[PATCH v17.2 0/4] xfs-4.19: online repair support

[PATCH v17.2 0/4] xfs-4.19: online repair support

[Darrick J. Wong]

Hi all,

This is the seventeenth revision of a patchset that adds to XFS kernel
support for online metadata scrubbing and repair.  There aren't any
on-disk format changes.

New for v17.2 are a few fixes suggested by Brian Foster in v17.1 and a
rebase of the series atop for-next, which adapts the repair code to the
new way of handling deferred log operations.

This series does not include any of the btree repair functions or the
controversial repair functionality that requires fs freezing; that has
been deferred to a later posting.  The only patches in this series are
the AG header repair functions.

The first patch tightens up the btree root block finder to check that
btree root candidates have no siblings and that there aren't multiple
blocks claiming to be on the root level.

Patches 2-4 implement reconstruction of the AGF/AGI/AGFL headers.

If you're going to start using this mess, you probably ought to just
pull from my git trees.  The kernel patches[1] should apply against
4.18-rc8.  xfsprogs[2] and xfstests[3] can be found in their usual
places.  The git trees contain all four series' worth of changes.

This is an extraordinary way to destroy everything.  Enjoy!
Comments and questions are, as always, welcome.

--D

[1] https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=djwong-devel
[2] https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=djwong-devel
[3] https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=djwong-devel

[PATCH 1/4] xfs: xrep_findroot_block should reject root blocks with siblings

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

In xrep_findroot_block, if we find a candidate root block with sibling
pointers or sibling blocks on the same tree level, we should not return
that block as a tree root because root blocks cannot have siblings.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/repair.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)


diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 85b048b341a0..6c199e2ebb81 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -727,6 +727,23 @@ xrep_findroot_block(
 	bp->b_ops->verify_read(bp);
 	if (bp->b_error)
 		goto out;
+
+	/* Root blocks can't have siblings. */
+	if (btblock->bb_u.s.bb_leftsib != cpu_to_be32(NULLAGBLOCK) ||
+	    btblock->bb_u.s.bb_rightsib != cpu_to_be32(NULLAGBLOCK))
+		goto out;
+
+	/*
+	 * If we find a second block at this level, ignore this level because
+	 * it can't possibly be a root level.  Maybe we'll find a higher level,
+	 * or maybe the rmap information is garbage.
+	 */
+	if (fab->root != NULLAGBLOCK &&
+	    fab->height == xfs_btree_get_level(btblock) + 1) {
+		fab->root = NULLAGBLOCK;
+		goto out;
+	}
+
 	fab->root = agbno;
 	fab->height = xfs_btree_get_level(btblock) + 1;
 	*found_it = true;

Re: [PATCH 1/4] xfs: xrep_findroot_block should reject root blocks with siblings

[Brian Foster]

On Tue, Aug 07, 2018 at 08:57:06PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> In xrep_findroot_block, if we find a candidate root block with sibling
> pointers or sibling blocks on the same tree level, we should not return
> that block as a tree root because root blocks cannot have siblings.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/scrub/repair.c |   17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> 
> diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
> index 85b048b341a0..6c199e2ebb81 100644
> --- a/fs/xfs/scrub/repair.c
> +++ b/fs/xfs/scrub/repair.c
> @@ -727,6 +727,23 @@ xrep_findroot_block(
>  	bp->b_ops->verify_read(bp);
>  	if (bp->b_error)
>  		goto out;
> +
> +	/* Root blocks can't have siblings. */
> +	if (btblock->bb_u.s.bb_leftsib != cpu_to_be32(NULLAGBLOCK) ||
> +	    btblock->bb_u.s.bb_rightsib != cpu_to_be32(NULLAGBLOCK))
> +		goto out;
> +
> +	/*
> +	 * If we find a second block at this level, ignore this level because
> +	 * it can't possibly be a root level.  Maybe we'll find a higher level,
> +	 * or maybe the rmap information is garbage.
> +	 */
> +	if (fab->root != NULLAGBLOCK &&
> +	    fab->height == xfs_btree_get_level(btblock) + 1) {
> +		fab->root = NULLAGBLOCK;
> +		goto out;
> +	}

Ok, but is this enough? Won't resetting fab->root like this mean that
we'd just reassign it to the next block we find at this level? I'm
wondering if we should maintain ->height independently and anticipate
that (height == <valid> && root == NULLAGBLOCK) means we couldn't find a
valid root. That may also allow for more efficient height filtering
during the query.

Brian

> +
>  	fab->root = agbno;
>  	fab->height = xfs_btree_get_level(btblock) + 1;
>  	*found_it = true;
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 1/4] xfs: xrep_findroot_block should reject root blocks with siblings

[Darrick J. Wong]

On Thu, Aug 09, 2018 at 09:08:39AM -0400, Brian Foster wrote:
> On Tue, Aug 07, 2018 at 08:57:06PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > In xrep_findroot_block, if we find a candidate root block with sibling
> > pointers or sibling blocks on the same tree level, we should not return
> > that block as a tree root because root blocks cannot have siblings.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/scrub/repair.c |   17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> > 
> > 
> > diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
> > index 85b048b341a0..6c199e2ebb81 100644
> > --- a/fs/xfs/scrub/repair.c
> > +++ b/fs/xfs/scrub/repair.c
> > @@ -727,6 +727,23 @@ xrep_findroot_block(
> >  	bp->b_ops->verify_read(bp);
> >  	if (bp->b_error)
> >  		goto out;
> > +
> > +	/* Root blocks can't have siblings. */
> > +	if (btblock->bb_u.s.bb_leftsib != cpu_to_be32(NULLAGBLOCK) ||
> > +	    btblock->bb_u.s.bb_rightsib != cpu_to_be32(NULLAGBLOCK))
> > +		goto out;
> > +
> > +	/*
> > +	 * If we find a second block at this level, ignore this level because
> > +	 * it can't possibly be a root level.  Maybe we'll find a higher level,
> > +	 * or maybe the rmap information is garbage.
> > +	 */
> > +	if (fab->root != NULLAGBLOCK &&
> > +	    fab->height == xfs_btree_get_level(btblock) + 1) {
> > +		fab->root = NULLAGBLOCK;
> > +		goto out;
> > +	}
> 
> Ok, but is this enough? Won't resetting fab->root like this mean that
> we'd just reassign it to the next block we find at this level? I'm
> wondering if we should maintain ->height independently and anticipate
> that (height == <valid> && root == NULLAGBLOCK) means we couldn't find a
> valid root. That may also allow for more efficient height filtering
> during the query.

Working through this again, I think we could just set fab->root = 0
when we encounter this situation.  I think the two height checks could
be combined as well, so I'll retest and repost.

Roughly, I think this whole section could be restructured as:

/* Make sure we pass the verifiers. */
...

/* Root blocks can't have siblings. */
...

/* If we've recorded a root candidate... */
block_level = xfs_btree_get_level(btblock);
if (fab->root != NULLAGBLOCK) {
	/*
	 * ...and this no-sibling root block candidate has the same
	 * level as the recorded candidate, there's no way we're going
	 * to accept any candidates at this tree level.  Stash a root
	 * block of zero because the height is still valid, but no AG
	 * btree can root at agblock 0.  Callers should verify the root
	 * agbno.
	 */
	if (block_level + 1 == fab->height) {
		fab->root = 0;
		goto out;
	}

	/*
	 * ...and this no-sibling root block is lower in the tree than
	 * the recorded root block candidate, just ignore it.  There's
	 * still a strong chance that something is wrong with the btree
	 * itself, but that's not what we're fixing right now.
	 */
	if (block_level < fab->height)
		goto out;
}

/* Record the candidate root block */
...

--D

> 
> Brian
> 
> > +
> >  	fab->root = agbno;
> >  	fab->height = xfs_btree_get_level(btblock) + 1;
> >  	*found_it = true;
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 2/4] xfs: repair the AGF

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Regenerate the AGF from the rmap data.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/agheader_repair.c |  370 ++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/repair.c          |   27 ++-
 fs/xfs/scrub/repair.h          |    2 
 fs/xfs/scrub/scrub.c           |    2 
 4 files changed, 391 insertions(+), 10 deletions(-)


diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index 1e96621ece3a..4842fc598c9b 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -17,12 +17,19 @@
 #include "xfs_sb.h"
 #include "xfs_inode.h"
 #include "xfs_alloc.h"
+#include "xfs_alloc_btree.h"
 #include "xfs_ialloc.h"
+#include "xfs_ialloc_btree.h"
 #include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_refcount.h"
+#include "xfs_refcount_btree.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/trace.h"
+#include "scrub/repair.h"
+#include "scrub/bitmap.h"
 
