Adding upstream version 1.47.0.upstream/1.47.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 972 insertions, 0 deletions

diff --git a/debugfs/do_journal.c b/debugfs/do_journal.c
new file mode 100644
index 0000000..38439c6
--- /dev/null
+++ b/debugfs/do_journal.c
@@ -0,0 +1,972 @@
+/*
+ * do_journal.c --- Scribble onto the journal!
+ *
+ * Copyright (C) 2014 Oracle.  This file may be redistributed
+ * under the terms of the GNU Public License.
+ */
+
+#include "config.h"
+#include <stdio.h>
+#ifdef HAVE_GETOPT_H
+#include <getopt.h>
+#else
+extern int optind;
+extern char *optarg;
+#endif
+#include <ctype.h>
+#include <unistd.h>
+#ifdef HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+
+#include "debugfs.h"
+#include "ext2fs/kernel-jbd.h"
+#include "journal.h"
+
+#undef DEBUG
+
+#ifdef DEBUG
+# define dbg_printf(f, a...)  do {printf("JFS DEBUG: " f, ## a); \
+	fflush(stdout); \
+} while (0)
+#else
+# define dbg_printf(f, a...)
+#endif
+
+#define JOURNAL_CHECK_TRANS_MAGIC(x)	\
+	do { \
+		if ((x)->magic != J_TRANS_MAGIC) \
+			return EXT2_ET_INVALID_ARGUMENT; \
+	} while (0)
+
+#define J_TRANS_MAGIC		0xD15EA5ED
+#define J_TRANS_OPEN		1
+#define J_TRANS_COMMITTED	2
+struct journal_transaction_s {
+	unsigned int magic;
+	ext2_filsys fs;
+	journal_t *journal;
+	blk64_t block;
+	blk64_t start, end;
+	tid_t tid;
+	int flags;
+};
+
+typedef struct journal_transaction_s journal_transaction_t;
+
+static journal_t *current_journal = NULL;
+
+static void journal_dump_trans(journal_transaction_t *trans EXT2FS_ATTR((unused)),
+			       const char *tag EXT2FS_ATTR((unused)))
+{
+	dbg_printf("TRANS %p(%s): tid=%u start=%llu block=%llu end=%llu "
+		   "flags=0x%x\n", trans, tag, trans->tid, trans->start,
+		   trans->block, trans->end, trans->flags);
+}
+
+static errcode_t journal_commit_trans(journal_transaction_t *trans)
+{
+	struct buffer_head *bh, *cbh = NULL;
+	struct commit_header *commit;
+#ifdef HAVE_SYS_TIME_H
+	struct timeval tv;
+#endif
+	errcode_t err;
+
+	JOURNAL_CHECK_TRANS_MAGIC(trans);
+
+	if ((trans->flags & J_TRANS_COMMITTED) ||
+	    !(trans->flags & J_TRANS_OPEN))
+		return EXT2_ET_INVALID_ARGUMENT;
+
+	bh = getblk(trans->journal->j_dev, 0, trans->journal->j_blocksize);
+	if (bh == NULL)
+		return ENOMEM;
+
+	/* write the descriptor block header */
+	commit = (struct commit_header *)bh->b_data;
+	commit->h_magic = ext2fs_cpu_to_be32(JBD2_MAGIC_NUMBER);
+	commit->h_blocktype = ext2fs_cpu_to_be32(JBD2_COMMIT_BLOCK);
+	commit->h_sequence = ext2fs_cpu_to_be32(trans->tid);
+	if (jbd2_has_feature_checksum(trans->journal)) {
+		__u32 csum_v1 = ~0;
+		blk64_t cblk;
+
+		cbh = getblk(trans->journal->j_dev, 0,
+			     trans->journal->j_blocksize);
+		if (cbh == NULL) {
+			err = ENOMEM;
+			goto error;
+		}
+
+		for (cblk = trans->start; cblk < trans->block; cblk++) {
+			err = jbd2_journal_bmap(trans->journal, cblk,
+						&cbh->b_blocknr);
+			if (err)
+				goto error;
+			mark_buffer_uptodate(cbh, 0);
+			ll_rw_block(REQ_OP_READ, 0, 1, &cbh);
+			err = cbh->b_err;
+			if (err)
+				goto error;
+			csum_v1 = ext2fs_crc32_be(csum_v1,
+					(unsigned char const *)cbh->b_data,
+					cbh->b_size);
+		}
+
+		commit->h_chksum_type = JBD2_CRC32_CHKSUM;
+		commit->h_chksum_size = JBD2_CRC32_CHKSUM_SIZE;
