From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> Alex Lyakas reported[1] that mounting an xfs filesystem with new sunit and swidth values could cause xfs_repair to fail loudly. The problem here is that repair calculates the where mkfs should have allocated the root inode, based on the superblock geometry. The allocation decisions depend on sunit, which means that we really can't go updating sunit if it would lead to a subsequent repair failure on an otherwise correct filesystem. Port the computation code from xfs_repair and teach mount to avoid the ondisk update if it would cause problems for repair. We allow the mount to proceed (and new allocations will reflect this new geometry) because we've never screened this kind of thing before. [1] https://lore.kernel.org/linux-xfs/20191125130744.GA44777@bfoster/T/#m00f9594b511e076e2fcdd489d78bc30216d72a7d Reported-by: Alex Lyakas <alex@xxxxxxxxxx> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> --- libxfs/xfs_ialloc.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++ libxfs/xfs_ialloc.h | 2 + 2 files changed, 90 insertions(+) diff --git a/libxfs/xfs_ialloc.c b/libxfs/xfs_ialloc.c index f039b287..fe6553d3 100644 --- a/libxfs/xfs_ialloc.c +++ b/libxfs/xfs_ialloc.c @@ -2848,3 +2848,91 @@ xfs_ialloc_setup_geometry( else igeo->ialloc_align = 0; } + +/* + * Compute the first and last inodes numbers of the inode chunk that was + * preallocated for the root directory. + */ +void +xfs_ialloc_find_prealloc( + struct xfs_mount *mp, + xfs_agino_t *first_agino, + xfs_agino_t *last_agino) +{ + struct xfs_ino_geometry *igeo = M_IGEO(mp); + xfs_agblock_t first_bno; + + /* + * Pre-calculate the geometry of ag 0. We know what it looks like + * because we know what mkfs does: 2 allocation btree roots (by block + * and by size), the inode allocation btree root, the free inode + * allocation btree root (if enabled) and some number of blocks to + * prefill the agfl. + * + * Because the current shape of the btrees may differ from the current + * shape, we open code the mkfs freelist block count here. mkfs creates + * single level trees, so the calculation is pertty straight forward for + * the trees that use the AGFL. + */ + + /* free space by block btree root comes after the ag headers */ + first_bno = howmany(4 * mp->m_sb.sb_sectsize, mp->m_sb.sb_blocksize); + + /* free space by length btree root */ + first_bno += 1; + + /* inode btree root */ + first_bno += 1; + + /* agfl */ + first_bno += (2 * min(2U, mp->m_ag_maxlevels)) + 1; + + if (xfs_sb_version_hasfinobt(&mp->m_sb)) + first_bno++; + + if (xfs_sb_version_hasrmapbt(&mp->m_sb)) { + first_bno += min(2U, mp->m_rmap_maxlevels); /* agfl blocks */ + first_bno++; + } + + if (xfs_sb_version_hasreflink(&mp->m_sb)) + first_bno++; + + /* + * If the log is allocated in the first allocation group we need to + * add the number of blocks used by the log to the above calculation. + * + * This can happens with filesystems that only have a single + * allocation group, or very odd geometries created by old mkfs + * versions on very small filesystems. + */ + if (mp->m_sb.sb_logstart && + XFS_FSB_TO_AGNO(mp, mp->m_sb.sb_logstart) == 0) { + + /* + * XXX(hch): verify that sb_logstart makes sense? + */ + first_bno += mp->m_sb.sb_logblocks; + } + + /* + * ditto the location of the first inode chunks in the fs ('/') + */ + if (xfs_sb_version_hasdalign(&mp->m_sb) && igeo->ialloc_align > 0) { + *first_agino = XFS_AGB_TO_AGINO(mp, + roundup(first_bno, mp->m_sb.sb_unit)); + } else if (xfs_sb_version_hasalign(&mp->m_sb) && + mp->m_sb.sb_inoalignmt > 1) { + *first_agino = XFS_AGB_TO_AGINO(mp, + roundup(first_bno, mp->m_sb.sb_inoalignmt)); + } else { + *first_agino = XFS_AGB_TO_AGINO(mp, first_bno); + } + + ASSERT(igeo->ialloc_blks > 0); + + if (igeo->ialloc_blks > 1) + *last_agino = *first_agino + XFS_INODES_PER_CHUNK; + else + *last_agino = XFS_AGB_TO_AGINO(mp, first_bno + 1); +} diff --git a/libxfs/xfs_ialloc.h b/libxfs/xfs_ialloc.h index 323592d5..9d9fe7b4 100644 --- a/libxfs/xfs_ialloc.h +++ b/libxfs/xfs_ialloc.h @@ -152,5 +152,7 @@ int xfs_inobt_insert_rec(struct xfs_btree_cur *cur, uint16_t holemask, int xfs_ialloc_cluster_alignment(struct xfs_mount *mp); void xfs_ialloc_setup_geometry(struct xfs_mount *mp); +void xfs_ialloc_find_prealloc(struct xfs_mount *mp, xfs_agino_t *first_agino, + xfs_agino_t *last_agino); #endif /* __XFS_IALLOC_H__ */