 /* Superblock */
 
@@ -54,3 +61,366 @@ xrep_superblock(
 	xfs_trans_log_buf(sc->tp, bp, 0, BBTOB(bp->b_length) - 1);
 	return error;
 }
+
+/* AGF */
+
+struct xrep_agf_allocbt {
+	struct xfs_scrub	*sc;
+	xfs_agblock_t		freeblks;
+	xfs_agblock_t		longest;
+};
+
+/* Record free space shape information. */
+STATIC int
+xrep_agf_walk_allocbt(
+	struct xfs_btree_cur		*cur,
+	struct xfs_alloc_rec_incore	*rec,
+	void				*priv)
+{
+	struct xrep_agf_allocbt		*raa = priv;
+	int				error = 0;
+
+	if (xchk_should_terminate(raa->sc, &error))
+		return error;
+
+	raa->freeblks += rec->ar_blockcount;
+	if (rec->ar_blockcount > raa->longest)
+		raa->longest = rec->ar_blockcount;
+	return error;
+}
+
+/* Does this AGFL block look sane? */
+STATIC int
+xrep_agf_check_agfl_block(
+	struct xfs_mount	*mp,
+	xfs_agblock_t		agbno,
+	void			*priv)
+{
+	struct xfs_scrub	*sc = priv;
+
+	if (!xfs_verify_agbno(mp, sc->sa.agno, agbno))
+		return -EFSCORRUPTED;
+	return 0;
+}
+
+/*
+ * Offset within the xrep_find_ag_btree array for each btree type.  Avoid the
+ * XFS_BTNUM_ names here to avoid creating a sparse array.
+ */
+enum {
+	XREP_AGF_BNOBT = 0,
+	XREP_AGF_CNTBT,
+	XREP_AGF_RMAPBT,
+	XREP_AGF_REFCOUNTBT,
+	XREP_AGF_END,
+	XREP_AGF_MAX
+};
+
+/*
+ * Given the btree roots described by *fab, find the roots, check them for
+ * sanity, and pass the root data back out via *fab.
+ *
+ * This is /also/ a chicken and egg problem because we have to use the rmapbt
+ * (rooted in the AGF) to find the btrees rooted in the AGF.  We also have no
+ * idea if the btrees make any sense.  If we hit obvious corruptions in those
+ * btrees we'll bail out.
+ */
+STATIC int
+xrep_agf_find_btrees(
+	struct xfs_scrub		*sc,
+	struct xfs_buf			*agf_bp,
+	struct xrep_find_ag_btree	*fab,
+	struct xfs_buf			*agfl_bp)
+{
+	struct xfs_agf			*old_agf = XFS_BUF_TO_AGF(agf_bp);
+	int				error;
+
+	/* Go find the root data. */
+	error = xrep_find_ag_btree_roots(sc, agf_bp, fab, agfl_bp);
+	if (error)
+		return error;
+
+	/* We must find the bnobt, cntbt, and rmapbt roots. */
+	if (fab[XREP_AGF_BNOBT].root == NULLAGBLOCK ||
+	    fab[XREP_AGF_BNOBT].height > XFS_BTREE_MAXLEVELS ||
+	    fab[XREP_AGF_CNTBT].root == NULLAGBLOCK ||
+	    fab[XREP_AGF_CNTBT].height > XFS_BTREE_MAXLEVELS ||
+	    fab[XREP_AGF_RMAPBT].root == NULLAGBLOCK ||
+	    fab[XREP_AGF_RMAPBT].height > XFS_BTREE_MAXLEVELS)
+		return -EFSCORRUPTED;
+
+	/*
+	 * We relied on the rmapbt to reconstruct the AGF.  If we get a
+	 * different root then something's seriously wrong.
+	 */
+	if (fab[XREP_AGF_RMAPBT].root !=
+	    be32_to_cpu(old_agf->agf_roots[XFS_BTNUM_RMAPi]))
+		return -EFSCORRUPTED;
+
+	/* We must find the refcountbt root if that feature is enabled. */
+	if (xfs_sb_version_hasreflink(&sc->mp->m_sb) &&
+	    (fab[XREP_AGF_REFCOUNTBT].root == NULLAGBLOCK ||
+	     fab[XREP_AGF_REFCOUNTBT].height > XFS_BTREE_MAXLEVELS))
+		return -EFSCORRUPTED;
+
+	return 0;
+}
+
+/*
+ * Reinitialize the AGF header, making an in-core copy of the old contents so
+ * that we know which in-core state needs to be reinitialized.
+ */
+STATIC void
+xrep_agf_init_header(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agf_bp,
+	struct xfs_agf		*old_agf)
+{
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agf_bp);
+
+	memcpy(old_agf, agf, sizeof(*old_agf));
+	memset(agf, 0, BBTOB(agf_bp->b_length));
+	agf->agf_magicnum = cpu_to_be32(XFS_AGF_MAGIC);
+	agf->agf_versionnum = cpu_to_be32(XFS_AGF_VERSION);
+	agf->agf_seqno = cpu_to_be32(sc->sa.agno);
+	agf->agf_length = cpu_to_be32(xfs_ag_block_count(mp, sc->sa.agno));
+	agf->agf_flfirst = old_agf->agf_flfirst;
+	agf->agf_fllast = old_agf->agf_fllast;
+	agf->agf_flcount = old_agf->agf_flcount;
+	if (xfs_sb_version_hascrc(&mp->m_sb))
+		uuid_copy(&agf->agf_uuid, &mp->m_sb.sb_meta_uuid);
+
+	/* Mark the incore AGF data stale until we're done fixing things. */
+	ASSERT(sc->sa.pag->pagf_init);
+	sc->sa.pag->pagf_init = 0;
+}
+
+/* Set btree root information in an AGF. */
+STATIC void
+xrep_agf_set_roots(
+	struct xfs_scrub		*sc,
+	struct xfs_agf			*agf,
+	struct xrep_find_ag_btree	*fab)
+{
+	agf->agf_roots[XFS_BTNUM_BNOi] =
+			cpu_to_be32(fab[XREP_AGF_BNOBT].root);
+	agf->agf_levels[XFS_BTNUM_BNOi] =
+			cpu_to_be32(fab[XREP_AGF_BNOBT].height);
+
+	agf->agf_roots[XFS_BTNUM_CNTi] =
+			cpu_to_be32(fab[XREP_AGF_CNTBT].root);
+	agf->agf_levels[XFS_BTNUM_CNTi] =
+			cpu_to_be32(fab[XREP_AGF_CNTBT].height);
+
+	agf->agf_roots[XFS_BTNUM_RMAPi] =
+			cpu_to_be32(fab[XREP_AGF_RMAPBT].root);
+	agf->agf_levels[XFS_BTNUM_RMAPi] =
+			cpu_to_be32(fab[XREP_AGF_RMAPBT].height);
+
+	if (xfs_sb_version_hasreflink(&sc->mp->m_sb)) {
+		agf->agf_refcount_root =
+				cpu_to_be32(fab[XREP_AGF_REFCOUNTBT].root);
+		agf->agf_refcount_level =
+				cpu_to_be32(fab[XREP_AGF_REFCOUNTBT].height);
+	}
+}
+
+/* Update all AGF fields which derive from btree contents. */
+STATIC int
+xrep_agf_calc_from_btrees(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agf_bp)
+{
+	struct xrep_agf_allocbt	raa = { .sc = sc };
+	struct xfs_btree_cur	*cur = NULL;
+	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agf_bp);
+	struct xfs_mount	*mp = sc->mp;
+	xfs_agblock_t		btreeblks;
+	xfs_agblock_t		blocks;
+	int			error;
+
+	/* Update the AGF counters from the bnobt. */
+	cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno,
+			XFS_BTNUM_BNO);
+	error = xfs_alloc_query_all(cur, xrep_agf_walk_allocbt, &raa);
+	if (error)
+		goto err;
+	error = xfs_btree_count_blocks(cur, &blocks);
+	if (error)
+		goto err;
+	xfs_btree_del_cursor(cur, error);
+	btreeblks = blocks - 1;
+	agf->agf_freeblks = cpu_to_be32(raa.freeblks);
+	agf->agf_longest = cpu_to_be32(raa.longest);
+
+	/* Update the AGF counters from the cntbt. */
+	cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno,
+			XFS_BTNUM_CNT);
+	error = xfs_btree_count_blocks(cur, &blocks);
+	if (error)
+		goto err;
+	xfs_btree_del_cursor(cur, error);
+	btreeblks += blocks - 1;
+
+	/* Update the AGF counters from the rmapbt. */
+	cur = xfs_rmapbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno);
+	error = xfs_btree_count_blocks(cur, &blocks);
+	if (error)
+		goto err;
+	xfs_btree_del_cursor(cur, error);
+	agf->agf_rmap_blocks = cpu_to_be32(blocks);
+	btreeblks += blocks - 1;
+
+	agf->agf_btreeblks = cpu_to_be32(btreeblks);
+
+	/* Update the AGF counters from the refcountbt. */
+	if (xfs_sb_version_hasreflink(&mp->m_sb)) {
+		cur = xfs_refcountbt_init_cursor(mp, sc->tp, agf_bp,
+				sc->sa.agno);
+		error = xfs_btree_count_blocks(cur, &blocks);
+		if (error)
+			goto err;
+		xfs_btree_del_cursor(cur, error);
+		agf->agf_refcount_blocks = cpu_to_be32(blocks);
+	}
+
+	return 0;
+err:
+	xfs_btree_del_cursor(cur, error);
+	return error;
+}
+
+/* Commit the new AGF and reinitialize the incore state. */
+STATIC int
+xrep_agf_commit_new(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agf_bp)
+{
+	struct xfs_perag	*pag;
+	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agf_bp);
+
+	/* Trigger fdblocks recalculation */
+	xfs_force_summary_recalc(sc->mp);
+
+	/* Write this to disk. */
+	xfs_trans_buf_set_type(sc->tp, agf_bp, XFS_BLFT_AGF_BUF);
+	xfs_trans_log_buf(sc->tp, agf_bp, 0, BBTOB(agf_bp->b_length) - 1);
+
+	/* Now reinitialize the in-core counters we changed. */
+	pag = sc->sa.pag;
+	pag->pagf_btreeblks = be32_to_cpu(agf->agf_btreeblks);
+	pag->pagf_freeblks = be32_to_cpu(agf->agf_freeblks);
+	pag->pagf_longest = be32_to_cpu(agf->agf_longest);
+	pag->pagf_levels[XFS_BTNUM_BNOi] =
+			be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNOi]);
+	pag->pagf_levels[XFS_BTNUM_CNTi] =
+			be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]);
+	pag->pagf_levels[XFS_BTNUM_RMAPi] =
+			be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAPi]);
+	pag->pagf_refcount_level = be32_to_cpu(agf->agf_refcount_level);
+	pag->pagf_init = 1;
+
+	return 0;
+}
+
+/* Repair the AGF. v5 filesystems only. */
+int
+xrep_agf(
+	struct xfs_scrub		*sc)
+{
+	struct xrep_find_ag_btree	fab[XREP_AGF_MAX] = {
+		[XREP_AGF_BNOBT] = {
+			.rmap_owner = XFS_RMAP_OWN_AG,
+			.buf_ops = &xfs_allocbt_buf_ops,
+			.magic = XFS_ABTB_CRC_MAGIC,
+		},
+		[XREP_AGF_CNTBT] = {
+			.rmap_owner = XFS_RMAP_OWN_AG,
+			.buf_ops = &xfs_allocbt_buf_ops,
+			.magic = XFS_ABTC_CRC_MAGIC,
+		},
+		[XREP_AGF_RMAPBT] = {
+			.rmap_owner = XFS_RMAP_OWN_AG,
+			.buf_ops = &xfs_rmapbt_buf_ops,
+			.magic = XFS_RMAP_CRC_MAGIC,
+		},
+		[XREP_AGF_REFCOUNTBT] = {
+			.rmap_owner = XFS_RMAP_OWN_REFC,
+			.buf_ops = &xfs_refcountbt_buf_ops,
+			.magic = XFS_REFC_CRC_MAGIC,
+		},
+		[XREP_AGF_END] = {
+			.buf_ops = NULL,
+		},
+	};
+	struct xfs_agf			old_agf;
+	struct xfs_mount		*mp = sc->mp;
+	struct xfs_buf			*agf_bp;
+	struct xfs_buf			*agfl_bp;
+	struct xfs_agf			*agf;
+	int				error;
+
+	/* We require the rmapbt to rebuild anything. */
+	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+		return -EOPNOTSUPP;
+
+	xchk_perag_get(sc->mp, &sc->sa);
+	/*
+	 * Make sure we have the AGF buffer, as scrub might have decided it
+	 * was corrupt after xfs_alloc_read_agf failed with -EFSCORRUPTED.
+	 */
+	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
+			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGF_DADDR(mp)),
+			XFS_FSS_TO_BB(mp, 1), 0, &agf_bp, NULL);
+	if (error)
+		return error;
+	agf_bp->b_ops = &xfs_agf_buf_ops;
+	agf = XFS_BUF_TO_AGF(agf_bp);
+
+	/*
+	 * Load the AGFL so that we can screen out OWN_AG blocks that are on
+	 * the AGFL now; these blocks might have once been part of the
+	 * bno/cnt/rmap btrees but are not now.  This is a chicken and egg
+	 * problem: the AGF is corrupt, so we have to trust the AGFL contents
+	 * because we can't do any serious cross-referencing with any of the
+	 * btrees rooted in the AGF.  If the AGFL contents are obviously bad
+	 * then we'll bail out.
+	 */
+	error = xfs_alloc_read_agfl(mp, sc->tp, sc->sa.agno, &agfl_bp);
+	if (error)
+		return error;
+
+	/*
+	 * Spot-check the AGFL blocks; if they're obviously corrupt then
+	 * there's nothing we can do but bail out.
+	 */
+	error = xfs_agfl_walk(sc->mp, XFS_BUF_TO_AGF(agf_bp), agfl_bp,
+			xrep_agf_check_agfl_block, sc);
+	if (error)
+		return error;
+
+	/*
+	 * Find the AGF btree roots.  This is also a chicken-and-egg situation;
+	 * see the function for more details.
+	 */
+	error = xrep_agf_find_btrees(sc, agf_bp, fab, agfl_bp);
+	if (error)
+		return error;
+
+	/* Start rewriting the header and implant the btrees we found. */
+	xrep_agf_init_header(sc, agf_bp, &old_agf);
+	xrep_agf_set_roots(sc, agf, fab);
+	error = xrep_agf_calc_from_btrees(sc, agf_bp);
+	if (error)
+		goto out_revert;
+
+	/* Commit the changes and reinitialize incore state. */
+	return xrep_agf_commit_new(sc, agf_bp);
+
+out_revert:
+	/* Mark the incore AGF state stale and revert the AGF. */
+	sc->sa.pag->pagf_init = 0;
+	memcpy(agf, &old_agf, sizeof(old_agf));
+	return error;
+}
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 6c199e2ebb81..183d9e84c7e5 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -128,9 +128,12 @@ xrep_roll_ag_trans(
 	int			error;
 
 	/* Keep the AG header buffers locked so we can keep going. */
-	xfs_trans_bhold(sc->tp, sc->sa.agi_bp);
-	xfs_trans_bhold(sc->tp, sc->sa.agf_bp);
-	xfs_trans_bhold(sc->tp, sc->sa.agfl_bp);
+	if (sc->sa.agi_bp)
+		xfs_trans_bhold(sc->tp, sc->sa.agi_bp);
+	if (sc->sa.agf_bp)
+		xfs_trans_bhold(sc->tp, sc->sa.agf_bp);
+	if (sc->sa.agfl_bp)
+		xfs_trans_bhold(sc->tp, sc->sa.agfl_bp);
 
 	/* Roll the transaction. */
 	error = xfs_trans_roll(&sc->tp);
@@ -138,9 +141,12 @@ xrep_roll_ag_trans(
 		goto out_release;
 
 	/* Join AG headers to the new transaction. */
-	xfs_trans_bjoin(sc->tp, sc->sa.agi_bp);
-	xfs_trans_bjoin(sc->tp, sc->sa.agf_bp);
-	xfs_trans_bjoin(sc->tp, sc->sa.agfl_bp);
+	if (sc->sa.agi_bp)
+		xfs_trans_bjoin(sc->tp, sc->sa.agi_bp);
+	if (sc->sa.agf_bp)
+		xfs_trans_bjoin(sc->tp, sc->sa.agf_bp);
+	if (sc->sa.agfl_bp)
+		xfs_trans_bjoin(sc->tp, sc->sa.agfl_bp);
 
 	return 0;
 
@@ -150,9 +156,12 @@ xrep_roll_ag_trans(
 	 * buffers will be released during teardown on our way out
 	 * of the kernel.
 	 */
-	xfs_trans_bhold_release(sc->tp, sc->sa.agi_bp);
-	xfs_trans_bhold_release(sc->tp, sc->sa.agf_bp);
-	xfs_trans_bhold_release(sc->tp, sc->sa.agfl_bp);
+	if (sc->sa.agi_bp)
+		xfs_trans_bhold_release(sc->tp, sc->sa.agi_bp);
+	if (sc->sa.agf_bp)
+		xfs_trans_bhold_release(sc->tp, sc->sa.agf_bp);
+	if (sc->sa.agfl_bp)
+		xfs_trans_bhold_release(sc->tp, sc->sa.agfl_bp);
 
 	return error;
 }
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index 5a4e92221916..6f0903c51a47 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -58,6 +58,7 @@ int xrep_ino_dqattach(struct xfs_scrub *sc);
 
 int xrep_probe(struct xfs_scrub *sc);
 int xrep_superblock(struct xfs_scrub *sc);
+int xrep_agf(struct xfs_scrub *sc);
 
 #else
 
@@ -81,6 +82,7 @@ xrep_calc_ag_resblks(
 
 #define xrep_probe			xrep_notsupported
 #define xrep_superblock			xrep_notsupported
+#define xrep_agf			xrep_notsupported
 
 #endif /* CONFIG_XFS_ONLINE_REPAIR */
 
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 6efb926f3cf8..1e8a17c8e2b9 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -214,7 +214,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
 		.type	= ST_PERAG,
 		.setup	= xchk_setup_fs,
 		.scrub	= xchk_agf,
-		.repair	= xrep_notsupported,
+		.repair	= xrep_agf,
 	},
 	[XFS_SCRUB_TYPE_AGFL]= {	/* agfl */
 		.type	= ST_PERAG,

Re: [PATCH 2/4] xfs: repair the AGF

[Brian Foster]

On Tue, Aug 07, 2018 at 08:57:12PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Regenerate the AGF from the rmap data.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/scrub/agheader_repair.c |  370 ++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/scrub/repair.c          |   27 ++-
>  fs/xfs/scrub/repair.h          |    2 
>  fs/xfs/scrub/scrub.c           |    2 
>  4 files changed, 391 insertions(+), 10 deletions(-)
> 
> 
> diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
> index 1e96621ece3a..4842fc598c9b 100644
> --- a/fs/xfs/scrub/agheader_repair.c
> +++ b/fs/xfs/scrub/agheader_repair.c
...
> @@ -54,3 +61,366 @@ xrep_superblock(
...
> +/* Commit the new AGF and reinitialize the incore state. */
> +STATIC int
> +xrep_agf_commit_new(
> +	struct xfs_scrub	*sc,
> +	struct xfs_buf		*agf_bp)
> +{
> +	struct xfs_perag	*pag;
> +	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agf_bp);
> +
> +	/* Trigger fdblocks recalculation */
> +	xfs_force_summary_recalc(sc->mp);
> +
> +	/* Write this to disk. */
> +	xfs_trans_buf_set_type(sc->tp, agf_bp, XFS_BLFT_AGF_BUF);
> +	xfs_trans_log_buf(sc->tp, agf_bp, 0, BBTOB(agf_bp->b_length) - 1);
> +
> +	/* Now reinitialize the in-core counters we changed. */
> +	pag = sc->sa.pag;
> +	pag->pagf_btreeblks = be32_to_cpu(agf->agf_btreeblks);
> +	pag->pagf_freeblks = be32_to_cpu(agf->agf_freeblks);
> +	pag->pagf_longest = be32_to_cpu(agf->agf_longest);
> +	pag->pagf_levels[XFS_BTNUM_BNOi] =
> +			be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNOi]);
> +	pag->pagf_levels[XFS_BTNUM_CNTi] =
> +			be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNTi]);
> +	pag->pagf_levels[XFS_BTNUM_RMAPi] =
> +			be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAPi]);
> +	pag->pagf_refcount_level = be32_to_cpu(agf->agf_refcount_level);
> +	pag->pagf_init = 1;

