path: root/fs/xfs/libxfs/xfs_rtbitmap.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_trans.h"
#include "xfs_rtalloc.h"
#include "xfs_error.h"
#include "xfs_rtbitmap.h"

/*
 * Realtime allocator bitmap functions shared with userspace.
 */

/*
 * Real time buffers need verifiers to avoid runtime warnings during IO.
 * We don't have anything to verify, however, so these are just dummy
 * operations.
 */
static void
xfs_rtbuf_verify_read(
	struct xfs_buf	*bp)
{
	return;
}

static void
xfs_rtbuf_verify_write(
	struct xfs_buf	*bp)
{
	return;
}

const struct xfs_buf_ops xfs_rtbuf_ops = {
	.name = "rtbuf",
	.verify_read = xfs_rtbuf_verify_read,
	.verify_write = xfs_rtbuf_verify_write,
};

/* Release cached rt bitmap and summary buffers. */
void
xfs_rtbuf_cache_relse(
	struct xfs_rtalloc_args	*args)
{
	if (args->rbmbp) {
		xfs_trans_brelse(args->tp, args->rbmbp);
		args->rbmbp = NULL;
		args->rbmoff = NULLFILEOFF;
	}
	if (args->sumbp) {
		xfs_trans_brelse(args->tp, args->sumbp);
		args->sumbp = NULL;
		args->sumoff = NULLFILEOFF;
	}
}

/*
 * Get a buffer for the bitmap or summary file block specified.
 * The buffer is returned read and locked.
 */
int
xfs_rtbuf_get(
	struct xfs_rtalloc_args	*args,
	xfs_fileoff_t		block,	/* block number in bitmap or summary */
	int			issum)	/* is summary not bitmap */
{
	struct xfs_mount	*mp = args->mp;
	struct xfs_buf		**cbpp;	/* cached block buffer */
	xfs_fileoff_t		*coffp;	/* cached block number */
	struct xfs_buf		*bp;	/* block buffer, result */
	struct xfs_inode	*ip;	/* bitmap or summary inode */
	struct xfs_bmbt_irec	map;
	enum xfs_blft		type;
	int			nmap = 1;
	int			error;

	if (issum) {
		cbpp = &args->sumbp;
		coffp = &args->sumoff;
		ip = mp->m_rsumip;
		type = XFS_BLFT_RTSUMMARY_BUF;
	} else {
		cbpp = &args->rbmbp;
		coffp = &args->rbmoff;
		ip = mp->m_rbmip;
		type = XFS_BLFT_RTBITMAP_BUF;
	}

	/*
	 * If we have a cached buffer, and the block number matches, use that.
	 */
	if (*cbpp && *coffp == block)
		return 0;

	/*
	 * Otherwise we have to have to get the buffer.  If there was an old
	 * one, get rid of it first.
	 */
	if (*cbpp) {
		xfs_trans_brelse(args->tp, *cbpp);
		*cbpp = NULL;
	}

	error = xfs_bmapi_read(ip, block, 1, &map, &nmap, 0);
	if (error)
		return error;

	if (XFS_IS_CORRUPT(mp, nmap == 0 || !xfs_bmap_is_written_extent(&map)))
		return -EFSCORRUPTED;

	ASSERT(map.br_startblock != NULLFSBLOCK);
	error = xfs_trans_read_buf(mp, args->tp, mp->m_ddev_targp,
				   XFS_FSB_TO_DADDR(mp, map.br_startblock),
				   mp->m_bsize, 0, &bp, &xfs_rtbuf_ops);
	if (error)
		return error;

	xfs_trans_buf_set_type(args->tp, bp, type);
	*cbpp = bp;
	*coffp = block;
	return 0;
}

/*
 * Searching backward from start to limit, find the first block whose
 * allocated/free state is different from start's.
 */
int
xfs_rtfind_back(
	struct xfs_rtalloc_args	*args,
	xfs_rtxnum_t		start,	/* starting rtext to look at */
	xfs_rtxnum_t		limit,	/* last rtext to look at */
	xfs_rtxnum_t		*rtx)	/* out: start rtext found */
{
	struct xfs_mount	*mp = args->mp;
	int			bit;	/* bit number in the word */
	xfs_fileoff_t		block;	/* bitmap block number */
	int			error;	/* error value */
	xfs_rtxnum_t		firstbit; /* first useful bit in the word */
	xfs_rtxnum_t		i;	/* current bit number rel. to start */
	xfs_rtxnum_t		len;	/* length of inspected area */
	xfs_rtword_t		mask;	/* mask of relevant bits for value */
	xfs_rtword_t		want;	/* mask for "good" values */
	xfs_rtword_t		wdiff;	/* difference from wanted value */
	xfs_rtword_t		incore;
	unsigned int		word;	/* word number in the buffer */

	/*
	 * Compute and re