db/bmap_inflate.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) 2022-2024 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#include "libxfs.h"
#include "command.h"
#include "init.h"
#include "output.h"
#include "io.h"
#include "libfrog/convert.h"

static void
bmapinflate_help(void)
{
	dbprintf(_(
"\n"
" Make the bmbt really big by cloning the first data fork mapping over and over.\n"
" -d     Constrain dirty buffers to this many bytes.\n"
" -e     Print the size and height of the btree and exit.\n"
" -n nr  Create this many copies of the mapping.\n"
"\n"
));

}

static int
find_mapping(
	struct xfs_trans	*tp,
	struct xfs_inode	*ip,
	struct xfs_bmbt_irec	*irec)
{
	struct xfs_iext_cursor	icur;
	int			error;

	if (!xfs_has_reflink(ip->i_mount)) {
		dbprintf(_("filesystem does not support reflink\n"));
		return 1;
	}

	if (ip->i_df.if_nextents != 1) {
		dbprintf(_("inode must have only one data fork mapping\n"));
		return 1;
	}

	error = -libxfs_iread_extents(tp, ip, XFS_DATA_FORK);
	if (error) {
		dbprintf(_("could not read data fork, err %d\n"), error);
		return 1;
	}

	libxfs_iext_first(&ip->i_df, &icur);
	if (!xfs_iext_get_extent(&ip->i_df, &icur, irec)) {
		dbprintf(_("could not read data fork mapping\n"));
		return 1;
	}

	if (irec->br_state != XFS_EXT_NORM) {
		dbprintf(_("cannot duplicate unwritten extent\n"));
		return 1;
	}

	return 0;
}

static int
set_nrext64(
	struct xfs_trans	*tp,
	struct xfs_inode	*ip,
	xfs_extnum_t		nextents)
{
	xfs_extnum_t		max_extents;
	bool			large_extcount;

	large_extcount = xfs_inode_has_large_extent_counts(ip);
	max_extents = xfs_iext_max_nextents(large_extcount, XFS_DATA_FORK);
	if (nextents <= max_extents)
		return 0;
	if (large_extcount)
		return EFSCORRUPTED;
	if (!xfs_has_large_extent_counts(ip->i_mount))
		return EFSCORRUPTED;

	max_extents = xfs_iext_max_nextents(true, XFS_DATA_FORK);
	if (nextents > max_extents)
		return EFSCORRUPTED;

	ip->i_diflags2 |= XFS_DIFLAG2_NREXT64;
	libxfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
	return 0;
}

static int
populate_extents(
	struct xfs_trans		*tp,
	struct xfs_inode		*ip,
	struct xbtree_ifakeroot		*ifake,
	const struct xfs_bmbt_irec	*template,
	xfs_extnum_t			nextents)
{
	struct xfs_bmbt_irec		irec = {
		.br_startoff		= 0,
		.br_startblock		= template->br_startblock,
		.br_blockcount		= template->br_blockcount,
		.br_state		= XFS_EXT_NORM,
	};
	struct xfs_iext_cursor		icur;
	struct xfs_ifork		*ifp = ifake->if_fork;
	unsigned long long		i;

	/* Add all the mappings to the incore extent tree. */
	libxfs_iext_first(ifp, &icur);
	for (i = 0; i < nextents; i++) {
		libxfs_iext_insert_raw(ifp, &icur, &irec);
		ifp->if_nextents++;
		libxfs_iext_next(ifp, &icur);

		irec.br_startoff += irec.br_blockcount;
	}

	ip->i_nblocks = template->br_blockcount * nextents;
	libxfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

	return 0;
}

struct bmbt_resv {
	struct list_head	list;
	xfs_fsblock_t		fsbno;
	xfs_extlen_t		len;
	xfs_extlen_t		used;
};

struct bmbt_data {
	struct xfs_bmbt_irec	irec;
	struct list_head	resv_list;
	unsigned long long	iblocks;
	unsigned long long	nr;
};

static int
alloc_bmbt_blocks(
	struct xfs_trans	**tpp,
	struct xfs_inode	*ip,
	struct bmbt_data	*bd,
	uint64_t		nr_blocks)
{
	struct xfs_mount	*mp = ip->i_mount;
	struct list_head	*resv_list = &bd->resv_list;
	int			error = 0;

	while (nr_blocks > 0) {
		struct xfs_alloc_arg	args = {
			.tp		= *tpp,
			.mp		= mp,
			.minlen		= 1,
			.maxlen		= nr_blocks,
			.prod		= 1,
			.resv		= XFS_AG_RESV_NONE,
		};
		struct bmbt_resv	*resv;
		xfs_fsblock_t		target = 0;

		if (xfs_has_rmapbt(mp)) {
			xfs_agnumber_t		tgt_agno;

