On Thu, Dec 19, 2019 at 08:21:30AM -0500, Brian Foster wrote: > On Wed, Dec 18, 2019 at 11:37:41AM -0800, Darrick J. Wong wrote: > > 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> > > --- > > fs/xfs/libxfs/xfs_ialloc.c | 70 ++++++++++++++++++++++++++++++++++++++++++++ > > fs/xfs/libxfs/xfs_ialloc.h | 1 + > > fs/xfs/xfs_mount.c | 45 ++++++++++++++++++++++++++++ > > fs/xfs/xfs_trace.h | 21 +++++++++++++ > > 4 files changed, 136 insertions(+), 1 deletion(-) > > > > > > diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c > > index 988cde7744e6..eeec7c8d93fd 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; > > What's the purpose of this check? Can this actually happen? I'd written the mkfs / repair callers to pass in -1 to read the superblock sunit value, but TBH it's not strictly necessary, so I'll pull it out. > That question aside, the rest LGTM: > > Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx> Thanks for the review. :) --D > > + > > + /* > > + * 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 happen 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 3750f0074c74..7f94c6b20920 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; > > @@ -359,6 +359,42 @@ 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. Returns true to update the sb, false otherwise. > > + */ > > +static inline int > > +xfs_check_new_dalign( > > + struct xfs_mount *mp, > > + int new_dalign, > > + bool *update_sb) > > +{ > > + 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) { > > + *update_sb = true; > > + return 0; > > + } > > + > > + 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 to fail the mount. Until then, spit out a warning > > + * that we're ignoring the administrator's instructions. > > + */ > > + xfs_warn(mp, "Skipping superblock stripe alignment update."); > > + *update_sb = false; > > + return 0; > > +} > > + > > /* > > * If we were provided with new sunit/swidth values as mount options, make sure > > * that they pass basic alignment and superblock feature checks, and convert > > @@ -422,10 +458,17 @@ xfs_update_alignment( > > struct xfs_sb *sbp = &mp->m_sb; > > > > if (mp->m_dalign) { > > + bool update_sb; > > + int error; > > + > > if (sbp->sb_unit == mp->m_dalign && > > sbp->sb_width == mp->m_swidth) > > return 0; > > > > + error = xfs_check_new_dalign(mp, mp->m_dalign, &update_sb); > > + if (error || !update_sb) > > + return error; > > + > > sbp->sb_unit = mp->m_dalign; > > sbp->sb_width = mp->m_swidth; > > mp->m_update_sb = 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 > > >
