On 7/30/18 6:38 PM, Darrick J. Wong wrote:
> On Mon, Jul 30, 2018 at 06:16:40PM -0500, Eric Sandeen wrote:
>> On 7/30/18 12:30 AM, Darrick J. Wong wrote:
>>> From: Bill O'Donnell <billodo@xxxxxxxxxx>
>>>
>>> Current sb verifier doesn't check bounds on sb_fdblocks and sb_ifree.
>>> Add sanity checks for these parameters.
>>>
>>> Signed-off-by: Bill O'Donnell <billodo@xxxxxxxxxx>
>>> [darrick: port to refactored sb validation predicates]
>>> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>>
>> comment nitpicks below, but otherwise
>>
>> Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
>>
>>> ---
>>> fs/xfs/libxfs/xfs_sb.c | 12 ++++++++++++
>>> 1 file changed, 12 insertions(+)
>>>
>>>
>>> diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
>>> index 516bef7b0f50..64bc471d57e6 100644
>>> --- a/fs/xfs/libxfs/xfs_sb.c
>>> +++ b/fs/xfs/libxfs/xfs_sb.c
>>> @@ -153,6 +153,18 @@ xfs_validate_sb_write(
>>> struct xfs_mount *mp,
>>> struct xfs_sb *sbp)
>>> {
>>> + /*
>>> + * Carry out additional sb sanity checks exclusively for writes.
>>
>> We're in xfs_validate_sb_write so that's obvious, can drop this line.
>>
>>> + * We don't do these checks for reads, since faulty parameters could
>>> + * be fixed in the log, and we shouldn't prohibit mounting for those
>>> + * cases.
>>> + */
>>
>> Hm, it's not really a log reaplay issue, right? These summary counters
>> get reinitialized at mount, so failing to mount before we overwrite them
>> anyway makes no sense.
>
> Well, we don't reinitialize them if ( (!lazysbcount) or (clean log) )
> and (non-crazy values)...
>
>> /*
>> * These summary counters get re-initialized after they are read
>> * during mount, so this is a write-only check.
>
> They're not always re-initialized -- only if we had a dirty lazysbcont
> fs or the values were crazy.
>
> /*
> * Carry out additional sb summary counter sanity checks when we write
> * the superblock. We skip this in the read validator because there
> * could be newer superblocks in the log and if the values are garbage
> * even after replay we'll recalculate them at the end of log mount.
> */
Oh, ok sure. Given my ongoing confusion an explicit/complete comment is
probably good. For me, if for nobody else. ;)
Thanks,
-Eric
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