Merge tag 'scrub-fix-ag-header-handling-6.2_2022-11-16' of...

Merge tag 'scrub-fix-ag-header-handling-6.2_2022-11-16' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.2-mergeA

xfs: fix handling of AG[IF] header buffers during scrub

While reading through the online fsck code, I noticed that the setup
code for AG metadata scrubs will attach the AGI, the AGF, and the AGFL
buffers to the transaction.  It isn't necessary to hold the AGFL buffer,
since any code that wants to do anything with the AGFL will need to hold
the AGF to know which parts of the AGFL are active.  Therefore, we only
need to hold the AGFL when scrubbing the AGFL itself.

The second bug fixed by this patchset is one that I observed while
testing online repair.  When a buffer is held across a transaction roll,
its buffer log item will be detached if the bli was clean before the
roll.  If we are holding the AG headers to maintain a lock on an AG, we
then need to set the buffer type on the new bli to avoid confusing the
logging code later.

There's also a bug fix for uninitialized memory in the directory scanner
that didn't fit anywhere else.

Ths patchset finishes off by teaching the AGFL repair function to look
for and discard crosslinked blocks instead of putting them back on the
AGFL.

v23.2: Log the buffers before rolling the transaction to keep the moving
forward in the log and avoid the bli falling off.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

* tag 'scrub-fix-ag-header-handling-6.2_2022-11-16' of git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: make AGFL repair function avoid crosslinked blocks
  xfs: log the AGI/AGF buffers when rolling transactions during an AG repair
  xfs: don't track the AGFL buffer in the scrub AG context
  xfs: fully initialize xfs_da_args in xchk_directory_blocks

fs/xfs/scrub/agheader.c

@@ -609,9 +609,16 @@ xchk_agf(
 /* AGFL */
 
 struct xchk_agfl_info {
-	unsigned int		sz_entries;
+	/* Number of AGFL entries that the AGF claims are in use. */
+	unsigned int		agflcount;
+
+	/* Number of AGFL entries that we found. */
 	unsigned int		nr_entries;
+
+	/* Buffer to hold AGFL entries for extent checking. */
 	xfs_agblock_t		*entries;
+
+	struct xfs_buf		*agfl_bp;
 	struct xfs_scrub	*sc;
 };
 
@@ -641,10 +648,10 @@ xchk_agfl_block(
 	struct xfs_scrub	*sc = sai->sc;
 
 	if (xfs_verify_agbno(sc->sa.pag, agbno) &&
-	    sai->nr_entries < sai->sz_entries)
+	    sai->nr_entries < sai->agflcount)
 		sai->entries[sai->nr_entries++] = agbno;
 	else
-		xchk_block_set_corrupt(sc, sc->sa.agfl_bp);
+		xchk_block_set_corrupt(sc, sai->agfl_bp);
 
 	xchk_agfl_block_xref(sc, agbno);
 
@@ -696,19 +703,26 @@ int
 xchk_agfl(
 	struct xfs_scrub	*sc)
 {
-	struct xchk_agfl_info	sai;
+	struct xchk_agfl_info	sai = {
+		.sc		= sc,
+	};
 	struct xfs_agf		*agf;
 	xfs_agnumber_t		agno = sc->sm->sm_agno;
-	unsigned int		agflcount;
 	unsigned int		i;
 	int			error;
 
+	/* Lock the AGF and AGI so that nobody can touch this AG. */
 	error = xchk_ag_read_headers(sc, agno, &sc->sa);
 	if (!xchk_process_error(sc, agno, XFS_AGFL_BLOCK(sc->mp), &error))
-		goto out;
+		return error;
 	if (!sc->sa.agf_bp)
 		return -EFSCORRUPTED;
-	xchk_buffer_recheck(sc, sc->sa.agfl_bp);
+
+	/* Try to read the AGFL, and verify its structure if we get it. */
+	error = xfs_alloc_read_agfl(sc->sa.pag, sc->tp, &sai.agfl_bp);
+	if (!xchk_process_error(sc, agno, XFS_AGFL_BLOCK(sc->mp), &error))
+		return error;
+	xchk_buffer_recheck(sc, sai.agfl_bp);
 
 	xchk_agfl_xref(sc);
 
