On 8/22/19 9:48 AM, Eric Sandeen wrote:
> On 8/22/19 1:01 AM, Dave Chinner wrote:
...
>> Hence scanning all the inodes in the first indoe chunk won't find
>> the root indoe if any of these situations has occurred, and we may
>> have to scan 1500 or more inodes in to find the root chunk (6 btree
>> roots - BNOBT,CNTBT,INOBT,FINOBT,RMAPBT,REFCBT - and 64k blocks).
>
> Hm. So, the one report I had of this had a root inode of 128, and
> bulkstat returned a first inode of 64, triggering the assert above.
> (but even then you're right, scanning 64 isn't enough)
>
> If it really can be that far off then maybe this is a bad way to go,
> although the long scan is going to be exceedingly rare I think. Most
> people will get the root inode on the first bulkstat call.
>
>> So I think the best thing to do here is try to calculate the root
>> inode number as per xfs_repair, and then bulkstat that. i.e. see
>> the calculation of "first_prealloc_ino" in repair/xfs_repair.c
>> (about line 450). Probably requires a XFS_IOC_FSGEOMETRY_V1 call to
>> get the necessary info to calculate it...
>
> I had started to go down that path and it seemed like a real mess.
> We need m_ag_maxlevels, m_rmap_maxlevels, sb_logstart, features,
> etc etc etc. I guess I can revisit it. I had thought about a common
> function to calculate this so we aren't coding it twice but I'm not
> sure we have the same sets of inputs for the various cases ...
I'm not sure it's possible without a ton of setup (or at all).
(repair has already done a full libxfs_mount setup, so it has what it needs.)
For example we need inode alignment; calculating that depends on whether
we have sparse inodes, and sparse inodes is an incompat feature not
reported by GEOM. :(
if (fp->inode_align) {
int cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
sbp->sb_versionnum |= XFS_SB_VERSION_ALIGNBIT;
if (cfg->sb_feat.crcs_enabled)
cluster_size *= cfg->inodesize / XFS_DINODE_MIN_SIZE;
sbp->sb_inoalignmt = cluster_size >> cfg->blocklog;
} else
sbp->sb_inoalignmt = 0;
...
/*
* Sparse inode chunk support has two main inode alignment requirements.
* First, sparse chunk alignment must match the cluster size. Second,
* full chunk alignment must match the inode chunk size.
*
* Copy the already calculated/scaled inoalignmt to spino_align and
* update the former to the full inode chunk size.
*/
if (fp->spinodes) {
sbp->sb_spino_align = sbp->sb_inoalignmt;
sbp->sb_inoalignmt = XFS_INODES_PER_CHUNK *
cfg->inodesize >> cfg->blocklog;
sbp->sb_features_incompat |= XFS_SB_FEAT_INCOMPAT_SPINODES;
}
-Eric