I still think the above could be factored into a helper since it looks
like a copy of the associated xfs_alloc_read_agf() code. That aside,
this looks fine now that the ->pagf_init thing is fixed:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> +
> +	return 0;
> +}
> +
> +/* Repair the AGF. v5 filesystems only. */
> +int
> +xrep_agf(
> +	struct xfs_scrub		*sc)
> +{
> +	struct xrep_find_ag_btree	fab[XREP_AGF_MAX] = {
> +		[XREP_AGF_BNOBT] = {
> +			.rmap_owner = XFS_RMAP_OWN_AG,
> +			.buf_ops = &xfs_allocbt_buf_ops,
> +			.magic = XFS_ABTB_CRC_MAGIC,
> +		},
> +		[XREP_AGF_CNTBT] = {
> +			.rmap_owner = XFS_RMAP_OWN_AG,
> +			.buf_ops = &xfs_allocbt_buf_ops,
> +			.magic = XFS_ABTC_CRC_MAGIC,
> +		},
> +		[XREP_AGF_RMAPBT] = {
> +			.rmap_owner = XFS_RMAP_OWN_AG,
> +			.buf_ops = &xfs_rmapbt_buf_ops,
> +			.magic = XFS_RMAP_CRC_MAGIC,
> +		},
> +		[XREP_AGF_REFCOUNTBT] = {
> +			.rmap_owner = XFS_RMAP_OWN_REFC,
> +			.buf_ops = &xfs_refcountbt_buf_ops,
> +			.magic = XFS_REFC_CRC_MAGIC,
> +		},
> +		[XREP_AGF_END] = {
> +			.buf_ops = NULL,
> +		},
> +	};
> +	struct xfs_agf			old_agf;
> +	struct xfs_mount		*mp = sc->mp;
> +	struct xfs_buf			*agf_bp;
> +	struct xfs_buf			*agfl_bp;
> +	struct xfs_agf			*agf;
> +	int				error;
> +
> +	/* We require the rmapbt to rebuild anything. */
> +	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
> +		return -EOPNOTSUPP;
> +
> +	xchk_perag_get(sc->mp, &sc->sa);
> +	/*
> +	 * Make sure we have the AGF buffer, as scrub might have decided it
> +	 * was corrupt after xfs_alloc_read_agf failed with -EFSCORRUPTED.
> +	 */
> +	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
> +			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGF_DADDR(mp)),
> +			XFS_FSS_TO_BB(mp, 1), 0, &agf_bp, NULL);
> +	if (error)
> +		return error;
> +	agf_bp->b_ops = &xfs_agf_buf_ops;
> +	agf = XFS_BUF_TO_AGF(agf_bp);
> +
> +	/*
> +	 * Load the AGFL so that we can screen out OWN_AG blocks that are on
> +	 * the AGFL now; these blocks might have once been part of the
> +	 * bno/cnt/rmap btrees but are not now.  This is a chicken and egg
> +	 * problem: the AGF is corrupt, so we have to trust the AGFL contents
> +	 * because we can't do any serious cross-referencing with any of the
> +	 * btrees rooted in the AGF.  If the AGFL contents are obviously bad
> +	 * then we'll bail out.
> +	 */
> +	error = xfs_alloc_read_agfl(mp, sc->tp, sc->sa.agno, &agfl_bp);
> +	if (error)
> +		return error;
> +
> +	/*
> +	 * Spot-check the AGFL blocks; if they're obviously corrupt then
> +	 * there's nothing we can do but bail out.
> +	 */
> +	error = xfs_agfl_walk(sc->mp, XFS_BUF_TO_AGF(agf_bp), agfl_bp,
> +			xrep_agf_check_agfl_block, sc);
> +	if (error)
> +		return error;
> +
> +	/*
> +	 * Find the AGF btree roots.  This is also a chicken-and-egg situation;
> +	 * see the function for more details.
> +	 */
> +	error = xrep_agf_find_btrees(sc, agf_bp, fab, agfl_bp);
> +	if (error)
> +		return error;
> +
> +	/* Start rewriting the header and implant the btrees we found. */
> +	xrep_agf_init_header(sc, agf_bp, &old_agf);
> +	xrep_agf_set_roots(sc, agf, fab);
> +	error = xrep_agf_calc_from_btrees(sc, agf_bp);
> +	if (error)
> +		goto out_revert;
> +
> +	/* Commit the changes and reinitialize incore state. */
> +	return xrep_agf_commit_new(sc, agf_bp);
> +
> +out_revert:
> +	/* Mark the incore AGF state stale and revert the AGF. */
> +	sc->sa.pag->pagf_init = 0;
> +	memcpy(agf, &old_agf, sizeof(old_agf));
> +	return error;
> +}
> diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
> index 6c199e2ebb81..183d9e84c7e5 100644
> --- a/fs/xfs/scrub/repair.c
> +++ b/fs/xfs/scrub/repair.c
> @@ -128,9 +128,12 @@ xrep_roll_ag_trans(
>  	int			error;
>  
>  	/* Keep the AG header buffers locked so we can keep going. */
> -	xfs_trans_bhold(sc->tp, sc->sa.agi_bp);
> -	xfs_trans_bhold(sc->tp, sc->sa.agf_bp);
> -	xfs_trans_bhold(sc->tp, sc->sa.agfl_bp);
> +	if (sc->sa.agi_bp)
> +		xfs_trans_bhold(sc->tp, sc->sa.agi_bp);
> +	if (sc->sa.agf_bp)
> +		xfs_trans_bhold(sc->tp, sc->sa.agf_bp);
> +	if (sc->sa.agfl_bp)
> +		xfs_trans_bhold(sc->tp, sc->sa.agfl_bp);
>  
>  	/* Roll the transaction. */
>  	error = xfs_trans_roll(&sc->tp);
> @@ -138,9 +141,12 @@ xrep_roll_ag_trans(
>  		goto out_release;
>  
>  	/* Join AG headers to the new transaction. */
> -	xfs_trans_bjoin(sc->tp, sc->sa.agi_bp);
> -	xfs_trans_bjoin(sc->tp, sc->sa.agf_bp);
> -	xfs_trans_bjoin(sc->tp, sc->sa.agfl_bp);
> +	if (sc->sa.agi_bp)
> +		xfs_trans_bjoin(sc->tp, sc->sa.agi_bp);
> +	if (sc->sa.agf_bp)
> +		xfs_trans_bjoin(sc->tp, sc->sa.agf_bp);
> +	if (sc->sa.agfl_bp)
> +		xfs_trans_bjoin(sc->tp, sc->sa.agfl_bp);
>  
>  	return 0;
>  
> @@ -150,9 +156,12 @@ xrep_roll_ag_trans(
>  	 * buffers will be released during teardown on our way out
>  	 * of the kernel.
>  	 */
> -	xfs_trans_bhold_release(sc->tp, sc->sa.agi_bp);
> -	xfs_trans_bhold_release(sc->tp, sc->sa.agf_bp);
> -	xfs_trans_bhold_release(sc->tp, sc->sa.agfl_bp);
> +	if (sc->sa.agi_bp)
> +		xfs_trans_bhold_release(sc->tp, sc->sa.agi_bp);
> +	if (sc->sa.agf_bp)
> +		xfs_trans_bhold_release(sc->tp, sc->sa.agf_bp);
> +	if (sc->sa.agfl_bp)
> +		xfs_trans_bhold_release(sc->tp, sc->sa.agfl_bp);
>  
>  	return error;
>  }
> diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
> index 5a4e92221916..6f0903c51a47 100644
> --- a/fs/xfs/scrub/repair.h
> +++ b/fs/xfs/scrub/repair.h
> @@ -58,6 +58,7 @@ int xrep_ino_dqattach(struct xfs_scrub *sc);
>  
>  int xrep_probe(struct xfs_scrub *sc);
>  int xrep_superblock(struct xfs_scrub *sc);
> +int xrep_agf(struct xfs_scrub *sc);
>  
>  #else
>  
> @@ -81,6 +82,7 @@ xrep_calc_ag_resblks(
>  
>  #define xrep_probe			xrep_notsupported
>  #define xrep_superblock			xrep_notsupported
> +#define xrep_agf			xrep_notsupported
>  
>  #endif /* CONFIG_XFS_ONLINE_REPAIR */
>  
> diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
> index 6efb926f3cf8..1e8a17c8e2b9 100644
> --- a/fs/xfs/scrub/scrub.c
> +++ b/fs/xfs/scrub/scrub.c
> @@ -214,7 +214,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
>  		.type	= ST_PERAG,
>  		.setup	= xchk_setup_fs,
>  		.scrub	= xchk_agf,
> -		.repair	= xrep_notsupported,
> +		.repair	= xrep_agf,
>  	},
>  	[XFS_SCRUB_TYPE_AGFL]= {	/* agfl */
>  		.type	= ST_PERAG,
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 3/4] xfs: repair the AGFL

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Repair the AGFL from the rmap data.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/agheader_repair.c |  284 ++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/bitmap.c          |   92 +++++++++++++
 fs/xfs/scrub/bitmap.h          |    4 +
 fs/xfs/scrub/repair.h          |    2 
 fs/xfs/scrub/scrub.c           |    2 
 5 files changed, 383 insertions(+), 1 deletion(-)


diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index 4842fc598c9b..0decf711b3c7 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -424,3 +424,287 @@ xrep_agf(
 	memcpy(agf, &old_agf, sizeof(old_agf));
 	return error;
 }
+
+/* AGFL */
+
+struct xrep_agfl {
+	/* Bitmap of other OWN_AG metadata blocks. */
+	struct xfs_bitmap	agmetablocks;
+
+	/* Bitmap of free space. */
+	struct xfs_bitmap	*freesp;
+
+	struct xfs_scrub	*sc;
+};
+
+/* Record all OWN_AG (free space btree) information from the rmap data. */
+STATIC int
+xrep_agfl_walk_rmap(
+	struct xfs_btree_cur	*cur,
+	struct xfs_rmap_irec	*rec,
+	void			*priv)
+{
+	struct xrep_agfl	*ra = priv;
+	xfs_fsblock_t		fsb;
+	int			error = 0;
+
+	if (xchk_should_terminate(ra->sc, &error))
+		return error;
+
+	/* Record all the OWN_AG blocks. */
+	if (rec->rm_owner == XFS_RMAP_OWN_AG) {
+		fsb = XFS_AGB_TO_FSB(cur->bc_mp, cur->bc_private.a.agno,
+				rec->rm_startblock);
+		error = xfs_bitmap_set(ra->freesp, fsb, rec->rm_blockcount);
+		if (error)
+			return error;
+	}
+
+	return xfs_bitmap_set_btcur_path(&ra->agmetablocks, cur);
+}
+
+/*
+ * Map out all the non-AGFL OWN_AG space in this AG so that we can deduce
+ * which blocks belong to the AGFL.
+ *
+ * Compute the set of old AGFL blocks by subtracting from the list of OWN_AG
+ * blocks the list of blocks owned by all other OWN_AG metadata (bnobt, cntbt,
+ * rmapbt).  These are the old AGFL blocks, so return that list and the number
+ * of blocks we're actually going to put back on the AGFL.
+ */
+STATIC int
+xrep_agfl_collect_blocks(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agf_bp,
+	struct xfs_bitmap	*agfl_extents,
+	xfs_agblock_t		*flcount)
+{
+	struct xrep_agfl	ra;
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_btree_cur	*cur;
+	struct xfs_bitmap_range	*br;
+	struct xfs_bitmap_range	*n;
+	int			error;
+
+	ra.sc = sc;
+	ra.freesp = agfl_extents;
+	xfs_bitmap_init(&ra.agmetablocks);
+
+	/* Find all space used by the free space btrees & rmapbt. */
+	cur = xfs_rmapbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno);
+	error = xfs_rmap_query_all(cur, xrep_agfl_walk_rmap, &ra);
+	if (error)
+		goto err;
+	xfs_btree_del_cursor(cur, error);
+
+	/* Find all blocks currently being used by the bnobt. */
+	cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno,
+			XFS_BTNUM_BNO);
+	error = xfs_bitmap_set_btblocks(&ra.agmetablocks, cur);
+	if (error)
+		goto err;
+	xfs_btree_del_cursor(cur, error);
+
+	/* Find all blocks currently being used by the cntbt. */
+	cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.agno,
+			XFS_BTNUM_CNT);
+	error = xfs_bitmap_set_btblocks(&ra.agmetablocks, cur);
+	if (error)
+		goto err;
+
+	xfs_btree_del_cursor(cur, error);
+
+	/*
+	 * Drop the freesp meta blocks that are in use by btrees.
+	 * The remaining blocks /should/ be AGFL blocks.
+	 */
+	error = xfs_bitmap_disunion(agfl_extents, &ra.agmetablocks);
+	xfs_bitmap_destroy(&ra.agmetablocks);
+	if (error)
+		return error;
+
+	/*
+	 * Calculate the new AGFL size.  If we found more blocks than fit in
+	 * the AGFL we'll free them later.
+	 */
+	*flcount = 0;
+	for_each_xfs_bitmap_extent(br, n, agfl_extents) {
+		*flcount += br->len;
+		if (*flcount > xfs_agfl_size(mp))
+			break;
+	}
+	if (*flcount > xfs_agfl_size(mp))
+		*flcount = xfs_agfl_size(mp);
+	return 0;
+
+err:
+	xfs_bitmap_destroy(&ra.agmetablocks);
+	xfs_btree_del_cursor(cur, error);
+	return error;
+}
+
+/* Update the AGF and reset the in-core state. */
+STATIC int
+xrep_agfl_update_agf(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agf_bp,
+	xfs_agblock_t		flcount)
+{
+	struct xfs_agf		*agf = XFS_BUF_TO_AGF(agf_bp);
+
+	ASSERT(flcount <= xfs_agfl_size(sc->mp));
+
+	/* Trigger fdblocks recalculation */
+	xfs_force_summary_recalc(sc->mp);
+
+	/* Update the AGF counters. */
+	if (sc->sa.pag->pagf_init)
+		sc->sa.pag->pagf_flcount = flcount;
+	agf->agf_flfirst = cpu_to_be32(0);
+	agf->agf_flcount = cpu_to_be32(flcount);
+	agf->agf_fllast = cpu_to_be32(flcount - 1);
+
+	xfs_alloc_log_agf(sc->tp, agf_bp,
+			XFS_AGF_FLFIRST | XFS_AGF_FLLAST | XFS_AGF_FLCOUNT);
+	return 0;
+}
+
+/* Write out a totally new AGFL. */
+STATIC void
+xrep_agfl_init_header(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agfl_bp,
+	struct xfs_bitmap	*agfl_extents,
+	xfs_agblock_t		flcount)
+{
+	struct xfs_mount	*mp = sc->mp;
+	__be32			*agfl_bno;
+	struct xfs_bitmap_range	*br;
+	struct xfs_bitmap_range	*n;
+	struct xfs_agfl		*agfl;
+	xfs_agblock_t		agbno;
+	unsigned int		fl_off;
+
+	ASSERT(flcount <= xfs_agfl_size(mp));
+
+	/*
+	 * Start rewriting the header by setting the bno[] array to
+	 * NULLAGBLOCK, then setting AGFL header fields.
+	 */
+	agfl = XFS_BUF_TO_AGFL(agfl_bp);
+	memset(agfl, 0xFF, BBTOB(agfl_bp->b_length));
+	agfl->agfl_magicnum = cpu_to_be32(XFS_AGFL_MAGIC);
+	agfl->agfl_seqno = cpu_to_be32(sc->sa.agno);
+	uuid_copy(&agfl->agfl_uuid, &mp->m_sb.sb_meta_uuid);
+
+	/*
+	 * Fill the AGFL with the remaining blocks.  If agfl_extents has more
+	 * blocks than fit in the AGFL, they will be freed in a subsequent
+	 * step.
+	 */
+	fl_off = 0;
+	agfl_bno = XFS_BUF_TO_AGFL_BNO(mp, agfl_bp);
+	for_each_xfs_bitmap_extent(br, n, agfl_extents) {
+		agbno = XFS_FSB_TO_AGBNO(mp, br->start);
+
+		trace_xrep_agfl_insert(mp, sc->sa.agno, agbno, br->len);
+
+		while (br->len > 0 && fl_off < flcount) {
+			agfl_bno[fl_off] = cpu_to_be32(agbno);
+			fl_off++;
+			agbno++;
+
+			/*
+			 * We've now used br->start by putting it in the AGFL,
+			 * so bump br so that we don't reap the block later.
+			 */
+			br->start++;
+			br->len--;
+		}
+
+		if (br->len)
+			break;
+		list_del(&br->list);
+		kmem_free(br);
+	}
+
+	/* Write new AGFL to disk. */
+	xfs_trans_buf_set_type(sc->tp, agfl_bp, XFS_BLFT_AGFL_BUF);
+	xfs_trans_log_buf(sc->tp, agfl_bp, 0, BBTOB(agfl_bp->b_length) - 1);
+}
+
+/* Repair the AGFL. */
+int
+xrep_agfl(
+	struct xfs_scrub	*sc)
+{
+	struct xfs_owner_info	oinfo;
+	struct xfs_bitmap	agfl_extents;
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_buf		*agf_bp;
+	struct xfs_buf		*agfl_bp;
+	xfs_agblock_t		flcount;
+	int			error;
+
+	/* We require the rmapbt to rebuild anything. */
+	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+		return -EOPNOTSUPP;
+
+	xchk_perag_get(sc->mp, &sc->sa);
+	xfs_bitmap_init(&agfl_extents);
+
+	/*
+	 * Read the AGF so that we can query the rmapbt.  We hope that there's
+	 * nothing wrong with the AGF, but all the AG header repair functions
+	 * have this chicken-and-egg problem.
+	 */
+	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
+	if (error)
+		return error;
+	if (!agf_bp)
+		return -ENOMEM;
+
+	/*
+	 * Make sure we have the AGFL buffer, as scrub might have decided it
+	 * was corrupt after xfs_alloc_read_agfl failed with -EFSCORRUPTED.
+	 */
+	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
+			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGFL_DADDR(mp)),
+			XFS_FSS_TO_BB(mp, 1), 0, &agfl_bp, NULL);
+	if (error)
+		return error;
+	agfl_bp->b_ops = &xfs_agfl_buf_ops;
+
+	/* Gather all the extents we're going to put on the new AGFL. */
+	error = xrep_agfl_collect_blocks(sc, agf_bp, &agfl_extents, &flcount);
+	if (error)
+		goto err;
+
+	/*
+	 * Update AGF and AGFL.  We reset the global free block counter when
+	 * we adjust the AGF flcount (which can fail) so avoid updating any
+	 * buffers until we know that part works.
+	 */
+	error = xrep_agfl_update_agf(sc, agf_bp, flcount);
+	if (error)
+		goto err;
+	xrep_agfl_init_header(sc, agfl_bp, &agfl_extents, flcount);
+
+	/*
+	 * Ok, the AGFL should be ready to go now.  Roll the transaction to
+	 * make the new AGFL permanent before we start using it to return
+	 * freespace overflow to the freespace btrees.
+	 */
+	sc->sa.agf_bp = agf_bp;
+	sc->sa.agfl_bp = agfl_bp;
+	error = xrep_roll_ag_trans(sc);
+	if (error)
+		goto err;
+
+	/* Dump any AGFL overflow. */
+	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
+	return xrep_reap_extents(sc, &agfl_extents, &oinfo, XFS_AG_RESV_AGFL);
+err:
+	xfs_bitmap_destroy(&agfl_extents);
+	return error;
+}
diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
index c770e2d0b6aa..fdadc9e1dc49 100644
--- a/fs/xfs/scrub/bitmap.c
+++ b/fs/xfs/scrub/bitmap.c
@@ -9,6 +9,7 @@
 #include "xfs_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_mount.h"
+#include "xfs_btree.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
@@ -209,3 +210,94 @@ xfs_bitmap_disunion(
 }
 #undef LEFT_ALIGNED
 #undef RIGHT_ALIGNED
+
+/*
+ * Record all btree blocks seen while iterating all records of a btree.
+ *
+ * We know that the btree query_all function starts at the left edge and walks
+ * towards the right edge of the tree.  Therefore, we know that we can walk up
+ * the btree cursor towards the root; if the pointer for a given level points
+ * to the first record/key in that block, we haven't seen this block before;
+ * and therefore we need to remember that we saw this block in the btree.
+ *
+ * So if our btree is:
+ *
+ *    4
+ *  / | \
+ * 1  2  3
+ *
+ * Pretend for this example that each leaf block has 100 btree records.  For
+ * the first btree record, we'll observe that bc_ptrs[0] == 1, so we record
+ * that we saw block 1.  Then we observe that bc_ptrs[1] == 1, so we record
+ * block 4.  The list is [1, 4].
+ *
+ * For the second btree record, we see that bc_ptrs[0] == 2, so we exit the
+ * loop.  The list remains [1, 4].
+ *
+ * For the 101st btree record, we've moved onto leaf block 2.  Now
+ * bc_ptrs[0] == 1 again, so we record that we saw block 2.  We see that
+ * bc_ptrs[1] == 2, so we exit the loop.  The list is now [1, 4, 2].
+ *
+ * For the 102nd record, bc_ptrs[0] == 2, so we continue.
+ *
+ * For the 201st record, we've moved on to leaf block 3.  bc_ptrs[0] == 1, so
+ * we add 3 to the list.  Now it is [1, 4, 2, 3].
+ *
+ * For the 300th record we just exit, with the list being [1, 4, 2, 3].
+ */
+
+/*
+ * Record all the buffers pointed to by the btree cursor.  Callers already
+ * engaged in a btree walk should call this function to capture the list of
+ * blocks going from the leaf towards the root.
+ */
+int
+xfs_bitmap_set_btcur_path(
+	struct xfs_bitmap	*bitmap,
+	struct xfs_btree_cur	*cur)
+{
+	struct xfs_buf		*bp;
+	xfs_fsblock_t		fsb;
+	int			i;
+	int			error;
+
+	for (i = 0; i < cur->bc_nlevels && cur->bc_ptrs[i] == 1; i++) {
+		xfs_btree_get_block(cur, i, &bp);
+		if (!bp)
+			continue;
+		fsb = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
+		error = xfs_bitmap_set(bitmap, fsb, 1);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+/* Collect a btree's block in the bitmap. */
+STATIC int
+xfs_bitmap_collect_btblock(
+	struct xfs_btree_cur	*cur,
+	int			level,
+	void			*priv)
+{
+	struct xfs_bitmap	*bitmap = priv;
+	struct xfs_buf		*bp;
+	xfs_fsblock_t		fsbno;
+
+	xfs_btree_get_block(cur, level, &bp);
+	if (!bp)
+		return 0;
+
+	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
+	return xfs_bitmap_set(bitmap, fsbno, 1);
+}
+
+/* Walk the btree and mark the bitmap wherever a btree block is found. */
+int
+xfs_bitmap_set_btblocks(
+	struct xfs_bitmap	*bitmap,
+	struct xfs_btree_cur	*cur)
+{
+	return xfs_btree_visit_blocks(cur, xfs_bitmap_collect_btblock, bitmap);
+}
diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
index dad652ee9177..ae8ecbce6fa6 100644
--- a/fs/xfs/scrub/bitmap.h
+++ b/fs/xfs/scrub/bitmap.h
@@ -28,5 +28,9 @@ void xfs_bitmap_destroy(struct xfs_bitmap *bitmap);
 
