xfs: online repair of realtime bitmaps

Fix all the file metadata surrounding the realtime bitmap file, which
includes the rt geometry, file size, forks, and space mappings.  The
bitmap contents themselves cannot be fixed without rt rmap, so that will
come later.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 202 insertions, 0 deletions

diff --git a/fs/xfs/scrub/rtbitmap_repair.c b/fs/xfs/scrub/rtbitmap_repair.c
new file mode 100644
index 000000000000..46f5d5f605c9
--- /dev/null
+++ b/fs/xfs/scrub/rtbitmap_repair.c
@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2020-2023 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_btree.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_inode.h"
+#include "xfs_bit.h"
+#include "xfs_bmap.h"
+#include "xfs_bmap_btree.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/trace.h"
+#include "scrub/repair.h"
+#include "scrub/xfile.h"
+#include "scrub/rtbitmap.h"
+
+/* Set up to repair the realtime bitmap file metadata. */
+int
+xrep_setup_rtbitmap(
+	struct xfs_scrub	*sc,
+	struct xchk_rtbitmap	*rtb)
+{
+	struct xfs_mount	*mp = sc->mp;
+	unsigned long long	blocks = 0;
+
+	/*
+	 * Reserve enough blocks to write out a completely new bmbt for a
+	 * maximally fragmented bitmap file.  We do not hold the rtbitmap
+	 * ILOCK yet, so this is entirely speculative.
+	 */
+	blocks = xfs_bmbt_calc_size(mp, mp->m_sb.sb_rbmblocks);
+	if (blocks > UINT_MAX)
+		return -EOPNOTSUPP;
+
+	rtb->resblks += blocks;
+	return 0;
+}
+
+/*
+ * Make sure that the given range of the data fork of the realtime file is
+ * mapped to written blocks.  The caller must ensure that the inode is joined
+ * to the transaction.
+ */
+STATIC int
+xrep_rtbitmap_data_mappings(
+	struct xfs_scrub	*sc,
+	xfs_filblks_t		len)
+{
+	struct xfs_bmbt_irec	map;
+	xfs_fileoff_t		off = 0;
+	int			error;
+
+	ASSERT(sc->ip != NULL);
+
+	while (off < len) {
+		int		nmaps = 1;
+
+		/*
+		 * If we have a real extent mapping this block then we're
+		 * in ok shape.
+		 */
+		error = xfs_bmapi_read(sc->ip, off, len - off, &map, &nmaps,
+				XFS_DATA_FORK);
+		if (error)
+			return error;
+		if (nmaps == 0) {
+			ASSERT(nmaps != 0);
+			return -EFSCORRUPTED;
+		}
+
+		/*
+		 * Written extents are ok.  Holes are not filled because we
+		 * do not know the freespace information.
+		 */
+		if (xfs_bmap_is_written_extent(&map) ||
+		    map.br_startblock == HOLESTARTBLOCK) {
+			off = map.br_startoff + map.br_blockcount;
+			continue;
+		}
+
+		/*
+		 * If we find a delalloc reservation then something is very
+		 * very wrong.  Bail out.
+		 */
+		if (map.br_startblock == DELAYSTARTBLOCK)
+			return -EFSCORRUPTED;
+
+		/* Make sure we're really converting an unwritten extent. */
+		if (map.br_state != XFS_EXT_UNWRITTEN) {
+			ASSERT(map.br_state == XFS_EXT_UNWRITTEN);
+			return -EFSCORRUPTED;
+		}
+
+		/* Make sure this block has a real zeroed extent mapped. */
+		nmaps = 1;
+		error = xfs_bmapi_write(sc->tp, sc->ip, map.br_startoff,
+				map.br_blockcount,
+				XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO,
+				0, &map, &nmaps);
+		if (error)
+			return error;
+		if (nmaps != 1)
+			return -EFSCORRUPTED;
+
+		/* Commit new extent and all deferred work. */
+		error = xrep_defer_finish(sc);
+		if (error)
+			return error;
+
+		off = map.br_startoff + map.br_blockcount;
+	}
+
+	return 0;
+}
+
+/* Fix broken rt volume geometry. */
+STATIC int
+xrep_rtbitmap_geometry(
+	struct xfs_scrub	*sc,
+	struct xchk_rtbitmap	*rtb)
+{
+	struct xfs_mount	*mp = sc->mp;
+	struct xfs_trans	*tp = sc->tp;
+
+	/* Superblock fields */
+	if (mp->m_sb.sb_rextents != rtb->rextents)
+		xfs_trans_mod_sb(sc->tp, XFS_TRANS_SB_REXTENTS,
+				rtb->rextents - mp->m_sb.sb_rextents);
+
+	if (mp->m_sb.sb_rbmblocks != rtb->rbmblocks)
+		xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBMBLOCKS,
+				rtb->rbmblocks - mp->m_sb.sb_rbmblocks);
+
+	if (mp->m_sb.sb_rextslog != rtb->rextslog)
+		xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSLOG,
+				rtb->rextslog - mp->m_sb.sb_rextslog);
+
+	/* Fix broken isize */
+	sc->ip->i_disk_size = roundup_64(sc->ip->i_disk_size,
+					 mp->m_sb.sb_blocksize);
+
+	if (sc->ip->i_disk_size < XFS_FSB_TO_B(mp, rtb->rbmblocks))
+		sc->ip->i_disk_size = XFS_FSB_TO_B(mp, rtb->rbmblocks);
+
+	xfs_trans_log_inode(sc->tp, sc->ip, XFS_ILOG_CORE);
+	return xrep_roll_trans(sc);
+}
+
+/* Repair the realtime bitmap file metadata. */
+int
+xrep_rtbitmap(
+	struct xfs_scrub	*sc)
+{
+	struct xchk_rtbitmap	*rtb = sc->buf;
+	struct xfs_mount	*mp = sc->mp;
+	unsigned long long	blocks = 0;
+	int			error;
+
+	/* Impossibly large rtbitmap means we can't touch the filesystem. */
+	if (rtb->rbmblocks > U32_MAX)
+		return 0;
+
+	/*
+	 * If the size of the rt bitmap file is larger than what we reserved,
+	 * figure out if we need to adjust the block reservation in the
+	 * transaction.
+	 */
+	blocks = xfs_bmbt_calc_size(mp, rtb->rbmblocks);
+	if (blocks > UINT_MAX)
+		return -EOPNOTSUPP;
+	if (blocks > rtb->resblks) {
+		error = xfs_trans_reserve_more(sc->tp, blocks, 0);
+		if (error)
+			return error;
+
+		rtb->resblks += blocks;
+	}
+
+	/* Fix inode core and forks. */
+	error = xrep_metadata_inode_forks(sc);
+	if (error)
+		return error;
+
+	xfs_trans_ijoin(sc->tp, sc->ip, 0);
+
+	/* Ensure no unwritten extents. */
+	error = xrep_rtbitmap_data_mappings(sc, rtb->rbmblocks);
+	if (error)
+		return error;
+
+	/* Fix inconsistent bitmap geometry */
+	return xrep_rtbitmap_geometry(sc, rtb);
+}