@@ -717,24 +731,21 @@ xchk_agfl(
 
 	/* Allocate buffer to ensure uniqueness of AGFL entries. */
 	agf = sc->sa.agf_bp->b_addr;
-	agflcount = be32_to_cpu(agf->agf_flcount);
-	if (agflcount > xfs_agfl_size(sc->mp)) {
+	sai.agflcount = be32_to_cpu(agf->agf_flcount);
+	if (sai.agflcount > xfs_agfl_size(sc->mp)) {
 		xchk_block_set_corrupt(sc, sc->sa.agf_bp);
 		goto out;
 	}
-	memset(&sai, 0, sizeof(sai));
-	sai.sc = sc;
-	sai.sz_entries = agflcount;
-	sai.entries = kmem_zalloc(sizeof(xfs_agblock_t) * agflcount,
-			KM_MAYFAIL);
+	sai.entries = kvcalloc(sai.agflcount, sizeof(xfs_agblock_t),
+			GFP_KERNEL | __GFP_RETRY_MAYFAIL);
 	if (!sai.entries) {
 		error = -ENOMEM;
 		goto out;
 	}
 
 	/* Check the blocks in the AGFL. */
-	error = xfs_agfl_walk(sc->mp, sc->sa.agf_bp->b_addr,
-			sc->sa.agfl_bp, xchk_agfl_block, &sai);
+	error = xfs_agfl_walk(sc->mp, sc->sa.agf_bp->b_addr, sai.agfl_bp,
+			xchk_agfl_block, &sai);
 	if (error == -ECANCELED) {
 		error = 0;
 		goto out_free;
@@ -742,7 +753,7 @@ xchk_agfl(
 	if (error)
 		goto out_free;
 
-	if (agflcount != sai.nr_entries) {
+	if (sai.agflcount != sai.nr_entries) {
 		xchk_block_set_corrupt(sc, sc->sa.agf_bp);
 		goto out_free;
 	}
@@ -758,7 +769,7 @@ xchk_agfl(
 	}
 
 out_free:
-	kmem_free(sai.entries);
+	kvfree(sai.entries);
 out:
 	return error;
 }

fs/xfs/scrub/agheader_repair.c

@@ -442,12 +442,18 @@ xrep_agf(
 /* AGFL */
 
 struct xrep_agfl {
+	/* Bitmap of alleged AGFL blocks that we're not going to add. */
+	struct xbitmap		crossed;
+
 	/* Bitmap of other OWN_AG metadata blocks. */
 	struct xbitmap		agmetablocks;
 
 	/* Bitmap of free space. */
 	struct xbitmap		*freesp;
 
+	/* rmapbt cursor for finding crosslinked blocks */
+	struct xfs_btree_cur	*rmap_cur;
+
 	struct xfs_scrub	*sc;
 };
 
@@ -477,6 +483,41 @@ xrep_agfl_walk_rmap(
 	return xbitmap_set_btcur_path(&ra->agmetablocks, cur);
 }
 
+/* Strike out the blocks that are cross-linked according to the rmapbt. */
+STATIC int
+xrep_agfl_check_extent(
+	struct xrep_agfl	*ra,
+	uint64_t		start,
+	uint64_t		len)
+{
+	xfs_agblock_t		agbno = XFS_FSB_TO_AGBNO(ra->sc->mp, start);
+	xfs_agblock_t		last_agbno = agbno + len - 1;
+	int			error;
+
+	ASSERT(XFS_FSB_TO_AGNO(ra->sc->mp, start) == ra->sc->sa.pag->pag_agno);
+
+	while (agbno <= last_agbno) {
+		bool		other_owners;
+
+		error = xfs_rmap_has_other_keys(ra->rmap_cur, agbno, 1,
+				&XFS_RMAP_OINFO_AG, &other_owners);
+		if (error)
+			return error;
+
+		if (other_owners) {
+			error = xbitmap_set(&ra->crossed, agbno, 1);
+			if (error)
+				return error;
+		}
+
+		if (xchk_should_terminate(ra->sc, &error))
+			return error;
+		agbno++;
+	}
+
+	return 0;
+}
+
 /*
  * Map out all the non-AGFL OWN_AG space in this AG so that we can deduce
  * which blocks belong to the AGFL.
@@ -496,44 +537,58 @@ xrep_agfl_collect_blocks(
 	struct xrep_agfl	ra;
 	struct xfs_mount	*mp = sc->mp;
 	struct xfs_btree_cur	*cur;
+	struct xbitmap_range	*br, *n;
 	int			error;
 
 	ra.sc = sc;
 	ra.freesp = agfl_extents;
 	xbitmap_init(&ra.agmetablocks);
+	xbitmap_init(&ra.crossed);
 