 int xfs_bitmap_set(struct xfs_bitmap *bitmap, uint64_t start, uint64_t len);
 int xfs_bitmap_disunion(struct xfs_bitmap *bitmap, struct xfs_bitmap *sub);
+int xfs_bitmap_set_btcur_path(struct xfs_bitmap *bitmap,
+		struct xfs_btree_cur *cur);
+int xfs_bitmap_set_btblocks(struct xfs_bitmap *bitmap,
+		struct xfs_btree_cur *cur);
 
 #endif	/* __XFS_SCRUB_BITMAP_H__ */
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index 6f0903c51a47..1d283360b5ab 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -59,6 +59,7 @@ int xrep_ino_dqattach(struct xfs_scrub *sc);
 int xrep_probe(struct xfs_scrub *sc);
 int xrep_superblock(struct xfs_scrub *sc);
 int xrep_agf(struct xfs_scrub *sc);
+int xrep_agfl(struct xfs_scrub *sc);
 
 #else
 
@@ -83,6 +84,7 @@ xrep_calc_ag_resblks(
 #define xrep_probe			xrep_notsupported
 #define xrep_superblock			xrep_notsupported
 #define xrep_agf			xrep_notsupported
+#define xrep_agfl			xrep_notsupported
 
 #endif /* CONFIG_XFS_ONLINE_REPAIR */
 
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 1e8a17c8e2b9..2670f4cf62f4 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -220,7 +220,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
 		.type	= ST_PERAG,
 		.setup	= xchk_setup_fs,
 		.scrub	= xchk_agfl,
-		.repair	= xrep_notsupported,
+		.repair	= xrep_agfl,
 	},
 	[XFS_SCRUB_TYPE_AGI] = {	/* agi */
 		.type	= ST_PERAG,

Re: [PATCH 3/4] xfs: repair the AGFL

[Brian Foster]

On Tue, Aug 07, 2018 at 08:57:19PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Repair the AGFL from the rmap data.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/scrub/agheader_repair.c |  284 ++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/scrub/bitmap.c          |   92 +++++++++++++
>  fs/xfs/scrub/bitmap.h          |    4 +
>  fs/xfs/scrub/repair.h          |    2 
>  fs/xfs/scrub/scrub.c           |    2 
>  5 files changed, 383 insertions(+), 1 deletion(-)
> 
> 
> diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
> index 4842fc598c9b..0decf711b3c7 100644
> --- a/fs/xfs/scrub/agheader_repair.c
> +++ b/fs/xfs/scrub/agheader_repair.c
> @@ -424,3 +424,287 @@ xrep_agf(
...
> +/* Repair the AGFL. */
> +int
> +xrep_agfl(
> +	struct xfs_scrub	*sc)
> +{
> +	struct xfs_owner_info	oinfo;
> +	struct xfs_bitmap	agfl_extents;
> +	struct xfs_mount	*mp = sc->mp;
> +	struct xfs_buf		*agf_bp;
> +	struct xfs_buf		*agfl_bp;
> +	xfs_agblock_t		flcount;
> +	int			error;
> +
> +	/* We require the rmapbt to rebuild anything. */
> +	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
> +		return -EOPNOTSUPP;
> +
> +	xchk_perag_get(sc->mp, &sc->sa);
> +	xfs_bitmap_init(&agfl_extents);
> +
> +	/*
> +	 * Read the AGF so that we can query the rmapbt.  We hope that there's
> +	 * nothing wrong with the AGF, but all the AG header repair functions
> +	 * have this chicken-and-egg problem.
> +	 */
> +	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
> +	if (error)
> +		return error;
> +	if (!agf_bp)
> +		return -ENOMEM;
> +
> +	/*
> +	 * Make sure we have the AGFL buffer, as scrub might have decided it
> +	 * was corrupt after xfs_alloc_read_agfl failed with -EFSCORRUPTED.
> +	 */
> +	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
> +			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGFL_DADDR(mp)),
> +			XFS_FSS_TO_BB(mp, 1), 0, &agfl_bp, NULL);
> +	if (error)
> +		return error;
> +	agfl_bp->b_ops = &xfs_agfl_buf_ops;
> +
> +	/* Gather all the extents we're going to put on the new AGFL. */
> +	error = xrep_agfl_collect_blocks(sc, agf_bp, &agfl_extents, &flcount);
> +	if (error)
> +		goto err;
> +
> +	/*
> +	 * Update AGF and AGFL.  We reset the global free block counter when
> +	 * we adjust the AGF flcount (which can fail) so avoid updating any
> +	 * buffers until we know that part works.
> +	 */
> +	error = xrep_agfl_update_agf(sc, agf_bp, flcount);
> +	if (error)
> +		goto err;
> +	xrep_agfl_init_header(sc, agfl_bp, &agfl_extents, flcount);
> +
> +	/*
> +	 * Ok, the AGFL should be ready to go now.  Roll the transaction to
> +	 * make the new AGFL permanent before we start using it to return
> +	 * freespace overflow to the freespace btrees.
> +	 */
> +	sc->sa.agf_bp = agf_bp;
> +	sc->sa.agfl_bp = agfl_bp;
> +	error = xrep_roll_ag_trans(sc);
> +	if (error)
> +		goto err;
> +
> +	/* Dump any AGFL overflow. */
> +	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
> +	return xrep_reap_extents(sc, &agfl_extents, &oinfo, XFS_AG_RESV_AGFL);
> +err:
> +	xfs_bitmap_destroy(&agfl_extents);
> +	return error;

Was there a reason we don't maintain the ability to revert the AGFL on
error as is done in the AGF repair case? I take it we'll end up shutting
down the fs if anything causes us to fail once we've logged the
associated agf fields in xrep_agfl_update_agf()..?

Brian

> +}
> diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
> index c770e2d0b6aa..fdadc9e1dc49 100644
> --- a/fs/xfs/scrub/bitmap.c
> +++ b/fs/xfs/scrub/bitmap.c
> @@ -9,6 +9,7 @@
>  #include "xfs_format.h"
>  #include "xfs_trans_resv.h"
>  #include "xfs_mount.h"
> +#include "xfs_btree.h"
>  #include "scrub/xfs_scrub.h"
>  #include "scrub/scrub.h"
>  #include "scrub/common.h"
> @@ -209,3 +210,94 @@ xfs_bitmap_disunion(
>  }
>  #undef LEFT_ALIGNED
>  #undef RIGHT_ALIGNED
> +
> +/*
> + * Record all btree blocks seen while iterating all records of a btree.
> + *
> + * We know that the btree query_all function starts at the left edge and walks
> + * towards the right edge of the tree.  Therefore, we know that we can walk up
> + * the btree cursor towards the root; if the pointer for a given level points
> + * to the first record/key in that block, we haven't seen this block before;
> + * and therefore we need to remember that we saw this block in the btree.
> + *
> + * So if our btree is:
> + *
> + *    4
> + *  / | \
> + * 1  2  3
> + *
> + * Pretend for this example that each leaf block has 100 btree records.  For
> + * the first btree record, we'll observe that bc_ptrs[0] == 1, so we record
> + * that we saw block 1.  Then we observe that bc_ptrs[1] == 1, so we record
> + * block 4.  The list is [1, 4].
> + *
> + * For the second btree record, we see that bc_ptrs[0] == 2, so we exit the
> + * loop.  The list remains [1, 4].
> + *
> + * For the 101st btree record, we've moved onto leaf block 2.  Now
> + * bc_ptrs[0] == 1 again, so we record that we saw block 2.  We see that
> + * bc_ptrs[1] == 2, so we exit the loop.  The list is now [1, 4, 2].
> + *
> + * For the 102nd record, bc_ptrs[0] == 2, so we continue.
> + *
> + * For the 201st record, we've moved on to leaf block 3.  bc_ptrs[0] == 1, so
> + * we add 3 to the list.  Now it is [1, 4, 2, 3].
> + *
> + * For the 300th record we just exit, with the list being [1, 4, 2, 3].
> + */
> +
> +/*
> + * Record all the buffers pointed to by the btree cursor.  Callers already
> + * engaged in a btree walk should call this function to capture the list of
> + * blocks going from the leaf towards the root.
> + */
> +int
> +xfs_bitmap_set_btcur_path(
> +	struct xfs_bitmap	*bitmap,
> +	struct xfs_btree_cur	*cur)
> +{
> +	struct xfs_buf		*bp;
> +	xfs_fsblock_t		fsb;
> +	int			i;
> +	int			error;
> +
> +	for (i = 0; i < cur->bc_nlevels && cur->bc_ptrs[i] == 1; i++) {
> +		xfs_btree_get_block(cur, i, &bp);
> +		if (!bp)
> +			continue;
> +		fsb = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
> +		error = xfs_bitmap_set(bitmap, fsb, 1);
> +		if (error)
> +			return error;
> +	}
> +
> +	return 0;
> +}
> +
> +/* Collect a btree's block in the bitmap. */
> +STATIC int
> +xfs_bitmap_collect_btblock(
> +	struct xfs_btree_cur	*cur,
> +	int			level,
> +	void			*priv)
> +{
> +	struct xfs_bitmap	*bitmap = priv;
> +	struct xfs_buf		*bp;
> +	xfs_fsblock_t		fsbno;
> +
> +	xfs_btree_get_block(cur, level, &bp);
> +	if (!bp)
> +		return 0;
> +
> +	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
> +	return xfs_bitmap_set(bitmap, fsbno, 1);
> +}
> +
> +/* Walk the btree and mark the bitmap wherever a btree block is found. */
> +int
> +xfs_bitmap_set_btblocks(
> +	struct xfs_bitmap	*bitmap,
> +	struct xfs_btree_cur	*cur)
> +{
> +	return xfs_btree_visit_blocks(cur, xfs_bitmap_collect_btblock, bitmap);
> +}
> diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
> index dad652ee9177..ae8ecbce6fa6 100644
> --- a/fs/xfs/scrub/bitmap.h
> +++ b/fs/xfs/scrub/bitmap.h
> @@ -28,5 +28,9 @@ void xfs_bitmap_destroy(struct xfs_bitmap *bitmap);
>  
>  int xfs_bitmap_set(struct xfs_bitmap *bitmap, uint64_t start, uint64_t len);
>  int xfs_bitmap_disunion(struct xfs_bitmap *bitmap, struct xfs_bitmap *sub);
> +int xfs_bitmap_set_btcur_path(struct xfs_bitmap *bitmap,
> +		struct xfs_btree_cur *cur);
> +int xfs_bitmap_set_btblocks(struct xfs_bitmap *bitmap,
> +		struct xfs_btree_cur *cur);
>  
>  #endif	/* __XFS_SCRUB_BITMAP_H__ */
> diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
> index 6f0903c51a47..1d283360b5ab 100644
> --- a/fs/xfs/scrub/repair.h
> +++ b/fs/xfs/scrub/repair.h
> @@ -59,6 +59,7 @@ int xrep_ino_dqattach(struct xfs_scrub *sc);
>  int xrep_probe(struct xfs_scrub *sc);
>  int xrep_superblock(struct xfs_scrub *sc);
>  int xrep_agf(struct xfs_scrub *sc);
> +int xrep_agfl(struct xfs_scrub *sc);
>  
>  #else
>  
> @@ -83,6 +84,7 @@ xrep_calc_ag_resblks(
>  #define xrep_probe			xrep_notsupported
>  #define xrep_superblock			xrep_notsupported
>  #define xrep_agf			xrep_notsupported
> +#define xrep_agfl			xrep_notsupported
>  
>  #endif /* CONFIG_XFS_ONLINE_REPAIR */
>  
> diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
> index 1e8a17c8e2b9..2670f4cf62f4 100644
> --- a/fs/xfs/scrub/scrub.c
> +++ b/fs/xfs/scrub/scrub.c
> @@ -220,7 +220,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
>  		.type	= ST_PERAG,
>  		.setup	= xchk_setup_fs,
>  		.scrub	= xchk_agfl,
> -		.repair	= xrep_notsupported,
> +		.repair	= xrep_agfl,
>  	},
>  	[XFS_SCRUB_TYPE_AGI] = {	/* agi */
>  		.type	= ST_PERAG,
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 3/4] xfs: repair the AGFL