+		commit->h_chksum[0] = ext2fs_cpu_to_be32(csum_v1);
+	} else {
+		commit->h_chksum_type = 0;
+		commit->h_chksum_size = 0;
+		commit->h_chksum[0] = 0;
+	}
+#ifdef HAVE_SYS_TIME_H
+	gettimeofday(&tv, NULL);
+	commit->h_commit_sec = ext2fs_cpu_to_be32(tv.tv_sec);
+	commit->h_commit_nsec = ext2fs_cpu_to_be32(tv.tv_usec * 1000);
+#else
+	commit->h_commit_sec = 0;
+	commit->h_commit_nsec = 0;
+#endif
+
+	/* Write block */
+	jbd2_commit_block_csum_set(trans->journal, bh);
+	err = jbd2_journal_bmap(trans->journal, trans->block, &bh->b_blocknr);
+	if (err)
+		goto error;
+
+	dbg_printf("Writing commit block at %llu:%llu\n", trans->block,
+		   bh->b_blocknr);
+	mark_buffer_dirty(bh);
+	ll_rw_block(REQ_OP_WRITE, 0, 1, &bh);
+	err = bh->b_err;
+	if (err)
+		goto error;
+	trans->flags |= J_TRANS_COMMITTED;
+	trans->flags &= ~J_TRANS_OPEN;
+	trans->block++;
+
+	ext2fs_set_feature_journal_needs_recovery(trans->fs->super);
+	ext2fs_mark_super_dirty(trans->fs);
+error:
+	if (cbh)
+		brelse(cbh);
+	brelse(bh);
+	return err;
+}
+
+static errcode_t journal_add_revoke_to_trans(journal_transaction_t *trans,
+					     blk64_t *revoke_list,
+					     size_t revoke_len)
+{
+	jbd2_journal_revoke_header_t *jrb;
+	void *buf;
+	size_t i, offset;
+	blk64_t curr_blk;
+	unsigned int sz;
+	unsigned csum_size = 0;
+	struct buffer_head *bh;
+	errcode_t err;
+
+	JOURNAL_CHECK_TRANS_MAGIC(trans);
+
+	if ((trans->flags & J_TRANS_COMMITTED) ||
+	    !(trans->flags & J_TRANS_OPEN))
+		return EXT2_ET_INVALID_ARGUMENT;
+
+	if (revoke_len == 0)
+		return 0;
+
+	/* Do we need to leave space at the end for a checksum? */
+	if (jbd2_journal_has_csum_v2or3(trans->journal))
+		csum_size = sizeof(struct jbd2_journal_block_tail);
+
+	curr_blk = trans->block;
+
+	bh = getblk(trans->journal->j_dev, curr_blk,
+		    trans->journal->j_blocksize);
+	if (bh == NULL)
+		return ENOMEM;
+	jrb = buf = bh->b_data;
+	jrb->r_header.h_magic = ext2fs_cpu_to_be32(JBD2_MAGIC_NUMBER);
+	jrb->r_header.h_blocktype = ext2fs_cpu_to_be32(JBD2_REVOKE_BLOCK);
+	jrb->r_header.h_sequence = ext2fs_cpu_to_be32(trans->tid);
+	offset = sizeof(*jrb);
+
+	if (jbd2_has_feature_64bit(trans->journal))
+		sz = 8;
+	else
+		sz = 4;
+
+	for (i = 0; i < revoke_len; i++) {
+		/* Block full, write to journal */
+		if (offset + sz > trans->journal->j_blocksize - csum_size) {
+			jrb->r_count = ext2fs_cpu_to_be32(offset);
+			jbd2_revoke_csum_set(trans->journal, bh);
+
+			err = jbd2_journal_bmap(trans->journal, curr_blk,
+						&bh->b_blocknr);
+			if (err)
+				goto error;
+			dbg_printf("Writing revoke block at %llu:%llu\n",
+				   curr_blk, bh->b_blocknr);
+			mark_buffer_dirty(bh);
+			ll_rw_block(REQ_OP_WRITE, 0, 1, &bh);
+			err = bh->b_err;
+			if (err)
+				goto error;
+
+			offset = sizeof(*jrb);
+			curr_blk++;
+		}
+
+		if (revoke_list[i] >=
+		    ext2fs_blocks_count(trans->journal->j_fs_dev->k_fs->super)) {
+			err = EXT2_ET_BAD_BLOCK_NUM;
+			goto error;
+		}
+
+		if (jbd2_has_feature_64bit(trans->journal))
+			*((__u64 *)(&((char *)buf)[offset])) =
+				ext2fs_cpu_to_be64(revoke_list[i]);
+		else
+			*((__u32 *)(&((char *)buf)[offset])) =
+				ext2fs_cpu_to_be32(revoke_list[i]);
+		offset += sz;
+	}
+
+	if (offset > 0) {
+		jrb->r_count = ext2fs_cpu_to_be32(offset);
