linux-kernel - Re: [PATCH 3/3] btrfs: migrate to the newer memparse

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Date: Wed, 27 Dec 2023 18:56:57 +1030
From: Qu Wenruo <quwenruo.btrfs@....com>
To: David Disseldorp <ddiss@...e.de>, Qu Wenruo <wqu@...e.com>
Cc: linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
 akpm@...ux-foundation.org, christophe.jaillet@...adoo.fr,
 andriy.shevchenko@...ux.intel.com, David.Laight@...LAB.COM
Subject: Re: [PATCH 3/3] btrfs: migrate to the newer memparse_safe() helper



On 2023/12/27 16:57, David Disseldorp wrote:
> On Sat, 23 Dec 2023 20:28:07 +1030, Qu Wenruo wrote:
>
>> The new helper has better error report and correct overflow detection,
>> furthermore the old @retptr behavior is also kept, thus there should be
>> no behavior change.
>>
>> Signed-off-by: Qu Wenruo <wqu@...e.com>
>> ---
>>   fs/btrfs/ioctl.c |  8 ++++++--
>>   fs/btrfs/super.c |  8 ++++++++
>>   fs/btrfs/sysfs.c | 14 +++++++++++---
>>   3 files changed, 25 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>> index 4e50b62db2a8..8bfd4b4ccf02 100644
>> --- a/fs/btrfs/ioctl.c
>> +++ b/fs/btrfs/ioctl.c
>> @@ -1175,8 +1175,12 @@ static noinline int btrfs_ioctl_resize(struct file *file,
>>   			mod = 1;
>>   			sizestr++;
>>   		}
>> -		new_size = memparse(sizestr, &retptr);
>> -		if (*retptr != '\0' || new_size == 0) {
>> +
>> +		ret = memparse_safe(sizestr, MEMPARSE_SUFFIXES_DEFAULT,
>> +				    &new_size, &retptr);
>> +		if (ret < 0)
>> +			goto out_finish;
>> +		if (*retptr != '\0') {
>
> Was dropping the -EINVAL return for new_size=0 intentional?

Oh, that's unintentional. Although we would reject the invalid string, a
dedicated "0" can still be parsed.
In that case we should still return -EINVAL.

I just got it confused with the old behavior for invalid string (where 0
is returned and @retptr is not advanced).
>
>>   			ret = -EINVAL;
>>   			goto out_finish;
>>   		}
>> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
>> index 3a677b808f0f..2bb6ea525e89 100644
>> --- a/fs/btrfs/super.c
>> +++ b/fs/btrfs/super.c
>> @@ -400,6 +400,14 @@ static int btrfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
>>   		ctx->thread_pool_size = result.uint_32;
>>   		break;
>>   	case Opt_max_inline:
>> +		int ret;
>> +
>> +		ret = memparse_safe(param->string, MEMPARSE_SUFFIXES_DEFAULT,
>> +				    &ctx->max_inline, NULL);
>> +		if (ret < 0) {
>> +			btrfs_err(NULL, "invalid string \"%s\"", param->string);
>> +			return ret;
>> +		}
>>   		ctx->max_inline = memparse(param->string, NULL);
>
> Looks like you overlooked removal of the old memparse() call above.

My bad, I forgot to remove the old line.

Furthermore, the declaration of "ret" inside case block is not allowed,
I'll fix it anyway.

Thanks,
Qu
>
> Cheers, David
>