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 from xfs_repair some code that computes the location of the root inode and teach mount to skip the ondisk update if it would cause problems for repair. Along the way we'll update the documentation, provide a function for computing the minimum AGFL size instead of open-coding it, and cut down some indenting in the mount code. Note that we allow the mount to proceed (and new allocations will reflect this new geometry) because we've never screened this kind of thing before. We'll have to wait for a new future incompat feature to enforce correct behavior, alas. Note that the geometry reporting always uses the superblock values, not the incore ones, so that is what xfs_info and xfs_growfs will report. [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> --- v2: refactor the agfl length calculations, clarify the fsgeometry ioctl behavior, fix a bunch of the comments and make it clearer how we compute the rootino location --- fs/xfs/libxfs/xfs_alloc.c | 18 ++++++--- fs/xfs/libxfs/xfs_ialloc.c | 70 ++++++++++++++++++++++++++++++++++ fs/xfs/libxfs/xfs_ialloc.h | 1 fs/xfs/xfs_mount.c | 90 ++++++++++++++++++++++++++++++-------------- fs/xfs/xfs_trace.h | 21 ++++++++++ 5 files changed, 166 insertions(+), 34 deletions(-) diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c index c284e10af491..fc93fd88ec89 100644 --- a/fs/xfs/libxfs/xfs_alloc.c +++ b/fs/xfs/libxfs/xfs_alloc.c @@ -2248,24 +2248,32 @@ xfs_alloc_longest_free_extent( return pag->pagf_flcount > 0 || pag->pagf_longest > 0; } +/* + * Compute the minimum length of the AGFL in the given AG. If @pag is NULL, + * return the largest possible minimum length. + */ unsigned int xfs_alloc_min_freelist( struct xfs_mount *mp, struct xfs_perag *pag) { + /* AG btrees have at least 1 level. */ + static const uint8_t fake_levels[XFS_BTNUM_AGF] = {1, 1, 1}; + const uint8_t *levels = pag ? pag->pagf_levels : fake_levels; unsigned int min_free; + ASSERT(mp->m_ag_maxlevels > 0); + /* space needed by-bno freespace btree */ - min_free = min_t(unsigned int, pag->pagf_levels[XFS_BTNUM_BNOi] + 1, + min_free = min_t(unsigned int, levels[XFS_BTNUM_BNOi] + 1, mp->m_ag_maxlevels); /* space needed by-size freespace btree */ - min_free += min_t(unsigned int, pag->pagf_levels[XFS_BTNUM_CNTi] + 1, + min_free += min_t(unsigned int, levels[XFS_BTNUM_CNTi] + 1, mp->m_ag_maxlevels); /* space needed reverse mapping used space btree */ if (xfs_sb_version_hasrmapbt(&mp->m_sb)) - min_free += min_t(unsigned int, - pag->pagf_levels[XFS_BTNUM_RMAPi] + 1, - mp->m_rmap_maxlevels); + min_free += min_t(unsigned int, levels[XFS_BTNUM_RMAPi] + 1, + mp->m_rmap_maxlevels); return min_free; } diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c index 988cde7744e6..7b4e76c75c58 100644 --- a/fs/xfs/libxfs/xfs_ialloc.c +++ b/fs/xfs/libxfs/xfs_ialloc.c @@ -2909,3 +2909,73 @@ xfs_ialloc_setup_geometry( else igeo->ialloc_align = 0; } + +/* + * Compute the location of the root directory inode that is laid out by mkfs. + * The @sunit parameter will be copied from the superblock if it is negative. + */ +xfs_ino_t +xfs_ialloc_calc_rootino( + struct xfs_mount *mp, + int sunit) +{ + struct xfs_ino_geometry *igeo = M_IGEO(mp); + xfs_agblock_t first_bno; + + if (sunit < 