Commit ea0b7b0d authored by Yue Hu's avatar Yue Hu Committed by Gao Xiang
Browse files

erofs: avoid the potentially wrong m_plen for big pcluster 



Actually, 'compressedlcs' stores compressed block count rather than
lcluster count. Therefore, the number of bits for shifting the count
should be 'LOG_BLOCK_SIZE' rather than 'lclusterbits' although current
lcluster size is 4K.

The value of 'm_plen' will be wrong once we enable the non 4K-sized
lcluster.

Signed-off-by: default avatarYue Hu <huyue2@coolpad.com>
Reviewed-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: default avatarChao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20220812060150.8510-1-huyue2@coolpad.com


Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
parent 5bd9628b

fs/erofs/zmap.c

+8 −8
Original line number Diff line number Diff line
@@ -141,7 +141,7 @@ struct z_erofs_maprecorder { 
	u8  type, headtype;

	u16 clusterofs;

	u16 delta[2];

	erofs_blk_t pblk, compressedlcs;

	erofs_blk_t pblk, compressedblks;

	erofs_off_t nextpackoff;

};
@@ -192,7 +192,7 @@ static int legacy_load_cluster_from_disk(struct z_erofs_maprecorder *m, 
				DBG_BUGON(1);

				return -EFSCORRUPTED;

			}

			m->compressedlcs = m->delta[0] &

			m->compressedblks = m->delta[0] &

				~Z_EROFS_VLE_DI_D0_CBLKCNT;

			m->delta[0] = 1;

		}
@@ -293,7 +293,7 @@ static int unpack_compacted_index(struct z_erofs_maprecorder *m, 
				DBG_BUGON(1);

				return -EFSCORRUPTED;

			}

			m->compressedlcs = lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;

			m->compressedblks = lo & ~Z_EROFS_VLE_DI_D0_CBLKCNT;

			m->delta[0] = 1;

			return 0;

		} else if (i + 1 != (int)vcnt) {
@@ -497,7 +497,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m, 
		return 0;

	}

	lcn = m->lcn + 1;

	if (m->compressedlcs)

	if (m->compressedblks)

		goto out;



	err = z_erofs_load_cluster_from_disk(m, lcn, false);
@@ -506,7 +506,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m, 


	/*

	 * If the 1st NONHEAD lcluster has already been handled initially w/o

	 * valid compressedlcs, which means at least it mustn't be CBLKCNT, or

	 * valid compressedblks, which means at least it mustn't be CBLKCNT, or

	 * an internal implemenatation error is detected.

	 *

	 * The following code can also handle it properly anyway, but let's
@@ -523,12 +523,12 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m, 
		 * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type

		 * rather than CBLKCNT, it's a 1 lcluster-sized pcluster.

		 */

		m->compressedlcs = 1;

		m->compressedblks = 1 << (lclusterbits - LOG_BLOCK_SIZE);

		break;

	case Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD:

		if (m->delta[0] != 1)

			goto err_bonus_cblkcnt;

		if (m->compressedlcs)

		if (m->compressedblks)

			break;

		fallthrough;

	default:
@@ -539,7 +539,7 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m, 
		return -EFSCORRUPTED;

	}

out:

	map->m_plen = (u64)m->compressedlcs << lclusterbits;

	map->m_plen = (u64)m->compressedblks << LOG_BLOCK_SIZE;

	return 0;

err_bonus_cblkcnt:

	erofs_err(m->inode->i_sb,