofs: use read_mapping_page instead of sb_bread (fe7c2423) · Commits · 戴 / test

As Christoph said [1], "This seems to be your only direct use of buffer heads, which while not deprecated are a bit of an ugly step child. So if you can easily avoid creating a buffer_head dependency in a new filesystem I think you should avoid it. " [1] https://lore.kernel.org/r/20190902125109.GA9826@infradead.org/ Reported-by:

Christoph Hellwig <hch@infradead.org> Signed-off-by:

Gao Xiang <gaoxiang25@huawei.com> Link: https://lore.kernel.org/r/20190904020912.63925-24-gaoxiang25@huawei.com Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/erofs/super.c

+9 −6

Original line number	Diff line number	Diff line
		@@ -98,20 +98,22 @@ static bool check_layout_compatibility(struct super_block *sb,
		static int erofs_read_superblock(struct super_block *sb)
		{
		struct erofs_sb_info *sbi;
		struct buffer_head *bh;
		struct page *page;
		struct erofs_super_block *dsb;
		unsigned int blkszbits;
		void *data;
		int ret;

		bh = sb_bread(sb, 0);

		if (!bh) {
		page = read_mapping_page(sb->s_bdev->bd_inode->i_mapping, 0, NULL);
		if (!page) {
		erofs_err(sb, "cannot read erofs superblock");
		return -EIO;
		}

		sbi = EROFS_SB(sb);
		dsb = (struct erofs_super_block *)(bh->b_data + EROFS_SUPER_OFFSET);

		data = kmap_atomic(page);
		dsb = (struct erofs_super_block *)(data + EROFS_SUPER_OFFSET);

		ret = -EINVAL;
		if (le32_to_cpu(dsb->magic) != EROFS_SUPER_MAGIC_V1) {
		@@ -153,7 +155,8 @@ static int erofs_read_superblock(struct super_block *sb)
		}
		ret = 0;
		out:
		brelse(bh);
		kunmap_atomic(data);
		put_page(page);
		return ret;
		}

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