On 3/17/25 01:17, Gao Xiang wrote:
> Hi Chao,
>
> On 2025/3/16 10:36, Chao Yu wrote:
>> On 2025/2/10 11:29, Hongzhen Luo wrote:
>>> There's no need to enumerate each type. No logic changes.
>>>
>>> Signed-off-by: Hongzhen Luo <hongz...@linux.alibaba.com>
>>
>> Looks good to me, feel free to add:
>>
>> Reviewed-by: Chao Yu <c...@kernel.org>
>>
>> And one minor comment below.
>>
>>> diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
>>> index 689437e99a5a..d278ebd60281 100644
>>> --- a/fs/erofs/zmap.c
>>> +++ b/fs/erofs/zmap.c
>>> @@ -265,26 +265,22 @@ static int z_erofs_extent_lookback(struct
>>> z_erofs_maprecorder *m,
>>> if (err)
>>> return err;
>>> - switch (m->type) {
>>> - case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
>>> + if (m->type >= Z_EROFS_LCLUSTER_TYPE_MAX) {
>>> + erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
>>> + m->type, lcn, vi->nid);
>>> + DBG_BUGON(1);
>>> + return -EOPNOTSUPP;
>> > + } else if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {>
>> lookback_distance = m->delta[0];
>>> if (!lookback_distance)
>>> - goto err_bogus;
>>> + break;
>>> continue;
>>> - case Z_EROFS_LCLUSTER_TYPE_PLAIN:
>>> - case Z_EROFS_LCLUSTER_TYPE_HEAD1:
>>> - case Z_EROFS_LCLUSTER_TYPE_HEAD2:
>>> + } else {
>>> m->headtype = m->type;
>>> m->map->m_la = (lcn << lclusterbits) | m->clusterofs;
>>> return 0;
>>> - default:
>>> - erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
>>> - m->type, lcn, vi->nid);
>>> - DBG_BUGON(1);
>>> - return -EOPNOTSUPP;
>>
>> Should return EFSCORRUPTED here? is m->type >= Z_EROFS_LCLUSTER_TYPE_MAX a
>> possible
>> case?
>
> It's impossible by the latest on-disk definition, see:
> #define Z_EROFS_LI_LCLUSTER_TYPE_MASK (Z_EROFS_LCLUSTER_TYPE_MAX - 1)
>
> Previously, it was useful before Z_EROFS_LCLUSTER_TYPE_HEAD2 was
> introduced, but the `default:` case is already deadcode now.
Xiang, thanks for the explanation.
So seems it can happen when mounting last image w/ old kernel which can not
support newly introduced Z_EROFS_LCLUSTER_TYPE_* type, then it makes sense to
return EOPNOTSUPP.
>
>>
>> Btw, we'd better to do sanity check for m->type in
>> z_erofs_load_full_lcluster(),
>> then we can treat m->type as reliable variable later.
>>
>> advise = le16_to_cpu(di->di_advise);
>> m->type = advise & Z_EROFS_LI_LCLUSTER_TYPE_MASK;
>> if (m->type >= Z_EROFS_LCLUSTER_TYPE_MAX) {
>
> It's always false here.
So, what do you think of this?
>From af584b2eacd468f145e9ee31ccdeedb7355d5afd Mon Sep 17 00:00:00 2001
From: Chao Yu <c...@kernel.org>
Date: Mon, 17 Mar 2025 13:57:55 +0800
Subject: [PATCH] erofs: remove dead codes for cleanup
z_erofs_extent_lookback() and z_erofs_get_extent_decompressedlen() tries
to do sanity check on m->type, however their caller z_erofs_map_blocks_fo()
has already checked that, so let's remove those dead codes.
Signed-off-by: Chao Yu <c...@kernel.org>
---
fs/erofs/zmap.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 8de50df05dfe..4d883ec212d7 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -265,17 +265,12 @@ static int z_erofs_extent_lookback(struct
z_erofs_maprecorder *m,
if (err)
return err;
- if (m->type >= Z_EROFS_LCLUSTER_TYPE_MAX) {
- erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
- m->type, lcn, vi->nid);
- DBG_BUGON(1);
- return -EOPNOTSUPP;
- } else if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
+ if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
lookback_distance = m->delta[0];
if (!lookback_distance)
break;
continue;
- } else {
+ } else if (m->type < Z_EROFS_LCLUSTER_TYPE_MAX) {
m->headtype = m->type;
m->map->m_la = (lcn << lclusterbits) | m->clusterofs;
return 0;
@@ -379,11 +374,6 @@ static int z_erofs_get_extent_decompressedlen(struct
z_erofs_maprecorder *m)
if (lcn != headlcn)
break; /* ends at the next HEAD lcluster */
m->delta[1] = 1;
- } else {
- erofs_err(inode->i_sb, "unknown type %u @ lcn %llu of
nid %llu",
- m->type, lcn, vi->nid);
- DBG_BUGON(1);
- return -EOPNOTSUPP;
}
lcn += m->delta[1];
}
--
2.48.1
>
> Thanks,
> Gao Xiang
>