+		jbd2_revoke_csum_set(trans->journal, bh);
+
+		err = jbd2_journal_bmap(trans->journal, curr_blk,
+					&bh->b_blocknr);
+		if (err)
+			goto error;
+		dbg_printf("Writing revoke block at %llu:%llu\n",
+			   curr_blk, bh->b_blocknr);
+		mark_buffer_dirty(bh);
+		ll_rw_block(REQ_OP_WRITE, 0, 1, &bh);
+		err = bh->b_err;
+		if (err)
+			goto error;
+		curr_blk++;
+	}
+
+error:
+	trans->block = curr_blk;
+	brelse(bh);
+	return err;
+}
+
+static errcode_t journal_add_blocks_to_trans(journal_transaction_t *trans,
+				      blk64_t *block_list, size_t block_len,
+				      FILE *fp)
+{
+	blk64_t curr_blk, jdb_blk;
+	size_t i, j;
+	int csum_size = 0;
+	journal_header_t *jdb;
+	journal_block_tag_t *jdbt;
+	int tag_bytes;
+	void *buf = NULL, *jdb_buf = NULL;
+	struct buffer_head *bh = NULL, *data_bh;
+	errcode_t err;
+
+	JOURNAL_CHECK_TRANS_MAGIC(trans);
+
+	if ((trans->flags & J_TRANS_COMMITTED) ||
+	    !(trans->flags & J_TRANS_OPEN))
+		return EXT2_ET_INVALID_ARGUMENT;
+
+	if (block_len == 0)
+		return 0;
+
+	/* Do we need to leave space at the end for a checksum? */
+	if (jbd2_journal_has_csum_v2or3(trans->journal))
+		csum_size = sizeof(struct jbd2_journal_block_tail);
+
+	curr_blk = jdb_blk = trans->block;
+
+	data_bh = getblk(trans->journal->j_dev, curr_blk,
+			 trans->journal->j_blocksize);
+	if (data_bh == NULL)
+		return ENOMEM;
+	buf = data_bh->b_data;
+
+	/* write the descriptor block header */
+	bh = getblk(trans->journal->j_dev, curr_blk,
+		    trans->journal->j_blocksize);
+	if (bh == NULL) {
+		err = ENOMEM;
+		goto error;
+	}
+	jdb = jdb_buf = bh->b_data;
+	jdb->h_magic = ext2fs_cpu_to_be32(JBD2_MAGIC_NUMBER);
+	jdb->h_blocktype = ext2fs_cpu_to_be32(JBD2_DESCRIPTOR_BLOCK);
+	jdb->h_sequence = ext2fs_cpu_to_be32(trans->tid);
+	jdbt = (journal_block_tag_t *)(jdb + 1);
+
+	curr_blk++;
+	for (i = 0; i < block_len; i++) {
+		j = fread(data_bh->b_data, trans->journal->j_blocksize, 1, fp);
+		if (j != 1) {
+			err = errno;
+			goto error;
+		}
+
+		tag_bytes = journal_tag_bytes(trans->journal);
+
+		/* No space left in descriptor block, write it out */
+		if ((char *)jdbt + tag_bytes >
+		    (char *)jdb_buf + trans->journal->j_blocksize - csum_size) {
+			jbd2_descr_block_csum_set(trans->journal, bh);
+			err = jbd2_journal_bmap(trans->journal, jdb_blk,
+					   &bh->b_blocknr);
+			if (err)
+				goto error;
+			dbg_printf("Writing descriptor block at %llu:%llu\n",
+				   jdb_blk, bh->b_blocknr);
+			mark_buffer_dirty(bh);
+			ll_rw_block(REQ_OP_WRITE, 0, 1, &bh);
+			err = bh->b_err;
+			if (err)
+				goto error;
+
+			jdbt = (journal_block_tag_t *)(jdb + 1);
+			jdb_blk = curr_blk;
+			curr_blk++;
+		}
+
+		if (block_list[i] >=
+		    ext2fs_blocks_count(trans->journal->j_fs_dev->k_fs->super)) {
+			err = EXT2_ET_BAD_BLOCK_NUM;
+			goto error;
+		}
+
+		/* Fill out the block tag */
+		jdbt->t_blocknr = ext2fs_cpu_to_be32(block_list[i] & 0xFFFFFFFF);
+		jdbt->t_flags = 0;
+		if (jdbt != (journal_block_tag_t *)(jdb + 1))
+			jdbt->t_flags |= ext2fs_cpu_to_be16(JBD2_FLAG_SAME_UUID);
+		else {
+			memcpy(jdbt + tag_bytes,
+			       trans->journal->j_superblock->s_uuid,
+			       sizeof(trans->journal->j_superblock->s_uuid));
+			tag_bytes += 16;
+		}
+		if (i == block_len - 1)