			/*
			 * Try to allocate bmbt blocks in a different AG so
			 * that we don't blow up the rmapbt with the bmbt
			 * records.
			 */
			tgt_agno = 1 + XFS_FSB_TO_AGNO(mp,
							bd->irec.br_startblock);
			if (tgt_agno >= mp->m_sb.sb_agcount)
				tgt_agno = 0;
			target = XFS_AGB_TO_FSB(mp, tgt_agno, 0);
		}

		libxfs_rmap_ino_bmbt_owner(&args.oinfo, ip->i_ino,
				XFS_DATA_FORK);

		error = -libxfs_alloc_vextent_start_ag(&args, target);
		if (error)
			return error;
		if (args.fsbno == NULLFSBLOCK)
			return ENOSPC;

		resv = kmalloc(sizeof(struct bmbt_resv), 0);
		if (!resv)
			return ENOMEM;

		INIT_LIST_HEAD(&resv->list);
		resv->fsbno = args.fsbno;
		resv->len = args.len;
		resv->used = 0;
		list_add_tail(&resv->list, resv_list);

		nr_blocks -= args.len;

		error = -libxfs_trans_roll_inode(tpp, ip);
		if (error)
			return error;
	}

	return 0;
}

static int
get_bmbt_records(
	struct xfs_btree_cur	*cur,
	unsigned int		idx,
	struct xfs_btree_block	*block,
	unsigned int		nr_wanted,
	void			*priv)
{
	struct xfs_bmbt_irec	*irec = &cur->bc_rec.b;
	struct bmbt_data	*bd = priv;
	union xfs_btree_rec	*block_rec;
	struct xfs_ifork	*ifp = cur->bc_ino.ifake->if_fork;
	unsigned int		loaded;

	for (loaded = 0; loaded < nr_wanted; loaded++, idx++) {
		memcpy(irec, &bd->irec, sizeof(struct xfs_bmbt_irec));

		block_rec = libxfs_btree_rec_addr(cur, idx, block);
		cur->bc_ops->init_rec_from_cur(cur, block_rec);
		ifp->if_nextents++;

		bd->irec.br_startoff += bd->irec.br_blockcount;
	}

	return loaded;
}

static int
claim_block(
	struct xfs_btree_cur	*cur,
	union xfs_btree_ptr	*ptr,
	void			*priv)
{
	struct bmbt_data	*bd = priv;
	struct bmbt_resv	*resv;
	xfs_fsblock_t		fsb;

	/*
	 * The first item in the list should always have a free block unless
	 * we're completely out.
	 */
	resv = list_first_entry(&bd->resv_list, struct bmbt_resv, list);
	if (resv->used == resv->len)
		return ENOSPC;

	fsb = resv->fsbno + resv->used;
	resv->used++;

	/* If we used all the blocks in this reservation, move it to the end. */
	if (resv->used == resv->len)
		list_move_tail(&resv->list, &bd->resv_list);

	ptr->l = cpu_to_be64(fsb);
	bd->iblocks++;
	return 0;
}

static size_t
iroot_size(
	struct xfs_btree_cur	*cur,
	unsigned int		level,
	unsigned int		nr_this_level,
	void			*priv)
{
	return xfs_bmap_broot_space_calc(cur->bc_mp, nr_this_level);
}

static int
populate_btree(
	struct xfs_trans		**tpp,
	struct xfs_inode		*ip,
	uint16_t			dirty_blocks,
	struct xbtree_ifakeroot		*ifake,
	struct xfs_btree_cur		*bmap_cur,
	const struct xfs_bmbt_irec	*template,
	xfs_extnum_t			nextents)
{
	struct xfs_btree_bload		bmap_bload = {
		.get_records		= get_bmbt_records,
		.claim_block		= claim_block,
		.iroot_size		= iroot_size,
		.max_dirty		= dirty_blocks,
		.leaf_slack		= 1,
		.node_slack		= 1,
	};
	struct bmbt_data		bd = {
		.irec			= {
			.br_startoff	= 0,
			.br_startblock	= template->br_startblock,
			.br_blockcount	= template->br_blockcount,
			.br_state	= XFS_EXT_NORM,
		},
		.iblocks		= 0,
	};
	struct bmbt_resv		*resv, *n;
	int				error;