0) + sunit = mp->m_sb.sb_unit; + + /* + * Pre-calculate the geometry of AG 0. We know what it looks like + * because libxfs knows how to create allocation groups now. + * + * first_bno is the first block in which mkfs could possibly have + * allocated the root directory inode, once we factor in the metadata + * that mkfs formats before it. Namely, the four AG headers... + */ + first_bno = howmany(4 * mp->m_sb.sb_sectsize, mp->m_sb.sb_blocksize); + + /* ...the two free space btree roots... */ + first_bno += 2; + + /* ...the inode btree root... */ + first_bno += 1; + + /* ...the initial AGFL... */ + first_bno += xfs_alloc_min_freelist(mp, NULL); + + /* ...the free inode btree root... */ + if (xfs_sb_version_hasfinobt(&mp->m_sb)) + first_bno++; + + /* ...the reverse mapping btree root... */ + if (xfs_sb_version_hasrmapbt(&mp->m_sb)) + first_bno++; + + /* ...the reference count btree... */ + if (xfs_sb_version_hasreflink(&mp->m_sb)) + first_bno++; + + /* + * ...and the log, if it is allocated in the first allocation group. + * + * 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) + first_bno += mp->m_sb.sb_logblocks; + + /* + * Now round first_bno up to whatever allocation alignment is given + * by the filesystem or was passed in. + */ + if (xfs_sb_version_hasdalign(&mp->m_sb) && igeo->ialloc_align > 0) + first_bno = roundup(first_bno, sunit); + else if (xfs_sb_version_hasalign(&mp->m_sb) && + mp->m_sb.sb_inoalignmt > 1) + first_bno = roundup(first_bno, mp->m_sb.sb_inoalignmt); + + return XFS_AGINO_TO_INO(mp, 0, XFS_AGB_TO_AGINO(mp, first_bno)); +} diff --git a/fs/xfs/libxfs/xfs_ialloc.h b/fs/xfs/libxfs/xfs_ialloc.h index 323592d563d5..72b3468b97b1 100644 --- a/fs/xfs/libxfs/xfs_ialloc.h +++ b/fs/xfs/libxfs/xfs_ialloc.h @@ -152,5 +152,6 @@ 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); +xfs_ino_t xfs_ialloc_calc_rootino(struct xfs_mount *mp, int sunit); #endif /* __XFS_IALLOC_H__ */ diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index fca65109cf24..19e0c77bf64c 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -31,7 +31,7 @@ #include "xfs_reflink.h" #include "xfs_extent_busy.h" #include "xfs_health.h" - +#include "xfs_trace.h" static DEFINE_MUTEX(xfs_uuid_table_mutex); static int xfs_uuid_table_size; @@ -359,13 +359,46 @@ xfs_readsb( return error; } +/* + * If the sunit/swidth change would move the precomputed root inode value, we + * must reject the ondisk change because repair will stumble over that. + * However, we allow the mount to proceed because we never rejected this + * combination before. + */ +static inline void +xfs_check_new_dalign( + struct xfs_mount *mp, + int new_dalign) +{ + struct xfs_sb *sbp = &mp->m_sb; + xfs_ino_t calc_ino; + + calc_ino = xfs_ialloc_calc_rootino(mp, new_dalign); + trace_xfs_check_new_dalign(mp, new_dalign, calc_ino); + + if (sbp->sb_rootino == calc_ino) + return; + + xfs_warn(mp, +"Cannot change stripe alignment; would require moving root inode."); + + /* + * XXX: Next time we add a new incompat feature, this should start + * returning -EINVAL. Until then, spit out a warning that we're + * ignoring the administrator's instructions. + */ + xfs_warn(mp, "Skipping superblock stripe alignment update."); + return; +} + /* * Update alignment values based on mount options