+			jdbt->t_flags |= ext2fs_cpu_to_be16(JBD2_FLAG_LAST_TAG);
+		if (*((__u32 *)buf) == ext2fs_cpu_to_be32(JBD2_MAGIC_NUMBER)) {
+			*((__u32 *)buf) = 0;
+			jdbt->t_flags |= ext2fs_cpu_to_be16(JBD2_FLAG_ESCAPE);
+		}
+		if (jbd2_has_feature_64bit(trans->journal))
+			jdbt->t_blocknr_high = ext2fs_cpu_to_be32(block_list[i] >> 32);
+		jbd2_block_tag_csum_set(trans->journal, jdbt, data_bh,
+					trans->tid);
+
+		/* Write the data block */
+		err = jbd2_journal_bmap(trans->journal, curr_blk,
+					&data_bh->b_blocknr);
+		if (err)
+			goto error;
+		dbg_printf("Writing data block %llu at %llu:%llu tag %d\n",
+			   block_list[i], curr_blk, data_bh->b_blocknr,
+			   tag_bytes);
+		mark_buffer_dirty(data_bh);
+		ll_rw_block(REQ_OP_WRITE, 0, 1, &data_bh);
+		err = data_bh->b_err;
+		if (err)
+			goto error;
+
+		curr_blk++;
+		jdbt = (journal_block_tag_t *)(((char *)jdbt) + tag_bytes);
+	}
+
+	/* Write out the last descriptor block */
+	if (jdbt != (journal_block_tag_t *)(jdb + 1)) {
+		jbd2_descr_block_csum_set(trans->journal, bh);
+		err = jbd2_journal_bmap(trans->journal, jdb_blk,
+					&bh->b_blocknr);
+		if (err)
+			goto error;
+		dbg_printf("Writing descriptor block at %llu:%llu\n",
+			   jdb_blk, bh->b_blocknr);
+		mark_buffer_dirty(bh);
+		ll_rw_block(REQ_OP_WRITE, 0, 1, &bh);
+		err = bh->b_err;
+		if (err)
+			goto error;
+	}
+
+error:
+	trans->block = curr_blk;
+	if (bh)
+		brelse(bh);
+	brelse(data_bh);
+	return err;
+}
+
+static blk64_t journal_guess_blocks(journal_t *journal, blk64_t data_blocks,
+				    blk64_t revoke_blocks)
+{
+	blk64_t ret = 1;
+	unsigned int bs, sz;
+
+	/* Estimate # of revoke blocks */
+	bs = journal->j_blocksize;
+	if (jbd2_journal_has_csum_v2or3(journal))
+		bs -= sizeof(struct jbd2_journal_block_tail);
+	sz = jbd2_has_feature_64bit(journal) ? sizeof(__u64) : sizeof(__u32);
+	ret += revoke_blocks * sz / bs;
+
+	/* Estimate # of data blocks */
+	bs = journal->j_blocksize - 16;
+	if (jbd2_journal_has_csum_v2or3(journal))
+		bs -= sizeof(struct jbd2_journal_block_tail);
+	sz = journal_tag_bytes(journal);
+	ret += data_blocks * sz / bs;
+
+	ret += data_blocks;
+
+	return ret;
+}
+
+static errcode_t journal_open_trans(journal_t *journal,
+				    journal_transaction_t *trans,
+				    blk64_t blocks)
+{
+	trans->fs = journal->j_fs_dev->k_fs;
+	trans->journal = journal;
+	trans->flags = J_TRANS_OPEN;
+
+	if (journal->j_tail == 0) {
+		/* Clean journal, start at the tail */
+		trans->tid = journal->j_tail_sequence;
+		trans->start = journal->j_first;
+	} else {
+		/* Put new transaction at the head of the list */
+		trans->tid = journal->j_transaction_sequence;
+		trans->start = journal->j_head;
+	}
+
+	trans->block = trans->start;
+	if (trans->start + blocks > journal->j_last)
+		return ENOSPC;
+	trans->end = trans->block + blocks;
+	journal_dump_trans(trans, "new transaction");
+
+	trans->magic = J_TRANS_MAGIC;
+	return 0;
+}
+
+static errcode_t journal_close_trans(journal_transaction_t *trans)
+{
+	journal_t *journal;
+
+	JOURNAL_CHECK_TRANS_MAGIC(trans);
+
+	if (!(trans->flags & J_TRANS_COMMITTED))
+		return 0;
+
+	journal = trans->journal;
+	if (journal->j_tail == 0) {
+		/* Update the tail */
+		journal->j_tail_sequence = trans->tid;
+		journal->j_tail = trans->start;
