linux/fs/jbd2/recovery.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * linux/fs/jbd2/recovery.c
 *
 * Written by Stephen C. Tweedie <[email protected]>, 1999
 *
 * Copyright 1999-2000 Red Hat Software --- All Rights Reserved
 *
 * Journal recovery routines for the generic filesystem journaling code;
 * part of the ext2fs journaling system.
 */

#ifndef __KERNEL__
#include "jfs_user.h"
#else
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/jbd2.h>
#include <linux/errno.h>
#include <linux/crc32.h>
#include <linux/blkdev.h>
#include <linux/string_choices.h>
#endif

/*
 * Maintain information about the progress of the recovery job, so that
 * the different passes can carry information between them.
 */
struct recovery_info
{ … };

static int do_one_pass(journal_t *journal,
				struct recovery_info *info, enum passtype pass);
static int scan_revoke_records(journal_t *, struct buffer_head *,
				tid_t, struct recovery_info *);

#ifdef __KERNEL__

/* Release readahead buffers after use */
static void journal_brelse_array(struct buffer_head *b[], int n)
{ … }


/*
 * When reading from the journal, we are going through the block device
 * layer directly and so there is no readahead being done for us.  We
 * need to implement any readahead ourselves if we want it to happen at
 * all.  Recovery is basically one long sequential read, so make sure we
 * do the IO in reasonably large chunks.
 *
 * This is not so critical that we need to be enormously clever about
 * the readahead size, though.  128K is a purely arbitrary, good-enough
 * fixed value.
 */

#define MAXBUF …
static int do_readahead(journal_t *journal, unsigned int start)
{ … }

#endif /* __KERNEL__ */


/*
 * Read a block from the journal
 */

static int jread(struct buffer_head **bhp, journal_t *journal,
		 unsigned int offset)
{ … }

static int jbd2_descriptor_block_csum_verify(journal_t *j, void *buf)
{ … }

/*
 * Count the number of in-use tags in a journal descriptor block.
 */

static int count_tags(journal_t *journal, struct buffer_head *bh)
{ … }


/* Make sure we wrap around the log correctly! */
#define wrap(journal, var) …

static int fc_do_one_pass(journal_t *journal,
			  struct recovery_info *info, enum passtype pass)
{ … }

/**
 * jbd2_journal_recover - recovers a on-disk journal
 * @journal: the journal to recover
 *
 * The primary function for recovering the log contents when mounting a
 * journaled device.
 *
 * Recovery is done in three passes.  In the first pass, we look for the
 * end of the log.  In the second, we assemble the list of revoke
 * blocks.  In the third and final pass, we replay any un-revoked blocks
 * in the log.
 */
int jbd2_journal_recover(journal_t *journal)
{ … }

/**
 * jbd2_journal_skip_recovery - Start journal and wipe exiting records
 * @journal: journal to startup
 *
 * Locate any valid recovery information from the journal and set up the
 * journal structures in memory to ignore it (presumably because the
 * caller has evidence that it is out of date).
 * This function doesn't appear to be exported..
 *
 * We perform one pass over the journal to allow us to tell the user how
 * much recovery information is being erased, and to let us initialise
 * the journal transaction sequence numbers to the next unused ID.
 */
int jbd2_journal_skip_recovery(journal_t *journal)
{ … }

static inline unsigned long long read_tag_block(journal_t *journal,
						journal_block_tag_t *tag)
{ … }

/*
 * calc_chksums calculates the checksums for the blocks described in the
 * descriptor block.
 */
static int calc_chksums(journal_t *journal, struct buffer_head *bh,
			unsigned long *next_log_block, __u32 *crc32_sum)
{ … }

static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
{ … }

static bool jbd2_commit_block_csum_verify_partial(journal_t *j, void *buf)
{ … }

static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
				      journal_block_tag3_t *tag3,
				      void *buf, __u32 sequence)
{ … }

static int do_one_pass(journal_t *journal,
			struct recovery_info *info, enum passtype pass)
{ … }

/* Scan a revoke record, marking all blocks mentioned as revoked. */

static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
			       tid_t sequence, struct recovery_info *info)
{ … }