erofs: localize erofs_grab_bio()

As Christoph pointed out [1], "erofs_grab_bio tries to
handle a bio_alloc failure, except that the function will
not actually fail due the mempool backing it."

Sorry about useless code, fix it now and
localize erofs_grab_bio [2].

[1] https://lore.kernel.org/r/20190830162812.GA10694@infradead.org/
[2] https://lore.kernel.org/r/20190902122016.GL15931@infradead.org/Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-16-gaoxiang25@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/erofs/data.c

@@ -38,6 +38,19 @@ static inline void read_endio(struct bio *bio)
 	bio_put(bio);
 }
 
+static struct bio *erofs_grab_raw_bio(struct super_block *sb,
+				      erofs_blk_t blkaddr,
+				      unsigned int nr_pages)
+{
+	struct bio *bio = bio_alloc(GFP_NOIO, nr_pages);
+
+	bio->bi_end_io = read_endio;
+	bio_set_dev(bio, sb->s_bdev);
+	bio->bi_iter.bi_sector = (sector_t)blkaddr << LOG_SECTORS_PER_BLOCK;
+	bio->bi_private = sb;
+	return bio;
+}
+
 /* prio -- true is used for dir */
 struct page *__erofs_get_meta_page(struct super_block *sb,
 				   erofs_blk_t blkaddr, bool prio, bool nofail)
@@ -62,12 +75,7 @@ struct page *__erofs_get_meta_page(struct super_block *sb,
 	if (!PageUptodate(page)) {
 		struct bio *bio;
 
-		bio = erofs_grab_bio(sb, blkaddr, 1, sb, read_endio, nofail);
-		if (IS_ERR(bio)) {
-			DBG_BUGON(nofail);
-			err = PTR_ERR(bio);
-			goto err_out;
-		}
+		bio = erofs_grab_raw_bio(sb, blkaddr, 1);
 
 		if (bio_add_page(bio, page, PAGE_SIZE, 0) != PAGE_SIZE) {
 			err = -EFAULT;
@@ -276,13 +284,7 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio,
 		if (nblocks > BIO_MAX_PAGES)
 			nblocks = BIO_MAX_PAGES;
 
-		bio = erofs_grab_bio(sb, blknr, nblocks, sb,
-				     read_endio, false);
-		if (IS_ERR(bio)) {
-			err = PTR_ERR(bio);
-			bio = NULL;
-			goto err_out;
-		}
+		bio = erofs_grab_raw_bio(sb, blknr, nblocks);
 	}
 
 	err = bio_add_page(bio, page, PAGE_SIZE, 0);

fs/erofs/internal.h

@@ -411,35 +411,6 @@ static inline int z_erofs_map_blocks_iter(struct inode *inode,
 #endif	/* !CONFIG_EROFS_FS_ZIP */
 
 /* data.c */
-static inline struct bio *erofs_grab_bio(struct super_block *sb,
-					 erofs_blk_t blkaddr,
-					 unsigned int nr_pages,
-					 void *bi_private, bio_end_io_t endio,
-					 bool nofail)
-{
-	const gfp_t gfp = GFP_NOIO;
-	struct bio *bio;
-
-	do {
-		if (nr_pages == 1) {
-			bio = bio_alloc(gfp | (nofail ? __GFP_NOFAIL : 0), 1);
-			if (!bio) {
-				DBG_BUGON(nofail);
-				return ERR_PTR(-ENOMEM);
-			}
-			break;
-		}
-		bio = bio_alloc(gfp, nr_pages);
-		nr_pages /= 2;
-	} while (!bio);
-
-	bio->bi_end_io = endio;
-	bio_set_dev(bio, sb->s_bdev);
-	bio->bi_iter.bi_sector = (sector_t)blkaddr << LOG_SECTORS_PER_BLOCK;
-	bio->bi_private = bi_private;
-	return bio;
-}
-
 static inline void __submit_bio(struct bio *bio, unsigned int op,
 				unsigned int op_flags)
 {

fs/erofs/zdata.c

@@ -1263,9 +1263,13 @@ static bool z_erofs_vle_submit_all(struct super_block *sb,
 		}
 
 		if (!bio) {
-			bio = erofs_grab_bio(sb, first_index + i,
-					     BIO_MAX_PAGES, bi_private,
-					     z_erofs_vle_read_endio, true);
+			bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
+
+			bio->bi_end_io = z_erofs_vle_read_endio;
+			bio_set_dev(bio, sb->s_bdev);
+			bio->bi_iter.bi_sector = (sector_t)(first_index + i) <<
+				LOG_SECTORS_PER_BLOCK;
+			bio->bi_private = bi_private;
 			++nr_bios;
 		}