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Message-ID: <4cefb5b1-648b-58f6-abd7-d3cabfe507ec@huawei.com>
Date: Tue, 22 Oct 2024 14:53:16 +0800
From: Yue Haibing <yuehaibing@...wei.com>
To: Johannes Thumshirn <Johannes.Thumshirn@....com>, "clm@...com"
<clm@...com>, "josef@...icpanda.com" <josef@...icpanda.com>,
"dsterba@...e.com" <dsterba@...e.com>, "mpdesouza@...e.com"
<mpdesouza@...e.com>, "gniebler@...e.com" <gniebler@...e.com>
CC: "linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] btrfs: Fix passing 0 to ERR_PTR in
btrfs_search_dir_index_item()
On 2024/10/22 14:37, Johannes Thumshirn wrote:
> On 22.10.24 05:22, Yue Haibing wrote:
>> On 2024/10/21 16:25, Johannes Thumshirn wrote:
>>> On 19.10.24 11:07, Yue Haibing wrote:
>>>> Return NULL instead of passing to ERR_PTR while ret is zero, this fix
>>>> smatch warnings:
>>>>
>>>> fs/btrfs/dir-item.c:353
>>>> btrfs_search_dir_index_item() warn: passing zero to 'ERR_PTR'
>>>>
>>>> Fixes: 9dcbe16fccbb ("btrfs: use btrfs_for_each_slot in btrfs_search_dir_index_item")
>>>> Signed-off-by: Yue Haibing <yuehaibing@...wei.com>
>>>> ---
>>>> fs/btrfs/dir-item.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
>>>> index 001c0c2f872c..cdb30ec7366a 100644
>>>> --- a/fs/btrfs/dir-item.c
>>>> +++ b/fs/btrfs/dir-item.c
>>>> @@ -350,7 +350,7 @@ btrfs_search_dir_index_item(struct btrfs_root *root, struct btrfs_path *path,
>>>> if (ret > 0)
>>>> ret = 0;
>>>>
>>>> - return ERR_PTR(ret);
>>>> + return ret ? ERR_PTR(ret) : NULL;
>>>> }
>>>>
>>>> struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
>>>
>>> The only caller to this is in btrfs_unlink_subvol(), which does the
>>> following:
>>>
>>>
>>> di = btrfs_search_dir_index_item(root, path, dir_ino,
>>> &fname.disk_name);
>>> if (IS_ERR_OR_NULL(di)) {
>>> if (!di)
>>> ret = -ENOENT;
>>> else
>>> ret = PTR_ERR(di);
>>> btrfs_abort_transaction(trans, ret);
>>> goto out;
>>> }
>>>
>>> to do:
>>>
>>> diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
>>> index d3093eba54a5..e755228d909a 100644
>>> --- a/fs/btrfs/dir-item.c
>>> +++ b/fs/btrfs/dir-item.c
>>> @@ -345,10 +345,7 @@ btrfs_search_dir_index_item(struct btrfs_root
>>> *root, struct btrfs_path *path,
>>> return di;
>>> }
>>> /* Adjust return code if the key was not found in the next leaf. */
>>
>>
>> ret is output variable of btrfs_for_each_slot, that return value can be 0, if a
>> valid slot was found, 1 if there were no more leaves, and < 0 if there was an
>> error.
>>
>
> Yes.
>
>>> - if (ret > 0)
>>> - ret = 0;
>>> -
>>> - return ERR_PTR(ret);
>>> + return ERR_PTR(-ENOENT);
>>
>> This overwrite other ret code, which expecting return to upstream caller
>
> Right for ret < 0, but for ret >= 0 we set it to 0 and then do return
> (void*)0 a.k.a. return NULL.
>
>>
>>> }
>>>
>>> struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle
>>> *trans,
>>> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
>>> index 35f89d14c110..00602634db3a 100644
>>> --- a/fs/btrfs/inode.c
>>> +++ b/fs/btrfs/inode.c
>>> @@ -4337,11 +4337,8 @@ static int btrfs_unlink_subvol(struct
>>> btrfs_trans_handle *trans,
>>> */
>>> if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
>>> di = btrfs_search_dir_index_item(root, path, dir_ino,
>>> &fname.disk_name);
>>> - if (IS_ERR_OR_NULL(di)) {
>>> - if (!di)
>>> - ret = -ENOENT;
>
>
> and then set it to ENOENT if it is NULL. So it should be
>
> if (ret >= 0)
> ret = -ENOENT;
> return ERR_PTR(-ENOENT);
Here should be
return ERR_PTR(ret);
Will rework and send v2, thanks!
>
> and in the caller
>
> if (IS_ERR(di)) {
> ret = PTR_ERR(di);
> btrfs_abort_transaction(...);
> break;
> }
>
>
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