	error = -libxfs_btree_bload_compute_geometry(bmap_cur, &bmap_bload,
			nextents);
	if (error)
		return error;

	error = -libxfs_trans_reserve_more(*tpp, bmap_bload.nr_blocks, 0);
	if (error)
		return error;

	INIT_LIST_HEAD(&bd.resv_list);
	error = alloc_bmbt_blocks(tpp, ip, &bd, bmap_bload.nr_blocks);
	if (error)
		return error;

	error = -libxfs_btree_bload(bmap_cur, &bmap_bload, &bd);
	if (error)
	       goto out_resv_list;

	ip->i_nblocks = bd.iblocks + (template->br_blockcount * nextents);
	libxfs_trans_log_inode(*tpp, ip, XFS_ILOG_CORE);

out_resv_list:
	/* Leak any unused blocks */
	list_for_each_entry_safe(resv, n, &bd.resv_list, list) {
		list_del(&resv->list);
		kfree(resv);
	}
	return error;
}

static int
build_new_datafork(
	struct xfs_trans		**tpp,
	struct xfs_inode		*ip,
	uint16_t			dirty_blocks,
	const struct xfs_bmbt_irec	*irec,
	xfs_extnum_t			nextents)
{
	struct xbtree_ifakeroot		ifake = {};
	struct xfs_btree_cur		*bmap_cur;
	int				error;

	error = set_nrext64(*tpp, ip, nextents);
	if (error)
		return error;

	/* Set up staging for the new bmbt */
	ifake.if_fork = kmem_cache_zalloc(xfs_ifork_cache, 0);
	ifake.if_fork_size = xfs_inode_fork_size(ip, XFS_DATA_FORK);
	bmap_cur = libxfs_bmbt_init_cursor(ip->i_mount, NULL, ip,
			XFS_STAGING_FORK);
	libxfs_btree_stage_ifakeroot(bmap_cur, &ifake);

	/*
	 * Figure out the size and format of the new fork, then fill it with
	 * the bmap record we want.
	 */
	if (nextents <= XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK)) {
		ifake.if_fork->if_format = XFS_DINODE_FMT_EXTENTS;
		error = populate_extents(*tpp, ip, &ifake, irec, nextents);
	} else {
		ifake.if_fork->if_format = XFS_DINODE_FMT_BTREE;
		error = populate_btree(tpp, ip, dirty_blocks, &ifake, bmap_cur,
				irec, nextents);
	}
	if (error) {
		libxfs_btree_del_cursor(bmap_cur, 0);
		goto err_ifork;
	}

	/* Install the new fork in the inode. */
	libxfs_bmbt_commit_staged_btree(bmap_cur, *tpp, XFS_DATA_FORK);
	libxfs_btree_del_cursor(bmap_cur, 0);

	/* Mark filesystem as needsrepair */
	dbprintf(_("filesystem is now inconsistent, xfs_repair required!\n"));
	mp->m_sb.sb_features_incompat |= XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR;
	libxfs_log_sb(*tpp);

err_ifork:
	kmem_cache_free(xfs_ifork_cache, ifake.if_fork);
	return error;
}

static int
estimate_size(
	struct xfs_inode		*ip,
	unsigned long long		dirty_blocks,
	xfs_extnum_t			nextents)
{
	struct xfs_btree_bload		bmap_bload = {
		.leaf_slack		= 1,
		.node_slack		= 1,
	};
	struct xbtree_ifakeroot		ifake = {};
	struct xfs_btree_cur		*bmap_cur;
	int				error;

