linux-kernel - [PATCH] erofs: avoid the potentially wrong m

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Message-Id: <20220812060150.8510-1-huyue2@coolpad.com>
Date:   Fri, 12 Aug 2022 14:01:50 +0800
From:   Yue Hu <zbestahu@...il.com>
To:     xiang@...nel.org, chao@...nel.org
Cc:     linux-erofs@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        huyue2@...lpad.com, zhangwen@...lpad.com
Subject: [PATCH] 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: Yue Hu <huyue2@...lpad.com>
---
 fs/erofs/zmap.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 572f0b8151ba..d58549ca1df9 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -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,
-- 
2.17.1