Re: [PATCH 1/2] block: introduce BLK_STS_OFFLINE

[Hannes Reinecke <hare@suse.de>]

On 2/3/22 07:52, Song Liu wrote:
> CC linux-block (it was a typo in the original email)
> 
> On Wed, Feb 2, 2022 at 10:40 PM Song Liu <song@kernel.org> wrote:
>>
>> Currently, drivers reports BLK_STS_IOERR for devices that are not full
>> online or being removed. This behavior could cause confusion for users,
>> as they are not really I/O errors from the device.
>>
>> Solve this issue with a new state BLK_STS_OFFLINE, which reports "device
>> offline error" in dmesg instead of "I/O error".
>>
>> Signed-off-by: Song Liu <song@kernel.org>
>> ---
>>   block/blk-core.c          | 1 +
>>   include/linux/blk_types.h | 7 +++++++
>>   2 files changed, 8 insertions(+)
>>
>> diff --git a/block/blk-core.c b/block/blk-core.c
>> index 61f6a0dc4511..24035dd2eef1 100644
>> --- a/block/blk-core.c
>> +++ b/block/blk-core.c
>> @@ -164,6 +164,7 @@ static const struct {
>>          [BLK_STS_RESOURCE]      = { -ENOMEM,    "kernel resource" },
>>          [BLK_STS_DEV_RESOURCE]  = { -EBUSY,     "device resource" },
>>          [BLK_STS_AGAIN]         = { -EAGAIN,    "nonblocking retry" },
>> +       [BLK_STS_OFFLINE]       = { -EIO,       "device offline" },
>>
>>          /* device mapper special case, should not leak out: */
>>          [BLK_STS_DM_REQUEUE]    = { -EREMCHG, "dm internal retry" },
>> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
>> index fe065c394fff..5561e58d158a 100644
>> --- a/include/linux/blk_types.h
>> +++ b/include/linux/blk_types.h
>> @@ -153,6 +153,13 @@ typedef u8 __bitwise blk_status_t;
>>    */
>>   #define BLK_STS_ZONE_ACTIVE_RESOURCE   ((__force blk_status_t)16)
>>
>> +/*
>> + * BLK_STS_OFFLINE is returned from the driver when the target device is offline
>> + * or is being taken offline. This could help differentiate the case where a
>> + * device is intentionally being shut down from a real I/O error.
>> + */
>> +#define BLK_STS_OFFLINE                ((__force blk_status_t)17)
>> +
>>   /**
>>    * blk_path_error - returns true if error may be path related
>>    * @error: status the request was completed with
>> --
>> 2.30.2
>>
Please do not overload EIO here.
EIO already is a catch-all error if we don't know any better, but for 
the 'device offline' case we do (or rather should).
Please map it onto 'ENODEV' or 'ENXIO'.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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