On 9/9/22 5:55 PM, JeffleXu wrote:
>
>
> On 9/2/22 6:53 PM, Jia Zhu wrote:
>> In erofs umount scenario, erofs_fscache_unregister_cookie() is called
>> twice in kill_sb() and put_super().
>>
>> It works for original semantics, cause 'ctx' will be set to NULL in
>> put_super() and will not be unregister again in kill_sb().
>> However, in shared domain scenario, we use refcount to maintain the
>> lifecycle of cookie. Unregister the cookie twice will cause it to be
>> released early.
Sorry, why can't we also set sbi->s_fscache to NULL after decrementing
the refcount in shared domain mode, to avoid the refcount being
decremented twice?
>>
>> For the above reasons, this patch removes duplicate unregister_cookie
>> and move fscache_unregister_* before shotdown_super() to prevent busy
>> inode(ctx->inode) when umount.
>>
>> Signed-off-by: Jia Zhu <zhujia.zj@xxxxxxxxxxxxx>
>> ---
>> fs/erofs/super.c | 16 ++++++++--------
>> 1 file changed, 8 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
>> index 69de1731f454..667a78f0ee70 100644
>> --- a/fs/erofs/super.c
>> +++ b/fs/erofs/super.c
>> @@ -919,19 +919,20 @@ static void erofs_kill_sb(struct super_block *sb)
>> kill_litter_super(sb);
>> return;
>> }
>> - if (erofs_is_fscache_mode(sb))
>> - generic_shutdown_super(sb);
>> - else
>> - kill_block_super(sb);
>> -
>> sbi = EROFS_SB(sb);
>> if (!sbi)
>> return;
>>
>> + if (erofs_is_fscache_mode(sb)) {
>> + erofs_fscache_unregister_cookie(&sbi->s_fscache);
>> + erofs_fscache_unregister_fs(sb);
>> + generic_shutdown_super(sb);
>
> Generally we can't do clean ups before generic_shutdown_super(), since
> generic_shutdown_super() may trigger IO, e.g. in sync_filesystem(),
> though it's not the case for erofs (read-only).
>
> How about embedding erofs_fscache_unregister_cookie() into
> erofs_fscache_unregister_fs(), and thus we can check domain_id in
> erofs_fscache_unregister_fs()?
>
>> + } else {
>> + kill_block_super(sb);
>> + }
>> +
>> erofs_free_dev_context(sbi->devs);
>> fs_put_dax(sbi->dax_dev, NULL);
>> - erofs_fscache_unregister_cookie(&sbi->s_fscache);
>> - erofs_fscache_unregister_fs(sb);
>> kfree(sbi->opt.fsid);
>> kfree(sbi->opt.domain_id);
>> kfree(sbi);
>> @@ -951,7 +952,6 @@ static void erofs_put_super(struct super_block *sb)
>> iput(sbi->managed_cache);
>> sbi->managed_cache = NULL;
>> #endif
>> - erofs_fscache_unregister_cookie(&sbi->s_fscache);
>> }
>>
>> struct file_system_type erofs_fs_type = {
>
--
Thanks,
Jingbo