+		journal->j_superblock->s_start = ext2fs_cpu_to_be32(trans->start);
+	}
+
+	/* Update the head */
+	journal->j_head = trans->end + 1;
+	journal->j_transaction_sequence = trans->tid + 1;
+
+	trans->magic = 0;
+
+	/* Mark ourselves as needing recovery */
+	if (!ext2fs_has_feature_journal_needs_recovery(trans->fs->super)) {
+		ext2fs_set_feature_journal_needs_recovery(trans->fs->super);
+		ext2fs_mark_super_dirty(trans->fs);
+	}
+
+	return 0;
+}
+
+#define JOURNAL_WRITE_NO_COMMIT		1
+static errcode_t journal_write(journal_t *journal,
+			       int flags, blk64_t *block_list,
+			       size_t block_len, blk64_t *revoke_list,
+			       size_t revoke_len, FILE *fp)
+{
+	blk64_t blocks;
+	journal_transaction_t trans;
+	errcode_t err;
+
+	if (revoke_len > 0) {
+		jbd2_set_feature_revoke(journal);
+		mark_buffer_dirty(journal->j_sb_buffer);
+	}
+
+	blocks = journal_guess_blocks(journal, block_len, revoke_len);
+	err = journal_open_trans(journal, &trans, blocks);
+	if (err)
+		goto error;
+
+	err = journal_add_blocks_to_trans(&trans, block_list, block_len, fp);
+	if (err)
+		goto error;
+
+	err = journal_add_revoke_to_trans(&trans, revoke_list, revoke_len);
+	if (err)
+		goto error;
+
+	if (!(flags & JOURNAL_WRITE_NO_COMMIT)) {
+		err = journal_commit_trans(&trans);
+		if (err)
+			goto error;
+	}
+
+	err = journal_close_trans(&trans);
+error:
+	return err;
+}
+
+void do_journal_write(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)),
+		      void *infop EXT2FS_ATTR((unused)))
+{
+	blk64_t *blist = NULL, *rlist = NULL;
+	size_t bn = 0, rn = 0;
+	FILE *fp = NULL;
+	int opt;
+	int flags = 0;
+	errcode_t err;
+
+	if (current_journal == NULL) {
+		printf("Journal not open.\n");
+		return;
+	}
+
+	reset_getopt();
+	while ((opt = getopt(argc, argv, "b:r:c")) != -1) {
+		switch (opt) {
+		case 'b':
+			err = read_list(optarg, &blist, &bn);
+			if (err) {
+				com_err(argv[0], err,
+					"while reading block list");
+				goto out;
+			}
+			break;
+		case 'r':
+			err = read_list(optarg, &rlist, &rn);
+			if (err) {
+				com_err(argv[0], err,
+					"while reading revoke list");
+				goto out;
+			}
+			break;
+		case 'c':
+			flags |= JOURNAL_WRITE_NO_COMMIT;
+			break;
+		default:
+			printf("%s [-b blocks] [-r revoke] [-c] file\n",
+			       argv[0]);
+			printf("-b: Write these blocks into transaction.\n");
+			printf("-c: Do not commit transaction.\n");
+			printf("-r: Revoke these blocks from transaction.\n");
+
+			goto out;
+		}
+	}
+
+	if (bn > 0 && optind != argc - 1) {
+		printf("Need a file to read blocks from.\n");
+		return;
+	}
+
+	if (bn > 0) {
+		fp = fopen(argv[optind], "r");
+		if (fp == NULL) {
+			com_err(argv[0], errno,
+				"while opening journal data file");
+			goto out;
+		}
+	}
+
+	err = journal_write(current_journal, flags, blist, bn,
+			    rlist, rn, fp);
+	if (err)
+		com_err("journal_write", err, "while writing journal");
+
+	if (fp)
+		fclose(fp);
+out:
+	if (blist)
+		free(blist);
+	if (rlist)
+		free(rlist);
+}
+
+/* Make sure we wrap around the log correctly! */
+#define wrap(journal, var)						\
+do {									\
+	if (var >= (journal)->j_last)					\
+		var -= ((journal)->j_last - (journal)->j_first);	\
+} while (0)
+
+/*
+ * Count the number of in-use tags in a journal descriptor block.
