On Fri, 24 Jan 2014 13:34:36 +0100, Andreas Rohner wrote:
> On 2014-01-24 12:56, Ryusuke Konishi wrote:
>> On Tue, 21 Jan 2014 15:00:29 +0100, Andreas Rohner wrote:
>>> This patch introduces the nilfs_sufile_set_suinfo function, which
>>> expects an array of nilfs_suinfo_update structures and updates the
>>> segment usage information accordingly.
>>>
>>> This is basically a helper function for the newly introduced
>>> NILFS_IOCTL_SET_SUINFO ioctl.
>>>
>>> Signed-off-by: Andreas Rohner <[email protected]>
>>> ---
>>> fs/nilfs2/sufile.c | 91
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> fs/nilfs2/sufile.h | 2 +-
>>> 2 files changed, 92 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
>>> index 3127e9f..81c3438 100644
>>> --- a/fs/nilfs2/sufile.c
>>> +++ b/fs/nilfs2/sufile.c
>>> @@ -870,6 +870,97 @@ ssize_t nilfs_sufile_get_suinfo(struct inode *sufile,
>>> __u64 segnum, void *buf,
>>> }
>>>
>>> /**
>>> + * nilfs_sufile_set_suinfo -
>>
>> Please fill the summary line of function even though
>> nilfs_sufile_get_suinfo() function lacks it.
>>
>> * nilfs_sufile_set_suinfo - update segment usage information
>>
>>> + * @sufile: inode of segment usage file
>>> + * @buf: array of suinfo
>>> + * @supsz: byte size of suinfo
>>> + * @nsup: size of suinfo array
>>> + *
>>> + * Description: Takes an array of nilfs_suinfo_update structs and updates
>>> + * segment usage accordingly.
>>> + *
>>> + * Return Value: On success, 0 is returned and .... On error, one of the
>>> + * following negative error codes is returned.
>>> + *
>>> + * %-EIO - I/O error.
>>> + *
>>> + * %-ENOMEM - Insufficient amount of memory available.
>>> + *
>>> + * %-EINVAL - Invalid segment number in input
>>> + */
>>> +ssize_t nilfs_sufile_set_suinfo(struct inode *sufile, void *buf,
>>> + unsigned supsz, size_t nsup)
>>> +{
>>> + struct buffer_head *bh;
>>> + struct nilfs_suinfo_update *sup, *supv = buf;
>>> + struct nilfs_segment_usage *su;
>>> + void *kaddr;
>>> + unsigned long blkoff, prev_blkoff;
>>> + size_t nerr = 0;
>>> + int ret = 0;
>>> +
>>> + if (unlikely(nsup == 0))
>>> + goto out;
>>> +
>>> + down_write(&NILFS_MDT(sufile)->mi_sem);
>>> + for (sup = supv; sup < supv + nsup; sup++) {
>>> + if (unlikely(sup->sup_segnum >=
>>> + nilfs_sufile_get_nsegments(sufile))) {
>>> + printk(KERN_WARNING
>>> + "%s: invalid segment number: %llu\n", __func__,
>>> + (unsigned long long)sup->sup_segnum);
>>> + nerr++;
>>> + }
>>> + }
>>> + if (nerr > 0) {
>>> + ret = -EINVAL;
>>> + goto out_sem;
>>> + }
>>
>> Seems that you can exit from inside the loop:
>>
>> for (sup = supv; sup < supv + nsup; sup++) {
>> if (unlikely(sup->sup_segnum >=
>> nilfs_sufile_get_nsegments(sufile))) {
>> printk(KERN_WARNING
>> "%s: invalid segment number: %llu\n", __func__,
>> (unsigned long long)sup->sup_segnum);
>> ret = -EINVAL;
>> goto out_sem;
>> }
An additional comment:
I think we should reject unknown sup_flags with -EINVAL here. It may
be used in a future version, but the current version cannot update the
corresponding field in sufile. Rejecting it looks better behavior
than ignoring it.
Regards,
Ryusuke Konishi
>> }
>
> Yes. I copied that from nilfs_sufile_updatev.
>
>>> +
>>> + sup = supv;
>>> + blkoff = nilfs_sufile_get_blkoff(sufile, sup->sup_segnum);
>>> + ret = nilfs_mdt_get_block(sufile, blkoff, 1, NULL, &bh);
>>> + if (ret < 0)
>>> + goto out_sem;
>>> +
>>> + for (;;) {
>>> + kaddr = kmap_atomic(bh->b_page);
>>> + su = nilfs_sufile_block_get_segment_usage(
>>> + sufile, sup->sup_segnum, bh, kaddr);
>>> +
>>> + if (nilfs_suinfo_update_lastmod(sup))
>>> + su->su_lastmod = cpu_to_le64(sup->sup_sui.sui_lastmod);
>>> +
>>> + if (nilfs_suinfo_update_nblocks(sup))
>>> + su->su_nblocks = cpu_to_le32(sup->sup_sui.sui_nblocks);
>>> +
>>> + if (nilfs_suinfo_update_flags(sup))
>>> + su->su_flags = cpu_to_le32(sup->sup_sui.sui_flags);
>>
>> You must also update the counter value of sh_ncleansegs, sh_ndirtysegs
>> in the nilfs_sufile_header struct of sufile header block based on the
>> change of these flags.
>>
>> In addition, you should ignore NILFS_SEGMENT_USAGE_ACTIVE_FLAG as
>> below because this flag is a virtual flag set by running nilfs kernel
>> code. The flag bit should not be written to sufile on disk.
>>
>> (sui_flags & ~(1UL << NILFS_SEGMENT_USAGE_ACTIVE))
>
> Yes. I didn't think of that.
>
>>> +
>>> + kunmap_atomic(kaddr);
>>> +
>>> + if (++sup >= supv + nsup)
>>
>> You must not use the automatic pointer operation of C language for
>> nilfs_suinfo_update because it may be extended in a future release.
>> This "++sup" breaks forward compatibility of the ioctl.
>>
>> You should do this by:
>>
>> sup = (void *)sup + supsz;
>>
>> Note that pointer type is automatically converted for "void *" type
>> variables.
>
>
> Makes sense. I guess I blindly copied that from nilfs_sufile_updatev,
> but with a simple array of __u64 it works of course. With a structure,
> that is subject to change, not so much any more.
>
>>> + break;
>>> + prev_blkoff = blkoff;
>>> + blkoff = nilfs_sufile_get_blkoff(sufile, sup->sup_segnum);
>>> + if (blkoff == prev_blkoff)
>>> + continue;
>>> +
>>> + /* get different block */
>>
>> You must mark bh that this function changed as dirty with
>> mark_buffer_dirty(bh). Otherwise, the change will be gone.
>>
>>
>>> + brelse(bh);
>>> + ret = nilfs_mdt_get_block(sufile, blkoff, 1, NULL, &bh);
>>> + if (unlikely(ret < 0))
>>> + goto out_sem;
>>> + }
>>> + brelse(bh);
>>> +
>>
>> The sufile should be marked as dirty (if any change happened):
>>
>> nilfs_mdt_mark_dirty(sufile);
>
> Of course. I am sorry that's a really stupid error. I will fix it right
> away.
>
> Thanks for your review. I am really embarrassed about all the stupid
> avoidable errors.
>
> br,
> Andreas Rohner
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