On Wednesday, February 15, 2017 11:03:11 AM Eric Sandeen wrote: > On 2/15/17 10:13 AM, Eric Sandeen wrote: > >> The root cause of the problem is due to the fact that > >> xfs_sb_version_hasalign() returns true when we are working on a V5 > >> filesystem. Due to this args.minalignslop (in xfs_ialloc_ag_alloc()) > >> gets the unsigned equivalent of -1 assigned to it. This later causes > >> alloc_len in xfs_alloc_space_available() to have a value of 0. In such a > >> scenario when args.total is also 0, the assert statement > >> "ASSERT(args->maxlen > 0);" fails. > > Hm, the intent of the _haslign() function is to say that V5 must always > > imply the "alignbit" - i.e. we don't want to grow an infinite feature > > matrix, and by the time you get to V5 supers, there are many things which > > cannot be turned on or off, such as this feature. > > > > So what happens here... xfs_ialloc_ag_alloc does: > > > > args.minalignslop = xfs_ialloc_cluster_alignment(args.mp) - 1; > > > > so you're saying that cluster_alignment comes out as 0? > > > > That function is checking _hasalign: > > > > static inline int > > xfs_ialloc_cluster_alignment( > > struct xfs_mount *mp) > > { > > if (xfs_sb_version_hasalign(&mp->m_sb) && > > mp->m_sb.sb_inoalignmt >= > > XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size)) > > return mp->m_sb.sb_inoalignmt; > > return 1; > > } > > > > So are you saying that this function returns 0? That would imply that > > sb_inoalignmt and m_inode_cluster_size are both zero, yes? Is this > > what you see? > > Sorry, I guess that means XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size)) is > zero; inode cluster size is 8192 in this case I think, and that is in fact > 0 filesystem blocks when computed with this macro. Yes, sb_inoalignmt is indeed 0 because of the following code from main() in xfsprogs/mkfs/xfs_mkfs.c, if (sb_feat.inode_align) { int cluster_size = XFS_INODE_BIG_CLUSTER_SIZE; if (sb_feat.crcs_enabled) cluster_size *= isize / XFS_DINODE_MIN_SIZE; sbp->sb_inoalignmt = cluster_size >> blocklog; sb_feat.inode_align = sbp->sb_inoalignmt != 0; } And XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size)) returns 0 as well. Hence the condition (xfs_sb_version_hasalign(&mp->m_sb) && mp->m_sb.sb_inoalignmt >= XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size)) evaluates to true. > > I need to think about this a little bit to convince myself that the inode > alignment bit really /should/ be off for a filesystem of this geometry, vs > changing the macro to recognize the case. > > -Eric > -- chandan -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html