On 2014-01-26 11:00, Ryusuke Konishi wrote:
> On Fri, 24 Jan 2014 21:00:03 +0100, Andreas Rohner wrote:
>> On 2014-01-24 19:26, Ryusuke Konishi wrote:
>>>> + ret = nilfs_set_suinfo(nilfs, supv, n);
>>>> + free(supv);
>>>> + if (ret >= 0) {
>>>> + /* success, tell caller
>>>> + * to try another segment/s */
>>>> + ret = -EGCTRYAGAIN;
>>>> + goto out_lock;
>>>> + }
>
> Returning -EGCTRYAGAIN looks confusing, since posix error code Exxxxx
> is usually stored in errno variable in userland. It also looks a bit
> hacky.
True. Vyacheslav had similar concerns.
> How about handling this as follows ?
>
> - Add a new structure to return result of GC, for instance, as
> follows:
>
> struct nilfs_reclaim_status {
> unsigned int ncleanedsegs; /* number of segments cleaned
> with nilfs_clean_segments() */
> unsigned int ndeferredsegs;/* number of segments deferred
> with nilfs_set_suinfo() */
> unsigned long nliveblocks; /* sum of live virtual blocks and live
> DAT blocks */
> unsigned long ndeadblocks; /* number of reclaimable blocks */
> unsigned long nlivevblocks; /* live virtual blocks */
> unsigned long nfreevblocks; /* freed virtual block addresses */
> ...
> };
>
> - Use the structure as an argument of the "new" API function
> (i.e. variant of nilfs_reclaim_segment() )
>
> - Rewrite the variant API function so that it returns a success value
> (0) also for the EGCTRYAGAIN case.
>
> - Store other status information in nilfs_reclaim_status structures.
>
>
> And, I think adding nilfs_set_suinfo() API should be a separate patch.
Yes EGCTRYAGAIN is not necessary for the nilfs_set_suinfo() API to work.
It is a good idea to use a separate patch for this.
br,
Andreas Rohner
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