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erofs: use read_mapping_page instead of sb_bread 

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>
alistair/sunxi64-5.4-dsi
Gao Xiang 2019-09-04 10:09:10 +08:00 committed by Greg Kroah-Hartman
parent 4f761fa253
commit fe7c242357
1 changed files with 9 additions and 6 deletions
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15
fs/erofs/super.c
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@ -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;
}