erofs: unify meta buffers in z_erofs_fill_inode()

There is no need to keep additional local metabufs since we already
have one in `struct erofs_map_blocks`.

This was actually a leftover when applying meta buffers to zmap
operations, see commit 09c543798c3c ("erofs: use meta buffers for
zmap operations").

Signed-off-by: Gao Xiang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

fs/erofs/zmap.c

···
 	return 0;
 }
 
-static int z_erofs_fill_inode_lazy(struct inode *inode)
+static int z_erofs_fill_inode(struct inode *inode, struct erofs_map_blocks *map)
 {
 	struct erofs_inode *const vi = EROFS_I(inode);
 	struct super_block *const sb = inode->i_sb;
 	int err, headnr;
 	erofs_off_t pos;
-	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
 	struct z_erofs_map_header *h;
 
 	if (test_bit(EROFS_I_Z_INITED_BIT, &vi->flags)) {
···
 		goto out_unlock;
 
 	pos = ALIGN(erofs_iloc(inode) + vi->inode_isize + vi->xattr_isize, 8);
-	h = erofs_read_metabuf(&buf, sb, pos);
+	h = erofs_read_metabuf(&map->buf, sb, pos);
 	if (IS_ERR(h)) {
 		err = PTR_ERR(h);
 		goto out_unlock;
···
 		erofs_err(sb, "unknown HEAD%u format %u for nid %llu, please upgrade kernel",
 			  headnr + 1, vi->z_algorithmtype[headnr], vi->nid);
 		err = -EOPNOTSUPP;
-		goto out_put_metabuf;
+		goto out_unlock;
 	}
 
 	if (!erofs_sb_has_big_pcluster(EROFS_SB(sb)) &&
···
 		erofs_err(sb, "per-inode big pcluster without sb feature for nid %llu",
 			  vi->nid);
 		err = -EFSCORRUPTED;
-		goto out_put_metabuf;
+		goto out_unlock;
 	}
 	if (vi->datalayout == EROFS_INODE_COMPRESSED_COMPACT &&
 	    !(vi->z_advise & Z_EROFS_ADVISE_BIG_PCLUSTER_1) ^
···
 		erofs_err(sb, "big pcluster head1/2 of compact indexes should be consistent for nid %llu",
 			  vi->nid);
 		err = -EFSCORRUPTED;
-		goto out_put_metabuf;
+		goto out_unlock;
 	}
 
 	if (vi->z_idata_size ||
 	    (vi->z_advise & Z_EROFS_ADVISE_FRAGMENT_PCLUSTER)) {
-		struct erofs_map_blocks map = {
+		struct erofs_map_blocks tm = {
 			.buf = __EROFS_BUF_INITIALIZER
 		};
 
-		err = z_erofs_map_blocks_fo(inode, &map,
+		err = z_erofs_map_blocks_fo(inode, &tm,
 					    EROFS_GET_BLOCKS_FINDTAIL);
-		erofs_put_metabuf(&map.buf);
+		erofs_put_metabuf(&tm.buf);
 		if (err < 0)
-			goto out_put_metabuf;
+			goto out_unlock;
 	}
 done:
 	/* paired with smp_mb() at the beginning of the function */
 	smp_mb();
 	set_bit(EROFS_I_Z_INITED_BIT, &vi->flags);
-out_put_metabuf:
-	erofs_put_metabuf(&buf);
 out_unlock:
 	clear_and_wake_up_bit(EROFS_I_BL_Z_BIT, &vi->flags);
 	return err;
···
 		map->m_la = inode->i_size;
 		map->m_flags = 0;
 	} else {
-		err = z_erofs_fill_inode_lazy(inode);
+		err = z_erofs_fill_inode(inode, map);
 		if (!err) {
 			if (vi->datalayout == EROFS_INODE_COMPRESSED_FULL &&
 			    (vi->z_advise & Z_EROFS_ADVISE_EXTENTS))