[PATCH v4] erofs: avoid using generic_block_bmap

[Huang Jianan <huangjianan@oppo.com>]

iblock indicates the number of i_blkbits-sized blocks rather than
sectors.

In addition, considering buffer_head limits mapped size to 32-bits,
should avoid using generic_block_bmap.

Fixes: 9da681e017a3 ("staging: erofs: support bmap")
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Guo Weichao <guoweichao@oppo.com>
---
 fs/erofs/data.c | 30 ++++++++++--------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 347be146884c..d6ea0a216b57 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -312,36 +312,26 @@ static void erofs_raw_access_readahead(struct readahead_control *rac)
 		submit_bio(bio);
 }
 
-static int erofs_get_block(struct inode *inode, sector_t iblock,
-			   struct buffer_head *bh, int create)
-{
-	struct erofs_map_blocks map = {
-		.m_la = iblock << 9,
-	};
-	int err;
-
-	err = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
-	if (err)
-		return err;
-
-	if (map.m_flags & EROFS_MAP_MAPPED)
-		bh->b_blocknr = erofs_blknr(map.m_pa);
-
-	return err;
-}
-
 static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
 {
 	struct inode *inode = mapping->host;
+	struct erofs_map_blocks map = {
+		.m_la = blknr_to_addr(block),
+	};
+	sector_t blknr = 0;
 
 	if (EROFS_I(inode)->datalayout == EROFS_INODE_FLAT_INLINE) {
 		erofs_blk_t blks = i_size_read(inode) >> LOG_BLOCK_SIZE;
 
 		if (block >> LOG_SECTORS_PER_BLOCK >= blks)
-			return 0;
+			goto out;
 	}
 
-	return generic_block_bmap(mapping, block, erofs_get_block);
+	if (!erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW))
+		blknr = erofs_blknr(map.m_pa);
+
+out:
+	return blknr;
 }
 
 /* for uncompressed (aligned) files and raw access for other files */
-- 
2.25.1