+ */
+
+static int count_tags(journal_t *journal, char *buf)
+{
+	char			*tagp;
+	journal_block_tag_t	*tag;
+	int			nr = 0, size = journal->j_blocksize;
+	int			tag_bytes = journal_tag_bytes(journal);
+
+	if (jbd2_journal_has_csum_v2or3(journal))
+		size -= sizeof(struct jbd2_journal_block_tail);
+
+	tagp = buf + sizeof(journal_header_t);
+
+	while ((tagp - buf + tag_bytes) <= size) {
+		tag = (journal_block_tag_t *) tagp;
+
+		nr++;
+		tagp += tag_bytes;
+		if (!(tag->t_flags & ext2fs_cpu_to_be16(JBD2_FLAG_SAME_UUID)))
+			tagp += 16;
+
+		if (tag->t_flags & ext2fs_cpu_to_be16(JBD2_FLAG_LAST_TAG))
+			break;
+	}
+
+	return nr;
+}
+
+static errcode_t journal_find_head(journal_t *journal)
+{
+	unsigned int		next_commit_ID;
+	blk64_t			next_log_block, head_block;
+	int			err;
+	journal_superblock_t	*sb;
+	journal_header_t	*tmp;
+	struct buffer_head	*bh;
+	unsigned int		sequence;
+	int			blocktype;
+
+	/*
+	 * First thing is to establish what we expect to find in the log
+	 * (in terms of transaction IDs), and where (in terms of log
+	 * block offsets): query the superblock.
+	 */
+
+	sb = journal->j_superblock;
+	next_commit_ID = ext2fs_be32_to_cpu(sb->s_sequence);
+	next_log_block = ext2fs_be32_to_cpu(sb->s_start);
+	head_block = next_log_block;
+
+	if (next_log_block == 0)
+		return 0;
+
+	bh = getblk(journal->j_dev, 0, journal->j_blocksize);
+	if (bh == NULL)
+		return ENOMEM;
+
+	/*
+	 * Now we walk through the log, transaction by transaction,
+	 * making sure that each transaction has a commit block in the
+	 * expected place.  Each complete transaction gets replayed back
+	 * into the main filesystem.
+	 */
+	while (1) {
+		dbg_printf("Scanning for sequence ID %u at %lu/%lu\n",
+			  next_commit_ID, (unsigned long)next_log_block,
+			  journal->j_last);
+
+		/* Skip over each chunk of the transaction looking
+		 * either the next descriptor block or the final commit
+		 * record. */
+		err = jbd2_journal_bmap(journal, next_log_block,
+					&bh->b_blocknr);
+		if (err)
+			goto err;
+		mark_buffer_uptodate(bh, 0);
+		ll_rw_block(REQ_OP_READ, 0, 1, &bh);
+		err = bh->b_err;
+		if (err)
+			goto err;
+
+		next_log_block++;
+		wrap(journal, next_log_block);
+
+		/* What kind of buffer is it?
