On 4/17/19 5:35 PM, Mike Snitzer wrote:
> On Wed, Apr 17 2019 at 10:19am -0400,
> Nikos Tsironis <ntsironis@xxxxxxxxxxx> wrote:
>
>> Add missing dm_bitset_cursor_next() to properly advance the bitset
>> cursor.
>>
>> Otherwise, the discarded state of all blocks is set according to the
>> discarded state of the first block.
>>
>> Fixes: ae4a46a1f6 ("dm cache metadata: use bitset cursor api to load discard bitset")
>> Signed-off-by: Nikos Tsironis <ntsironis@xxxxxxxxxxx>
>
> Nice catch, I'll obviously mark this for stable@ too.
>
> One comment below.
>
>> ---
>> drivers/md/dm-cache-metadata.c | 9 ++++++++-
>> 1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
>> index 6fc93834da44..151aa95775be 100644
>> --- a/drivers/md/dm-cache-metadata.c
>> +++ b/drivers/md/dm-cache-metadata.c
>> @@ -1167,11 +1167,18 @@ static int __load_discards(struct dm_cache_metadata *cmd,
>> if (r)
>> return r;
>>
>> - for (b = 0; b < from_dblock(cmd->discard_nr_blocks); b++) {
>> + for (b = 0; ; b++) {
>> r = fn(context, cmd->discard_block_size, to_dblock(b),
>> dm_bitset_cursor_get_value(&c));
>> if (r)
>> break;
>> +
>> + if (b >= (from_dblock(cmd->discard_nr_blocks) - 1))
>> + break;
>
> Not understanding why you moved the conditional inside the loop, I'd
> rather keep it in the for(). Or did you have some reason for this?
>
After processing the last block, i.e., b == (from_dblock(cmd->discard_nr_blocks) - 1),
dm_bitset_cursor_next() will return -ENODATA. It seemed to me simpler to move the
conditional inside the loop, rather than check explicitly for -ENODATA and handle
it differently, e.g., set r = 0, if r == -ENODATA.
Nikos.
>> +
>> + r = dm_bitset_cursor_next(&c);
>> + if (r)
>> + break;
>> }
>>
>> dm_bitset_cursor_end(&c);
>> --
>> 2.11.0
>>
--
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