and sb values */ STATIC int -xfs_update_alignment(xfs_mount_t *mp) +xfs_update_alignment( + struct xfs_mount *mp) { - xfs_sb_t *sbp = &(mp->m_sb); + struct xfs_sb *sbp = &mp->m_sb; if (mp->m_dalign) { /* @@ -398,28 +431,26 @@ xfs_update_alignment(xfs_mount_t *mp) } } - /* - * Update superblock with new values - * and log changes - */ - if (xfs_sb_version_hasdalign(sbp)) { - if (sbp->sb_unit != mp->m_dalign) { - sbp->sb_unit = mp->m_dalign; - mp->m_update_sb = true; - } - if (sbp->sb_width != mp->m_swidth) { - sbp->sb_width = mp->m_swidth; - mp->m_update_sb = true; - } - } else { + /* Update superblock with new values and log changes. */ + if (!xfs_sb_version_hasdalign(sbp)) { xfs_warn(mp, "cannot change alignment: superblock does not support data alignment"); return -EINVAL; } + + if (sbp->sb_unit == mp->m_dalign && + sbp->sb_width == mp->m_swidth) + return 0; + + xfs_check_new_dalign(mp, mp->m_dalign); + + sbp->sb_unit = mp->m_dalign; + sbp->sb_width = mp->m_swidth; + mp->m_update_sb = true; } else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN && xfs_sb_version_hasdalign(&mp->m_sb)) { - mp->m_dalign = sbp->sb_unit; - mp->m_swidth = sbp->sb_width; + mp->m_dalign = sbp->sb_unit; + mp->m_swidth = sbp->sb_width; } return 0; @@ -647,16 +678,6 @@ xfs_mountfs( mp->m_update_sb = true; } - /* - * Check if sb_agblocks is aligned at stripe boundary - * If sb_agblocks is NOT aligned turn off m_dalign since - * allocator alignment is within an ag, therefore ag has - * to be aligned at stripe boundary. - */ - error = xfs_update_alignment(mp); - if (error) - goto out; - xfs_alloc_compute_maxlevels(mp); xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK); xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK); @@ -664,6 +685,17 @@ xfs_mountfs( xfs_rmapbt_compute_maxlevels(mp); xfs_refcountbt_compute_maxlevels(mp); + /* + * Check if sb_agblocks is aligned at stripe boundary. If sb_agblocks + * is NOT aligned turn off m_dalign since allocator alignment is within + * an ag, therefore ag has to be aligned at stripe boundary. Note that + * we must compute the free space and rmap btree geometry before doing + * this. + */ + error = xfs_update_alignment(mp); + if (error) + goto out; + /* enable fail_at_unmount as default */ mp->m_fail_unmount = true; diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h index c13bb3655e48..a86be7f807ee 100644 --- a/fs/xfs/xfs_trace.h +++ b/fs/xfs/xfs_trace.h @@ -3573,6 +3573,27 @@ DEFINE_KMEM_EVENT(kmem_alloc_large); DEFINE_KMEM_EVENT(kmem_realloc); DEFINE_KMEM_EVENT(kmem_zone_alloc); +TRACE_EVENT(xfs_check_new_dalign, + TP_PROTO(struct xfs_mount *mp, int new_dalign, xfs_ino_t calc_rootino), + TP_ARGS(mp, new_dalign, calc_rootino), + TP_STRUCT__entry( + __field(dev_t, dev) + __field(int, new_dalign) + __field(xfs_ino_t, sb_rootino) + __field(xfs_ino_t, calc_rootino) + ), + TP_fast_assign( + __entry->dev = mp->m_super->s_dev; + __entry->new_dalign = new_dalign; + __entry->sb_rootino = mp->m_sb.sb_rootino; + __entry->calc_rootino = calc_rootino; + ), + TP_printk("dev %d:%d new_dalign %d sb_rootino %llu calc_rootino %llu", + MAJOR(__entry->dev), MINOR(__entry->dev), + __entry->new_dalign, __entry->sb_rootino, + __entry->calc_rootino) +) + #endif /* _TRACE_XFS_H */ #undef TRACE_INCLUDE_PATH