	/* FMT_EXTENTS means we report zero btblocks and zero height */
	if (nextents <= XFS_IFORK_MAXEXT(ip, XFS_DATA_FORK))
		goto report;

	ifake.if_fork = kmem_cache_zalloc(xfs_ifork_cache, 0);
	ifake.if_fork_size = xfs_inode_fork_size(ip, XFS_DATA_FORK);

	bmap_cur = libxfs_bmbt_init_cursor(ip->i_mount, NULL, ip,
			XFS_STAGING_FORK);
	libxfs_btree_stage_ifakeroot(bmap_cur, &ifake);
	error = -libxfs_btree_bload_compute_geometry(bmap_cur, &bmap_bload,
			nextents);
	libxfs_btree_del_cursor(bmap_cur, error);

	kmem_cache_free(xfs_ifork_cache, ifake.if_fork);

	if (error)
		return error;

report:
	dbprintf(_("ino 0x%llx nextents %llu btblocks %llu btheight %u dirty %u\n"),
			ip->i_ino, nextents, bmap_bload.nr_blocks,
			bmap_bload.btree_height, dirty_blocks);

	return 0;
}

static int
bmapinflate_f(
	int			argc,
	char			**argv)
{
	struct xfs_bmbt_irec	irec;
	struct xfs_inode	*ip;
	struct xfs_trans	*tp;
	char			*p;
	unsigned long long	nextents = 0;
	unsigned long long	dirty_bytes = 60U << 20; /* 60MiB */
	unsigned long long	dirty_blocks;
	unsigned int		resblks;
	bool			estimate = false;
	int			c, error;

	if (iocur_top->ino == NULLFSINO) {
		dbprintf(_("no current inode\n"));
		return 0;
	}

	optind = 0;
	while ((c = getopt(argc, argv, "d:en:")) != EOF) {
		switch (c) {
		case 'e':
			estimate = true;
			break;
		case 'n':
			errno = 0;
			nextents = strtoull(optarg, &p, 0);
			if (errno) {
				perror(optarg);
				return 1;
			}
			break;
		case 'd':
			errno = 0;
			dirty_bytes = cvtnum(mp->m_sb.sb_blocksize,
					     mp->m_sb.sb_sectsize, optarg);
			if (errno) {
				perror(optarg);
				return 1;
			}
			break;
		default:
			dbprintf(_("bad option for bmap command\n"));
			return 0;
		}
	}

	dirty_blocks = XFS_B_TO_FSBT(mp, dirty_bytes);
	if (dirty_blocks >= UINT16_MAX)
		dirty_blocks = UINT16_MAX - 1;

	error = -libxfs_iget(mp, NULL, iocur_top->ino, 0, &ip);
	if (error) {
		dbprintf(_("could not grab inode 0x%llx, err %d\n"),
				iocur_top->ino, error);
		return 1;
	}

	error = estimate_size(ip, dirty_blocks, nextents);
	if (error)
		goto out_irele;
	if (estimate)
		goto done;

	resblks = libxfs_bmbt_calc_size(mp, nextents);
	error = -libxfs_trans_alloc_inode(ip, &M_RES(mp)->tr_itruncate,
			resblks, 0, false, &tp);
	if (error) {
		dbprintf(_("could not allocate transaction, err %d\n"),
				error);
		return 1;
	}

	error = find_mapping(tp, ip, &irec);
	if (error)
		goto out_cancel;

	error = build_new_datafork(&tp, ip, dirty_blocks, &irec, nextents);
	if (error) {
		dbprintf(_("could not build new data fork, err %d\n"),
				error);
		exitcode = 1;
		goto out_cancel;
	}

	error = -libxfs_trans_commit(tp);
	if (error) {
		dbprintf(_("could not commit transaction, err %d\n"),
				error);
		exitcode = 1;
		return 1;
	}

done:
	libxfs_irele(ip);
	return 0;

out_cancel:
	libxfs_trans_cancel(tp);
out_irele:
	libxfs_irele(ip);
	return 1;
}

static const struct cmdinfo bmapinflate_cmd = {
	.name		= "bmapinflate",
	.cfunc		= bmapinflate_f,
	.argmin		= 0,
	.argmax		= -1,
	.canpush	= 0,
	.args		= N_("[-n copies] [-e] [-d maxdirty]"),
	.oneline	= N_("inflate bmbt by copying mappings"),
	.help		= bmapinflate_help,
};

void
bmapinflate_init(void)
{
	if (!expert_mode)
		return;

	add_command(&bmapinflate_cmd);
}