path: root/fs/ubifs/replay.c

/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Adrian Hunter
 *          Artem Bityutskiy (Битюцкий Артём)
 */

/*
 * This file contains journal replay code. It runs when the file-system is being
 * mounted and requires no locking.
 *
 * The larger is the journal, the longer it takes to scan it, so the longer it
 * takes to mount UBIFS. This is why the journal has limited size which may be
 * changed depending on the system requirements. But a larger journal gives
 * faster I/O speed because it writes the index less frequently. So this is a
 * trade-off. Also, the journal is indexed by the in-memory index (TNC), so the
 * larger is the journal, the more memory its index may consume.
 */

#include "ubifs.h"
#include <linux/list_sort.h>

/**
 * struct replay_entry - replay list entry.
 * @lnum: logical eraseblock number of the node
 * @offs: node offset
 * @len: node length
 * @deletion: non-zero if this entry corresponds to a node deletion
 * @sqnum: node sequence number
 * @list: links the replay list
 * @key: node key
 * @nm: directory entry name
 * @old_size: truncation old size
 * @new_size: truncation new size
 *
 * The replay process first scans all buds and builds the replay list, then
 * sorts the replay list in nodes sequence number order, and then inserts all
 * the replay entries to the TNC.
 */
struct replay_entry {
	int lnum;
	int offs;
	int len;
	unsigned int deletion:1;
	unsigned long long sqnum;
	struct list_head list;
	union ubifs_key key;
	union {
		struct qstr nm;
		struct {
			loff_t old_size;
			loff_t new_size;
		};
	};
};

/**
 * struct bud_entry - entry in the list of buds to replay.
 * @list: next bud in the list
 * @bud: bud description object
 * @sqnum: reference node sequence number
 * @free: free bytes in the bud
 * @dirty: dirty bytes in the bud
 */
struct bud_entry {
	struct list_head list;
	struct ubifs_bud *bud;
	unsigned long long sqnum;
	int free;
	int dirty;
};

/**
 * set_bud_lprops - set free and dirty space used by a bud.
 * @c: UBIFS file-system description object
 * @b: bud entry which describes the bud
 *
 * This function makes sure the LEB properties of bud @b are set correctly
 * after the replay. Returns zero in case of success and a negative error code
 * in case of failure.
 */
static int set_bud_lprops(struct ubifs_info *c, struct bud_entry *b)
{
	const struct ubifs_lprops *lp;
	int err = 0, dirty;

	ubifs_get_lprops(c);

	lp = ubifs_lpt_lookup_dirty(c, b->bud->lnum);
	if (IS_ERR(lp)) {
		err = PTR_ERR(lp);
		goto out;
	}

	dirty = lp->dirty;
	if (b->bud->start == 0 && (lp->free != c->leb_size || lp->dirty != 0)) {
		/*
		 * The LEB was added to the journal with a starting offset of
		 * zero which means the LEB must have been empty. The LEB
		 * property values should be @lp->free == @c->leb_size and
		 * @lp->dirty == 0, but that is not the case. The reason is that
		 * the LEB had been garbage collected before it became the bud,
		 * and there was not commit inbetween. The garbage collector
		 * resets the free and dirty space without recording it
		 * anywhere except lprops, so if there was no commit then
		 * lprops does not have that information.
		 *
		 * We do not need to adjust free space because the scan has told
		 * us the exact value which is recorded in the replay entry as
		 * @b->free.
		 *
		 * However we do need to subtract from the dirty space the
		 * amount of space that the garbage collector reclaimed, which
		 * is the whole LEB minus the amount of space that was free.
		 */
		dbg_mnt("bud LEB %d was GC'd (%d free, %d dirty)", b->bud->lnum,
			lp->free, lp->dirty);
		dbg_gc("bud LEB %d was GC'd (%d free, %d dirty)", b->bud->lnum,
			lp->free, lp->dirty);
		dirty -= c->leb_size - lp->free;
		/*
		 * If the replay order was perfect the dirty space would now be
		 * zero. The order is not perfect because the journal heads
		 * race with each other. This is not a problem but is does mean
		 * that the dirty space may temporarily exceed c->leb_size
		 * during the replay.
		 */
		if (dirty != 0)
			dbg_mnt("LEB %d lp: %d free %d dirty replay: %d free %d dirty",
				b->bud->lnum, lp->free, lp->dirty, b->free,
				b->dirty);
	}
	lp = ubifs_change_lp(c, lp, b->free, dirty + b->dirty,
			     lp->flags | LPROPS_TAKEN, 0);
	if (IS_ERR(lp)) {
		err = PTR_ERR(lp);
		goto out;
	}

	/* Make sure the journal head points to the latest bud */
	err = ubifs_wbuf_seek_nolock(&c->jheads[b->bud->jhead].wbuf,
				     b->bud->lnum, c->leb_size - b->free);

out:
	ubifs_release_lprops(c);
	return err;
}

/**
 * set_buds_lprops - set free and dirty space for all replayed buds.
 * @c: UBIFS file-system description object
 *
 * This function sets LEB properties for all replayed buds. Returns zero in
 * case of success and a negative error code in case of failure.
 */
static int set_buds_lprops(struct ubifs_info *c)
{
	struct bud_entry *b;
	int err;

	list_for_