----- Original Message ----- > On Thu, Apr 21, 2011 at 01:05:18AM -0400, Lachlan McIlroy wrote: > > ----- Original Message ----- > > > From: Dave Chinner <dchinner@xxxxxxxxxx> > > > > > > When allocating an extent that is long enough to consume the > > > remaining free space in an AG, we need to ensure that the > > > allocation > > > leaves enough space in the AG for any subsequent bmap btree blocks > > > that are needed to track the new extent. These have to be > > > allocated > > > in the same AG as we only reserve enough blocks in an allocation > > > transaction for modification of the freespace trees in a single > > > AG. > > > > > > xfs_alloc_fix_minleft() has been considering blocks on the AGFL as > > > free blocks available for extent and bmbt block allocation, which > > > is > > > not correct - blocks on the AGFL are there exclusively for the use > > > of the free space btrees. As a result, when minleft is less than > > > the > > > number of blocks on the AGFL, xfs_alloc_fix_minleft() does not > > > trim > > > the given extent to leave minleft blocks available for bmbt > > > allocation, and hence we can fail allocation during bmbt record > > > insertion. > > > > > > A further problem is that bmbt block allocation doesn't set the > > > total number of blocks correctly for the allocation, thereby > > > allowing it to allocate a block from the AGFL before failing on > > > the > > > second block in xfs_alloc_fix_freelist(). The total needs to be > > > set > > > so that it skips AGs that only have the minimum reserved > > > amount of AGFL blocks free in them. > > > > > > Similarly, xfs_inobt_alloc_block() needs to set args->total as > > > well. > > > > Dave, you seem to have dropped the args->total changes? > > yeah I did - I forgot to update the commit message. It passes test > 250 without the args.total changes, so I figured that the minimum > change needed was the best approach. I'll fix the commit message. Yes I agree, best to keep the change to a minimum. Perhaps we need another test case that exhausts almost all space in all AGs to demonstrate the need for the args->total change (and ensure that the low space algorithm gets triggered). > > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx > > _______________________________________________ > xfs mailing list > xfs@xxxxxxxxxxx > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