[Darrick J. Wong]

On Thu, Aug 09, 2018 at 09:08:58AM -0400, Brian Foster wrote:
> On Tue, Aug 07, 2018 at 08:57:19PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Repair the AGFL from the rmap data.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/scrub/agheader_repair.c |  284 ++++++++++++++++++++++++++++++++++++++++
> >  fs/xfs/scrub/bitmap.c          |   92 +++++++++++++
> >  fs/xfs/scrub/bitmap.h          |    4 +
> >  fs/xfs/scrub/repair.h          |    2 
> >  fs/xfs/scrub/scrub.c           |    2 
> >  5 files changed, 383 insertions(+), 1 deletion(-)
> > 
> > 
> > diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
> > index 4842fc598c9b..0decf711b3c7 100644
> > --- a/fs/xfs/scrub/agheader_repair.c
> > +++ b/fs/xfs/scrub/agheader_repair.c
> > @@ -424,3 +424,287 @@ xrep_agf(
> ...
> > +/* Repair the AGFL. */
> > +int
> > +xrep_agfl(
> > +	struct xfs_scrub	*sc)
> > +{
> > +	struct xfs_owner_info	oinfo;
> > +	struct xfs_bitmap	agfl_extents;
> > +	struct xfs_mount	*mp = sc->mp;
> > +	struct xfs_buf		*agf_bp;
> > +	struct xfs_buf		*agfl_bp;
> > +	xfs_agblock_t		flcount;
> > +	int			error;
> > +
> > +	/* We require the rmapbt to rebuild anything. */
> > +	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
> > +		return -EOPNOTSUPP;
> > +
> > +	xchk_perag_get(sc->mp, &sc->sa);
> > +	xfs_bitmap_init(&agfl_extents);
> > +
> > +	/*
> > +	 * Read the AGF so that we can query the rmapbt.  We hope that there's
> > +	 * nothing wrong with the AGF, but all the AG header repair functions
> > +	 * have this chicken-and-egg problem.
> > +	 */
> > +	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
> > +	if (error)
> > +		return error;
> > +	if (!agf_bp)
> > +		return -ENOMEM;
> > +
> > +	/*
> > +	 * Make sure we have the AGFL buffer, as scrub might have decided it
> > +	 * was corrupt after xfs_alloc_read_agfl failed with -EFSCORRUPTED.
> > +	 */
> > +	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
> > +			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGFL_DADDR(mp)),
> > +			XFS_FSS_TO_BB(mp, 1), 0, &agfl_bp, NULL);
> > +	if (error)
> > +		return error;
> > +	agfl_bp->b_ops = &xfs_agfl_buf_ops;
> > +
> > +	/* Gather all the extents we're going to put on the new AGFL. */
> > +	error = xrep_agfl_collect_blocks(sc, agf_bp, &agfl_extents, &flcount);
> > +	if (error)
> > +		goto err;
> > +
> > +	/*
> > +	 * Update AGF and AGFL.  We reset the global free block counter when
> > +	 * we adjust the AGF flcount (which can fail) so avoid updating any
> > +	 * buffers until we know that part works.
> > +	 */
> > +	error = xrep_agfl_update_agf(sc, agf_bp, flcount);
> > +	if (error)
> > +		goto err;
> > +	xrep_agfl_init_header(sc, agfl_bp, &agfl_extents, flcount);
> > +
> > +	/*
> > +	 * Ok, the AGFL should be ready to go now.  Roll the transaction to
> > +	 * make the new AGFL permanent before we start using it to return
> > +	 * freespace overflow to the freespace btrees.
> > +	 */
> > +	sc->sa.agf_bp = agf_bp;
> > +	sc->sa.agfl_bp = agfl_bp;
> > +	error = xrep_roll_ag_trans(sc);
> > +	if (error)
> > +		goto err;
> > +
> > +	/* Dump any AGFL overflow. */
> > +	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
> > +	return xrep_reap_extents(sc, &agfl_extents, &oinfo, XFS_AG_RESV_AGFL);
> > +err:
> > +	xfs_bitmap_destroy(&agfl_extents);
> > +	return error;
> 
> Was there a reason we don't maintain the ability to revert the AGFL on
> error as is done in the AGF repair case? I take it we'll end up shutting
> down the fs if anything causes us to fail once we've logged the
> associated agf fields in xrep_agfl_update_agf()..?

Yep.  Once we've started logging we don't really want to deal with the
complexity of rolling back a transaction.  The fs will shut down and the
admin can run xfs_repair instead.

--D

> Brian
> 
> > +}
> > diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
> > index c770e2d0b6aa..fdadc9e1dc49 100644
> > --- a/fs/xfs/scrub/bitmap.c
> > +++ b/fs/xfs/scrub/bitmap.c
> > @@ -9,6 +9,7 @@
> >  #include "xfs_format.h"
> >  #include "xfs_trans_resv.h"
> >  #include "xfs_mount.h"
> > +#include "xfs_btree.h"
> >  #include "scrub/xfs_scrub.h"
> >  #include "scrub/scrub.h"
> >  #include "scrub/common.h"
> > @@ -209,3 +210,94 @@ xfs_bitmap_disunion(
> >  }
> >  #undef LEFT_ALIGNED
> >  #undef RIGHT_ALIGNED
> > +
> > +/*
> > + * Record all btree blocks seen while iterating all records of a btree.
> > + *
> > + * We know that the btree query_all function starts at the left edge and walks
> > + * towards the right edge of the tree.  Therefore, we know that we can walk up
> > + * the btree cursor towards the root; if the pointer for a given level points
> > + * to the first record/key in that block, we haven't seen this block before;
> > + * and therefore we need to remember that we saw this block in the btree.
> > + *
> > + * So if our btree is:
> > + *
> > + *    4
> > + *  / | \
> > + * 1  2  3
> > + *
> > + * Pretend for this example that each leaf block has 100 btree records.  For
> > + * the first btree record, we'll observe that bc_ptrs[0] == 1, so we record
> > + * that we saw block 1.  Then we observe that bc_ptrs[1] == 1, so we record
> > + * block 4.  The list is [1, 4].
> > + *
> > + * For the second btree record, we see that bc_ptrs[0] == 2, so we exit the
> > + * loop.  The list remains [1, 4].
> > + *
> > + * For the 101st btree record, we've moved onto leaf block 2.  Now
> > + * bc_ptrs[0] == 1 again, so we record that we saw block 2.  We see that
> > + * bc_ptrs[1] == 2, so we exit the loop.  The list is now [1, 4, 2].
> > + *
> > + * For the 102nd record, bc_ptrs[0] == 2, so we continue.
> > + *
> > + * For the 201st record, we've moved on to leaf block 3.  bc_ptrs[0] == 1, so
> > + * we add 3 to the list.  Now it is [1, 4, 2, 3].
> > + *
> > + * For the 300th record we just exit, with the list being [1, 4, 2, 3].
> > + */
> > +
> > +/*
> > + * Record all the buffers pointed to by the btree cursor.  Callers already
> > + * engaged in a btree walk should call this function to capture the list of
> > + * blocks going from the leaf towards the root.
> > + */
> > +int
> > +xfs_bitmap_set_btcur_path(
> > +	struct xfs_bitmap	*bitmap,
> > +	struct xfs_btree_cur	*cur)
> > +{
> > +	struct xfs_buf		*bp;
> > +	xfs_fsblock_t		fsb;
> > +	int			i;
> > +	int			error;
> > +
> > +	for (i = 0; i < cur->bc_nlevels && cur->bc_ptrs[i] == 1; i++) {
> > +		xfs_btree_get_block(cur, i, &bp);
> > +		if (!bp)
> > +			continue;
> > +		fsb = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
> > +		error = xfs_bitmap_set(bitmap, fsb, 1);
> > +		if (error)
> > +			return error;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +/* Collect a btree's block in the bitmap. */
> > +STATIC int
> > +xfs_bitmap_collect_btblock(
> > +	struct xfs_btree_cur	*cur,
> > +	int			level,
> > +	void			*priv)
> > +{
> > +	struct xfs_bitmap	*bitmap = priv;
> > +	struct xfs_buf		*bp;
> > +	xfs_fsblock_t		fsbno;
> > +
> > +	xfs_btree_get_block(cur, level, &bp);
> > +	if (!bp)
> > +		return 0;
> > +
> > +	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
> > +	return xfs_bitmap_set(bitmap, fsbno, 1);
> > +}
> > +
> > +/* Walk the btree and mark the bitmap wherever a btree block is found. */
> > +int
> > +xfs_bitmap_set_btblocks(
> > +	struct xfs_bitmap	*bitmap,
> > +	struct xfs_btree_cur	*cur)
> > +{
> > +	return xfs_btree_visit_blocks(cur, xfs_bitmap_collect_btblock, bitmap);
> > +}
> > diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
> > index dad652ee9177..ae8ecbce6fa6 100644
> > --- a/fs/xfs/scrub/bitmap.h
> > +++ b/fs/xfs/scrub/bitmap.h
> > @@ -28,5 +28,9 @@ void xfs_bitmap_destroy(struct xfs_bitmap *bitmap);
> >  
> >  int xfs_bitmap_set(struct xfs_bitmap *bitmap, uint64_t start, uint64_t len);
> >  int xfs_bitmap_disunion(struct xfs_bitmap *bitmap, struct xfs_bitmap *sub);
> > +int xfs_bitmap_set_btcur_path(struct xfs_bitmap *bitmap,
> > +		struct xfs_btree_cur *cur);
> > +int xfs_bitmap_set_btblocks(struct xfs_bitmap *bitmap,
> > +		struct xfs_btree_cur *cur);
> >  
> >  #endif	/* __XFS_SCRUB_BITMAP_H__ */
> > diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
> > index 6f0903c51a47..1d283360b5ab 100644
> > --- a/fs/xfs/scrub/repair.h
> > +++ b/fs/xfs/scrub/repair.h
> > @@ -59,6 +59,7 @@ int xrep_ino_dqattach(struct xfs_scrub *sc);
> >  int xrep_probe(struct xfs_scrub *sc);
> >  int xrep_superblock(struct xfs_scrub *sc);
> >  int xrep_agf(struct xfs_scrub *sc);
> > +int xrep_agfl(struct xfs_scrub *sc);
> >  
> >  #else
> >  
> > @@ -83,6 +84,7 @@ xrep_calc_ag_resblks(
> >  #define xrep_probe			xrep_notsupported
> >  #define xrep_superblock			xrep_notsupported
> >  #define xrep_agf			xrep_notsupported
> > +#define xrep_agfl			xrep_notsupported
> >  
> >  #endif /* CONFIG_XFS_ONLINE_REPAIR */
> >  
> > diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
> > index 1e8a17c8e2b9..2670f4cf62f4 100644
> > --- a/fs/xfs/scrub/scrub.c
> > +++ b/fs/xfs/scrub/scrub.c
> > @@ -220,7 +220,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
> >  		.type	= ST_PERAG,
> >  		.setup	= xchk_setup_fs,
> >  		.scrub	= xchk_agfl,
> > -		.repair	= xrep_notsupported,
> > +		.repair	= xrep_agfl,
> >  	},
> >  	[XFS_SCRUB_TYPE_AGI] = {	/* agi */
> >  		.type	= ST_PERAG,
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 3/4] xfs: repair the AGFL

[Brian Foster]

