udf: replace ll_rw_block()

ll_rw_block() is not safe for the sync read path because it cannot
guarantee that submitting read IO if the buffer has been locked. We
could get false positive EIO after wait_on_buffer() if the buffer has
been locked by others. So stop using ll_rw_block(). We also switch to
new bh_readahead_batch() helper for the buffer array readahead path.

Link: https://lkml.kernel.org/r/20220901133505.2510834-11-yi.zhang@huawei.comSigned-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/udf/dir.c

@@ -130,7 +130,7 @@ static int udf_readdir(struct file *file, struct dir_context *ctx)
 					brelse(tmp);
 			}
 			if (num) {
-				ll_rw_block(REQ_OP_READ | REQ_RAHEAD, num, bha);
+				bh_readahead_batch(num, bha, REQ_RAHEAD);
 				for (i = 0; i < num; i++)
 					brelse(bha[i]);
 			}

fs/udf/directory.c

@@ -89,7 +89,7 @@ struct fileIdentDesc *udf_fileident_read(struct inode *dir, loff_t *nf_pos,
 					brelse(tmp);
 			}
 			if (num) {
-				ll_rw_block(REQ_OP_READ | REQ_RAHEAD, num, bha);
+				bh_readahead_batch(num, bha, REQ_RAHEAD);
 				for (i = 0; i < num; i++)
 					brelse(bha[i]);
 			}

fs/udf/inode.c

@@ -1211,13 +1211,7 @@ struct buffer_head *udf_bread(struct inode *inode, udf_pblk_t block,
 	if (!bh)
 		return NULL;
 
-	if (buffer_uptodate(bh))
-		return bh;
-
-	ll_rw_block(REQ_OP_READ, 1, &bh);
-
-	wait_on_buffer(bh);
-	if (buffer_uptodate(bh))
+	if (bh_read(bh, 0) >= 0)
 		return bh;
 
 	brelse(bh);