+		 *
+		 * If it is a descriptor block, check that it has the
+		 * expected sequence number.  Otherwise, we're all done
+		 * here. */
+
+		tmp = (journal_header_t *)bh->b_data;
+
+		if (tmp->h_magic != ext2fs_cpu_to_be32(JBD2_MAGIC_NUMBER)) {
+			dbg_printf("JBD2: wrong magic 0x%x\n", tmp->h_magic);
+			goto err;
+		}
+
+		blocktype = ext2fs_be32_to_cpu(tmp->h_blocktype);
+		sequence = ext2fs_be32_to_cpu(tmp->h_sequence);
+		dbg_printf("Found magic %d, sequence %d\n",
+			  blocktype, sequence);
+
+		if (sequence != next_commit_ID) {
+			dbg_printf("JBD2: Wrong sequence %d (wanted %d)\n",
+				   sequence, next_commit_ID);
+			goto err;
+		}
+
+		/* OK, we have a valid descriptor block which matches
+		 * all of the sequence number checks.  What are we going
+		 * to do with it?  That depends on the pass... */
+
+		switch (blocktype) {
+		case JBD2_DESCRIPTOR_BLOCK:
+			next_log_block += count_tags(journal, bh->b_data);
+			wrap(journal, next_log_block);
+			continue;
+
+		case JBD2_COMMIT_BLOCK:
+			head_block = next_log_block;
+			next_commit_ID++;
+			continue;
+
+		case JBD2_REVOKE_BLOCK:
+			continue;
+
+		default:
+			dbg_printf("Unrecognised magic %d, end of scan.\n",
+				  blocktype);
+			err = -EINVAL;
+			goto err;
+		}
+	}
+
+err:
+	if (err == 0) {
+		dbg_printf("head seq=%d blk=%llu\n", next_commit_ID,
+			   head_block);
+		journal->j_transaction_sequence = next_commit_ID;
+		journal->j_head = head_block;
+	}
+	brelse(bh);
+	return err;
+}
+
+static void update_journal_csum(journal_t *journal, int ver)
+{
+	journal_superblock_t *jsb;
+
+	if (journal->j_format_version < 2)
+		return;
+
+	if (journal->j_tail != 0 ||
+	    ext2fs_has_feature_journal_needs_recovery(
+					journal->j_fs_dev->k_fs->super)) {
+		printf("Journal needs recovery, will not add csums.\n");
+		return;
+	}
+
+	/* metadata_csum implies journal csum v3 */
+	jsb = journal->j_superblock;
+	if (ext2fs_has_feature_metadata_csum(journal->j_fs_dev->k_fs->super)) {
+		printf("Setting csum v%d\n", ver);
+		switch (ver) {
+		case 2:
+			jbd2_clear_feature_csum3(journal);
+			jbd2_set_feature_csum2(journal);
+			jbd2_clear_feature_checksum(journal);
+			break;
+		case 3:
+			jbd2_set_feature_csum3(journal);
+			jbd2_clear_feature_csum2(journal);
+			jbd2_clear_feature_checksum(journal);
+			break;
+		default:
+			printf("Unknown checksum v%d\n", ver);
+			break;
+		}
+		journal->j_superblock->s_checksum_type = JBD2_CRC32C_CHKSUM;
+		journal->j_csum_seed = jbd2_chksum(journal, ~0, jsb->s_uuid,
+						   sizeof(jsb->s_uuid));
+	} else {
+		jbd2_clear_feature_csum3(journal);
+		jbd2_clear_feature_csum2(journal);
+		jbd2_set_feature_checksum(journal);
+	}
+}
+
+static void update_uuid(journal_t *journal)
+{
+	size_t z;
+	ext2_filsys fs;
+
+	if (journal->j_format_version < 2)
+		return;
+
+	for (z = 0; z < sizeof(journal->j_superblock->s_uuid); z++)
+		if (journal->j_superblock->s_uuid[z])
+			break;
+	if (z == 0)
+		return;
+
+	fs = journal->j_fs_dev->k_fs;
+	if (!ext2fs_has_feature_64bit(fs->super))
+		return;
+
+	if (jbd2_has_feature_64bit(journal) &&
+	    ext2fs_has_feature_64bit(fs->super))
+		return;
+
+	if (journal->j_tail != 0 ||
+	    ext2fs_has_feature_journal_needs_recovery(fs->super)) {
+		printf("Journal needs recovery, will not set 64bit.\n");
+		return;
+	}
+
+	memcpy(journal->j_superblock->s_uuid, fs->super->s_uuid,
+	       sizeof(fs->super->s_uuid));