 	/* Find all space used by the free space btrees & rmapbt. */
 	cur = xfs_rmapbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.pag);
 	error = xfs_rmap_query_all(cur, xrep_agfl_walk_rmap, &ra);
-	if (error)
-		goto err;
 	xfs_btree_del_cursor(cur, error);
+	if (error)
+		goto out_bmp;
 
 	/* Find all blocks currently being used by the bnobt. */
 	cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp,
 			sc->sa.pag, XFS_BTNUM_BNO);
 	error = xbitmap_set_btblocks(&ra.agmetablocks, cur);
-	if (error)
-		goto err;
 	xfs_btree_del_cursor(cur, error);
+	if (error)
+		goto out_bmp;
 
 	/* Find all blocks currently being used by the cntbt. */
 	cur = xfs_allocbt_init_cursor(mp, sc->tp, agf_bp,
 			sc->sa.pag, XFS_BTNUM_CNT);
 	error = xbitmap_set_btblocks(&ra.agmetablocks, cur);
-	if (error)
-		goto err;
-
 	xfs_btree_del_cursor(cur, error);
+	if (error)
+		goto out_bmp;
 
 	/*
 	 * Drop the freesp meta blocks that are in use by btrees.
 	 * The remaining blocks /should/ be AGFL blocks.
 	 */
 	error = xbitmap_disunion(agfl_extents, &ra.agmetablocks);
-	xbitmap_destroy(&ra.agmetablocks);
 	if (error)
-		return error;
+		goto out_bmp;
+
+	/* Strike out the blocks that are cross-linked. */
+	ra.rmap_cur = xfs_rmapbt_init_cursor(mp, sc->tp, agf_bp, sc->sa.pag);
+	for_each_xbitmap_extent(br, n, agfl_extents) {
+		error = xrep_agfl_check_extent(&ra, br->start, br->len);
+		if (error)
+			break;
+	}
+	xfs_btree_del_cursor(ra.rmap_cur, error);
+	if (error)
+		goto out_bmp;
+	error = xbitmap_disunion(agfl_extents, &ra.crossed);
+	if (error)
+		goto out_bmp;
 
 	/*
 	 * Calculate the new AGFL size.  If we found more blocks than fit in
@@ -541,11 +596,10 @@ xrep_agfl_collect_blocks(
 	 */
 	*flcount = min_t(uint64_t, xbitmap_hweight(agfl_extents),
 			 xfs_agfl_size(mp));
-	return 0;
 
-err:
+out_bmp:
+	xbitmap_destroy(&ra.crossed);
 	xbitmap_destroy(&ra.agmetablocks);
-	xfs_btree_del_cursor(cur, error);
 	return error;
 }
 
@@ -697,7 +751,6 @@ xrep_agfl(
 	 * 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;

fs/xfs/scrub/common.c

@@ -424,10 +424,6 @@ xchk_ag_read_headers(
 	if (error && want_ag_read_header_failure(sc, XFS_SCRUB_TYPE_AGF))
 		return error;
 
-	error = xfs_alloc_read_agfl(sa->pag, sc->tp, &sa->agfl_bp);
-	if (error && want_ag_read_header_failure(sc, XFS_SCRUB_TYPE_AGFL))
-		return error;
-
 	return 0;
 }
 