On Thu, Aug 09, 2018 at 11:06:04AM -0700, Darrick J. Wong wrote:
> On Thu, Aug 09, 2018 at 09:08:58AM -0400, Brian Foster wrote:
> > On Tue, Aug 07, 2018 at 08:57:19PM -0700, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <darrick.wong@oracle.com>
> > > 
> > > Repair the AGFL from the rmap data.
> > > 
> > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > > ---
> > >  fs/xfs/scrub/agheader_repair.c |  284 ++++++++++++++++++++++++++++++++++++++++
> > >  fs/xfs/scrub/bitmap.c          |   92 +++++++++++++
> > >  fs/xfs/scrub/bitmap.h          |    4 +
> > >  fs/xfs/scrub/repair.h          |    2 
> > >  fs/xfs/scrub/scrub.c           |    2 
> > >  5 files changed, 383 insertions(+), 1 deletion(-)
> > > 
> > > 
> > > diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
> > > index 4842fc598c9b..0decf711b3c7 100644
> > > --- a/fs/xfs/scrub/agheader_repair.c
> > > +++ b/fs/xfs/scrub/agheader_repair.c
> > > @@ -424,3 +424,287 @@ xrep_agf(
> > ...
> > > +/* Repair the AGFL. */
> > > +int
> > > +xrep_agfl(
> > > +	struct xfs_scrub	*sc)
> > > +{
> > > +	struct xfs_owner_info	oinfo;
> > > +	struct xfs_bitmap	agfl_extents;
> > > +	struct xfs_mount	*mp = sc->mp;
> > > +	struct xfs_buf		*agf_bp;
> > > +	struct xfs_buf		*agfl_bp;
> > > +	xfs_agblock_t		flcount;
> > > +	int			error;
> > > +
> > > +	/* We require the rmapbt to rebuild anything. */
> > > +	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
> > > +		return -EOPNOTSUPP;
> > > +
> > > +	xchk_perag_get(sc->mp, &sc->sa);
> > > +	xfs_bitmap_init(&agfl_extents);
> > > +
> > > +	/*
> > > +	 * Read the AGF so that we can query the rmapbt.  We hope that there's
> > > +	 * nothing wrong with the AGF, but all the AG header repair functions
> > > +	 * have this chicken-and-egg problem.
> > > +	 */
> > > +	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
> > > +	if (error)
> > > +		return error;
> > > +	if (!agf_bp)
> > > +		return -ENOMEM;
> > > +
> > > +	/*
> > > +	 * Make sure we have the AGFL buffer, as scrub might have decided it
> > > +	 * was corrupt after xfs_alloc_read_agfl failed with -EFSCORRUPTED.
> > > +	 */
> > > +	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
> > > +			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGFL_DADDR(mp)),
> > > +			XFS_FSS_TO_BB(mp, 1), 0, &agfl_bp, NULL);
> > > +	if (error)
> > > +		return error;
> > > +	agfl_bp->b_ops = &xfs_agfl_buf_ops;
> > > +
> > > +	/* Gather all the extents we're going to put on the new AGFL. */
> > > +	error = xrep_agfl_collect_blocks(sc, agf_bp, &agfl_extents, &flcount);
> > > +	if (error)
> > > +		goto err;
> > > +
> > > +	/*
> > > +	 * Update AGF and AGFL.  We reset the global free block counter when
> > > +	 * we adjust the AGF flcount (which can fail) so avoid updating any
> > > +	 * buffers until we know that part works.
> > > +	 */
> > > +	error = xrep_agfl_update_agf(sc, agf_bp, flcount);
> > > +	if (error)
> > > +		goto err;
> > > +	xrep_agfl_init_header(sc, agfl_bp, &agfl_extents, flcount);
> > > +
> > > +	/*
> > > +	 * Ok, the AGFL should be ready to go now.  Roll the transaction to
> > > +	 * make the new AGFL permanent before we start using it to return
> > > +	 * freespace overflow to the freespace btrees.
> > > +	 */
> > > +	sc->sa.agf_bp = agf_bp;
> > > +	sc->sa.agfl_bp = agfl_bp;
> > > +	error = xrep_roll_ag_trans(sc);
> > > +	if (error)
> > > +		goto err;
> > > +
> > > +	/* Dump any AGFL overflow. */
> > > +	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
> > > +	return xrep_reap_extents(sc, &agfl_extents, &oinfo, XFS_AG_RESV_AGFL);
> > > +err:
> > > +	xfs_bitmap_destroy(&agfl_extents);
> > > +	return error;
> > 
> > Was there a reason we don't maintain the ability to revert the AGFL on
> > error as is done in the AGF repair case? I take it we'll end up shutting
> > down the fs if anything causes us to fail once we've logged the
> > associated agf fields in xrep_agfl_update_agf()..?
> 
> Yep.  Once we've started logging we don't really want to deal with the
> complexity of rolling back a transaction.  The fs will shut down and the
> admin can run xfs_repair instead.
> 

Right, but AFAICT AGF repair avoids logging (despite changing on-disk
buffers) to the transaction until the last step of calling
xrep_agf_commit_new(). This facilitates the ability to revert to the old
structure if something fails before the commit.

The AGFL repair logs earlier, directly in the associated modifier
functions (xrep_agfl_update_agf(), xrep_agfl_init_header()). Looking
again, perhaps this is simply because there is no error vector here
analogous to the xrep_agf_calc_from_btrees() work on the agf side (i.e.,
no need for a _commit_new() helper either). Since xrep_agfl_update_agf()
only ever returns zero, this may be a bit more obvious if we changed
that to a void to show that there is no error path out of the code
sequence that updates the repaired structure.

That nit aside, the rest looks good to me:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> --D
> 
> > Brian
> > 
> > > +}
> > > diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
> > > index c770e2d0b6aa..fdadc9e1dc49 100644
> > > --- a/fs/xfs/scrub/bitmap.c
> > > +++ b/fs/xfs/scrub/bitmap.c
> > > @@ -9,6 +9,7 @@
> > >  #include "xfs_format.h"
> > >  #include "xfs_trans_resv.h"
> > >  #include "xfs_mount.h"
> > > +#include "xfs_btree.h"
> > >  #include "scrub/xfs_scrub.h"
> > >  #include "scrub/scrub.h"
> > >  #include "scrub/common.h"
> > > @@ -209,3 +210,94 @@ xfs_bitmap_disunion(
> > >  }
> > >  #undef LEFT_ALIGNED
> > >  #undef RIGHT_ALIGNED
> > > +
> > > +/*
> > > + * Record all btree blocks seen while iterating all records of a btree.
> > > + *
> > > + * We know that the btree query_all function starts at the left edge and walks
> > > + * towards the right edge of the tree.  Therefore, we know that we can walk up
> > > + * the btree cursor towards the root; if the pointer for a given level points
> > > + * to the first record/key in that block, we haven't seen this block before;
> > > + * and therefore we need to remember that we saw this block in the btree.
> > > + *
> > > + * So if our btree is:
> > > + *
> > > + *    4
> > > + *  / | \
> > > + * 1  2  3
> > > + *
> > > + * Pretend for this example that each leaf block has 100 btree records.  For
> > > + * the first btree record, we'll observe that bc_ptrs[0] == 1, so we record
> > > + * that we saw block 1.  Then we observe that bc_ptrs[1] == 1, so we record
> > > + * block 4.  The list is [1, 4].
> > > + *
> > > + * For the second btree record, we see that bc_ptrs[0] == 2, so we exit the
> > > + * loop.  The list remains [1, 4].
> > > + *
> > > + * For the 101st btree record, we've moved onto leaf block 2.  Now
> > > + * bc_ptrs[0] == 1 again, so we record that we saw block 2.  We see that
> > > + * bc_ptrs[1] == 2, so we exit the loop.  The list is now [1, 4, 2].
> > > + *
> > > + * For the 102nd record, bc_ptrs[0] == 2, so we continue.
> > > + *
> > > + * For the 201st record, we've moved on to leaf block 3.  bc_ptrs[0] == 1, so
> > > + * we add 3 to the list.  Now it is [1, 4, 2, 3].
> > > + *
> > > + * For the 300th record we just exit, with the list being [1, 4, 2, 3].
> > > + */
> > > +
> > > +/*
> > > + * Record all the buffers pointed to by the btree cursor.  Callers already
> > > + * engaged in a btree walk should call this function to capture the list of
> > > + * blocks going from the leaf towards the root.
> > > + */
> > > +int
> > > +xfs_bitmap_set_btcur_path(
> > > +	struct xfs_bitmap	*bitmap,
> > > +	struct xfs_btree_cur	*cur)
> > > +{
> > > +	struct xfs_buf		*bp;
> > > +	xfs_fsblock_t		fsb;
> > > +	int			i;
> > > +	int			error;
> > > +
> > > +	for (i = 0; i < cur->bc_nlevels && cur->bc_ptrs[i] == 1; i++) {
> > > +		xfs_btree_get_block(cur, i, &bp);
> > > +		if (!bp)
> > > +			continue;
> > > +		fsb = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
> > > +		error = xfs_bitmap_set(bitmap, fsb, 1);
> > > +		if (error)
> > > +			return error;
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +/* Collect a btree's block in the bitmap. */
> > > +STATIC int
> > > +xfs_bitmap_collect_btblock(
> > > +	struct xfs_btree_cur	*cur,
> > > +	int			level,
> > > +	void			*priv)
> > > +{
> > > +	struct xfs_bitmap	*bitmap = priv;
> > > +	struct xfs_buf		*bp;
> > > +	xfs_fsblock_t		fsbno;
> > > +
> > > +	xfs_btree_get_block(cur, level, &bp);
> > > +	if (!bp)
> > > +		return 0;
> > > +
> > > +	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
> > > +	return xfs_bitmap_set(bitmap, fsbno, 1);
> > > +}
> > > +
> > > +/* Walk the btree and mark the bitmap wherever a btree block is found. */
> > > +int
> > > +xfs_bitmap_set_btblocks(
> > > +	struct xfs_bitmap	*bitmap,
> > > +	struct xfs_btree_cur	*cur)
> > > +{
> > > +	return xfs_btree_visit_blocks(cur, xfs_bitmap_collect_btblock, bitmap);
> > > +}
> > > diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
> > > index dad652ee9177..ae8ecbce6fa6 100644
> > > --- a/fs/xfs/scrub/bitmap.h
> > > +++ b/fs/xfs/scrub/bitmap.h
> > > @@ -28,5 +28,9 @@ void xfs_bitmap_destroy(struct xfs_bitmap *bitmap);
> > >  
> > >  int xfs_bitmap_set(struct xfs_bitmap *bitmap, uint64_t start, uint64_t len);
> > >  int xfs_bitmap_disunion(struct xfs_bitmap *bitmap, struct xfs_bitmap *sub);
> > > +int xfs_bitmap_set_btcur_path(struct xfs_bitmap *bitmap,
> > > +		struct xfs_btree_cur *cur);
> > > +int xfs_bitmap_set_btblocks(struct xfs_bitmap *bitmap,
> > > +		struct xfs_btree_cur *cur);
> > >  
> > >  #endif	/* __XFS_SCRUB_BITMAP_H__ */
> > > diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
> > > index 6f0903c51a47..1d283360b5ab 100644
> > > --- a/fs/xfs/scrub/repair.h
> > > +++ b/fs/xfs/scrub/repair.h
> > > @@ -59,6 +59,7 @@ int xrep_ino_dqattach(struct xfs_scrub *sc);
> > >  int xrep_probe(struct xfs_scrub *sc);
> > >  int xrep_superblock(struct xfs_scrub *sc);
> > >  int xrep_agf(struct xfs_scrub *sc);
> > > +int xrep_agfl(struct xfs_scrub *sc);
> > >  
> > >  #else
> > >  
> > > @@ -83,6 +84,7 @@ xrep_calc_ag_resblks(
> > >  #define xrep_probe			xrep_notsupported
> > >  #define xrep_superblock			xrep_notsupported
> > >  #define xrep_agf			xrep_notsupported
> > > +#define xrep_agfl			xrep_notsupported
> > >  
> > >  #endif /* CONFIG_XFS_ONLINE_REPAIR */
> > >  
> > > diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
> > > index 1e8a17c8e2b9..2670f4cf62f4 100644
> > > --- a/fs/xfs/scrub/scrub.c
> > > +++ b/fs/xfs/scrub/scrub.c
> > > @@ -220,7 +220,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
> > >  		.type	= ST_PERAG,
> > >  		.setup	= xchk_setup_fs,
> > >  		.scrub	= xchk_agfl,
> > > -		.repair	= xrep_notsupported,
> > > +		.repair	= xrep_agfl,
> > >  	},
> > >  	[XFS_SCRUB_TYPE_AGI] = {	/* agi */
> > >  		.type	= ST_PERAG,
> > > 
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 3/4] xfs: repair the AGFL

[Darrick J. Wong]

On Fri, Aug 10, 2018 at 06:34:17AM -0400, Brian Foster wrote:
> On Thu, Aug 09, 2018 at 11:06:04AM -0700, Darrick J. Wong wrote:
> > On Thu, Aug 09, 2018 at 09:08:58AM -0400, Brian Foster wrote:
> > > On Tue, Aug 07, 2018 at 08:57:19PM -0700, Darrick J. Wong wrote:
> > > > From: Darrick J. Wong <darrick.wong@oracle.com>
> > > > 
> > > > Repair the AGFL from the rmap data.
> > > > 
> > > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > > > ---
> > > >  fs/xfs/scrub/agheader_repair.c |  284 ++++++++++++++++++++++++++++++++++++++++
> > > >  fs/xfs/scrub/bitmap.c          |   92 +++++++++++++
> > > >  fs/xfs/scrub/bitmap.h          |    4 +
> > > >  fs/xfs/scrub/repair.h          |    2 
> > > >  fs/xfs/scrub/scrub.c           |    2 
> > > >  5 files changed, 383 insertions(+), 1 deletion(-)
> > > > 
> > > > 
> > > > diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
> > > > index 4842fc598c9b..0decf711b3c7 100644
> > > > --- a/fs/xfs/scrub/agheader_repair.c
> > > > +++ b/fs/xfs/scrub/agheader_repair.c
> > > > @@ -424,3 +424,287 @@ xrep_agf(
> > > ...
> > > > +/* Repair the AGFL. */
> > > > +int
> > > > +xrep_agfl(
> > > > +	struct xfs_scrub	*sc)
> > > > +{
> > > > +	struct xfs_owner_info	oinfo;
> > > > +	struct xfs_bitmap	agfl_extents;
> > > > +	struct xfs_mount	*mp = sc->mp;
> > > > +	struct xfs_buf		*agf_bp;
> > > > +	struct xfs_buf		*agfl_bp;
> > > > +	xfs_agblock_t		flcount;
> > > > +	int			error;
> > > > +
> > > > +	/* We require the rmapbt to rebuild anything. */
> > > > +	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
> > > > +		return -EOPNOTSUPP;
> > > > +
> > > > +	xchk_perag_get(sc->mp, &sc->sa);
> > > > +	xfs_bitmap_init(&agfl_extents);
> > > > +
> > > > +	/*
> > > > +	 * Read the AGF so that we can query the rmapbt.  We hope that there's
> > > > +	 * nothing wrong with the AGF, but all the AG header repair functions
> > > > +	 * have this chicken-and-egg problem.
> > > > +	 */
> > > > +	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
> > > > +	if (error)
> > > > +		return error;
> > > > +	if (!agf_bp)
> > > > +		return -ENOMEM;
> > > > +
> > > > +	/*
> > > > +	 * Make sure we have the AGFL buffer, as scrub might have decided it
> > > > +	 * was corrupt after xfs_alloc_read_agfl failed with -EFSCORRUPTED.
> > > > +	 */
> > > > +	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
> > > > +			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGFL_DADDR(mp)),
> > > > +			XFS_FSS_TO_BB(mp, 1), 0, &agfl_bp, NULL);
> > > > +	if (error)
> > > > +		return error;
> > > > +	agfl_bp->b_ops = &xfs_agfl_buf_ops;
> > > > +
> > > > +	/* Gather all the extents we're going to put on the new AGFL. */
> > > > +	error = xrep_agfl_collect_blocks(sc, agf_bp, &agfl_extents, &flcount);
> > > > +	if (error)
> > > > +		goto err;
> > > > +
> > > > +	/*
> > > > +	 * Update AGF and AGFL.  We reset the global free block counter when
> > > > +	 * we adjust the AGF flcount (which can fail) so avoid updating any
> > > > +	 * buffers until we know that part works.
> > > > +	 */
> > > > +	error = xrep_agfl_update_agf(sc, agf_bp, flcount);
> > > > +	if (error)
> > > > +		goto err;
> > > > +	xrep_agfl_init_header(sc, agfl_bp, &agfl_extents, flcount);
> > > > +
> > > > +	/*
> > > > +	 * Ok, the AGFL should be ready to go now.  Roll the transaction to
> > > > +	 * make the new AGFL permanent before we start using it to return
> > > > +	 * freespace overflow to the freespace btrees.
> > > > +	 */
> > > > +	sc->sa.agf_bp = agf_bp;
> > > > +	sc->sa.agfl_bp = agfl_bp;
> > > > +	error = xrep_roll_ag_trans(sc);
> > > > +	if (error)
> > > > +		goto err;
> > > > +
> > > > +	/* Dump any AGFL overflow. */
> > > > +	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_AG);
> > > > +	return xrep_reap_extents(sc, &agfl_extents, &oinfo, XFS_AG_RESV_AGFL);
> > > > +err:
> > > > +	xfs_bitmap_destroy(&agfl_extents);
> > > > +	return error;
> > > 
> > > Was there a reason we don't maintain the ability to revert the AGFL on
> > > error as is done in the AGF repair case? I take it we'll end up shutting
> > > down the fs if anything causes us to fail once we've logged the
> > > associated agf fields in xrep_agfl_update_agf()..?
> > 
> > Yep.  Once we've started logging we don't really want to deal with the
> > complexity of rolling back a transaction.  The fs will shut down and the
> > admin can run xfs_repair instead.
> > 
> 
> Right, but AFAICT AGF repair avoids logging (despite changing on-disk
> buffers) to the transaction until the last step of calling
> xrep_agf_commit_new(). This facilitates the ability to revert to the old
> structure if something fails before the commit.