+}
+
+static void update_64bit_flag(journal_t *journal)
+{
+	if (journal->j_format_version < 2)
+		return;
+
+	if (!ext2fs_has_feature_64bit(journal->j_fs_dev->k_fs->super))
+		return;
+
+	if (jbd2_has_feature_64bit(journal) &&
+	    ext2fs_has_feature_64bit(journal->j_fs_dev->k_fs->super))
+		return;
+
+	if (journal->j_tail != 0 ||
+	    ext2fs_has_feature_journal_needs_recovery(
+				journal->j_fs_dev->k_fs->super)) {
+		printf("Journal needs recovery, will not set 64bit.\n");
+		return;
+	}
+
+	jbd2_set_feature_64bit(journal);
+}
+
+void do_journal_open(int argc, char *argv[], int sci_idx EXT2FS_ATTR((unused)),
+		     void *infop EXT2FS_ATTR((unused)))
+{
+	int opt, enable_csum = 0, csum_ver = 3;
+	journal_t *journal;
+	errcode_t err;
+
+	if (check_fs_open(argv[0]))
+		return;
+	if (check_fs_read_write(argv[0]))
+		return;
+	if (check_fs_bitmaps(argv[0]))
+		return;
+	if (current_journal) {
+		printf("Journal is already open.\n");
+		return;
+	}
+	if (!ext2fs_has_feature_journal(current_fs->super)) {
+		printf("Journalling is not enabled on this filesystem.\n");
+		return;
+	}
+
+	reset_getopt();
+	while ((opt = getopt(argc, argv, "cv:f:")) != -1) {
+		switch (opt) {
+		case 'c':
+			enable_csum = 1;
+			break;
+		case 'f':
+			if (current_fs->journal_name)
+				free(current_fs->journal_name);
+			current_fs->journal_name = strdup(optarg);
+			break;
+		case 'v':
+			csum_ver = atoi(optarg);
+			if (csum_ver != 2 && csum_ver != 3) {
+				printf("Unknown journal csum v%d\n", csum_ver);
+				csum_ver = 3;
+			}
+			break;
+		default:
+			printf("%s: [-c] [-v ver] [-f ext_jnl]\n", argv[0]);
+			printf("-c: Enable journal checksumming.\n");
+			printf("-v: Use this version checksum format.\n");
+			printf("-f: Load this external journal.\n");
+		}
+	}
+
+	err = ext2fs_open_journal(current_fs, &current_journal);
+	if (err) {
+		com_err(argv[0], err, "while opening journal");
+		return;
+	}
+	journal = current_journal;
+
+	dbg_printf("JOURNAL: seq=%u tailseq=%u start=%lu first=%lu "
+		   "maxlen=%lu\n", journal->j_tail_sequence,
+		   journal->j_transaction_sequence, journal->j_tail,
+		   journal->j_first, journal->j_last);
+
+	update_uuid(journal);
+	update_64bit_flag(journal);
+	if (enable_csum)
+		update_journal_csum(journal, csum_ver);
+
+	err = journal_find_head(journal);
+	if (err)
+		com_err(argv[0], err, "while examining journal");
+}
+
+void do_journal_close(int argc EXT2FS_ATTR((unused)),
+		      char *argv[] EXT2FS_ATTR((unused)),
+		      int sci_idx EXT2FS_ATTR((unused)),
+		      void *infop EXT2FS_ATTR((unused)))
+{
+	if (current_journal == NULL) {
+		printf("Journal not open.\n");
+		return;
+	}
+
+	ext2fs_close_journal(current_fs, &current_journal);
+}
+
+void do_journal_run(int argc EXT2FS_ATTR((unused)), char *argv[],
+		    int sci_idx EXT2FS_ATTR((unused)),
+		    void *infop EXT2FS_ATTR((unused)))
+{
+	errcode_t err;
+
+	if (check_fs_open(argv[0]))
+		return;
+	if (check_fs_read_write(argv[0]))
+		return;
+	if (check_fs_bitmaps(argv[0]))
+		return;
+	if (current_journal) {
+		printf("Please close the journal before recovering it.\n");
+		return;
+	}
+
+	err = ext2fs_run_ext3_journal(&current_fs);
+	if (err)
+		com_err("journal_run", err, "while recovering journal");
+	else {
+		ext2fs_clear_feature_journal_needs_recovery(current_fs->super);
+		ext2fs_mark_super_dirty(current_fs);
+	}
+}