@@ -515,10 +511,6 @@ xchk_ag_free(
 	struct xchk_ag		*sa)
 {
 	xchk_ag_btcur_free(sa);
-	if (sa->agfl_bp) {
-		xfs_trans_brelse(sc->tp, sa->agfl_bp);
-		sa->agfl_bp = NULL;
-	}
 	if (sa->agf_bp) {
 		xfs_trans_brelse(sc->tp, sa->agf_bp);
 		sa->agf_bp = NULL;

fs/xfs/scrub/dir.c

@@ -666,7 +666,12 @@ xchk_directory_blocks(
 	struct xfs_scrub	*sc)
 {
 	struct xfs_bmbt_irec	got;
-	struct xfs_da_args	args;
+	struct xfs_da_args	args = {
+		.dp		= sc ->ip,
+		.whichfork	= XFS_DATA_FORK,
+		.geo		= sc->mp->m_dir_geo,
+		.trans		= sc->tp,
+	};
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(sc->ip, XFS_DATA_FORK);
 	struct xfs_mount	*mp = sc->mp;
 	xfs_fileoff_t		leaf_lblk;
@@ -689,9 +694,6 @@ xchk_directory_blocks(
 	free_lblk = XFS_B_TO_FSB(mp, XFS_DIR2_FREE_OFFSET);
 
 	/* Is this a block dir? */
-	args.dp = sc->ip;
-	args.geo = mp->m_dir_geo;
-	args.trans = sc->tp;
 	error = xfs_dir2_isblock(&args, &is_block);
 	if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))
 		goto out;

fs/xfs/scrub/repair.c

@@ -121,32 +121,40 @@ xrep_roll_ag_trans(
 {
 	int			error;
 
-	/* Keep the AG header buffers locked so we can keep going. */
-	if (sc->sa.agi_bp)
+	/*
+	 * Keep the AG header buffers locked while we roll the transaction.
+	 * Ensure that both AG buffers are dirty and held when we roll the
+	 * transaction so that they move forward in the log without losing the
+	 * bli (and hence the bli type) when the transaction commits.
+	 *
+	 * Normal code would never hold clean buffers across a roll, but repair
+	 * needs both buffers to maintain a total lock on the AG.
+	 */
+	if (sc->sa.agi_bp) {
+		xfs_ialloc_log_agi(sc->tp, sc->sa.agi_bp, XFS_AGI_MAGICNUM);
 		xfs_trans_bhold(sc->tp, sc->sa.agi_bp);
-	if (sc->sa.agf_bp)
+	}
+
+	if (sc->sa.agf_bp) {
+		xfs_alloc_log_agf(sc->tp, sc->sa.agf_bp, XFS_AGF_MAGICNUM);
 		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.  We still own the buffer and the buffer lock
-	 * regardless of whether or not the roll succeeds.  If the roll fails,
-	 * the buffers will be released during teardown on our way out of the
-	 * kernel.  If it succeeds, we join them to the new transaction and
-	 * move on.
+	 * Roll the transaction.  We still hold the AG header buffers locked
+	 * regardless of whether or not that succeeds.  On failure, the buffers
+	 * will be released during teardown on our way out of the kernel.  If
+	 * successful, join the buffers to the new transaction and move on.
 	 */
 	error = xfs_trans_roll(&sc->tp);
 	if (error)
 		return error;
 
-	/* Join AG headers to the new transaction. */
+	/* Join the AG headers to the new transaction. */
 	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;
 }
@@ -498,6 +506,7 @@ xrep_put_freelist(
 	struct xfs_scrub	*sc,
 	xfs_agblock_t		agbno)
 {
+	struct xfs_buf		*agfl_bp;
 	int			error;
 
 	/* Make sure there's space on the freelist. */
@@ -516,8 +525,12 @@ xrep_put_freelist(
 		return error;
 
 	/* Put the block on the AGFL. */
+	error = xfs_alloc_read_agfl(sc->sa.pag, sc->tp, &agfl_bp);
+	if (error)
+		return error;
+
 	error = xfs_alloc_put_freelist(sc->sa.pag, sc->tp, sc->sa.agf_bp,
-			sc->sa.agfl_bp, agbno, 0);
+			agfl_bp, agbno, 0);
 	if (error)
 		return error;
 	xfs_extent_busy_insert(sc->tp, sc->sa.pag, agbno, 1,

fs/xfs/scrub/scrub.h

@@ -39,7 +39,6 @@ struct xchk_ag {
 
 	/* AG btree roots */
 	struct xfs_buf		*agf_bp;
-	struct xfs_buf		*agfl_bp;
 	struct xfs_buf		*agi_bp;
 
 	/* AG btrees */