Hmm.  One thought I had is to have the AG header repairers allocate a
sc->buf buffer big enough to hold the old contents of the AGF/AGFL/AGI,
that way we get that off the stack for the AGF/AGI repair and for AGFL
repair we actually /can/ revert the AGF fl* fields and the AGFL itself
in the case of repair failure.

> The AGFL repair logs earlier, directly in the associated modifier
> functions (xrep_agfl_update_agf(), xrep_agfl_init_header()). Looking
> again, perhaps this is simply because there is no error vector here
> analogous to the xrep_agf_calc_from_btrees() work on the agf side (i.e.,
> no need for a _commit_new() helper either). Since xrep_agfl_update_agf()
> only ever returns zero, this may be a bit more obvious if we changed
> that to a void to show that there is no error path out of the code
> sequence that updates the repaired structure.

<nod> I think Dave was nudging me towards having common names in all the
repair functions to make them a little easier to understand, since they
(mostly) have the same structure.

> That nit aside, the rest looks good to me:
> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>

Thanks for the review!

--D

> 
> > --D
> > 
> > > Brian
> > > 
> > > > +}
> > > > diff --git a/fs/xfs/scrub/bitmap.c b/fs/xfs/scrub/bitmap.c
> > > > index c770e2d0b6aa..fdadc9e1dc49 100644
> > > > --- a/fs/xfs/scrub/bitmap.c
> > > > +++ b/fs/xfs/scrub/bitmap.c
> > > > @@ -9,6 +9,7 @@
> > > >  #include "xfs_format.h"
> > > >  #include "xfs_trans_resv.h"
> > > >  #include "xfs_mount.h"
> > > > +#include "xfs_btree.h"
> > > >  #include "scrub/xfs_scrub.h"
> > > >  #include "scrub/scrub.h"
> > > >  #include "scrub/common.h"
> > > > @@ -209,3 +210,94 @@ xfs_bitmap_disunion(
> > > >  }
> > > >  #undef LEFT_ALIGNED
> > > >  #undef RIGHT_ALIGNED
> > > > +
> > > > +/*
> > > > + * Record all btree blocks seen while iterating all records of a btree.
> > > > + *
> > > > + * We know that the btree query_all function starts at the left edge and walks
> > > > + * towards the right edge of the tree.  Therefore, we know that we can walk up
> > > > + * the btree cursor towards the root; if the pointer for a given level points
> > > > + * to the first record/key in that block, we haven't seen this block before;
> > > > + * and therefore we need to remember that we saw this block in the btree.
> > > > + *
> > > > + * So if our btree is:
> > > > + *
> > > > + *    4
> > > > + *  / | \
> > > > + * 1  2  3
> > > > + *
> > > > + * Pretend for this example that each leaf block has 100 btree records.  For
> > > > + * the first btree record, we'll observe that bc_ptrs[0] == 1, so we record
> > > > + * that we saw block 1.  Then we observe that bc_ptrs[1] == 1, so we record
> > > > + * block 4.  The list is [1, 4].
> > > > + *
> > > > + * For the second btree record, we see that bc_ptrs[0] == 2, so we exit the
> > > > + * loop.  The list remains [1, 4].
> > > > + *
> > > > + * For the 101st btree record, we've moved onto leaf block 2.  Now
> > > > + * bc_ptrs[0] == 1 again, so we record that we saw block 2.  We see that
> > > > + * bc_ptrs[1] == 2, so we exit the loop.  The list is now [1, 4, 2].
> > > > + *
> > > > + * For the 102nd record, bc_ptrs[0] == 2, so we continue.
> > > > + *
> > > > + * For the 201st record, we've moved on to leaf block 3.  bc_ptrs[0] == 1, so
> > > > + * we add 3 to the list.  Now it is [1, 4, 2, 3].
> > > > + *
> > > > + * For the 300th record we just exit, with the list being [1, 4, 2, 3].
> > > > + */
> > > > +
> > > > +/*
> > > > + * Record all the buffers pointed to by the btree cursor.  Callers already
> > > > + * engaged in a btree walk should call this function to capture the list of
> > > > + * blocks going from the leaf towards the root.
> > > > + */
> > > > +int
> > > > +xfs_bitmap_set_btcur_path(
> > > > +	struct xfs_bitmap	*bitmap,
> > > > +	struct xfs_btree_cur	*cur)
> > > > +{
> > > > +	struct xfs_buf		*bp;
> > > > +	xfs_fsblock_t		fsb;
> > > > +	int			i;
> > > > +	int			error;
> > > > +
> > > > +	for (i = 0; i < cur->bc_nlevels && cur->bc_ptrs[i] == 1; i++) {
> > > > +		xfs_btree_get_block(cur, i, &bp);
> > > > +		if (!bp)
> > > > +			continue;
> > > > +		fsb = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
> > > > +		error = xfs_bitmap_set(bitmap, fsb, 1);
> > > > +		if (error)
> > > > +			return error;
> > > > +	}
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > > +/* Collect a btree's block in the bitmap. */
> > > > +STATIC int
> > > > +xfs_bitmap_collect_btblock(
> > > > +	struct xfs_btree_cur	*cur,
> > > > +	int			level,
> > > > +	void			*priv)
> > > > +{
> > > > +	struct xfs_bitmap	*bitmap = priv;
> > > > +	struct xfs_buf		*bp;
> > > > +	xfs_fsblock_t		fsbno;
> > > > +
> > > > +	xfs_btree_get_block(cur, level, &bp);
> > > > +	if (!bp)
> > > > +		return 0;
> > > > +
> > > > +	fsbno = XFS_DADDR_TO_FSB(cur->bc_mp, bp->b_bn);
> > > > +	return xfs_bitmap_set(bitmap, fsbno, 1);
> > > > +}
> > > > +
> > > > +/* Walk the btree and mark the bitmap wherever a btree block is found. */
> > > > +int
> > > > +xfs_bitmap_set_btblocks(
> > > > +	struct xfs_bitmap	*bitmap,
> > > > +	struct xfs_btree_cur	*cur)
> > > > +{
> > > > +	return xfs_btree_visit_blocks(cur, xfs_bitmap_collect_btblock, bitmap);
> > > > +}
> > > > diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
> > > > index dad652ee9177..ae8ecbce6fa6 100644
> > > > --- a/fs/xfs/scrub/bitmap.h
> > > > +++ b/fs/xfs/scrub/bitmap.h
> > > > @@ -28,5 +28,9 @@ void xfs_bitmap_destroy(struct xfs_bitmap *bitmap);
> > > >  
> > > >  int xfs_bitmap_set(struct xfs_bitmap *bitmap, uint64_t start, uint64_t len);
> > > >  int xfs_bitmap_disunion(struct xfs_bitmap *bitmap, struct xfs_bitmap *sub);
> > > > +int xfs_bitmap_set_btcur_path(struct xfs_bitmap *bitmap,
> > > > +		struct xfs_btree_cur *cur);
> > > > +int xfs_bitmap_set_btblocks(struct xfs_bitmap *bitmap,
> > > > +		struct xfs_btree_cur *cur);
> > > >  
> > > >  #endif	/* __XFS_SCRUB_BITMAP_H__ */
> > > > diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
> > > > index 6f0903c51a47..1d283360b5ab 100644
> > > > --- a/fs/xfs/scrub/repair.h
> > > > +++ b/fs/xfs/scrub/repair.h
> > > > @@ -59,6 +59,7 @@ int xrep_ino_dqattach(struct xfs_scrub *sc);
> > > >  int xrep_probe(struct xfs_scrub *sc);
> > > >  int xrep_superblock(struct xfs_scrub *sc);
> > > >  int xrep_agf(struct xfs_scrub *sc);
> > > > +int xrep_agfl(struct xfs_scrub *sc);
> > > >  
> > > >  #else
> > > >  
> > > > @@ -83,6 +84,7 @@ xrep_calc_ag_resblks(
> > > >  #define xrep_probe			xrep_notsupported
> > > >  #define xrep_superblock			xrep_notsupported
> > > >  #define xrep_agf			xrep_notsupported
> > > > +#define xrep_agfl			xrep_notsupported
> > > >  
> > > >  #endif /* CONFIG_XFS_ONLINE_REPAIR */
> > > >  
> > > > diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
> > > > index 1e8a17c8e2b9..2670f4cf62f4 100644
> > > > --- a/fs/xfs/scrub/scrub.c
> > > > +++ b/fs/xfs/scrub/scrub.c
> > > > @@ -220,7 +220,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
> > > >  		.type	= ST_PERAG,
> > > >  		.setup	= xchk_setup_fs,
> > > >  		.scrub	= xchk_agfl,
> > > > -		.repair	= xrep_notsupported,
> > > > +		.repair	= xrep_agfl,
> > > >  	},
> > > >  	[XFS_SCRUB_TYPE_AGI] = {	/* agi */
> > > >  		.type	= ST_PERAG,
> > > > 
> > > > --
> > > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > > > the body of a message to majordomo@vger.kernel.org
> > > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH 4/4] xfs: repair the AGI

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Rebuild the AGI header items with some help from the rmapbt.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/agheader_repair.c |  219 ++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/repair.h          |    2 
 fs/xfs/scrub/scrub.c           |    2 
 3 files changed, 222 insertions(+), 1 deletion(-)


diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
index 0decf711b3c7..df8657a5d475 100644
--- a/fs/xfs/scrub/agheader_repair.c
+++ b/fs/xfs/scrub/agheader_repair.c
@@ -708,3 +708,222 @@ xrep_agfl(
 	xfs_bitmap_destroy(&agfl_extents);
 	return error;
 }
+
+/* AGI */
+
+/*
+ * Offset within the xrep_find_ag_btree array for each btree type.  Avoid the
+ * XFS_BTNUM_ names here to avoid creating a sparse array.
+ */
+enum {
+	XREP_AGI_INOBT = 0,
+	XREP_AGI_FINOBT,
+	XREP_AGI_END,
+	XREP_AGI_MAX
+};
+
+/*
+ * Given the inode btree roots described by *fab, find the roots, check them
+ * for sanity, and pass the root data back out via *fab.
+ */
+STATIC int
+xrep_agi_find_btrees(
+	struct xfs_scrub		*sc,
+	struct xrep_find_ag_btree	*fab)
+{
+	struct xfs_buf			*agf_bp;
+	struct xfs_mount		*mp = sc->mp;
+	int				error;
+
+	/* Read the AGF. */
+	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
+	if (error)
+		return error;
+	if (!agf_bp)
+		return -ENOMEM;
+
+	/* Find the btree roots. */
+	error = xrep_find_ag_btree_roots(sc, agf_bp, fab, NULL);
+	if (error)
+		return error;
+
+	/* We must find the inobt root. */
+	if (fab[XREP_AGI_INOBT].root == NULLAGBLOCK ||
+	    fab[XREP_AGI_INOBT].height > XFS_BTREE_MAXLEVELS)
+		return -EFSCORRUPTED;
+
+	/* We must find the finobt root if that feature is enabled. */
+	if (xfs_sb_version_hasfinobt(&mp->m_sb) &&
+	    (fab[XREP_AGI_FINOBT].root == NULLAGBLOCK ||
+	     fab[XREP_AGI_FINOBT].height > XFS_BTREE_MAXLEVELS))
+		return -EFSCORRUPTED;
+
+	return 0;
+}
+
+/*
+ * Reinitialize the AGI header, making an in-core copy of the old contents so
+ * that we know which in-core state needs to be reinitialized.
+ */
+STATIC void
+xrep_agi_init_header(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agi_bp,
+	struct xfs_agi		*old_agi)
+{
+	struct xfs_agi		*agi = XFS_BUF_TO_AGI(agi_bp);
+	struct xfs_mount	*mp = sc->mp;
+
+	memcpy(old_agi, agi, sizeof(*old_agi));
+	memset(agi, 0, BBTOB(agi_bp->b_length));
+	agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
+	agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
+	agi->agi_seqno = cpu_to_be32(sc->sa.agno);
+	agi->agi_length = cpu_to_be32(xfs_ag_block_count(mp, sc->sa.agno));
+	agi->agi_newino = cpu_to_be32(NULLAGINO);
+	agi->agi_dirino = cpu_to_be32(NULLAGINO);
+	if (xfs_sb_version_hascrc(&mp->m_sb))
+		uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid);
+
+	/* We don't know how to fix the unlinked list yet. */
+	memcpy(&agi->agi_unlinked, &old_agi->agi_unlinked,
+			sizeof(agi->agi_unlinked));
+
+	/* Mark the incore AGF data stale until we're done fixing things. */
+	ASSERT(sc->sa.pag->pagi_init);
+	sc->sa.pag->pagi_init = 0;
+}
+
+/* Set btree root information in an AGI. */
+STATIC void
+xrep_agi_set_roots(
+	struct xfs_scrub		*sc,
+	struct xfs_agi			*agi,
+	struct xrep_find_ag_btree	*fab)
+{
+	agi->agi_root = cpu_to_be32(fab[XREP_AGI_INOBT].root);
+	agi->agi_level = cpu_to_be32(fab[XREP_AGI_INOBT].height);
+
+	if (xfs_sb_version_hasfinobt(&sc->mp->m_sb)) {
+		agi->agi_free_root = cpu_to_be32(fab[XREP_AGI_FINOBT].root);
+		agi->agi_free_level = cpu_to_be32(fab[XREP_AGI_FINOBT].height);
+	}
+}
+
+/* Update the AGI counters. */
+STATIC int
+xrep_agi_calc_from_btrees(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agi_bp)
+{
+	struct xfs_btree_cur	*cur;
+	struct xfs_agi		*agi = XFS_BUF_TO_AGI(agi_bp);
+	struct xfs_mount	*mp = sc->mp;
+	xfs_agino_t		count;
+	xfs_agino_t		freecount;
+	int			error;
+
+	cur = xfs_inobt_init_cursor(mp, sc->tp, agi_bp, sc->sa.agno,
+			XFS_BTNUM_INO);
+	error = xfs_ialloc_count_inodes(cur, &count, &freecount);
+	if (error)
+		goto err;
+	xfs_btree_del_cursor(cur, error);
+
+	agi->agi_count = cpu_to_be32(count);
+	agi->agi_freecount = cpu_to_be32(freecount);
+	return 0;
+err:
+	xfs_btree_del_cursor(cur, error);
+	return error;
+}
+
+/* Trigger reinitialization of the in-core data. */
+STATIC int
+xrep_agi_commit_new(
+	struct xfs_scrub	*sc,
+	struct xfs_buf		*agi_bp)
+{
+	struct xfs_perag	*pag;
+	struct xfs_agi		*agi = XFS_BUF_TO_AGI(agi_bp);
+
+	/* Trigger inode count recalculation */
+	xfs_force_summary_recalc(sc->mp);
+
+	/* Write this to disk. */
+	xfs_trans_buf_set_type(sc->tp, agi_bp, XFS_BLFT_AGI_BUF);
+	xfs_trans_log_buf(sc->tp, agi_bp, 0, BBTOB(agi_bp->b_length) - 1);
+
+	/* Now reinitialize the in-core counters if necessary. */
+	pag = sc->sa.pag;
+	pag->pagi_count = be32_to_cpu(agi->agi_count);
+	pag->pagi_freecount = be32_to_cpu(agi->agi_freecount);
+	pag->pagi_init = 1;
+
+	return 0;
+}
+
+/* Repair the AGI. */
+int
+xrep_agi(
+	struct xfs_scrub		*sc)
+{
+	struct xrep_find_ag_btree	fab[XREP_AGI_MAX] = {
+		[XREP_AGI_INOBT] = {
+			.rmap_owner = XFS_RMAP_OWN_INOBT,
+			.buf_ops = &xfs_inobt_buf_ops,
+			.magic = XFS_IBT_CRC_MAGIC,
+		},
+		[XREP_AGI_FINOBT] = {
+			.rmap_owner = XFS_RMAP_OWN_INOBT,
+			.buf_ops = &xfs_inobt_buf_ops,
+			.magic = XFS_FIBT_CRC_MAGIC,
+		},
+		[XREP_AGI_END] = {
+			.buf_ops = NULL
+		},
+	};
+	struct xfs_agi			old_agi;
+	struct xfs_mount		*mp = sc->mp;
+	struct xfs_buf			*agi_bp;
+	struct xfs_agi			*agi;
+	int				error;
+
+	/* We require the rmapbt to rebuild anything. */
+	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+		return -EOPNOTSUPP;
+
+	xchk_perag_get(sc->mp, &sc->sa);
+	/*
+	 * Make sure we have the AGI buffer, as scrub might have decided it
+	 * was corrupt after xfs_ialloc_read_agi failed with -EFSCORRUPTED.
+	 */
+	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
+			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGI_DADDR(mp)),
+			XFS_FSS_TO_BB(mp, 1), 0, &agi_bp, NULL);
+	if (error)
+		return error;
+	agi_bp->b_ops = &xfs_agi_buf_ops;
+	agi = XFS_BUF_TO_AGI(agi_bp);
+
+	/* Find the AGI btree roots. */
+	error = xrep_agi_find_btrees(sc, fab);
+	if (error)
+		return error;
+
+	/* Start rewriting the header and implant the btrees we found. */
+	xrep_agi_init_header(sc, agi_bp, &old_agi);
+	xrep_agi_set_roots(sc, agi, fab);
+	error = xrep_agi_calc_from_btrees(sc, agi_bp);
+	if (error)
+		goto out_revert;
+
+	/* Reinitialize in-core state. */
+	return xrep_agi_commit_new(sc, agi_bp);
+
+out_revert:
+	/* Mark the incore AGI state stale and revert the AGI. */
+	sc->sa.pag->pagi_init = 0;
+	memcpy(agi, &old_agi, sizeof(old_agi));
+	return error;
+}
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index 1d283360b5ab..9de321eee4ab 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -60,6 +60,7 @@ int xrep_probe(struct xfs_scrub *sc);
 int xrep_superblock(struct xfs_scrub *sc);
 int xrep_agf(struct xfs_scrub *sc);
 int xrep_agfl(struct xfs_scrub *sc);
+int xrep_agi(struct xfs_scrub *sc);
 
 #else
 
@@ -85,6 +86,7 @@ xrep_calc_ag_resblks(
 #define xrep_superblock			xrep_notsupported
 #define xrep_agf			xrep_notsupported
 #define xrep_agfl			xrep_notsupported
+#define xrep_agi			xrep_notsupported
 
 #endif /* CONFIG_XFS_ONLINE_REPAIR */
 
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 2670f4cf62f4..4bfae1e61d30 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -226,7 +226,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
 		.type	= ST_PERAG,
 		.setup	= xchk_setup_fs,
 		.scrub	= xchk_agi,
-		.repair	= xrep_notsupported,
+		.repair	= xrep_agi,
 	},
 	[XFS_SCRUB_TYPE_BNOBT] = {	/* bnobt */
 		.type	= ST_PERAG,

Re: [PATCH 4/4] xfs: repair the AGI

[Brian Foster]

On Tue, Aug 07, 2018 at 08:57:25PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Rebuild the AGI header items with some help from the rmapbt.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/scrub/agheader_repair.c |  219 ++++++++++++++++++++++++++++++++++++++++
>  fs/xfs/scrub/repair.h          |    2 
>  fs/xfs/scrub/scrub.c           |    2 
>  3 files changed, 222 insertions(+), 1 deletion(-)
> 
> 
> diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c
> index 0decf711b3c7..df8657a5d475 100644
> --- a/fs/xfs/scrub/agheader_repair.c
> +++ b/fs/xfs/scrub/agheader_repair.c
> @@ -708,3 +708,222 @@ xrep_agfl(
>  	xfs_bitmap_destroy(&agfl_extents);
>  	return error;
>  }
> +
> +/* AGI */
> +
> +/*
> + * Offset within the xrep_find_ag_btree array for each btree type.  Avoid the
> + * XFS_BTNUM_ names here to avoid creating a sparse array.
> + */
> +enum {
> +	XREP_AGI_INOBT = 0,
> +	XREP_AGI_FINOBT,
> +	XREP_AGI_END,
> +	XREP_AGI_MAX
> +};
> +
> +/*
> + * Given the inode btree roots described by *fab, find the roots, check them
> + * for sanity, and pass the root data back out via *fab.
> + */
> +STATIC int
> +xrep_agi_find_btrees(
> +	struct xfs_scrub		*sc,
> +	struct xrep_find_ag_btree	*fab)
> +{
> +	struct xfs_buf			*agf_bp;
> +	struct xfs_mount		*mp = sc->mp;
> +	int				error;
> +
> +	/* Read the AGF. */
> +	error = xfs_alloc_read_agf(mp, sc->tp, sc->sa.agno, 0, &agf_bp);
> +	if (error)
> +		return error;
> +	if (!agf_bp)
> +		return -ENOMEM;
> +
> +	/* Find the btree roots. */
> +	error = xrep_find_ag_btree_roots(sc, agf_bp, fab, NULL);
> +	if (error)
> +		return error;
> +
> +	/* We must find the inobt root. */
> +	if (fab[XREP_AGI_INOBT].root == NULLAGBLOCK ||
> +	    fab[XREP_AGI_INOBT].height > XFS_BTREE_MAXLEVELS)
> +		return -EFSCORRUPTED;
> +
> +	/* We must find the finobt root if that feature is enabled. */
> +	if (xfs_sb_version_hasfinobt(&mp->m_sb) &&
> +	    (fab[XREP_AGI_FINOBT].root == NULLAGBLOCK ||
> +	     fab[XREP_AGI_FINOBT].height > XFS_BTREE_MAXLEVELS))
> +		return -EFSCORRUPTED;
> +
> +	return 0;
> +}
> +
> +/*
> + * Reinitialize the AGI header, making an in-core copy of the old contents so
> + * that we know which in-core state needs to be reinitialized.
> + */
> +STATIC void
> +xrep_agi_init_header(
> +	struct xfs_scrub	*sc,
> +	struct xfs_buf		*agi_bp,
> +	struct xfs_agi		*old_agi)
> +{
> +	struct xfs_agi		*agi = XFS_BUF_TO_AGI(agi_bp);
> +	struct xfs_mount	*mp = sc->mp;
> +
> +	memcpy(old_agi, agi, sizeof(*old_agi));
> +	memset(agi, 0, BBTOB(agi_bp->b_length));
> +	agi->agi_magicnum = cpu_to_be32(XFS_AGI_MAGIC);
> +	agi->agi_versionnum = cpu_to_be32(XFS_AGI_VERSION);
> +	agi->agi_seqno = cpu_to_be32(sc->sa.agno);
> +	agi->agi_length = cpu_to_be32(xfs_ag_block_count(mp, sc->sa.agno));
> +	agi->agi_newino = cpu_to_be32(NULLAGINO);
> +	agi->agi_dirino = cpu_to_be32(NULLAGINO);
> +	if (xfs_sb_version_hascrc(&mp->m_sb))
> +		uuid_copy(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid);
> +
> +	/* We don't know how to fix the unlinked list yet. */
> +	memcpy(&agi->agi_unlinked, &old_agi->agi_unlinked,
> +			sizeof(agi->agi_unlinked));
> +
> +	/* Mark the incore AGF data stale until we're done fixing things. */
> +	ASSERT(sc->sa.pag->pagi_init);
> +	sc->sa.pag->pagi_init = 0;
> +}
> +
> +/* Set btree root information in an AGI. */
> +STATIC void
> +xrep_agi_set_roots(
> +	struct xfs_scrub		*sc,
> +	struct xfs_agi			*agi,
> +	struct xrep_find_ag_btree	*fab)
> +{
> +	agi->agi_root = cpu_to_be32(fab[XREP_AGI_INOBT].root);
> +	agi->agi_level = cpu_to_be32(fab[XREP_AGI_INOBT].height);
> +
> +	if (xfs_sb_version_hasfinobt(&sc->mp->m_sb)) {
> +		agi->agi_free_root = cpu_to_be32(fab[XREP_AGI_FINOBT].root);
> +		agi->agi_free_level = cpu_to_be32(fab[XREP_AGI_FINOBT].height);
> +	}
> +}
> +
> +/* Update the AGI counters. */
> +STATIC int
> +xrep_agi_calc_from_btrees(
> +	struct xfs_scrub	*sc,
> +	struct xfs_buf		*agi_bp)
> +{
> +	struct xfs_btree_cur	*cur;
> +	struct xfs_agi		*agi = XFS_BUF_TO_AGI(agi_bp);
> +	struct xfs_mount	*mp = sc->mp;
> +	xfs_agino_t		count;
> +	xfs_agino_t		freecount;
> +	int			error;
> +
> +	cur = xfs_inobt_init_cursor(mp, sc->tp, agi_bp, sc->sa.agno,
> +			XFS_BTNUM_INO);
> +	error = xfs_ialloc_count_inodes(cur, &count, &freecount);
> +	if (error)
> +		goto err;
> +	xfs_btree_del_cursor(cur, error);
> +
> +	agi->agi_count = cpu_to_be32(count);
> +	agi->agi_freecount = cpu_to_be32(freecount);
> +	return 0;
> +err:
> +	xfs_btree_del_cursor(cur, error);
> +	return error;
> +}
> +
> +/* Trigger reinitialization of the in-core data. */
> +STATIC int
> +xrep_agi_commit_new(
> +	struct xfs_scrub	*sc,
> +	struct xfs_buf		*agi_bp)
> +{
> +	struct xfs_perag	*pag;
> +	struct xfs_agi		*agi = XFS_BUF_TO_AGI(agi_bp);
> +
> +	/* Trigger inode count recalculation */
> +	xfs_force_summary_recalc(sc->mp);
> +
> +	/* Write this to disk. */
> +	xfs_trans_buf_set_type(sc->tp, agi_bp, XFS_BLFT_AGI_BUF);
> +	xfs_trans_log_buf(sc->tp, agi_bp, 0, BBTOB(agi_bp->b_length) - 1);
> +
> +	/* Now reinitialize the in-core counters if necessary. */
> +	pag = sc->sa.pag;
> +	pag->pagi_count = be32_to_cpu(agi->agi_count);
> +	pag->pagi_freecount = be32_to_cpu(agi->agi_freecount);
> +	pag->pagi_init = 1;
> +
> +	return 0;
> +}
> +
> +/* Repair the AGI. */
> +int
> +xrep_agi(
> +	struct xfs_scrub		*sc)
> +{
> +	struct xrep_find_ag_btree	fab[XREP_AGI_MAX] = {
> +		[XREP_AGI_INOBT] = {
> +			.rmap_owner = XFS_RMAP_OWN_INOBT,
> +			.buf_ops = &xfs_inobt_buf_ops,
> +			.magic = XFS_IBT_CRC_MAGIC,
> +		},
> +		[XREP_AGI_FINOBT] = {
> +			.rmap_owner = XFS_RMAP_OWN_INOBT,
> +			.buf_ops = &xfs_inobt_buf_ops,
> +			.magic = XFS_FIBT_CRC_MAGIC,
> +		},
> +		[XREP_AGI_END] = {
> +			.buf_ops = NULL
> +		},
> +	};
> +	struct xfs_agi			old_agi;
> +	struct xfs_mount		*mp = sc->mp;
> +	struct xfs_buf			*agi_bp;
> +	struct xfs_agi			*agi;
> +	int				error;
> +
> +	/* We require the rmapbt to rebuild anything. */
> +	if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
> +		return -EOPNOTSUPP;
> +
> +	xchk_perag_get(sc->mp, &sc->sa);
> +	/*
> +	 * Make sure we have the AGI buffer, as scrub might have decided it
> +	 * was corrupt after xfs_ialloc_read_agi failed with -EFSCORRUPTED.
> +	 */
> +	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
> +			XFS_AG_DADDR(mp, sc->sa.agno, XFS_AGI_DADDR(mp)),
> +			XFS_FSS_TO_BB(mp, 1), 0, &agi_bp, NULL);
> +	if (error)
> +		return error;
> +	agi_bp->b_ops = &xfs_agi_buf_ops;
> +	agi = XFS_BUF_TO_AGI(agi_bp);
> +
> +	/* Find the AGI btree roots. */
> +	error = xrep_agi_find_btrees(sc, fab);
> +	if (error)
> +		return error;
> +
> +	/* Start rewriting the header and implant the btrees we found. */
> +	xrep_agi_init_header(sc, agi_bp, &old_agi);
> +	xrep_agi_set_roots(sc, agi, fab);
> +	error = xrep_agi_calc_from_btrees(sc, agi_bp);
> +	if (error)
> +		goto out_revert;
> +
> +	/* Reinitialize in-core state. */
> +	return xrep_agi_commit_new(sc, agi_bp);
> +
> +out_revert:
> +	/* Mark the incore AGI state stale and revert the AGI. */
> +	sc->sa.pag->pagi_init = 0;
> +	memcpy(agi, &old_agi, sizeof(old_agi));
> +	return error;
> +}
> diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
> index 1d283360b5ab..9de321eee4ab 100644
> --- a/fs/xfs/scrub/repair.h
> +++ b/fs/xfs/scrub/repair.h
> @@ -60,6 +60,7 @@ int xrep_probe(struct xfs_scrub *sc);
>  int xrep_superblock(struct xfs_scrub *sc);
>  int xrep_agf(struct xfs_scrub *sc);
>  int xrep_agfl(struct xfs_scrub *sc);
> +int xrep_agi(struct xfs_scrub *sc);
>  
>  #else
>  
> @@ -85,6 +86,7 @@ xrep_calc_ag_resblks(
>  #define xrep_superblock			xrep_notsupported
>  #define xrep_agf			xrep_notsupported
>  #define xrep_agfl			xrep_notsupported
> +#define xrep_agi			xrep_notsupported
>  
>  #endif /* CONFIG_XFS_ONLINE_REPAIR */
>  
> diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
> index 2670f4cf62f4..4bfae1e61d30 100644
> --- a/fs/xfs/scrub/scrub.c
> +++ b/fs/xfs/scrub/scrub.c
> @@ -226,7 +226,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
>  		.type	= ST_PERAG,
>  		.setup	= xchk_setup_fs,
>  		.scrub	= xchk_agi,
> -		.repair	= xrep_notsupported,
> +		.repair	= xrep_agi,
>  	},
>  	[XFS_SCRUB_TYPE_BNOBT] = {	/* bnobt */
>  		.type	= ST_PERAG,
> 
> --
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